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Astrophysics for People in a Hurry: Neil deGrasse Tyson …

Neil deGrasse Tyson makes a big bang with Astrophysics for People in a Hurry.- Sloane Crosley, Vanity Fair

Tyson is a master of streamlining and simplification….taking mind-bogglingly complex ideas, stripping them down to their nuts and bolts, padding them with colorful allegories and dorky jokes, and making them accessible to the layperson- Salon

This book will keep you fascinated with succinct and dynamic explanations of a wide variety of astronomical topics. A winner that every astronomy enthusiast should have on the bookshelf!- David J. Eicher, Astronomy

This may have been written for people in a hurry, but I urge you to take your time. It will all be over far too soon.- BBC’s Sky at Night

Engaging and illuminating.- GoodReads

Tyson manifests science brilliantly….[his] insights are valuable for any leader, teacher, scientist or educator.- Forbes

Astrophysics for People in a Hurry will blow your mind….it is awesome.- Hackernoon

Infectiously enthusiastic, humorous and, above all, accessible….reading Astrophysics for People in a Hurry is both a humbling and exhilarating experience.- BookPage

The rest is here:

Astrophysics for People in a Hurry: Neil deGrasse Tyson …

www.cfa.harvard.edu/

The explosions of stars, known as supernovae, can be so bright they outshine their host galaxies. They take months or years to fade away, and sometimes, the gaseous remains of the explosion slam into hydrogen-rich gas and temporarily get bright again but could they remain luminous without any outside interference?

Read the original here:

http://www.cfa.harvard.edu/

Company Seven | Astro-Optics Index Page

To learn more about how this site is arranged and how to navigate it, or for those new to Company Seven please Click Here. To learn more about the latest activities, web page changes, and developments at Company Seven then visit our News and Developments page. For those new to astronomy, we also provide Observing Plan Aids to help them learn the sky.

We fondly remember:

Bruce Roy Wrinkle (b. 7 August 1945, d. 28 April 2013) was the soul of our showroom; kind, witty, intelligent, and able to greet you with a funny joke. Bruce was was amazingly well read, able to hold conversations with doctors and scientists on matters from prions to dark matter. And he was our friend, a true friend in every sense of the word and every day without him lacks some luster.

And Robert Kim Carter (b. 18 Jan 1962, d. 23 April 2005) whose friendship and support originally brought this site on line in 1994. Robert founded one of the first Internet Service Providers of “Internet Valley”, Digital Gateway Systems, Inc. in Vienna, Virginia. DGS used to be to ISP’s, as Company Seven is to our industry.

Go here to see the original:

Company Seven | Astro-Optics Index Page

Astrophysics – Wikipedia

This article is about the use of physics and chemistry to determine the nature of astronomical objects. For the use of physics to determine their positions and motions, see Celestial mechanics. For the physical study of the largest-scale structures of the universe, see Physical cosmology. For the journal, see Astrophysics (journal).

Astrophysics is the branch of astronomy that employs the principles of physics and chemistry “to ascertain the nature of the astronomical objects, rather than their positions or motions in space”.[1][2] Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background.[3][4] Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

In practice, modern astronomical research often involves a substantial amount of work in the realms of theoretical and observational physics. Some areas of study for astrophysicists include their attempts to determine: the properties of dark matter, dark energy, and black holes; whether or not time travel is possible, wormholes can form, or the multiverse exists; and the origin and ultimate fate of the universe.[3] Topics also studied by theoretical astrophysicists include: Solar System formation and evolution; stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics.

Although astronomy is as ancient as recorded history itself, it was long separated from the study of terrestrial physics. In the Aristotelian worldview, bodies in the sky appeared to be unchanging spheres whose only motion was uniform motion in a circle, while the earthly world was the realm which underwent growth and decay and in which natural motion was in a straight line and ended when the moving object reached its goal. Consequently, it was held that the celestial region was made of a fundamentally different kind of matter from that found in the terrestrial sphere; either Fire as maintained by Plato, or Aether as maintained by Aristotle.[5][6]During the 17th century, natural philosophers such as Galileo,[7] Descartes,[8] and Newton[9] began to maintain that the celestial and terrestrial regions were made of similar kinds of material and were subject to the same natural laws.[10] Their challenge was that the tools had not yet been invented with which to prove these assertions.[11]

For much of the nineteenth century, astronomical research was focused on the routine work of measuring the positions and computing the motions of astronomical objects.[12][13] A new astronomy, soon to be called astrophysics, began to emerge when William Hyde Wollaston and Joseph von Fraunhofer independently discovered that, when decomposing the light from the Sun, a multitude of dark lines (regions where there was less or no light) were observed in the spectrum.[14] By 1860 the physicist, Gustav Kirchhoff, and the chemist, Robert Bunsen, had demonstrated that the dark lines in the solar spectrum corresponded to bright lines in the spectra of known gases, specific lines corresponding to unique chemical elements.[15] Kirchhoff deduced that the dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere.[16] In this way it was proved that the chemical elements found in the Sun and stars were also found on Earth.

Among those who extended the study of solar and stellar spectra was Norman Lockyer, who in 1868 detected bright, as well as dark, lines in solar spectra. Working with the chemist, Edward Frankland, to investigate the spectra of elements at various temperatures and pressures, he could not associate a yellow line in the solar spectrum with any known elements. He thus claimed the line represented a new element, which was called helium, after the Greek Helios, the Sun personified.[17][18]

In 1885, Edward C. Pickering undertook an ambitious program of stellar spectral classification at Harvard College Observatory, in which a team of woman computers, notably Williamina Fleming, Antonia Maury, and Annie Jump Cannon, classified the spectra recorded on photographic plates. By 1890, a catalog of over 10,000 stars had been prepared that grouped them into thirteen spectral types. Following Pickering’s vision, by 1924 Cannon expanded the catalog to nine volumes and over a quarter of a million stars, developing the Harvard Classification Scheme which was accepted for worldwide use in 1922.[19]

In 1895, George Ellery Hale and James E. Keeler, along with a group of ten associate editors from Europe and the United States,[20] established The Astrophysical Journal: An International Review of Spectroscopy and Astronomical Physics.[21] It was intended that the journal would fill the gap between journals in astronomy and physics, providing a venue for publication of articles on astronomical applications of the spectroscope; on laboratory research closely allied to astronomical physics, including wavelength determinations of metallic and gaseous spectra and experiments on radiation and absorption; on theories of the Sun, Moon, planets, comets, meteors, and nebulae; and on instrumentation for telescopes and laboratories.[20]

Around 1920, following the discovery of the Hertsprung-Russell diagram still used as the basis for classifying stars and their evolution, Arthur Eddington anticipated the discovery and mechanism of nuclear fusion processes in stars, in his paper The Internal Constitution of the Stars.[22][23] At that time, the source of stellar energy was a complete mystery; Eddington correctly speculated that the source was fusion of hydrogen into helium, liberating enormous energy according to Einstein’s equation E = mc2. This was a particularly remarkable development since at that time fusion and thermonuclear energy, and even that stars are largely composed of hydrogen (see metallicity), had not yet been discovered.[non-primary source needed]

In 1925 Cecilia Helena Payne (later Cecilia Payne-Gaposchkin) wrote an influential doctoral dissertation at Radcliffe College, in which she applied ionization theory to stellar atmospheres to relate the spectral classes to the temperature of stars.[24] Most significantly, she discovered that hydrogen and helium were the principal components of stars. Despite Eddington’s suggestion, this discovery was so unexpected that her dissertation readers convinced her to modify the conclusion before publication. However, later research confirmed her discovery.[25]

By the end of the 20th century, studies of astronomical spectra had expanded to cover wavelengths extending from radio waves through optical, x-ray, and gamma wavelengths.[26] In the 21st century it further expanded to include observations based on gravitational waves.

Observational astronomy is a division of the astronomical science that is concerned with recording data, in contrast with theoretical astrophysics, which is mainly concerned with finding out the measurable implications of physical models. It is the practice of observing celestial objects by using telescopes and other astronomical apparatus.

The majority of astrophysical observations are made using the electromagnetic spectrum.

Other than electromagnetic radiation, few things may be observed from the Earth that originate from great distances. A few gravitational wave observatories have been constructed, but gravitational waves are extremely difficult to detect. Neutrino observatories have also been built, primarily to study our Sun. Cosmic rays consisting of very high energy particles can be observed hitting the Earth’s atmosphere.

Observations can also vary in their time scale. Most optical observations take minutes to hours, so phenomena that change faster than this cannot readily be observed. However, historical data on some objects is available, spanning centuries or millennia. On the other hand, radio observations may look at events on a millisecond timescale (millisecond pulsars) or combine years of data (pulsar deceleration studies). The information obtained from these different timescales is very different.

The study of our very own Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Our understanding of our own Sun serves as a guide to our understanding of other stars.

The topic of how stars change, or stellar evolution, is often modeled by placing the varieties of star types in their respective positions on the HertzsprungRussell diagram, which can be viewed as representing the state of a stellar object, from birth to destruction.

Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.[27][28]

Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models. This helps allow observers to look for data that can refute a model or help in choosing between several alternate or conflicting models.

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

Topics studied by theoretical astrophysicists include: stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole (astro)physics and the study of gravitational waves.

Some widely accepted and studied theories and models in astrophysics, now included in the Lambda-CDM model, are the Big Bang, cosmic inflation, dark matter, dark energy and fundamental theories of physics. Wormholes are examples of hypotheses which are yet to be proven (or disproven).

The roots of astrophysics can be found in the seventeenth century emergence of a unified physics, in which the same laws applied to the celestial and terrestrial realms.[10] There were scientists who were qualified in both physics and astronomy who laid the firm foundation for the current science of astrophysics. In modern times, students continue to be drawn to astrophysics due to its popularization by the Royal Astronomical Society and notable educators such as prominent professors Lawrence Krauss, Subrahmanyan Chandrasekhar, Stephen Hawking, Hubert Reeves, Carl Sagan and Neil deGrasse Tyson. The efforts of the early, late, and present scientists continue to attract young people to study the history and science of astrophysics.[29][30][31]

Excerpt from:

Astrophysics – Wikipedia

Unitronitalia.com: 10 MICRON, AVALON LINEAR MUNO M1 …

Unitronitalia.com is tracked by us since April, 2014. Over the time it has been ranked as high as 916 799 in the world, while most of its traffic comes from Italy, where it reached as high as 24 291 position. It was owned by several entities, from Giovanni Alberto Quarra Sacco of Giovanni Alberto Quarra Sacco to Data Protected Data Protected of Data Protected, it was hosted by Aruba S.p.A. – Shared Hosting and Mail services and Aruba S.p.A. – Shared Hosting Windows.

Unitronitalia has a decent Google pagerank and bad results in terms of Yandex topical citation index. We found that Unitronitalia.com is poorly socialized in respect to any social network. According to Siteadvisor and Google safe browsing analytics, Unitronitalia.com is quite a safe domain with no visitor reviews.

Read this article:

Unitronitalia.com: 10 MICRON, AVALON LINEAR MUNO M1 …

Astrophysics School of Physics

The Astrophysics group in the School of Physics spans cosmology, extragalactic astronomy, extreme objects, relativistic astrophysics, and knowledge management associated with virtual observatories and software telescopes. Our research programs, comprising theoretical, observational and computational studies, are aligned with the major international facilities such as the Murchison Widefield Array (MWA), Square-Kilometer Array (SKA), Australian Square-Kilometer Array Project (ASKAP), the Hubble space telescope, South Pole Telescope (SPT), POLARBEAR and the Simons Array, Simons Observatory and Laser Interferometer Gravitational Wave Observatory (LIGO). We are also leading Australias first space telescope program, SkyHopper.

The Astrophysics group currently hosts nodes in three ARC Centres of Excellence: OzGrav for gravitational wave astronomy, CAASTRO for all-sky astronomy, and ASTRO-3D to study the Universe in 3 dimensions.

Please contact us to learn more about the research projects and study opportunities available in our group, for undergraduate, Masters, and PhD students. More information can be found on the Study link. We invite applications for our Master of Science (MSc) and Doctorate (PhD) Physics degrees!

View of the Murchison Widefield Array. Credit: MWA

Follow this link:

Astrophysics School of Physics

Company Seven | Astro-Optics Index Page

To learn more about how this site is arranged and how to navigate it, or for those new to Company Seven please Click Here. To learn more about the latest activities, web page changes, and developments at Company Seven then visit our News and Developments page. For those new to astronomy, we also provide Observing Plan Aids to help them learn the sky.

We fondly remember:

Bruce Roy Wrinkle (b. 7 August 1945, d. 28 April 2013) was the soul of our showroom; kind, witty, intelligent, and able to greet you with a funny joke. Bruce was was amazingly well read, able to hold conversations with doctors and scientists on matters from prions to dark matter. And he was our friend, a true friend in every sense of the word and every day without him lacks some luster.

And Robert Kim Carter (b. 18 Jan 1962, d. 23 April 2005) whose friendship and support originally brought this site on line in 1994. Robert founded one of the first Internet Service Providers of “Internet Valley”, Digital Gateway Systems, Inc. in Vienna, Virginia. DGS used to be to ISP’s, as Company Seven is to our industry.

Read the rest here:

Company Seven | Astro-Optics Index Page

NASA Astrophysics | Science Mission Directorate

In the Science Mission Directorate (SMD), the Astrophysics division studies the universe.The science goals of the SMD Astrophysics Division are breathtaking: we seek to understand the universe and our place in it. We are starting to investigate the very moment of creation of the universe and are close to learning the full history of stars and galaxies. We are discovering how planetary systems form and how environments hospitable for life develop. And we will search for the signature of life on other worlds, perhaps to learn that we are not alone.

NASA’s goal in Astrophysics is to “Discover how the universe works, explore how it began and evolved, and search for life on planets around other stars.” Three broad scientific questions emanate from these goals.

Astrophysics comprises of three focused and two cross-cutting programs. These focused programs provide an intellectual framework for advancing science and conducting strategic planning. They include:

The Astrophysics current missions include three of the Great Observatories originally planned in the 1980s and launched over the past 28 years. The current suite of operational Great Observatories include the Hubble Space Telescope, the Chandra X-ray Observatory, and the Spitzer Space Telescope. Additionally, the Fermi Gamma-ray Space Telescope explores the high-energy end of the spectrum. Innovative Explorer missions, such as the Neil Gehrels Swift Observatory, NuSTAR, TESS, as well as Mission of Opportunity NICER, complement the Astrophysics strategic missions. SOFIA, an airborne observatory for infrared astronomy, is in its operational phase and the Kepler mission is engaged in K2 extended mission operations. All of the missions together account for much of humanity’s accumulated knowledge of the heavens. Many of these missions have achieved their prime science goals, but continue to produce spectacular results in their extended operations.

NASA-funded investigators also participate in observations, data analysis and developed instruments for the astrophysics missions of our international partners, including ESA’s XMM-Newton.

The near future will be dominated by several missions. Currently in development, with especially broad scientific utility, is the James Webb Space Telescope. Also in work are detectors for ESA’s Euclid mission and hardware for JAXA’s XRISM (X-Ray Imaging and Spectroscopy, previously named XARM) to provide breakthroughs in the study of structure formation of the universe, outflows from galaxy nuclei, and dark matter.

Completing the missions in development, supporting the operational missions, and funding the research and analysis programs will consume most of the Astrophysics Division resources.

In February 2016, NASA formally started the top Astro2010 decadal recommendation, the Wide Field Infrared Survey Telescope (WFIRST). WFIRST will aid researchers in their efforts to unravel the secrets of dark energy and dark matter, and explore the evolution of the cosmos. It will also discover new worlds outside our solar system and advance the search for worlds that could be suitable for life.

In January 2017, NASA selected the new Small Explorer (SMEX) mission IXPE (Imaging X-ray Polarimetry Explorer) which uses the polarization state of light from astrophysical sources to provide insight into our understanding of X-ray production in objects such as neutron stars and pulsar wind nebulae, as well as stellar and supermassive black holes.

In March 2017, NASA selected the Explorer Mission of Opportunity GUSTO (Galactic/Extragalactic ULDB Spectroscopic Terahertz Observatory) to measure emissions from the interstellar medium to help scientists determine the life cycle of interstellar gas in our Milky Way, witness the formation and destruction of star-forming clouds, and understand the dynamics and gas flow in the vicinity of the center of our galaxy.

Since the 2001 decadal survey, the way the universe is viewed has changed dramatically. More than 3400 planets have been discovered orbiting distant stars. Black holes are now known to be present at the center of most galaxies, including the Milky Way galaxy. The age, size and shape of the universe have been mapped based on the primordial radiation left by the big bang. And it has been learned that most of the matter in the universe is dark and invisible, and the universe is not only expanding, but accelerating in an unexpected way.

For the long term future, the Astrophysics goals will be guided based on the results of the 2010 Decadal survey New Worlds, New Horizons in Astronomy and Astrophysics. The priority science objectives chosen by the survey committee include: searching for the first stars, galaxies, and black holes; seeking nearby habitable planets; and advancing understanding of the fundamental physics of the universe.In 2016 the New Worlds, New Horizons: A Midterm Assessment was released.

In 2012 the Astrophysics Implementation Plan was released (updated in 2014 and again in 2016) which describes the activities currently being undertaken in response to the decadal survey recommendations within the current budgetary constraints.

The Astrophysics roadmap Enduring Quests, Daring Visions was developed by a task force of the Astrophysics Subcommittee (APS) in 2013. The Roadmap presents a 30-year vision for astrophysics using the most recent decadal survey as the starting point.

Work on the upcoming 2020 decadal survey has commenced. Please visit the “2020 Decadal Planning” page for additional information about the Large Mission and Probe Mission concept studies currently underway.

Read more from the original source:

NASA Astrophysics | Science Mission Directorate

Astrophysics – Wikipedia

This article is about the use of physics and chemistry to determine the nature of astronomical objects. For the use of physics to determine their positions and motions, see Celestial mechanics. For the physical study of the largest-scale structures of the universe, see Physical cosmology. For the journal, see Astrophysics (journal).

Astrophysics is the branch of astronomy that employs the principles of physics and chemistry “to ascertain the nature of the astronomical objects, rather than their positions or motions in space”.[1][2] Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background.[3][4] Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

In practice, modern astronomical research often involves a substantial amount of work in the realms of theoretical and observational physics. Some areas of study for astrophysicists include their attempts to determine: the properties of dark matter, dark energy, and black holes; whether or not time travel is possible, wormholes can form, or the multiverse exists; and the origin and ultimate fate of the universe.[3] Topics also studied by theoretical astrophysicists include: Solar System formation and evolution; stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics.

Although astronomy is as ancient as recorded history itself, it was long separated from the study of terrestrial physics. In the Aristotelian worldview, bodies in the sky appeared to be unchanging spheres whose only motion was uniform motion in a circle, while the earthly world was the realm which underwent growth and decay and in which natural motion was in a straight line and ended when the moving object reached its goal. Consequently, it was held that the celestial region was made of a fundamentally different kind of matter from that found in the terrestrial sphere; either Fire as maintained by Plato, or Aether as maintained by Aristotle.[5][6]During the 17th century, natural philosophers such as Galileo,[7] Descartes,[8] and Newton[9] began to maintain that the celestial and terrestrial regions were made of similar kinds of material and were subject to the same natural laws.[10] Their challenge was that the tools had not yet been invented with which to prove these assertions.[11]

For much of the nineteenth century, astronomical research was focused on the routine work of measuring the positions and computing the motions of astronomical objects.[12][13] A new astronomy, soon to be called astrophysics, began to emerge when William Hyde Wollaston and Joseph von Fraunhofer independently discovered that, when decomposing the light from the Sun, a multitude of dark lines (regions where there was less or no light) were observed in the spectrum.[14] By 1860 the physicist, Gustav Kirchhoff, and the chemist, Robert Bunsen, had demonstrated that the dark lines in the solar spectrum corresponded to bright lines in the spectra of known gases, specific lines corresponding to unique chemical elements.[15] Kirchhoff deduced that the dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere.[16] In this way it was proved that the chemical elements found in the Sun and stars were also found on Earth.

Among those who extended the study of solar and stellar spectra was Norman Lockyer, who in 1868 detected bright, as well as dark, lines in solar spectra. Working with the chemist, Edward Frankland, to investigate the spectra of elements at various temperatures and pressures, he could not associate a yellow line in the solar spectrum with any known elements. He thus claimed the line represented a new element, which was called helium, after the Greek Helios, the Sun personified.[17][18]

In 1885, Edward C. Pickering undertook an ambitious program of stellar spectral classification at Harvard College Observatory, in which a team of woman computers, notably Williamina Fleming, Antonia Maury, and Annie Jump Cannon, classified the spectra recorded on photographic plates. By 1890, a catalog of over 10,000 stars had been prepared that grouped them into thirteen spectral types. Following Pickering’s vision, by 1924 Cannon expanded the catalog to nine volumes and over a quarter of a million stars, developing the Harvard Classification Scheme which was accepted for worldwide use in 1922.[19]

In 1895, George Ellery Hale and James E. Keeler, along with a group of ten associate editors from Europe and the United States,[20] established The Astrophysical Journal: An International Review of Spectroscopy and Astronomical Physics.[21] It was intended that the journal would fill the gap between journals in astronomy and physics, providing a venue for publication of articles on astronomical applications of the spectroscope; on laboratory research closely allied to astronomical physics, including wavelength determinations of metallic and gaseous spectra and experiments on radiation and absorption; on theories of the Sun, Moon, planets, comets, meteors, and nebulae; and on instrumentation for telescopes and laboratories.[20]

Around 1920, following the discovery of the Hertsprung-Russell diagram still used as the basis for classifying stars and their evolution, Arthur Eddington anticipated the discovery and mechanism of nuclear fusion processes in stars, in his paper The Internal Constitution of the Stars.[22][23] At that time, the source of stellar energy was a complete mystery; Eddington correctly speculated that the source was fusion of hydrogen into helium, liberating enormous energy according to Einstein’s equation E = mc2. This was a particularly remarkable development since at that time fusion and thermonuclear energy, and even that stars are largely composed of hydrogen (see metallicity), had not yet been discovered.[non-primary source needed]

In 1925 Cecilia Helena Payne (later Cecilia Payne-Gaposchkin) wrote an influential doctoral dissertation at Radcliffe College, in which she applied ionization theory to stellar atmospheres to relate the spectral classes to the temperature of stars.[24] Most significantly, she discovered that hydrogen and helium were the principal components of stars. Despite Eddington’s suggestion, this discovery was so unexpected that her dissertation readers convinced her to modify the conclusion before publication. However, later research confirmed her discovery.[25]

By the end of the 20th century, studies of astronomical spectra had expanded to cover wavelengths extending from radio waves through optical, x-ray, and gamma wavelengths.[26] In the 21st century it further expanded to include observations based on gravitational waves.

Observational astronomy is a division of the astronomical science that is concerned with recording data, in contrast with theoretical astrophysics, which is mainly concerned with finding out the measurable implications of physical models. It is the practice of observing celestial objects by using telescopes and other astronomical apparatus.

The majority of astrophysical observations are made using the electromagnetic spectrum.

Other than electromagnetic radiation, few things may be observed from the Earth that originate from great distances. A few gravitational wave observatories have been constructed, but gravitational waves are extremely difficult to detect. Neutrino observatories have also been built, primarily to study our Sun. Cosmic rays consisting of very high energy particles can be observed hitting the Earth’s atmosphere.

Observations can also vary in their time scale. Most optical observations take minutes to hours, so phenomena that change faster than this cannot readily be observed. However, historical data on some objects is available, spanning centuries or millennia. On the other hand, radio observations may look at events on a millisecond timescale (millisecond pulsars) or combine years of data (pulsar deceleration studies). The information obtained from these different timescales is very different.

The study of our very own Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Our understanding of our own Sun serves as a guide to our understanding of other stars.

The topic of how stars change, or stellar evolution, is often modeled by placing the varieties of star types in their respective positions on the HertzsprungRussell diagram, which can be viewed as representing the state of a stellar object, from birth to destruction.

Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.[27][28]

Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models. This helps allow observers to look for data that can refute a model or help in choosing between several alternate or conflicting models.

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

Topics studied by theoretical astrophysicists include: stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole (astro)physics and the study of gravitational waves.

Some widely accepted and studied theories and models in astrophysics, now included in the Lambda-CDM model, are the Big Bang, cosmic inflation, dark matter, dark energy and fundamental theories of physics. Wormholes are examples of hypotheses which are yet to be proven (or disproven).

The roots of astrophysics can be found in the seventeenth century emergence of a unified physics, in which the same laws applied to the celestial and terrestrial realms.[10] There were scientists who were qualified in both physics and astronomy who laid the firm foundation for the current science of astrophysics. In modern times, students continue to be drawn to astrophysics due to its popularization by the Royal Astronomical Society and notable educators such as prominent professors Lawrence Krauss, Subrahmanyan Chandrasekhar, Stephen Hawking, Hubert Reeves, Carl Sagan and Neil deGrasse Tyson. The efforts of the early, late, and present scientists continue to attract young people to study the history and science of astrophysics.[29][30][31]

Visit link:

Astrophysics – Wikipedia

Astrophysics School of Physics

The Astrophysics group in the School of Physics spans cosmology, extragalactic astronomy, extreme objects, relativistic astrophysics, and knowledge management associated with virtual observatories and software telescopes. Our research programs, comprising theoretical, observational and computational studies, are aligned with the major international facilities such as the Murchison Widefield Array (MWA), Square-Kilometer Array (SKA), Australian Square-Kilometer Array Project (ASKAP), the Hubble space telescope, South Pole Telescope (SPT), POLARBEAR and the Simons Array, Simons Observatory and Laser Interferometer Gravitational Wave Observatory (LIGO). We are also leading Australias first space telescope program, SkyHopper.

The Astrophysics group currently hosts nodes in three ARC Centres of Excellence: OzGrav for gravitational wave astronomy, CAASTRO for all-sky astronomy, and ASTRO-3D to study the Universe in 3 dimensions.

Please contact us to learn more about the research projects and study opportunities available in our group, for undergraduate, Masters, and PhD students. More information can be found on the Study link. We invite applications for our Master of Science (MSc) and Doctorate (PhD) Physics degrees!

View of the Murchison Widefield Array. Credit: MWA

View original post here:

Astrophysics School of Physics

Astrophysics – Wikipedia

This article is about the use of physics and chemistry to determine the nature of astronomical objects. For the use of physics to determine their positions and motions, see Celestial mechanics. For the physical study of the largest-scale structures of the universe, see Physical cosmology. For the journal, see Astrophysics (journal).

Astrophysics is the branch of astronomy that employs the principles of physics and chemistry “to ascertain the nature of the astronomical objects, rather than their positions or motions in space”.[1][2] Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background.[3][4] Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

In practice, modern astronomical research often involves a substantial amount of work in the realms of theoretical and observational physics. Some areas of study for astrophysicists include their attempts to determine: the properties of dark matter, dark energy, and black holes; whether or not time travel is possible, wormholes can form, or the multiverse exists; and the origin and ultimate fate of the universe.[3] Topics also studied by theoretical astrophysicists include: Solar System formation and evolution; stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics.

Although astronomy is as ancient as recorded history itself, it was long separated from the study of terrestrial physics. In the Aristotelian worldview, bodies in the sky appeared to be unchanging spheres whose only motion was uniform motion in a circle, while the earthly world was the realm which underwent growth and decay and in which natural motion was in a straight line and ended when the moving object reached its goal. Consequently, it was held that the celestial region was made of a fundamentally different kind of matter from that found in the terrestrial sphere; either Fire as maintained by Plato, or Aether as maintained by Aristotle.[5][6]During the 17th century, natural philosophers such as Galileo,[7] Descartes,[8] and Newton[9] began to maintain that the celestial and terrestrial regions were made of similar kinds of material and were subject to the same natural laws.[10] Their challenge was that the tools had not yet been invented with which to prove these assertions.[11]

For much of the nineteenth century, astronomical research was focused on the routine work of measuring the positions and computing the motions of astronomical objects.[12][13] A new astronomy, soon to be called astrophysics, began to emerge when William Hyde Wollaston and Joseph von Fraunhofer independently discovered that, when decomposing the light from the Sun, a multitude of dark lines (regions where there was less or no light) were observed in the spectrum.[14] By 1860 the physicist, Gustav Kirchhoff, and the chemist, Robert Bunsen, had demonstrated that the dark lines in the solar spectrum corresponded to bright lines in the spectra of known gases, specific lines corresponding to unique chemical elements.[15] Kirchhoff deduced that the dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere.[16] In this way it was proved that the chemical elements found in the Sun and stars were also found on Earth.

Among those who extended the study of solar and stellar spectra was Norman Lockyer, who in 1868 detected bright, as well as dark, lines in solar spectra. Working with the chemist, Edward Frankland, to investigate the spectra of elements at various temperatures and pressures, he could not associate a yellow line in the solar spectrum with any known elements. He thus claimed the line represented a new element, which was called helium, after the Greek Helios, the Sun personified.[17][18]

In 1885, Edward C. Pickering undertook an ambitious program of stellar spectral classification at Harvard College Observatory, in which a team of woman computers, notably Williamina Fleming, Antonia Maury, and Annie Jump Cannon, classified the spectra recorded on photographic plates. By 1890, a catalog of over 10,000 stars had been prepared that grouped them into thirteen spectral types. Following Pickering’s vision, by 1924 Cannon expanded the catalog to nine volumes and over a quarter of a million stars, developing the Harvard Classification Scheme which was accepted for worldwide use in 1922.[19]

In 1895, George Ellery Hale and James E. Keeler, along with a group of ten associate editors from Europe and the United States,[20] established The Astrophysical Journal: An International Review of Spectroscopy and Astronomical Physics.[21] It was intended that the journal would fill the gap between journals in astronomy and physics, providing a venue for publication of articles on astronomical applications of the spectroscope; on laboratory research closely allied to astronomical physics, including wavelength determinations of metallic and gaseous spectra and experiments on radiation and absorption; on theories of the Sun, Moon, planets, comets, meteors, and nebulae; and on instrumentation for telescopes and laboratories.[20]

Around 1920, following the discovery of the Hertsprung-Russell diagram still used as the basis for classifying stars and their evolution, Arthur Eddington anticipated the discovery and mechanism of nuclear fusion processes in stars, in his paper The Internal Constitution of the Stars.[22][23] At that time, the source of stellar energy was a complete mystery; Eddington correctly speculated that the source was fusion of hydrogen into helium, liberating enormous energy according to Einstein’s equation E = mc2. This was a particularly remarkable development since at that time fusion and thermonuclear energy, and even that stars are largely composed of hydrogen (see metallicity), had not yet been discovered.[non-primary source needed]

In 1925 Cecilia Helena Payne (later Cecilia Payne-Gaposchkin) wrote an influential doctoral dissertation at Radcliffe College, in which she applied ionization theory to stellar atmospheres to relate the spectral classes to the temperature of stars.[24] Most significantly, she discovered that hydrogen and helium were the principal components of stars. Despite Eddington’s suggestion, this discovery was so unexpected that her dissertation readers convinced her to modify the conclusion before publication. However, later research confirmed her discovery.[25]

By the end of the 20th century, studies of astronomical spectra had expanded to cover wavelengths extending from radio waves through optical, x-ray, and gamma wavelengths.[26] In the 21st century it further expanded to include observations based on gravitational waves.

Observational astronomy is a division of the astronomical science that is concerned with recording data, in contrast with theoretical astrophysics, which is mainly concerned with finding out the measurable implications of physical models. It is the practice of observing celestial objects by using telescopes and other astronomical apparatus.

The majority of astrophysical observations are made using the electromagnetic spectrum.

Other than electromagnetic radiation, few things may be observed from the Earth that originate from great distances. A few gravitational wave observatories have been constructed, but gravitational waves are extremely difficult to detect. Neutrino observatories have also been built, primarily to study our Sun. Cosmic rays consisting of very high energy particles can be observed hitting the Earth’s atmosphere.

Observations can also vary in their time scale. Most optical observations take minutes to hours, so phenomena that change faster than this cannot readily be observed. However, historical data on some objects is available, spanning centuries or millennia. On the other hand, radio observations may look at events on a millisecond timescale (millisecond pulsars) or combine years of data (pulsar deceleration studies). The information obtained from these different timescales is very different.

The study of our very own Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Our understanding of our own Sun serves as a guide to our understanding of other stars.

The topic of how stars change, or stellar evolution, is often modeled by placing the varieties of star types in their respective positions on the HertzsprungRussell diagram, which can be viewed as representing the state of a stellar object, from birth to destruction.

Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.[27][28]

Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models. This helps allow observers to look for data that can refute a model or help in choosing between several alternate or conflicting models.

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

Topics studied by theoretical astrophysicists include: stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole (astro)physics and the study of gravitational waves.

Some widely accepted and studied theories and models in astrophysics, now included in the Lambda-CDM model, are the Big Bang, cosmic inflation, dark matter, dark energy and fundamental theories of physics. Wormholes are examples of hypotheses which are yet to be proven (or disproven).

The roots of astrophysics can be found in the seventeenth century emergence of a unified physics, in which the same laws applied to the celestial and terrestrial realms.[10] There were scientists who were qualified in both physics and astronomy who laid the firm foundation for the current science of astrophysics. In modern times, students continue to be drawn to astrophysics due to its popularization by the Royal Astronomical Society and notable educators such as prominent professors Lawrence Krauss, Subrahmanyan Chandrasekhar, Stephen Hawking, Hubert Reeves, Carl Sagan and Neil deGrasse Tyson. The efforts of the early, late, and present scientists continue to attract young people to study the history and science of astrophysics.[29][30][31]

The rest is here:

Astrophysics – Wikipedia

Astrophysics School of Physics

The Astrophysics group in the School of Physics spans cosmology, extragalactic astronomy, extreme objects, relativistic astrophysics, and knowledge management associated with virtual observatories and software telescopes. Our research programs, comprising theoretical, observational and computational studies, are aligned with the major international facilities such as the Murchison Widefield Array (MWA), Square-Kilometer Array (SKA), Australian Square-Kilometer Array Project (ASKAP), the Hubble space telescope, South Pole Telescope (SPT), POLARBEAR and the Simons Array, Simons Observatory and Laser Interferometer Gravitational Wave Observatory (LIGO). We are also leading Australias first space telescope program, SkyHopper.

The Astrophysics group currently hosts nodes in three ARC Centres of Excellence: OzGrav for gravitational wave astronomy, CAASTRO for all-sky astronomy, and ASTRO-3D to study the Universe in 3 dimensions.

Please contact us to learn more about the research projects and study opportunities available in our group, for undergraduate, Masters, and PhD students. More information can be found on the Study link. We invite applications for our Master of Science (MSc) and Doctorate (PhD) Physics degrees!

View of the Murchison Widefield Array. Credit: MWA

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Astrophysics School of Physics

Astrophysics – Wikipedia

This article is about the use of physics and chemistry to determine the nature of astronomical objects. For the use of physics to determine their positions and motions, see Celestial mechanics. For the physical study of the largest-scale structures of the universe, see Physical cosmology. For the journal, see Astrophysics (journal).

Astrophysics is the branch of astronomy that employs the principles of physics and chemistry “to ascertain the nature of the astronomical objects, rather than their positions or motions in space”.[1][2] Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background.[3][4] Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

In practice, modern astronomical research often involves a substantial amount of work in the realms of theoretical and observational physics. Some areas of study for astrophysicists include their attempts to determine: the properties of dark matter, dark energy, and black holes; whether or not time travel is possible, wormholes can form, or the multiverse exists; and the origin and ultimate fate of the universe.[3] Topics also studied by theoretical astrophysicists include: Solar System formation and evolution; stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics.

Although astronomy is as ancient as recorded history itself, it was long separated from the study of terrestrial physics. In the Aristotelian worldview, bodies in the sky appeared to be unchanging spheres whose only motion was uniform motion in a circle, while the earthly world was the realm which underwent growth and decay and in which natural motion was in a straight line and ended when the moving object reached its goal. Consequently, it was held that the celestial region was made of a fundamentally different kind of matter from that found in the terrestrial sphere; either Fire as maintained by Plato, or Aether as maintained by Aristotle.[5][6]During the 17th century, natural philosophers such as Galileo,[7] Descartes,[8] and Newton[9] began to maintain that the celestial and terrestrial regions were made of similar kinds of material and were subject to the same natural laws.[10] Their challenge was that the tools had not yet been invented with which to prove these assertions.[11]

For much of the nineteenth century, astronomical research was focused on the routine work of measuring the positions and computing the motions of astronomical objects.[12][13] A new astronomy, soon to be called astrophysics, began to emerge when William Hyde Wollaston and Joseph von Fraunhofer independently discovered that, when decomposing the light from the Sun, a multitude of dark lines (regions where there was less or no light) were observed in the spectrum.[14] By 1860 the physicist, Gustav Kirchhoff, and the chemist, Robert Bunsen, had demonstrated that the dark lines in the solar spectrum corresponded to bright lines in the spectra of known gases, specific lines corresponding to unique chemical elements.[15] Kirchhoff deduced that the dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere.[16] In this way it was proved that the chemical elements found in the Sun and stars were also found on Earth.

Among those who extended the study of solar and stellar spectra was Norman Lockyer, who in 1868 detected bright, as well as dark, lines in solar spectra. Working with the chemist, Edward Frankland, to investigate the spectra of elements at various temperatures and pressures, he could not associate a yellow line in the solar spectrum with any known elements. He thus claimed the line represented a new element, which was called helium, after the Greek Helios, the Sun personified.[17][18]

In 1885, Edward C. Pickering undertook an ambitious program of stellar spectral classification at Harvard College Observatory, in which a team of woman computers, notably Williamina Fleming, Antonia Maury, and Annie Jump Cannon, classified the spectra recorded on photographic plates. By 1890, a catalog of over 10,000 stars had been prepared that grouped them into thirteen spectral types. Following Pickering’s vision, by 1924 Cannon expanded the catalog to nine volumes and over a quarter of a million stars, developing the Harvard Classification Scheme which was accepted for worldwide use in 1922.[19]

In 1895, George Ellery Hale and James E. Keeler, along with a group of ten associate editors from Europe and the United States,[20] established The Astrophysical Journal: An International Review of Spectroscopy and Astronomical Physics.[21] It was intended that the journal would fill the gap between journals in astronomy and physics, providing a venue for publication of articles on astronomical applications of the spectroscope; on laboratory research closely allied to astronomical physics, including wavelength determinations of metallic and gaseous spectra and experiments on radiation and absorption; on theories of the Sun, Moon, planets, comets, meteors, and nebulae; and on instrumentation for telescopes and laboratories.[20]

Around 1920, following the discovery of the Hertsprung-Russell diagram still used as the basis for classifying stars and their evolution, Arthur Eddington anticipated the discovery and mechanism of nuclear fusion processes in stars, in his paper The Internal Constitution of the Stars.[22][23] At that time, the source of stellar energy was a complete mystery; Eddington correctly speculated that the source was fusion of hydrogen into helium, liberating enormous energy according to Einstein’s equation E = mc2. This was a particularly remarkable development since at that time fusion and thermonuclear energy, and even that stars are largely composed of hydrogen (see metallicity), had not yet been discovered.[non-primary source needed]

In 1925 Cecilia Helena Payne (later Cecilia Payne-Gaposchkin) wrote an influential doctoral dissertation at Radcliffe College, in which she applied ionization theory to stellar atmospheres to relate the spectral classes to the temperature of stars.[24] Most significantly, she discovered that hydrogen and helium were the principal components of stars. Despite Eddington’s suggestion, this discovery was so unexpected that her dissertation readers convinced her to modify the conclusion before publication. However, later research confirmed her discovery.[25]

By the end of the 20th century, studies of astronomical spectra had expanded to cover wavelengths extending from radio waves through optical, x-ray, and gamma wavelengths.[26] In the 21st century it further expanded to include observations based on gravitational waves.

Observational astronomy is a division of the astronomical science that is concerned with recording data, in contrast with theoretical astrophysics, which is mainly concerned with finding out the measurable implications of physical models. It is the practice of observing celestial objects by using telescopes and other astronomical apparatus.

The majority of astrophysical observations are made using the electromagnetic spectrum.

Other than electromagnetic radiation, few things may be observed from the Earth that originate from great distances. A few gravitational wave observatories have been constructed, but gravitational waves are extremely difficult to detect. Neutrino observatories have also been built, primarily to study our Sun. Cosmic rays consisting of very high energy particles can be observed hitting the Earth’s atmosphere.

Observations can also vary in their time scale. Most optical observations take minutes to hours, so phenomena that change faster than this cannot readily be observed. However, historical data on some objects is available, spanning centuries or millennia. On the other hand, radio observations may look at events on a millisecond timescale (millisecond pulsars) or combine years of data (pulsar deceleration studies). The information obtained from these different timescales is very different.

The study of our very own Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Our understanding of our own Sun serves as a guide to our understanding of other stars.

The topic of how stars change, or stellar evolution, is often modeled by placing the varieties of star types in their respective positions on the HertzsprungRussell diagram, which can be viewed as representing the state of a stellar object, from birth to destruction.

Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.[27][28]

Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models. This helps allow observers to look for data that can refute a model or help in choosing between several alternate or conflicting models.

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

Topics studied by theoretical astrophysicists include: stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole (astro)physics and the study of gravitational waves.

Some widely accepted and studied theories and models in astrophysics, now included in the Lambda-CDM model, are the Big Bang, cosmic inflation, dark matter, dark energy and fundamental theories of physics. Wormholes are examples of hypotheses which are yet to be proven (or disproven).

The roots of astrophysics can be found in the seventeenth century emergence of a unified physics, in which the same laws applied to the celestial and terrestrial realms.[10] There were scientists who were qualified in both physics and astronomy who laid the firm foundation for the current science of astrophysics. In modern times, students continue to be drawn to astrophysics due to its popularization by the Royal Astronomical Society and notable educators such as prominent professors Lawrence Krauss, Subrahmanyan Chandrasekhar, Stephen Hawking, Hubert Reeves, Carl Sagan and Neil deGrasse Tyson. The efforts of the early, late, and present scientists continue to attract young people to study the history and science of astrophysics.[29][30][31]

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Astrophysics – Wikipedia

General Index to Sidereal Messenger, Vol; 1-10, March …

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Astrophysics – Play it now at Coolmath-Games.com

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Company Seven | Astro-Physics 305mm f3.5 / 12 Inch f3.8 …

Astro-Physics 305mm f3.5 / 12 Inch f3.8 Riccardi-Honders Astrographic Telescope (P/N 305RHA)An amazing 1,160mm f3.8 Apo Lens!

Development of the Riccardi-Honders Design

Astro-Physics Company are known for making the world’s most advanced, versatile, and desired lines of apochromatic refractor telescopes. In 2000 after more than a decade of research and development to “get it right” they surprised the astronomy community with the announcement of their first production Catadioptric telescope. This is designated the Astro-Physics Astro Physics 10″ f14.6 Maksutov-Cassegrain telescope, a compact 33 lb. (15 kg) high resolution instrument designed to provide refractor like views (and images) of the brighter, small objects including the planets, moon, double stars, and the like.

Right: Astro-Physics 305mm Honders telescope (OTA to the left) as introduced in 2009 atop the Astro-Physics 3600GTO ‘El Capitan’ German Equatorial Mount (79,387 bytes). Image courtesy of David Illig.Click on image to see enlarged view (253,556 bytes).

Since then Astro-Physics has been working to perfect a new catadioptric telescope, one ideally suited for imaging wide areas of sky and not compromised by considering visual applications. This new telescope would be compact, perform well in temperature extremes around the world, and meet their traditional exacting requirements for optical and mechanical excellence. The result is a telescope that is the first of its kind: the Astro-Physics 305mm f3.8 Astrograph. The ‘Honders” as it is known here at Company Seven and in most of the community is based on Klaas Honder’s original idea of a fast optical system using a crown glass objective and meniscus correcting mirror in a Newtonian configuration. By adding a secondary mirror and field lens, Italian designer Massimo Riccardi was able to design an ultra-fast (short focal ratio) astrograph using only comparatively affordable crown glass elements. Astro-Physics has added their more than years of telescope design experience to create a truly unique and fast astrograph to take full advantage of today’s CCD imaging cameras. With this telescope you will collect photons most efficiently producing wide-field of view images that you could previously only have imagined.

A further goal in this development effort was to equal or to approach the performance of their highly prized triplet apochromatic refractors in at least certain applications. One thought in producing these Catadioptric telescopes is that if a number of customers who do not require the versatility of the Apo refractors (which perform superbly well at extremely high magnifications, and down to very low magnifications) will order the Mak telescopes instead of the triplet Apos then this may take some of the burden from the Triplet production line, and thereby help Astro-Physics to satisfy a far greater number of the more demanding amateur and professional clientele.

In April 2008 Roland Christen had presented a paper entitled “Optical Design for High Resolution Imaging” discussing the advantages of the Riccardi-Honders optical design. The prototype 305mm f3.8 Riccardi-Honders Astrograph prototype was introduced to the public on 18 April 2009 (image at right) although by then it had already proved itself with numerous amazing images taken while at the Astro-Physics observatory. It was shown mounted in parallel with the prototype 305mm f12.5 Maksutov-Cassegrain telescope atop the Astro-Physics 3600GTO ‘El Capitan’ German Equatorial Mount. Pricing was announced in August 2010 as the first invitations to order were sent out. Deliveries from the first production run will commence in limited numbers in the Fall of the year 2010.OPTICAL CHARACTERISTICS

The system includes the optical tube assembly, a 3.5 inch diameter focuser, Dewcap (Lens Shade), Dust Cover, pair of Mounting Rings, and Carrying Case. Company Seven will offer an optional Airline Transport Association Approved (ATA) shipping case for this instrument.

Any optical imperfections such as a degree of surface roughness and zonal errors on the optical surface will compound the problem.Astro-Physics tested a commercial telescope where the central obstruction, optical errors and surface roughness were large enough to cause the first diffraction ring and central Airy disc to have almost equal brightness (with a 35% obstruction, theoretically there should be at least a4 to 1 difference). Even so, this sample telescope “tested” very well on the star test – it had quite similar inside and outside Fresnel patterns and might be judged to be textbook perfect by the star test. Yet it was a very poor performer on all but the most steady of nights, when the seeing was essentially perfect. The slightest motion in the atmosphere would result in a display of “cotton ball” stars. This is one reason whyAstro-Physics and Company Seven have not been a major fans of the “star test” to evaluate the actual performance of a telescope. The only unbiased way to measure an optic is with interferometry, or by an MTF (modulation transfer function) test, or with a PSF (point spread function) test, which measures the relative strength of the Airy disc versus the diffraction rings with the image in focus.

Astro-Physics has endeavored to achieve the highest absorption of stray light possible by employing state of the art baffling and anti-reflection techniques; this will help to provide the user with maximum contrast. The exterior of the telescope is finished in a durable textured off white finish, with black anodized focuser and cells; these will retain their beauty for many years. You will appreciate the unique design and fine craftsmanship of this telescope.

Knife edge baffles are machined into the walls of the telescope optical tube and of the focuser draw tube, these and painted flat black in order to maximize contrast by essentially eliminating any internal reflections. The inside diameter (I.D.) of the draw tube permits the avid astrophotographer to employ up to a 35mm format film or CCD camera to capture images. While this is designed as an astrographic instrument, you can attach a Barlow lens then attach standard 2 inch diameter accessories, and with the furnished 1.25 inch adapter (threaded for 48mm filters) to use common oculars and accessories too. Recessed brass locking rings are installed at each thumbscrew location; as you tighten a thumbscrew a brass locking ring clamps onto the part that has been inserted; consequently the focuser draw tube and any accessories are held securely in place and will not mar the surface of your accessories. This is particularly important considering the heavy and expensive accessories that you may use.

* Specifications are subject to change without notice.

Right: Company Seven ATA Case custom fitted for a Astro-Physics 13cm EDT Apochromat Telescope with 2.7 inch Focuser (65,974 bytes).Click on image to see enlarged view (215,942 bytes).

Features include:

Left: Astro-Physics Model 900 Mount in optional Company Seven ATA case.Case 1 of 2 shown here, with Declination housing (left side shown) with GTO Keypad Controllerand Counterweight Shaft (94,326 bytes).

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Company Seven | Astro-Physics 305mm f3.5 / 12 Inch f3.8 …

Astrophysics – Wikipedia

This article is about the use of physics and chemistry to determine the nature of astronomical objects. For the use of physics to determine their positions and motions, see Celestial mechanics. For the physical study of the largest-scale structures of the universe, see Physical cosmology. For the journal, see Astrophysics (journal).

Astrophysics is the branch of astronomy that employs the principles of physics and chemistry “to ascertain the nature of the astronomical objects, rather than their positions or motions in space”.[1][2] Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background.[3][4] Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

In practice, modern astronomical research often involves a substantial amount of work in the realms of theoretical and observational physics. Some areas of study for astrophysicists include their attempts to determine: the properties of dark matter, dark energy, and black holes; whether or not time travel is possible, wormholes can form, or the multiverse exists; and the origin and ultimate fate of the universe.[3] Topics also studied by theoretical astrophysicists include: Solar System formation and evolution; stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics.

Although astronomy is as ancient as recorded history itself, it was long separated from the study of terrestrial physics. In the Aristotelian worldview, bodies in the sky appeared to be unchanging spheres whose only motion was uniform motion in a circle, while the earthly world was the realm which underwent growth and decay and in which natural motion was in a straight line and ended when the moving object reached its goal. Consequently, it was held that the celestial region was made of a fundamentally different kind of matter from that found in the terrestrial sphere; either Fire as maintained by Plato, or Aether as maintained by Aristotle.[5][6]During the 17th century, natural philosophers such as Galileo,[7] Descartes,[8] and Newton[9] began to maintain that the celestial and terrestrial regions were made of similar kinds of material and were subject to the same natural laws.[10] Their challenge was that the tools had not yet been invented with which to prove these assertions.[11]

For much of the nineteenth century, astronomical research was focused on the routine work of measuring the positions and computing the motions of astronomical objects.[12][13] A new astronomy, soon to be called astrophysics, began to emerge when William Hyde Wollaston and Joseph von Fraunhofer independently discovered that, when decomposing the light from the Sun, a multitude of dark lines (regions where there was less or no light) were observed in the spectrum.[14] By 1860 the physicist, Gustav Kirchhoff, and the chemist, Robert Bunsen, had demonstrated that the dark lines in the solar spectrum corresponded to bright lines in the spectra of known gases, specific lines corresponding to unique chemical elements.[15] Kirchhoff deduced that the dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere.[16] In this way it was proved that the chemical elements found in the Sun and stars were also found on Earth.

Among those who extended the study of solar and stellar spectra was Norman Lockyer, who in 1868 detected bright, as well as dark, lines in solar spectra. Working with the chemist, Edward Frankland, to investigate the spectra of elements at various temperatures and pressures, he could not associate a yellow line in the solar spectrum with any known elements. He thus claimed the line represented a new element, which was called helium, after the Greek Helios, the Sun personified.[17][18]

In 1885, Edward C. Pickering undertook an ambitious program of stellar spectral classification at Harvard College Observatory, in which a team of woman computers, notably Williamina Fleming, Antonia Maury, and Annie Jump Cannon, classified the spectra recorded on photographic plates. By 1890, a catalog of over 10,000 stars had been prepared that grouped them into thirteen spectral types. Following Pickering’s vision, by 1924 Cannon expanded the catalog to nine volumes and over a quarter of a million stars, developing the Harvard Classification Scheme which was accepted for worldwide use in 1922.[19]

In 1895, George Ellery Hale and James E. Keeler, along with a group of ten associate editors from Europe and the United States,[20] established The Astrophysical Journal: An International Review of Spectroscopy and Astronomical Physics.[21] It was intended that the journal would fill the gap between journals in astronomy and physics, providing a venue for publication of articles on astronomical applications of the spectroscope; on laboratory research closely allied to astronomical physics, including wavelength determinations of metallic and gaseous spectra and experiments on radiation and absorption; on theories of the Sun, Moon, planets, comets, meteors, and nebulae; and on instrumentation for telescopes and laboratories.[20]

Around 1920, following the discovery of the Hertsprung-Russell diagram still used as the basis for classifying stars and their evolution, Arthur Eddington anticipated the discovery and mechanism of nuclear fusion processes in stars, in his paper The Internal Constitution of the Stars.[22][23] At that time, the source of stellar energy was a complete mystery; Eddington correctly speculated that the source was fusion of hydrogen into helium, liberating enormous energy according to Einstein’s equation E = mc2. This was a particularly remarkable development since at that time fusion and thermonuclear energy, and even that stars are largely composed of hydrogen (see metallicity), had not yet been discovered.[non-primary source needed]

In 1925 Cecilia Helena Payne (later Cecilia Payne-Gaposchkin) wrote an influential doctoral dissertation at Radcliffe College, in which she applied ionization theory to stellar atmospheres to relate the spectral classes to the temperature of stars.[24] Most significantly, she discovered that hydrogen and helium were the principal components of stars. Despite Eddington’s suggestion, this discovery was so unexpected that her dissertation readers convinced her to modify the conclusion before publication. However, later research confirmed her discovery.[25]

By the end of the 20th century, studies of astronomical spectra had expanded to cover wavelengths extending from radio waves through optical, x-ray, and gamma wavelengths.[26] In the 21st century it further expanded to include observations based on gravitational waves.

Observational astronomy is a division of the astronomical science that is concerned with recording data, in contrast with theoretical astrophysics, which is mainly concerned with finding out the measurable implications of physical models. It is the practice of observing celestial objects by using telescopes and other astronomical apparatus.

The majority of astrophysical observations are made using the electromagnetic spectrum.

Other than electromagnetic radiation, few things may be observed from the Earth that originate from great distances. A few gravitational wave observatories have been constructed, but gravitational waves are extremely difficult to detect. Neutrino observatories have also been built, primarily to study our Sun. Cosmic rays consisting of very high energy particles can be observed hitting the Earth’s atmosphere.

Observations can also vary in their time scale. Most optical observations take minutes to hours, so phenomena that change faster than this cannot readily be observed. However, historical data on some objects is available, spanning centuries or millennia. On the other hand, radio observations may look at events on a millisecond timescale (millisecond pulsars) or combine years of data (pulsar deceleration studies). The information obtained from these different timescales is very different.

The study of our very own Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Our understanding of our own Sun serves as a guide to our understanding of other stars.

The topic of how stars change, or stellar evolution, is often modeled by placing the varieties of star types in their respective positions on the HertzsprungRussell diagram, which can be viewed as representing the state of a stellar object, from birth to destruction.

Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.[27][28]

Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models. This helps allow observers to look for data that can refute a model or help in choosing between several alternate or conflicting models.

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

Topics studied by theoretical astrophysicists include: stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole (astro)physics and the study of gravitational waves.

Some widely accepted and studied theories and models in astrophysics, now included in the Lambda-CDM model, are the Big Bang, cosmic inflation, dark matter, dark energy and fundamental theories of physics. Wormholes are examples of hypotheses which are yet to be proven (or disproven).

The roots of astrophysics can be found in the seventeenth century emergence of a unified physics, in which the same laws applied to the celestial and terrestrial realms.[10] There were scientists who were qualified in both physics and astronomy who laid the firm foundation for the current science of astrophysics. In modern times, students continue to be drawn to astrophysics due to its popularization by the Royal Astronomical Society and notable educators such as prominent professors Lawrence Krauss, Subrahmanyan Chandrasekhar, Stephen Hawking, Hubert Reeves, Carl Sagan and Neil deGrasse Tyson. The efforts of the early, late, and present scientists continue to attract young people to study the history and science of astrophysics.[29][30][31]

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Astrophysics – Wikipedia

Astrophysics – Wikipedia

This article is about the use of physics and chemistry to determine the nature of astronomical objects. For the use of physics to determine their positions and motions, see Celestial mechanics. For the physical study of the largest-scale structures of the universe, see Physical cosmology. For the journal, see Astrophysics (journal).

Astrophysics is the branch of astronomy that employs the principles of physics and chemistry “to ascertain the nature of the astronomical objects, rather than their positions or motions in space”.[1][2] Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background.[3][4] Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

In practice, modern astronomical research often involves a substantial amount of work in the realms of theoretical and observational physics. Some areas of study for astrophysicists include their attempts to determine: the properties of dark matter, dark energy, and black holes; whether or not time travel is possible, wormholes can form, or the multiverse exists; and the origin and ultimate fate of the universe.[3] Topics also studied by theoretical astrophysicists include: Solar System formation and evolution; stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics.

Although astronomy is as ancient as recorded history itself, it was long separated from the study of terrestrial physics. In the Aristotelian worldview, bodies in the sky appeared to be unchanging spheres whose only motion was uniform motion in a circle, while the earthly world was the realm which underwent growth and decay and in which natural motion was in a straight line and ended when the moving object reached its goal. Consequently, it was held that the celestial region was made of a fundamentally different kind of matter from that found in the terrestrial sphere; either Fire as maintained by Plato, or Aether as maintained by Aristotle.[5][6]During the 17th century, natural philosophers such as Galileo,[7] Descartes,[8] and Newton[9] began to maintain that the celestial and terrestrial regions were made of similar kinds of material and were subject to the same natural laws.[10] Their challenge was that the tools had not yet been invented with which to prove these assertions.[11]

For much of the nineteenth century, astronomical research was focused on the routine work of measuring the positions and computing the motions of astronomical objects.[12][13] A new astronomy, soon to be called astrophysics, began to emerge when William Hyde Wollaston and Joseph von Fraunhofer independently discovered that, when decomposing the light from the Sun, a multitude of dark lines (regions where there was less or no light) were observed in the spectrum.[14] By 1860 the physicist, Gustav Kirchhoff, and the chemist, Robert Bunsen, had demonstrated that the dark lines in the solar spectrum corresponded to bright lines in the spectra of known gases, specific lines corresponding to unique chemical elements.[15] Kirchhoff deduced that the dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere.[16] In this way it was proved that the chemical elements found in the Sun and stars were also found on Earth.

Among those who extended the study of solar and stellar spectra was Norman Lockyer, who in 1868 detected bright, as well as dark, lines in solar spectra. Working with the chemist, Edward Frankland, to investigate the spectra of elements at various temperatures and pressures, he could not associate a yellow line in the solar spectrum with any known elements. He thus claimed the line represented a new element, which was called helium, after the Greek Helios, the Sun personified.[17][18]

In 1885, Edward C. Pickering undertook an ambitious program of stellar spectral classification at Harvard College Observatory, in which a team of woman computers, notably Williamina Fleming, Antonia Maury, and Annie Jump Cannon, classified the spectra recorded on photographic plates. By 1890, a catalog of over 10,000 stars had been prepared that grouped them into thirteen spectral types. Following Pickering’s vision, by 1924 Cannon expanded the catalog to nine volumes and over a quarter of a million stars, developing the Harvard Classification Scheme which was accepted for worldwide use in 1922.[19]

In 1895, George Ellery Hale and James E. Keeler, along with a group of ten associate editors from Europe and the United States,[20] established The Astrophysical Journal: An International Review of Spectroscopy and Astronomical Physics.[21] It was intended that the journal would fill the gap between journals in astronomy and physics, providing a venue for publication of articles on astronomical applications of the spectroscope; on laboratory research closely allied to astronomical physics, including wavelength determinations of metallic and gaseous spectra and experiments on radiation and absorption; on theories of the Sun, Moon, planets, comets, meteors, and nebulae; and on instrumentation for telescopes and laboratories.[20]

Around 1920, following the discovery of the Hertsprung-Russell diagram still used as the basis for classifying stars and their evolution, Arthur Eddington anticipated the discovery and mechanism of nuclear fusion processes in stars, in his paper The Internal Constitution of the Stars.[22][23] At that time, the source of stellar energy was a complete mystery; Eddington correctly speculated that the source was fusion of hydrogen into helium, liberating enormous energy according to Einstein’s equation E = mc2. This was a particularly remarkable development since at that time fusion and thermonuclear energy, and even that stars are largely composed of hydrogen (see metallicity), had not yet been discovered.[non-primary source needed]

In 1925 Cecilia Helena Payne (later Cecilia Payne-Gaposchkin) wrote an influential doctoral dissertation at Radcliffe College, in which she applied ionization theory to stellar atmospheres to relate the spectral classes to the temperature of stars.[24] Most significantly, she discovered that hydrogen and helium were the principal components of stars. Despite Eddington’s suggestion, this discovery was so unexpected that her dissertation readers convinced her to modify the conclusion before publication. However, later research confirmed her discovery.[25]

By the end of the 20th century, studies of astronomical spectra had expanded to cover wavelengths extending from radio waves through optical, x-ray, and gamma wavelengths.[26] In the 21st century it further expanded to include observations based on gravitational waves.

Observational astronomy is a division of the astronomical science that is concerned with recording data, in contrast with theoretical astrophysics, which is mainly concerned with finding out the measurable implications of physical models. It is the practice of observing celestial objects by using telescopes and other astronomical apparatus.

The majority of astrophysical observations are made using the electromagnetic spectrum.

Other than electromagnetic radiation, few things may be observed from the Earth that originate from great distances. A few gravitational wave observatories have been constructed, but gravitational waves are extremely difficult to detect. Neutrino observatories have also been built, primarily to study our Sun. Cosmic rays consisting of very high energy particles can be observed hitting the Earth’s atmosphere.

Observations can also vary in their time scale. Most optical observations take minutes to hours, so phenomena that change faster than this cannot readily be observed. However, historical data on some objects is available, spanning centuries or millennia. On the other hand, radio observations may look at events on a millisecond timescale (millisecond pulsars) or combine years of data (pulsar deceleration studies). The information obtained from these different timescales is very different.

The study of our very own Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Our understanding of our own Sun serves as a guide to our understanding of other stars.

The topic of how stars change, or stellar evolution, is often modeled by placing the varieties of star types in their respective positions on the HertzsprungRussell diagram, which can be viewed as representing the state of a stellar object, from birth to destruction.

Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.[27][28]

Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models. This helps allow observers to look for data that can refute a model or help in choosing between several alternate or conflicting models.

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

Topics studied by theoretical astrophysicists include: stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole (astro)physics and the study of gravitational waves.

Some widely accepted and studied theories and models in astrophysics, now included in the Lambda-CDM model, are the Big Bang, cosmic inflation, dark matter, dark energy and fundamental theories of physics. Wormholes are examples of hypotheses which are yet to be proven (or disproven).

The roots of astrophysics can be found in the seventeenth century emergence of a unified physics, in which the same laws applied to the celestial and terrestrial realms.[10] There were scientists who were qualified in both physics and astronomy who laid the firm foundation for the current science of astrophysics. In modern times, students continue to be drawn to astrophysics due to its popularization by the Royal Astronomical Society and notable educators such as prominent professors Lawrence Krauss, Subrahmanyan Chandrasekhar, Stephen Hawking, Hubert Reeves, Carl Sagan and Neil deGrasse Tyson. The efforts of the early, late, and present scientists continue to attract young people to study the history and science of astrophysics.[29][30][31]

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Astrophysics – Wikipedia

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‘); } else { //console.log(“User may have come from google or is within the free game limit “+ (freeGameLimit-userPlayedGames) ); //TODO Display Game removeAdSwfJWPLayer(); } } //display to user how many free games left once page load completes. if (window.addEventListener) window.addEventListener(‘load’, checkPageLoad, false); else if (window.attachEvent) window.attachEvent(‘onload’, checkPageLoad); else window.onload = checkPageLoad; }}function checkPageLoad() {//console.log(“checkPageLoad: Checkers test “); if(freeGameLimit) { freeGamesLeft = ((freeGameLimit – userPlayedGames)); } else { freeGamesLeft = 0; } if(freeGamesLeft === 0) { var zeroFreeGamesLeftUsers =localStorage.getItem(“zeroFreeGamesLeftUsers”); if(zeroFreeGamesLeftUsers == null) { localStorage.setItem(“zeroFreeGamesLeftUsers”,”1″); if(typeof __gaTracker !== “undefined”) { __gaTracker(‘send’, { ‘hitType’: ‘event’, // Required. ‘eventCategory’: “ZeroFreeGamesLeftUsers”, // Required. ‘eventAction’: subscriberLeg, // Required. ‘eventLabel’: document.title, ‘eventValue’: “0”, ‘nonInteraction’: 1 }); } } } //Replace Go Ad Free header promo with parents and teachers promo if(typeof freeTrialUser !== ‘undefined’ && freeTrialUser && typeof targeted_state !== ‘undefined’ && targeted_state && jQuery(‘.panel-pane.pane-block.pane-bean-subscriber-promo’).length) { jQuery(‘.panel-pane.pane-block.pane-bean-subscriber-promo’).replaceWith(”) } else if(typeof freeTrialUser !== ‘undefined’ && freeTrialUser && typeof targeted_state !== ‘undefined’ && targeted_state && jQuery(‘.panel-pane.pane-block .pane-bean-subscriber-promo’).length) { jQuery(‘.panel-pane.pane-block .pane-bean-subscriber-promo’).replaceWith(”) } subscriptionSignUpUrl(); if(Drupal.settings.isSubscriptionActive == false && getCookie(‘cmg_l’) !== null) { subscribeNowAlienClass = “subscribe-now-alien-subscribe”; }else if(getCookie(‘cmg_l’) == null) { subscribeNowAlienClass = “subscribe-now-alien”; }else if(getCookie(‘cmg_l’) == null && subscriberLeg == ‘Default Leg’) { subscribeNowAlienClass = “subscribe-now-signup”; } var alreadySubscriberText = ‘

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Company Seven | Vixen GPDX German Equatorial Mount page

Overview: What is the GPDX and when do we recommend it?

The GPDX is one of the most massive of the three “Great Polaris” series German equatorial mounts manufactured by Vixen Co., Ltd. The other model GP mounts include the lighter weight GPE model, and another which is similar in appearance to the GPE but is its better accessorized cousin the GP. The GP series are the descendants of the Vixen “Super Polaris” mounts which came to dominate the 1980’s. In the USA the Super Polaris were distributed under the Celestron trademark. The heavier duty “Super Polaris DX” was not made available in the USA until 1989 when it was evaluated by Roland Christen, founder of Astro-Physics company who imported it for sale to the USA through both Astro-Physics and Company Seven. The SP-DX was considered a suitable but relatively economical platform for their then new 12cm f8.4 ED doublet Apochromat, and their 4 and 5 Inch f8 Apo telescopes.

The Great Polaris are an improved, modular German equatorial mount system where the customer is allowed to tailor the system to their particular needs choosing from a broad selection of accessories. The GP-DX mount closely resembles the more compact and portable GP mount however, this belies it’s notably superior payload handling and tracking. The GP-DX differences include durable steel is used for the R.A. and Declination Axes shafts, the worm wheels are made of brass (to about double the tolerance of the GP) on improved bearings to provide smooth and stable operation. Accordingly, the GP-DX mount head weighs almost twice as much as the GP.

alignment to within 3 minute accuracy possible, bubble-level, fine adjustment knobs for both altitude and azimuth, and one 8 lb / 3. kg counterweight are provided. Refinements include a Dovetail Plate hardware mechanism to facilitate the quick interchange of payloads, a better selection of tripods and electronic drive systems.

Company Seven recommends the GPDX to accommodate payloads including:

* there are factors acting upon a German mount affecting its suitability including: payload weight and length (torque), payload area and profile exposed to winds, desired tracking accuracy, tripod or pier resonance’s, etc. What are most important to the user is how rigidly the mount holds the payload, how smoothly it tracks (amplitude and smoothness of the periodic error of a gear), and how well it overcomes the moment imparted by the load. The final operating weight put onto a mount can also depend on how the instrument is to be accessorized.

If you wish to buy a most economical, and relatively light weight refined mount that can manage your payload for manual visual operations, or for simple driven uses then the GPDX can make sense. The GPDX can provide a lifetime of service, and it is deserved by many better quality telescopes including the Astro-Physics 105 ‘Traveler’ or 130 mm f6 EDF, or the TeleVue NP101 and 102 or 127, etc. where the cost of the GPDX can be readily justified. And the choices of simple electronic drive systems are better for the GPDX than those available for most other mounts at or below the cost of the GPDX mounts. But when one gets to the point of buying a complete new GPDX delivered with dual axis drive controller, two motors, two clutches, etc. then the cost climbs into the realm of superior alternatives.

For those who observe from wind prone locations, or for those who intend to become involved in longer time exposure astrophotography or CCD imaging then we suggest you consider one of the following mounts because of their more sophisticated electronics, and even better weight bearing and tracking performance:

The GPDX mount is available as a Mount Head with Quick Release Saddle including Counterweight Shaft, 8.14 lb / 3.7 kg Counterweight, 6x 20mm Pole Alignment Finder telescope with illuminated North and Southern hemisphere reticle, bubble-level, and fine adjustment knobs for both altitude and azimuth. To arrange a complete system one orders the other components “ala carte” buying only what is needed from a selection of good choices.

Below Right: A complete Vixen 150mm f5 reflecting telescope shown on an GPDX German Equatorial Mount with standard 3.7 andwith optional 1.9 kg counterweights, DS-1 Single Axis Drive, HAL110 Aluminum Field Tripod (39,881 bytes).Click on image to see enlarged view (164,592 bytes)

A complete GPE mount system will usually consist of these components:

Company Seven offers a number of third party accessories for the GP/GPDX mounts. These include Digital Setting Circle with Encoder sets, or optional fitted Carrying Bag (sample shown at right) which can provide for safer, and more convenient transport the mount with tripod attached, or one for the Tripod alone. Please understand that these are very convenient and padded lightweight bags however, these are not suitable for shipping a telescope or mount. Company Seven do offer rather costly buy sometimes necessary Airline Transport Association approved shipping cases for these products which are suitable for check in on aircraft, or shipping by common carriers.

Please visit Company Seven’s showroom to see examples of these Vixen systems firsthand. Or you may Contact Company Seven for help putting together a system for you.

GPE Features and Specifications

Vixen GPE Optional SD-1 Electronic Drive Specifications

Vixen GPE Optional DD-1 Electronic Drive Specifications

Specifications and availability subject to change

Drive System Power Requirements, Sources

The SD-1 Drive Controller for the GPE/GPDX mounts operates from 9 volt DC power sources, it is provided with a cluster battery holder for six alkaline “C” cell batteries, and power cord. For convenience it is probably best to keep feeding the SD-1 the provided battery pack as it needs them. For operations in below freezing conditions then we recommend you keep the battery pack for the SD-1 in a warm area, possibly in a coat pocket when working near the telescope. Otherwise you may use more costly lithium batteries which perform better at lower temperatures.

The DD-1 Drive Controller for the GPE/GPDX mounts is provided with a cluster battery holder for eight alkaline “D” cell batteries, and power cord. The DD-1 and other common telescope powered accessories (Kendrick Dew/Frost Prevention System, CCD cameras, etc.) require a 12 volt D.C. power source. If you prefer a longer life or more cost effective power supply then Company Seven suggests the user consider one of these following options:

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Company Seven | Vixen GPDX German Equatorial Mount page


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