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The Evolutionary Perspective
Daily Archives: January 16, 2020
Posted: January 16, 2020 at 2:46 pm
In the nearly five years since their first direct detection, gravitational waves have become one of the hottest topics in astronomy. With facilities such as the Laser Interferometer Gravitational-Wave Observatory (LIGO), researchers have mostly used these ripples in spacetime to study the inner workings of merging black holes, but LIGO has also detected gravitational waves from other sorts of celestial crashes, such as the collisions of ultradense stellar remnants called neutron stars. Sometimes, however, LIGO serves up gravitational waves that leave astronomers scratching their headsas was the case for GW190425, an event detected last April that was recently attributed to a neutron star merger.
The trouble is that LIGOs data suggest this neutron star pair was substantially overweightcollectively, some 3.4 times the mass of the sun, which is half a solar mass heavier than the most massive neutron star binaries ever seen. It is the heaviest known by a pretty wide margin, says Chad Hanna, an astrophysicist at Pennsylvania State University who hunts gravitational waves.
That extra weight has some theorists suspecting that GW190425 did not arise from colliding neutron stars at all but rather something much more exotic: A merger of two primordial black holes (PBHs), never before seen objects that are considered a dark horse candidate for dark matterthe invisible, unidentified something that makes up most of the matter in the universe. Theorized to have formed from density fluctuations in the very early universe, these ancient black holes could still exist today and could explain the mass discrepancy identified in the recent LIGO observations.
Almost a half-century ago, cosmologist Stephen Hawking proposed that PBHs could have sprung fully formed from regions of the infant universe that were especially dense with matter. Since then, the ideas popularity among astrophysicists and cosmologists has wildly waxed and waned. Today, in the absence of direct evidence for their existence, PBHs are seen by many researchers as a hypothesis of last resort, only to be considered when no other scenario readily fits observations. The possibility that PBHs are real and widespread throughout the universe cannot yet be dismissed, howeverespecially as searches for other dark matter candidates come up empty.
PBHs make an appealing candidate for dark matter for several reasons, but the most important one is that, being black holes, they are quite dark yet still pack a hefty gravitational pull. Despite that fact, Hanna says that if PBHs were abundant enough to account for all of the universes dark matter, astronomical surveys that hunted for them should not have come up empty. Consequently, he adds, PBHs can only make up a small fraction of dark matterif they exist at all.
Not everyone agrees. Primordial black holes can comprise the whole of dark matter, says Juan Garca-Bellido, a theoretical cosmologist at the Autonomous University of Madrid. The trick, he adds, is for the ancient objects to exhibit an array of masses rather than a single definitive size. If PBHs run the gamut from a thousand times less massive than the sun to a billion times larger, they could make up all of the universes dark matter. All published constraints that claim to rule out primordial black holes as dark matter assume they exist in a monochromatic, or single-mass, spectrum and are uniformly distributed in space, Garca-Bellido says. For such large mass ranges to manifest, the PBHs would have to cluster in compact groups in which they could occasionally collide, merge and grow larger.
Because PBHs would have been created shortly after the big bang, they initially could have easily connected with one another. The early universe was a much smaller place than it is today after dramatically expanding for nearly 14 billion years, making it easier for the objects to find other PBHs and pair up with them. As the universe continued to expand, and the first stars and galaxies emerged, however, those connections would have become increasingly rare. So while it is possible that LIGO has observed merging PBHs, it is unlikely, according to astronomer Katerina Chatziioannou, a LIGO team member at the Flatiron Institute in New York City and co-author of a study set to appear in the Astrophysical Journal Letters that pegs GW190425 as the product of colliding neutron stars.
Last April, alerted to LIGOs detection of GW190425, telescopes around the world hunted for a corresponding electromagnetic signal that would typically be expected from the explosive collision of two neutron stars. But the skies remained dark, as they would if a pair of primordial black holes had slammed together. We would not have expected any light to have come out of the merger of two primordial black holes, Chatziioannou says. Even so, she adds, the lack of light does not rule out neutron stars. Massive neutron stars could have had a relatively placid merger, collapsing directly into a black hole before sparking any celestial fireworks. It is also possible that the events location in the sky could be from somewhere that Earth-bound telescopes could not probe, such as in a region behind the sun. There are good reasons for them to have missed it if there was any light, she says.
The newest observations provide only tantalizing hints that PBHs might be out there, occasionally coming together in the cosmic dark. A clearer signature would come from a pair of black holes in which each weighed less than the sun. If you find a black hole below a solar mass, that, at the very least, comes from a mechanism that no one has predicted, astrophysically, outside of a primordial black hole, Hanna says. Garca-Bellido concurs. The smoking gun would be the discovery of a less than one-solar-mass black holeor a black hole with a mass larger than 50 [times the sun], he says.
Although LIGOs observations could mark the first detection of PBHs, both Chatziioannou and Hanna agree that it is more likely that the gravitational waves merely came from overweight neutron stars. Theories for the formation of such bulky neutron stars already exist, and they require no speculative scenarios from the dawn of the universe. Its definitely a lot less likely that [the sources of these events] are primordial black holes than just neutron stars that are heavier than what we see in the galaxy, Chatziioannou says. It's not impossible; its just less likely.
Although Hanna calls the case for GW190425 as a primordial black hole binary weak, Garca-Bellido remains more optimistic. All LIGO events could be due to primordial black holes, he says. Only timeand more datawill tell.
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Posted: at 2:46 pm
HONOLULU Heated conversations at the American Astronomical Society's January meeting are usually about stars and galaxies, distant worlds and elaborate calculations.
This year, however, a more terrestrial controversy echoed through both formal presentations and casual conversations at the "Super Bowl of Astronomy," which was held here last week. The debate surrounded the Thirty Meter Telescope (TMT), a massive observatory approved for construction on the Big Island of Hawaii. Specifically, it would join the astronomy-rich summit of Maunakea, sometimes written as Mauna Kea.
Astronomers say the instrument would offer deep insight into the earliest days of the universe and study mysteries like black holes and alien worlds. But a vocal subset of the native population of the Hawaiian Islands opposes the construction for a host of historical, cultural and environmental reasons. The dispute has reached such a tenor that some called the situation an "existential crisis" for astronomy.
Related: Thirty Meter Telescope: Hawaii's giant space eye (gallery)Complete coverage: The 235th American Astronomical Society meeting
The ongoing controversy came to a head last July, when TMT project leaders announced that they would begin construction. Kpuna native Hawaiian elders and others opposing the telescope flocked to Maunakea to block the road leading to the construction site and the dozen existing observatory facilities. Local and state officials dispatched law enforcement personnel and three dozen people were arrested.
Then, stalemate: For five months, TMT opponents calling themselves kia'i, or protectors, camped out on the road leading to the summit. Eventually, they agreed to allow staff up to the existing observatories via a side road. In December, David Ige, the governor of Hawaii, announced that he would temporarily withdraw law enforcement, since telescope construction wasn't in a state to proceed. Just after Christmas, the kpuna and kia'i moved to allow normal access to the summit, but they remained beside the road in case the situation changed again.
And then, five islands to the northwest and 6,500 feet lower in altitude, in the early days of the new year, 3,500 astronomers poured into Honolulu. They came armed with poster tubes and PowerPoint slides, ready to share and discuss a year's worth of scientific discoveries; among them were supporters and opponents of the TMT, as well as others who weren't sure either way.
The discussions unfurled throughout the conference and in a range of formats. On the opening morning of the conference (Jan. 5), about two dozen people greeted attendees in front of the convention center, demonstrating their support for the telescope with posters reading "Imua TMT," using a Hawaiian word that means to go forward.
But not all the discussions boiled down to such straightforward declarations. Near the end of the conference, a session that was a late addition to the program gave the podium to two kia'i. They shared with astronomers not their reasons for opposing the telescope, but the daily rituals they are following on Maunakea and an invitation to visit their roadside outpost.
That was a deliberate choice. "This is different, perhaps, from what you thought this would be," said Pua Case, a native Hawaiian who has been organizing against the TMT for a decade. "We're not presenting our side to get another side, we're not going to do that. You know why? Because we're meeting you for the first time, most of you."
Instead, she explained that they wanted to offer astronomers a glimpse into their world. "The way we create relationship is through ceremony, ritual, tradition, ancestral passing down of knowledge and protocol," Case said. That's also how the kia'i have arrived at their opposition of the project and how their daily prayers on the mountain continue their process of determining how to live with Maunakea. "We have no choice but to stand, so we're letting you know that," she said.
On all sides, speakers at the conference acknowledged how knotty they consider the situation to be. "One of the reasons why we're stuck is because the conversation has been restricted to a very small, binary choice," Greg Chun, a psychologist and native Hawaiian who currently leads Maunakea stewardship at the University of Hawai'i, which oversees the astronomy community's use of the mountain, said during a presentation. "We're also stuck because the ecosystem that we're trying to have this conversation is not set up to solve these problems."
"We're also stuck because everybody's right," Chun said. "Those people sitting in the middle of the road have suffered. I'm Native Hawaiian; I know the social and historical injustices and the impacts of those injustices. Similarly, TMT is right. They've done everything they're supposed to do legally."
For now, the uncertain truce on the mountain continues.
What comes next is less clear.
And the truce itself isn't very clear either, on closer inspection. Ige's statement on withdrawing law enforcement from the mountain in December read, "We made this decision after we were informed that TMT is not prepared to move forward with construction on Mauna Kea at this time."
But Gordon Squires, TMT's vice president for external relations, told Space.com that he wasn't sure how the withdrawal came about. "It wasn't initiated by us at all, although we're very hopeful that this opportunity, now this space has been created, is a space where something good will happen," he said.
As to when construction may resume, Squires called the late February time frame that has been discussed with equally vague origins realistic. And when asked how long TMT might be willing to wait to sort out the situation at Maunakea before moving the facility to another location, the answer was more uncertainty.
"I don't know. What I've been saying for the last few months, I guess, is we need to get started soon, but I don't know what soon means. I honestly don't know," Squires said. "Eventually, you need a home, and that time is coming where we can't continue in a place where we don't have a home to build the telescope."
Email Meghan Bartels at firstname.lastname@example.org or follow her @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.
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Posted: at 2:46 pm
The International Astronomical Unions Office of Astronomy for Development (IAU OAD) has concluded its eighth annual call for proposals.
According to a release by the organisation, it has selected a total of 17 projects for funding, including six projects from Africa. The final list of projects emerged after a thorough review and evaluation processes carried out in two stages by both officials of the IAU-OAD and an independent review panel. The Call had 107 applicants from all over the world narrowed down to 39 after the first stage, and finally to 17 projects.
The Astronomy for Development funds sponsor projects that will address challenges around the globe using astronomy-based interventions. The 17 selected projects will receive the sum of 110,834 to support and carry out their activities for the year.
Projects selected in Africa include an astronomy program coupled with counselling sessions to support children in internally displaced camps in Nigeria; various projects to inspire, stimulate, and educate children from poorer socio-economic backgrounds in South Africa and East African countries, including:
Astro Molo Mhlaba project targets the issues of inclusivity in South African science by engaging its most underrepresented group black girls from underserved communities in astronomy programs at various stages of education. The project provides these girls with tools and the motivation to be passionate about science, and to pursue a career in STEM.
The funding received by the project will cover the costs of continuing its programme in the schools where it is enrolled.
Hands-on Astronomy Curriculum Training for Primary and Secondary School Teachers (HOACTS) is a sustainable local socio-economic development workshop through Astronomy, designed to promote astronomy appreciation among primary and secondary school science teachers with Physics and Engineering education students.
The project aims to promote Astronomy awareness using the CBSS 15cm David Levy comet Hunter Optical telescope with deep sky imaging camera and the 15cm Lunt Solar Telescope alongside relevant observing filters and software. It also looks to promote indigenous design and fabrication of small locally made optical telescopes using the CBSS 3-D Printer.
The funding from OAD will finance a 6-day practical workshop targeting two different zones (Northern and Western)of the country.
IDP Childrens Astronomy Outreach aims to teach the children to embrace peace and togetherness by bringing in seasoned counsellors and professionals to be a part of the project.
In its activities for 2020, it will use Astronomy as a tool to educate participants. The project expects to install solar-powered learning hubs in an IDP camp in Garki area of Abuja.
LAMPS seeks to address misconception at grassroots levels by leveraging the existence of the future radio astronomy African VLBI Network (AVN) site in Arivonimamo, a rural town of around 30,000 population. Through Astronomy and STEM-oriented activities, it aims to promote STEM education; demonstrate the relevance of STEM for local socio-economic development; inform learners on the importance of Astronomy and STEM fields in daily life, and encourage them to pursue STEM-oriented studies and careers.
LAMPS is a two-stage outreach led by Ikala STEM, an association of women in STEM from Madagascar.
The project strives to strengthen the east Africa region astronomical community partnership via science diplomacy. It also aims to deliver short-term training that focuses on improving skills and competitiveness of careers of BSc and MSc graduates and students in astronomy and science-related fields.
EA-SA training incorporates how to use, practice and apply astronomical instruments, astronomical software, big data analysis and science communication skills. These skills, it believes, applies to multi-sector fields at governmental and industry level, that fits the modern technology and global market demand.
The Networking and Skilling In Astronomy Project is a capacity-building project with a focus on a program that will be integrated into the existing Masters or Bachelors programmes in Physics and Mathematics. The project also involves all key actors (university students, teachers, secondary teachers, and amateur astronomers) in the process.
Funds received from OAD will go into 6-days training sessions focused around two themes:a) acquiring astronomical data remotely with Astrolab,b) data processing using the python programming language with the library Astropy.
The IAU is the international astronomical organisation that brings together about 13,000 distinguished astronomers from around the world. Its mission is to promote and safeguard the science of astronomy in all its aspects through international cooperation. The IAU also serves as the internationally recognised authority for assigning designations to celestial bodies and the surface features on them. Founded in 1919, the IAU is the worlds largest professional body for astronomers.
The IAU established the Office of Astronomy for Development (OAD) in partnership with the South African National Research Foundation (NRF), and supported by the South African Department of Science and Innovation. The OAD, located at the South African Astronomical Observatory (SAAO) in Cape Town, South Africa, aims to help further the use of astronomy, including its practitioners, skills and infrastructures, as a tool for development.
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Department of Physics and Astronomy and the Health Professions Program Joint Colloquium – My Journey in Becoming a Hand and Upper Extremity Surgeon,…
Posted: at 2:46 pm
My Journey in Becoming a Hand and Upper Extremity Surgeon
Bilal Mahmood, M.D. (U'08)
Assistant Professor, Department of Orthopaedics, University of Rochester Medical Center
At Union, I majored in Mathematics and Physics. I've always considered the purity of mathematics unrivaled in all the sciences, with physics its closest sibling. The physics department remained home-base, thanks in large part to the welcoming nature of Colleen Palleschi, the department's administrative assistant. I was privileged to do research with Professors Koopmann and Newman, and truly enjoyed my time in the department. I decided to pursue medicine while a second year. It wasn't until the beginning of fourth year in medical school that I settled on Orthopaedic Surgery. Once in residency, it did not take long to focus in on Hand Surgery as a subspecialty. Formalized in World War II, Hand Surgery developed as a distinct subspecialty because of the mixture of orthopaedics, plastics, general surgery, neurosurgery, vascular surgery, micro surgery, and even psychiatry involved. A hand surgeon is responsible for the musculoskeletal system, soft tissue, vascular system, and peripheral nerves. The idea of being fully responsible for one part of the body and providing complete care was my reason for choosing Hand Surgery. In this talk, I will share my journey in becoming a hand surgeon. I will show my day to day life, and show common as well as interesting cases in Hand and Upper Extremity Surgery.
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Posted: at 2:46 pm
Vera Rubin, a young astronomer at the Carnegie Institution in Washington, was on the run in the 1970s when she overturned the universe.
Seeking refuge from the controversies and ego-bashing of cosmology, she decided to immerse herself in the pearly swirlings of spiral galaxies, only to find that there was more to them than she and almost everybody else had thought.
For millenniums, humans had presumed that when we gaze out at the universe, what we see is a fair representation of reality. Dr. Rubin, with her colleague Kent Ford, discovered that was not true. The universe all those galaxies and the vast spaces between was awash with dark matter, an invisible something with sufficient gravity to mold the large scale structures of the universe.
Esteemed astronomers dismissed her findings at first. But half a century later, the still futile quest to identify this dark matter is a burning question for both particle physics and astronomy. Its a pursuit that stretches from underground particle colliders to orbiting telescopes, with all manner of ground-based observatories in between.
Last week the National Science Foundation announced that the newest observatory joining this cause will be named the Vera C. Rubin Observatory. The name replaces the mouthful by which the project was previously known: the Large Synoptic Survey Telescope, or L.S.S.T.
The observatory, jointly financed by the N.S.F. and the Department of Energy, under construction on a mountain called Cerro Pachon, in Chile, will begin operating in 2022. By recording images of the entire sky every few days, it will produce a time-lapse movie of the universe.
It is the first national observatory to have been named for a woman, the announcement said. Named after an astronomer who provided important evidence of the existence of dark matter, wrote France Crdova, the Foundations outgoing director, the NSF Vera C. Rubin Observatory seems destined to make science history with its extraordinary capabilities that will come to bear in the next few years.
The Rubin Observatory joins a handful of smaller astronomical facilities that have been named for women. The Maria Mitchell Observatories in Nantucket, Mass., is named after the first American woman to discover a comet. The Swope telescope, at Carnegies Las Campanas Observatory in Chile, is named after Henrietta Swope, who worked at the Harvard College Observatory in the early 20th century. She used a relationship between the luminosities and periodicities of variable stars to measure distances to galaxies.
And finally there is the new Annie Maunder Astrographic Telescope at the venerable Royal Greenwich Observatory, just outside London. It is named after Annie Maunder, who with her husband Walter made pioneering observations of the sun and solar cycle of sunspots in the late 1800s.
Heros of science, all of them.
In a field known for grandiloquent statements and frightening intellectual ambitions, Dr. Rubin was known for simple statements about how stupid we are. In an interview in 2000 posted on the American Museum of Natural History website, Dr. Rubin said:
In a spiral galaxy, the ratio of dark-to-light matter is about a factor of 10. Thats probably a good number for the ratio of our ignorance to knowledge. Were out of kindergarten, but only in about third grade.
Once upon a time cosmologists thought there might be enough dark matter in the universe for its gravity to stop the expansion of the cosmos and pull everything back together in a Big Crunch. Then astronomers discovered an even more exotic feature of the universe, now called dark energy, which is pushing the galaxies apart and speeding up the cosmic expansion.
These discoveries have transformed cosmology still further, into a kind of Marvel Comics super-struggle between invisible, titanic forces. One, dark matter, pulls everything together toward its final doom; the other, dark energy, pushes everything apart toward the ultimate dispersal, some times termed the Big Rip. The rest of us, the terrified populace looking up at this cosmic war, are bystanders, made of atoms, which are definitely a minority population of the universe. Which force will ultimately prevail? Which side should we root for?
Until recently the money was on dark energy and eventual dissolution of the cosmos. But lately cracks have appeared in the data, suggesting that additional forces may be at work beneath the surface of our present knowledge.
The discoverers of dark energy won the Nobel Prize in 2011. So far, dark matter has not been so honored. Dr. Rubin was perennially mentioned as a possible candidate for the prize. But she died in 2016, a poster child for the consistent failure lamented every October, when the prizes are announced of the Nobel committee to honor women, and of the general struggle of women in science to receive respect and opportunity.
Once, summoned to a meeting with an eminent astrophysicist, Dr. Rubin arrived to be told they would have to talk in the lobby, because women were not allowed upstairs in the offices. Years later, when she finally gained access to the 200-inch Palomar telescope in California, she found that there was no womens restroom there. So she taped an outline of a womens skirt over the image of the man on the door, turning it into a ladies room.
Now she has an observatory of her own. Among its main missions, the Rubin Observatory will investigate the cosmic push-pull between dark matter and dark energy, peeling back layers of the sky and of the past. Its data will chart how fast clusters of galaxies (drawn together by dark matter gravity) have grown over cosmic time, and how fast the spaces between these clusters (created by the push of dark energy) have grown as the universe has expanded.
The Rubin Observatory is expected to significantly advance what we know about dark matter and dark energy, Dr. Crdova said. So the Rubin name will have yet another way to inspire women and men eager to investigate. Dr. Crdova went on to praise Congress, which has steadfastly defended the foundations budget against White House cuts over the last few years.
Natalie Batalha, an astronomer at the University of California, Santa Cruz, who was one of the leaders of NASAs Kepler planet-hunting space mission, said, Its heartening and highly appropriate to see Vera Rubin honored in this way.
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Posted: at 2:45 pm
This looping animation depicts a southwesterly view one hour after sunset from 1331January 2020 at two-day intervals as seen from the heart of the UK. Dazzling magnitude-4.1 Venus passes just 4arcminutes (one-fifteenth of a degree) south of Neptune at 8pmGMT on Monday, 27January 2020, so both planets will fit in the same high-power telescope view from 6pmGMT until they set. Dont miss magnitude+4.2 naked-eye star Phi()Aquarii that lies within 0.9 east of magnitude+7.9 Neptune throughout the period. Note that the Moons apparent size on 27 and 29January is enlarged for clarity. AN animation by Ade Ashford.Even casual skywatchers cannot fail to notice brightest planet Venus currently hanging like a lantern above the southwest horizon at nautical dusk, which is presently about 6pmGMT for the centre of the British Isles. On 11January, Venus crossed the constellation border into Aquarius where it resides for the remainder of the month.
Neptune also currently lies in the constellation of Aquarius. Since the outermost planet shines at magnitude +7.9, its too faint to see with the naked eye, but it is a viable binocular target if you know where to look. Fortunately for skywatchers, Venus makes an increasingly convenient celestial signpost to Neptunes position as the gap between them closes throughout this month, culminating in a close conjunction on 27January 2020.Venus passes one-fifteenth of a degree south of Neptune at 8pmGMT at 27January 2020, but the pair will be very low in the UK sky. Observers in the British Isles are advised to look at 6pmGMT around the onset of nautical twilight when the two planets are about 19 high in the southwest. Their separation is slightly more than 7arcminutes at this time. In this simulated one-degree telescope field of view the magnification is 40-50. AN graphic by Ade Ashford.While there will no difficulty in identifying Venus in your telescope on the evening of 27January, Neptune may prove a little more difficult to see in the glare of its planetary sibling. Their difference amounts to a whopping 12 magnitudes, which is another way of saying that Venus is 63,000 times brighter than Neptune! If the outermost planet is lost in Venus dazzle, try to spot magnitude +4.2 star Phi()Aquarii in the same field of view shown above.
Venus narrowly misses PhiAquarii, passing just 56arcseconds south of the star at 05:20UT (5:20amGMT) on 28January. Sadly, this event will not be visible from Western Europe as the timing favours the North Pacific Ocean and the Hawaiian Islands. Neptune has its own close encounter with the star, passing just 2arcminutes north of PhiAquarii at 8:15pmGMT (20:15UT) on 10February 2020; observers in the UK can see the conjunction low in the west-southwest shortly after 6pmGMT that night.
Returning to this month, if you do succeed in viewing Venus and Neptune in the same telescope field of view, do bear in mind that their apparent proximity is merely a line of sight effect. On the evening of 27January, Venus lies a little more than 167million kilometres (or 1.117 astronomical units) from Earth, but outermost planet Neptune is a staggering 4,590million kilometres (or 30.683 astronomical units) distant.
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Posted: at 2:45 pm
Astronomers have detected five new planets, eight planet candidates, and confirmed three previously reported planets, around nine nearby M-dwarf (red dwarf) stars. Among the new planets, Gliese 180d and Gliese 229Ac are super-Earths located in the conservative habitable zones of their host stars; Gliese 433c is a cold super-Neptune candidate belonging to an unexplored population of Neptune-like planets.
An artists concept of the Gliese 180 planetary system, which is located 39 light-years away in the constellation of Eridanus. Image credit: Robin Dienel, Carnegie Institution for Science.
M-dwarfs are the most common stars in our Milky Way Galaxy and the primary class of stars known to host terrestrial planets.
The first terrestrial-mass planet was found around the M-dwarf Gliese 876.
Over the past decade M-dwarfs have been the principle targets for potentially habitable planets because their habitable zones are much closer to the star, and thus the potentially habitable planets have much shorter periods than those orbiting around Sun-like stars.
Many planets that orbit red dwarfs in the habitable zone are tidally locked, meaning that the period at which they spin around their axes is the same as the period at which they orbit their host star, said lead author Dr. Fabo Feng, an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Science.
This is similar to how our Moon is tidally locked to Earth, meaning that we only ever see one side of it from here.
As a result, these exoplanets are a very cold permanent night on one side and very hot permanent day on the other not good for habitability.
Gliese 180d is the nearest temperate super-Earth to us that is not tidally locked to its star, which probably boosts its likelihood of being able to host and sustain life, he added.
Gliese 180d has a minimum mass of 7.49 times that of Earth and an orbital period of 106 days.
An artists concept of Gliese 229Ac, which is located 18.8 light-years away from Earth. It is the nearest temperate super-Earth to us that is in a system in which the host star has a brown dwarf companion. Image credit: Robin Dienel, Carnegie Institution for Science.
The other potentially habitable planet, Gliese 229Ac, is 7.93 times more massive than Earth. It orbits its parent star once every 122 days.
It is the nearest temperate super-Earth to us located in a system in which the host star has a brown dwarf companion.
The brown dwarf in this system, Gliese 229B, was one of the first brown dwarfs to be imaged.
It is not known if they can host exoplanets on their own, but this planetary system is a perfect case study for how exoplanets form and evolve in a star-brown dwarf binary system.
Our discovery adds to the list of planets that can potentially be directly imaged by the next generation of telescopes, Dr. Feng said.
Ultimately, we are working toward the goal of being able to determine if planets orbiting nearby stars host life.
The Neptune-mass planet Gliese 433c orbits its star at a distance at which surface water is likely to be frozen.
This planet is probably the first realistic candidate for direct imaging of cold Neptunes.
The team also detected three planets Gliese 422b, 433d, and 3082b and seven planet candidates Gliese 173b, 229Ab, 620b, 620c, 739b, 739c, and 911b.
We eventually want to build a map of all of the planets orbiting the nearest stars to our own Solar System, especially those that are potentially habitable, said co-author Dr. Jeff Crane, an astronomer at the Observatories of the Carnegie Institution for Science.
The findings appear in two papers in the Astrophysical Journal Supplement Series and the Astronomical Journal.
Fabo Feng et al. 2020. Search for Nearby Earth Analogs. II. Detection of Five New Planets, Eight Planet Candidates, and Confirmation of Three Planets around Nine Nearby M Dwarfs. ApJS 246, 11; doi: 10.3847/1538-4365/ab5e7c
R.P. Butler et al. 2019. A Reanalysis of the UVES M Dwarf Planet Search Program. AJ 158, 251; doi: 10.3847/1538-3881/ab4905
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Astronomers Detect Radiation Stimulated By Heatwave Of Intense Thermal Energy From A Massive New-born Star – Space in Africa
Posted: at 2:45 pm
The Milky Way Galaxy contains billions of massive bright stars. These high-mass stars have masses ranging from tens to hundreds of times the mass of the Sun. Their existence plays a role which is paramount in astrophysics.
They end their lives as supernovae which dramatically influences their environment. Yet, how they form still remains a mystery. The best current theories predict an upper limit of only about eight times the mass of the Sun.
For these stars, this leads to a discrepancy between theory and observation, which resulted in several competing theories emerging to explain this. One prominent emerging theory proposes that high-mass stars achieve their final mass from bursts of episodic accretion onto the protostar to achieve its final mass.
This theory predicts short-lived, intense accretion bursts through which the protostar gains mass from its surrounding accretion-disk, followed by long periods of inactivity, possibly lasting hundreds to thousands of years. In January 2019, astronomers at Ibaraki University in Japan noticed that one such massive protostar, G358-MM1, showed signs of new activity indicative of a potential accretion burst.
In response, a collaboration of astronomers, the Maser Monitoring Organization (M2O), gathered several radio telescopes from Australia, New Zealand and South Africa (HartRAO) to form a telescope array capable of detecting small-scale emission stimulated by the heat of the accreting protostar.
The team, led by Dr Ross Burns (NAOJ and JIVE), compared multiple images over the span of a month which revealed a heat-wave of energy radiating outward from the location of G358-MM1. According to Dr Fanie van den Heever (HartRAO/SARAO, South Africa), the observations made by M2O is the first real-time evidence supporting the episodic accretion theory for high-mass star formation.
The global community of astronomers, astrophysicists and theoreticians are benefiting tremendously from the work done by M2O and the recent results obtained by this group. The paper was published in Nature Astronomy on Monday, 13 January 2020.
About the authors
The work is led by Dr Ross Burns in collaboration with other M2O members. Dr Burns is affiliated to the National Astronomical Observatory of Japan (NAOJ) and the Joint Institute for VLBI in Europe (JIVE).
The South African contributors include:
Credit to Katharina Immer, affiliated with JIVE, for the artists impression.
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Posted: at 2:45 pm
PUBLISHED: 06:30 15 January 2020
(Original Caption) William Herschel (1738-1822), famous astronomer discovering the planet Uranus. He is assisted by his sister, Caroline Lucretia (1750-1848).
The great European astronomer Caroline Herschel discovered more than eight comets. CHARLIE CONNELLY adds to her star-borne legacy
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"At the heavens there is no getting, for the high roofs of the opposite houses." It was Boxing Day, 1822, when Caroline Herschel wrote these words in a letter to her nephew. She was 72 years old and had recently returned to her home town of Hannover after spending 50 years in England becoming one of the most important women in the history of astronomy. The discoverer of eight comets and a visionary cataloguer of the heavens, she had spent countless nights squinting through her one good eye into a telescope, sweeping the night's canopy for uncharted stars or the tell-tale twinkle of a new comet arcing through distant skies.
The death four months earlier of her brother William, founding president of the Royal Astronomical Society and since 1782 the King's Astronomer, with whom she had worked tirelessly for half a century, affected her deeply. It was grief that prompted the ill-judged decision to abandon England and return to the town where she had spent her formative years. Being away from the telescopes she had helped William to build was one thing, being crowded out of the night sky altogether by the tall Hannoverian buildings only increased her sense of ennui. She could barely see the moon.
Today there is a crater in the bed of the moon's Sea of Showers named for Caroline Herschel and the comet 35P/Herschel-Rigollet that passes within sight of the Earth every 155 years is also a tribute to her work. Back on Earth, in 1838 she became the first woman to receive the gold medal awarded by the Royal Astronomical Society - it would be 158 years before another woman received the award - and in 1846, her 96th year, she received a Gold Medal for Science from the King of Prussia, recognising her "valuable services to astronomy" rendered by "discoveries, observations, and laborious calculations".
Such honours still lay ahead of her as she cricked her neck at the window trying to see the stars that first Christmas without her brother in a land at once familiar yet strange: Hannover had changed almost beyond recognition in 50 years. Without her beloved brother, blocked from the stars and having already lived to a grand age, she must have felt as if her time was almost up but, as ever, Caroline Herschel wasn't done yet. She would live for another 26 years, still making a valuable scientific contribution through cataloguing and interpreting data even if she couldn't scan the heavens herself.
Such longevity was unthinkable when at the age of 10 she contracted typhus. Ill for months, sometimes dangerously so, the fact she only grew to be 4ft 3in was attributed to a disease that also deprived her of the sight in her left eye. For her mother Anna this meant only one thing: this daughter, her eighth child, would never marry and from an early age Caroline was prepared for life as a housemaid. Educating her would be a waste of time and money.
Her father Isaac disagreed. An oboist and conductor in the military, he recognised Caroline's intelligence and sought to encourage it. Long absences from a home where his wife ruled the roost frustrated attempts to give his daughter options, however. And, despite his teaching her whenever he had the chance, by the time she embarked on her twenties Caroline's only significant education was as a seamstress. When Isaac died in 1772 it appeared her course was set but William, 12 years her senior and a music teacher in Bath, had other ideas. He sensed his sister's melancholy from her letters and returned to Hannover determined she would accompany him to England where he would train her as a singer. It took several weeks to persuade Anna but on August 16, 1772, Caroline crossed the English Channel to a new life, aiming to "make the trial if by his instruction I might not become a useful singer for his winter concerts and oratorios".
William sought to coax the potential he'd recognised from a woman conditioned to believe she was practically worthless. Noting a nascent talent he coached her tirelessly and before long Caroline was a well-regarded soprano performing with him in the concert halls and salons of Bath and Bristol, taking leading roles in major works like Handel's Messiah.
Performing in public could not shift entirely the conditioning that had battered her self-esteem, however, and whenever other impresarios or conductors would approach her with offers of roles she would refuse them all. The thought of singing under anyone but her brother terrified her. Thus when William eventually abandoned music for his new passion of astronomy in the late 1770s it spelt the end of Caroline's singing career. He'd been spending spare evenings engrossed in books about the stars, repeating what he'd learned the previous night to his sister over breakfast. She absorbed everything. Before long he was enlisting Caroline's help in grinding and polishing lenses for the telescopes he was building and made Caroline his assistant, calling out his observations to her from his seat at the telescope to record in the copious notebooks she would fill for the rest of her life. Caroline was no mere stenographer, however. The data she was recording required advanced mathematical skills to interpret, something that came to her quite naturally.
By the turn of the 1780s, thanks in no small part to Caroline's labours with grinder and pen, William was able to abandon music altogether, discover the planet Uranus and be appointed to the post of King's Astronomer. Prestigious though the role was it had its drawbacks. Not only was it a reduced salary from his musical activities, the job necessitated a move closer to George III's royal residence at Windsor as the King's Astronomer was required to be available at the whim of the monarch. The Herschels moved first to Datchet and then to the observatory at Slough, and while Caroline was never a mainstay of Bath society the contrast between the lively, cultured city and the provincial backwater that became her home was marked.
She combatted loneliness and isolation by working tirelessly, sometimes at great physical cost. On New Year's Eve 1782 she was badly injured during a nocturnal observation, impaling her leg on an iron hook as William called for her to adjust the angle of his 40-foot telescope.
"[William] and the workmen were instantly with me but they could not lift me without leaving nearly two ounces of my flesh behind," she wrote later. "A workman's wife was called but was afraid to do anything and I was obliged to be my own surgeon by applying aquabusade and tying a kerchief about it for some days till Dr Lind, hearing of my accident, brought me ointment and lint, and told me how to use them."
The doctor told William later that "if a soldier had met with such a hurt he would have been entitled to six weeks' nursing in a hospital". Caroline Herschel was back recording observations within a couple of days. When William married a local widow in 1783 it could have exacerbated the dislocation Caroline felt in Berkshire. Instead she grasped her new intellectual freedom and gradually felt confident enough to begin making her own observations. "It was not till the last two months of the same year before I felt the least encouragement for spending the starlit nights on a grass-plot covered by dew or hoar frost without a human being near enough to be within call," she wrote of work she would come to describe as 'minding the stars'.
Within three years she had become the first woman to discover a comet and in 1796 became the first woman scientist to receive a salary when George III awarded her an annual stipend of 50. That year she commenced work on her other great achievement: reworking and updating John Flamsteed's 1725 British Catalogue of the stars he had observed from the Royal Observatory at Greenwich. It took nearly two years but Caroline Herschel's Catalogue of Stars not only corrected many errors but introduced 560 new heavenly bodies in a work that remains a valuable resource today.
Even when she returned to Hannover she kept up her cataloguing work, reorganising, correcting and indexing notebooks for her nephew and fellow astronomer John Herschel. Despite her clear gifts and achievements, the early intellectual and social stifling by her mother left Caroline's self-confidence in tatters for the rest of her life. When invited to the Royal Observatory at Greenwich by the Astronomer Royal Nevil Maskelyne during the 1790s she told him, "I am nothing. I have done nothing". She did add, however, that the invitation had "flattered my vanity", before adding revealingly that "among gentlemen this commodity is generally styled 'ambition'".
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Posted: at 2:45 pm
UCLA researchers have found that the black hole at the center of our galaxy may have a companion.
Many researchers currently believe that all stars in the Milky Way orbit a single supermassive black hole, known as Sagittarius A*. However, a recent UCLA-led study published in December discovered that a second black hole may exist alongside it.
Smadar Naoz, an associate professor of physics and astronomy at UCLA and the lead author of the paper, said most galaxies evolve by merging with other galaxies. As the majority of galaxies have a supermassive black hole at their centers, a galaxy could have multiple black holes at its center after merging with another galaxy, she added.
Its a cannibalism of galaxies, and if theres a supermassive black hole at the center of each galaxy, then just from gravity they will sink into the center, Naoz said.
Since researchers know theres a black hole in the center of the Milky Way, they expect that the black hole either had a younger sibling in the past or has one currently, Naoz said. She added that Sagittarius A* is unique because of its proximity to Earth.
Its a great lab to go and try to understand things that we have no chance of even detecting in other galaxies, Naoz said.
Clifford Will, a distinguished professor of physics at the University of Florida and a co-author of the study, said if there were a companion to Sagittarius A*, then its gravity would affect the orbits of the stars revolving around it, which is how researchers would find if there is a second black hole.
If there is a companion black hole to the big black hole that we know is there, its gravitational tug would perturb the orbits of the stars that we know are orbiting that black hole, Will said. Just the same way that the orbit of Jupiter perturbs the orbit of Uranus because Jupiter has its own gravitational attraction.
Tuan Do, a research scientist and deputy director at the Galactic Center Group at UCLA and a co-author of the study, said understanding this process is interesting because it is one of the ways black holes can grow. He added it is also interesting because when two black holes merge, they produce a lot of gravitational waves.
Will added that finding a companion black hole, or finding an absence of one, will lead to interesting insights about the Milky Ways past. If a second black hole is found, then the discovery could point out other processes that produce black holes in the center of existing galaxies. Additionally, the discovery could challenge current ideas of galaxy mergers, Will said.
Naoz said an absence of an additional black hole would mean that the Milky Way has not had any major mergers for about 10 million years. Sagittarius A* is only about 4 million solar masses, which means 4 million times the mass of the sun.
Our supermassive black hole is not one of the larger ones, Naoz said. So its not a bonafide billion. If we had any merger in the past, it was a minor merger. That means that smaller flimsy galaxies came to merge with us.
Naoz said they used measurements of the brightest star orbiting Sagittarius A*, called SO-2, to predict how the star should move going forward if there were a second black hole within its orbit. She added the environment at the galaxys center is very dense and the second black holes gravity should affect the orbits of these stars if it exists.
Between Earth (or) our solar system and the closest star, there is nothing, there are no more stars, Naoz said. But in the same distance, around the supermassive black hole, there are millions of stars. Thats how dense this place is.
Do added that SO-2s orbit around Sagittarius A* looks like an ellipse that slightly rotates every time the star completes one revolution. This motion is called precession, he said.
Naoz said precession resembles a flower pattern. If there was a second source of gravity affecting the orbits, she said, then this pattern would wobble slightly, creating a flower crown.
Using measurements of the orbit, Naoz said they could comfortably tell where the second black hole cannot be, as well as its range of mass.
We have a part of the parameter of space and mass and the separation (between) the supermassive black hole and its friend, (within which) its fair game, Naoz said. It can be there.
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