Daily Archives: May 23, 2017

Cygnus A is an elliptical galaxy nearly 800 million light-years from Earth. In its center is a supermassive black hole at least a billion times the mass of our Sun, which appears to have recently gained a companion. New observations of this galaxy with the National Science Foundations Very Large Array (VLA)have unveiled a second bright object located near its central supermassive black hole an object that radio astronomers think is a second supermassive black hole, destined to merge with the first.

Based on radio observations taken with the VLA in 2015 and 2016, astronomers have spotted a new object within 1,500 light-years of the galaxys supermassive black hole. This object was not visible in previous radio images of the galaxy, the most recent of which prior to the discovery were taken in 1996. It wasnt until recent upgrades were made to the VLA in 2012 that observers considered a return to this famous galaxy, which was discovered by radio astronomy Grote Reber in 1939.

To our surprise, we found a prominent new feature near the galaxys nucleus that did not appear in any previous published images. This new feature is bright enough that we definitely would have seen it in the earlier images if nothing had changed, said Rick Perley of the National Radio Astronomy Observatory (NRAO) in a press release announcing the discovery. That means it must have turned on sometime between 1996 and now.

The new radio observations were made by a group of astronomers that included Perley and his son, Daniel Perley of the Astrophysics Research Institute of Liverpool John Moores University in the U.K., as well as NRAO researchers Vivek Dhawan and Chris Carilli. The results will be published in theAstrophysical Journal.

Following their 2015-2016 observations, the team used the Very Long Baseline Array in late 2016 to more clearly separate the new object from the galaxys previously known supermassive black hole. The new object also shows up in infrared images taken with the Hubble Space Telescope and at the Keck Observatory between 1994 and 2002, when it was originally thought to represent a dense group of stars. But the fact that the object has grown brighter in radio wavelengths since then has prompted new consideration.

Now, there are two possibilities based on the data: The new object is either a supernova explosion or a supermassive black hole. Supernovae are massive stellar explosions that are easily seen in distant galaxies. However, Because of this extraordinary brightness, we consider the supernova explanation unlikely, Dhawan said. The object is both too bright and has remained visible for too long to fit any current known supernova type.

Thus, said, Carilli, We think weve found a second supermassive black hole in this galaxy, indicating that it has merged with another galaxy in the astronomically recent past. These two would be one of the closest pairs of supermassive black holes ever discovered, likely themselves to merge in the future.

What does that kind of merger look like? At least two possibilities have recently come to light: the recoiling black holes CXO J101527.2+625911 and 3C 186.

So if this object is a billion-solar-mass black hole, why wasnt it obvious before now? It may not have been as active, and only recently come into contact with new material, such as stars or dust, to accrete, causing it to turn on and give off observable radiation. Further observations will help us resolve some of these questions. In addition, if this is a secondary black hole, we may be able to find others in similar galaxies, said Daniel Perley.

Rick Perley was among the astronomers responsible for the very first observations of Cygnus A when the VLA first came online in the early 1980s. These observations provided the detail necessary for astronomers to begin understanding how supermassive back holes produce jets of materials that can span regions of space larger than their host galaxies. At the time, Daniel was only two years old.

The VLA images of Cygnus A from the 1980s marked the state of the observational capability at that time, said Rick Perley. Because of that, we didnt look at Cygnus A again until 1996, when new VLA electronics had provided a new range of radio frequencies for our observations.

But now that these newest observations have revealed a surprise, Daniel Perley said, This new object may have much to tell us about the history of this galaxy.

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A familiar galaxy with a new surprise: Two supermassive black holes - Astronomy Magazine

Ever since NASA announced that the TRAPPIST-1 system had seven planets instead of the original three, scientists have been interested in learning more about the bizarre system. Now after much research and some suspected details, scientists have found orbital details about the systems farthest planet, TRAPPIST-1h.

Using data from the Kepler spacecraft, scientists studying the exoplanets have confirmed that the outermost planet, about six million miles from the TRAPPIST-1, has a 19-day orbit around its host star.

Studying data from the Spitzer Space Telescope, the team noticed a predictable pattern, also called an orbital resonance, among the first six planets in the system. An orbital resonance is when orbiting bodies show a consistent gravitational influence on each other, like how Jupiters moon Europa orbits twice in the same length of time Ganymede takes to complete four orbits.

The team then used the Spitzer data to calculate six potential resonant periods. After gathering more data, only one of those potential periods remained.

"All of this indicates that these orbital relationships were forged early in the life of the TRAPPIST-1 system, during the planet formation process, Rodrigo Luger, a doctoral student at UW in Seattle and lead author of the study, said in a press release. "The resonant structure is no coincidence, and points to an interesting dynamical history in which the planets likely migrated inward in lock-step. This makes the system a great laboratory for planet formation and migration theories.

NASA has had its eye on the seven-planet system, which orbits the ultracool dwarf star TRAPPIST-1, since December 2016. The system is somewhere between 3 and 8 billion years old. It was originally thought to only have three planets until Spitzer data revealed four additional planets.

NASAs Hubble Space Telescope is now looking for more information about the planets' atmospheres; when the James Webb Space Telescope launches in October 2018, it will join the search for information about TRAPPIST-1.

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Astronomers know TRAPPIST-1h's orbit - Astronomy Magazine

More than four decades ago, astronomers discovered the first gamma-ray emission coming from outside the solar system. This high-energy signal is associated with the destruction of roughly 1043 positrons a type of antimatter each second. Despite extensive follow-up, astronomers today are still looking for the exact source (or sources) of this emission, which could run the gamut from mundane (natural processes in a stars life) to exotic (dark matter) origins. Recently, a group of astronomers has determined that positrons resulting from white dwarf mergers could contribute significantly to the signal we see.

The emission associated with galactic positron annihilation occurs when a positron meets its counterpart, an electron, destroying both particles in the process. Thus, this emission requires a ready source of antimatter, which has remained mysterious ever since its initial detection.

Measurements suggest that the signal is nearly one and a half times higher in the bulge, or central regions of the Milky Way, than in the arms. This particular aspect of the emission has led to the development of several models that speculate an overabundance of positrons in this area could be due to processes related to dark matter or our galaxys central supermassive black hole. However, many astronomers are still searching for less exotic ways the positrons were seeing undergo annihilation could be produced.

In a paper published May 22 in Nature Astronomy, first author Roland M. Crocker of the Research School of Astronomy and Astrophysics at Australian National University and his co-authors examine a possible stellar source of galactic positrons that could be responsible for the signal: white dwarf mergers.

White dwarfs are the remnant cores of Sun-like stars, left behind after the star runs out of fuel and dies. If two low-mass stars (between about 1.4 and 2 times the mass of our Sun) circle each other closely in a binary system, they can interact via a process called mass transfer, where gas from the stars is exchanged. The end result is two white dwarfs that may eventually merge, and that merger can result in the production of radioactive isotopes that decay into positrons.

There are several clues that have led Crocker and his co-authors to this conclusion. The ratio of the signals strength in the bulge and arms is similar to the ratio of the stellar mass (essentially the number of stars) in these two structures as well. This led the astronomers to consider that the positron production could be related to an older stellar population, such as white dwarfs. Additionally, by looking at the processes that produce positrons through radioactive decay, they determined that the decay of 44Ti into positrons is the most likely source.

However, this material is not produced in sufficient amounts in most core collapse supernovae, which occur when a massive star reaches the end of its life. While supernovae triggered by the merger of two white dwarfs are much rarer, these events should produce more 44Ti per merger, which would then decay and produce the number of positrons required to create the emission line from their subsequent annihilation.

The current resolution of instruments used to study this emission is not high enough to find point sources, such as individual supernova remnants, in the bulge. Thus, more precise measurements and computer simulations will be needed to determine the positron production rates from such events. The authors also state that white dwarf mergers are likely not the only source of antimatter in our galaxy, which still includes contributions from massive stars and black holes, even if dark matter is eventually ruled out as a viable source for this emission.

Read more here:

Merging white dwarfs may create most of our galaxy's antimatter ... - Astronomy Magazine

[The moon of the distant object 2007 OR10 was spotted in Hubble images from 2009 and 2010. Credit:NASA,ESA, C. Kiss (Konkoly Observatory), and J. Stansberry (STScI)]

To be honest, theres not a huge amount we know about the distant solar system object provisionally named (225088) 2007 OR10. But nowwe know something new: It has a moon.

Thats actually very cool. And terribly important. Or it will be, soon.

Let me sum up. No, it is too important. Let me explain.

2007 OR10 is a member of our solar system, a world orbiting well past Neptune. And by well, I mean well: The closest it ever gets to the Sun is about 5 billion kilometers, roughly the same distance out as Pluto. But its orbit is very elliptical, and at its furthest, it gets 15 billion kilometers from the Sun. Thats a long, long way.

Which to be fair, is why we dont know much about it. Right now its about 13 billion km out. Thats a tremendous distance, making it difficult to observe. Heck, it was only discovered in 2007.

Besides its orbit,we know its very red; observations of it using different filters (as well as spectra; that is, breaking its light up into individual colors) indicate its much better at reflecting red light than blue. This happens a lot with worlds out in the distant solar system: The simple molecule methane breaks down when exposed to the ultraviolet light from the Sun, then build back up into more complex molecules called tholins, which can be various shades of red and brown. We see this on Pluto, for example, and OR10 is the right size and distance from the Sun to undergo this as well.

Its size can be estimated by its brightness ... though thats not easy. If you use visible light its hard; it could be small and shiny or bigger and dark. However, this can be nailed down by looking in the infrared, where warm objects emit light in well-understood ways. From those observations, OR10 was previously found to be about 1535 km (960 miles) across, about half the diameter of Earths moon. That makes it the third largest object in this region of the solar system known; only Pluto and Eris are known to be bigger.

Interestingly, every object in the solar system out past Neptune (called Trans Neptunian Objects or TNOs) bigger than 1000 km in size has been found to have at least one moon. It would actually be rather weird if OR10 didnt. Not only that, but careful measurements of its brightness over time showed it had a rotation period (a day) of about 45 hours, which is much longer than average for most TNOs (which are usually around 24 hours). A moon can interact gravitationally with its primary to slow the spin via tides, so astronomers got suspicious. Does OR10 have a moon?

Thats why a group of astronomers looked through archived observations of OR10 made by Hubble back in 2009 and 2010. Careful examination of the data revealed that yes, OR10 has a moon, so faint it was missed in previous analysis(Note: the moon was actually announced in 2016 at a conference; this news announcement coincides with the release of the official scientific paper)!

The moon is about 240 km (150 miles) across, so its pretty big compared to OR10...assuming its about the same composition and reflectance (that is, red). If its more reflective it could be smaller. Ill note that Plutos moon Charon is much darker than Pluto, so its possible the calculated diameter of OR10s moon will change with further observations.

Unfortunately, the moon is only seen in a handful of images (theres one set of observations made in 2009 and another in 2010). Thats not enough to determine its orbit, and thats the most critical aspect of all this! Why?

Once you can calculate the orbit of the moon, you can also find the mass of both objects. Thats huge! If we know the size and the mass, that means we can calculate the density, and that tells you (at least in part) what the objects are made of. Water ice, for example, is less dense than rock. A mix of the two would have a density somewhere in between. So seeing the moon move around enough to determine the orbit leads to great things.

I find that amazing; if you see an object with a moon and observe it for a while, you can determine their distance, orbits, separations, masses, and even guess at their composition! Thats so cool.

Weve found over the years that objects out there past Neptune are pretty diverse. Makemake, for example, is about the same size as OR10 but much more reflective. Other TNOs with moons show variations in reflectivity as well, so theres clearly a complicated and dynamic history to these objects. Moons are probably the product of collisions between bodies out there; the debris ejected coalesces to form a moon or moons. This isnt hugely well understood right now, so the more of these we find the more clues we have for their origins.

And one last note. 2007 OR10 is the largest known object in the solar system that doesnt have a name. Astronomers who find these worlds get the honor of naming them, generally giving them a handle that reflects their nature in some way; TNOs are typically named after native culture gods of the underworld (following the path of Pluto, named for the Roman god). Hopefully, given this new discovery of a moon, we wont have to wait too much longer before we can call 207 OR10 by something a bit less prosaic.

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Bad Astronomy | Astronomers find a moon for a distant, frigid world ... - Blastr

Children enjoy launching rockets at Astrofest on BYU campus. (Ari Davis)

The Erying Science Center was a flurry of sights, colors and sounds last Saturday during BYUs ninthannual Astrofest as hundreds of local children and parents participated in astronomy and physics themed games and activities.

Astrofest was started in the summer of 2009 by several BYU faculty members and students.

The main purpose of the event is to provide opportunities for families and kids to learn about physical science and astronomy in a fun environment, said BYU professor and event volunteer Darin Ragozzine. We offer a variety of activities that are fun for a variety of ages.

The ground floor of the Eyring Science Center was ground zero for activities as attendees signed in and experimented with all of the different displays available in the lobby. Tours of BYUs Multiple Agent IntelligentCoordination andControlLab and the Eyring Science Centers Research Labs bounced in and out,creating a steady streamof parents and wide-eyed children.

The excitement carried up through the higher floors of the Eyring Science Center as stations with origami, paper airplanes and star wheels were crowded with children and adults alike. The fourth floor planetarium was packed with strollers and attendees as the Planetarium offered free shows every half hour.

Oohs and aahs could be heard on the centers roof as BYU students, alumni and faculty taught about basic astronomy and positioned solar telescopes for attendees to view sun spots.

Astrofest is a great way to introduce difficult concepts like astronomy to kids, said recent BYU alumna and program volunteer Leanne Farnbach. Its a great way to really teach the science behind how the earth works in a friendly environment.

Outside, the trees of the Joseph Smith Building courtyard were littered with homemade rockets thanks to Astrofests main event. Prospective astronauts were able to create and launch their designs hundreds of feet in the air under the supervision of local high school and BYU students.

We have a modified sprinkler valve and an air compressor. Just put a rocket on top, press the button and the compressor will send them flying, said Mountain View High School junior Timothy Taylor.

Between the indoor and outdoor events, Astrofest typically attracts between 2000 and 3000 attendees in a single afternoon said BYU physics professor Eric Hintze.

We have the materials for about 1700 rockets and 550 patches for the Scouts, said Hintze. Almost all of them are gone by the end of the day.

Astrofest is held annually and overseen byBYU faculty and students.For those interested in volunteering or attending, the event is heldon an annual basis in the mid-spring.

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Astrofest teaches about astronomy and physics - Universe.byu.edu