Sometimes deep sky objects are so striking that I have no choice but to write about them, even if they weren't on the agenda for today. 114 million light years from Earth in the direction of Canis Major we see an interacting pair of galaxies. Michele Kaufman (Ohio State University) and colleagues have found arcs of star formation here that give the visual impression of eyelids. They're evidence of an encounter between the two galaxies, one brought into vivid focus by the Atacama Large Millimeter/submillimeter Array (ALMA). Image: Dazzling eyelid-like features bursting with stars in galaxy IC 2163 formed from a tsunami of stars and gas triggered by a glancing collision with galaxy NGC 2207 (a portion of its spiral arm is shown on right side of image). ALMA image of carbon monoxide (orange), which revealed motion of the gas in these features, is shown on top of Hubble image (blue) of the galaxy. Credit: M. Kaufman; B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble Space...

I had thought while the power was out this past week that I would like to write about cosmology when it came back. That's because there's nothing like a prolonged power outage to adjust your perspective. The big picture beckons. In my case, it was thinking about how trivial being out of power was compared to those who had lost so much more in the wake of the recent hurricane. So thinking about the cosmos became my shelter from the storm. I appreciated the emails from so many of you, but aside from a major chunk of tree that landed on the roof, we did just fine. In fact, it was deeply moving to see people from the neighborhood -- some I knew, some I only recognized -- turn up to get up on the roof and move that tree. I'm always reminded to do more for the people around me when I see something like this, and apprehensive that my resolution to do so all too often gets put aside as normal life returns. The Universe We Can See Reading by candlelight really is wonderful, and I ask myself...

The European Space Agency's Gaia satellite has delivered a catalog of more than a billion stars -- 1142 million, to be more specific -- as it continues the work of mapping our galaxy in three dimensions. To be sure, we can expect much more from Gaia, but the September 14 data release is a milestone, offering distances and proper motion for more than 2 million stars. The mission's first public release collects 14 months of data, from July 2014 to September 2015. "The beautiful map we are publishing today shows the density of stars measured by Gaia across the entire sky, and confirms that it collected superb data during its first year of operations," says Timo Prusti, Gaia project scientist at ESA. To get an idea of Gaia's long-term promise, recall that we are looking at the galaxy with Hubble-like precision. We may have more than a billion stars in today's release, but 400 million of these are appearing in a catalog for the first time. Image: An all-sky view of stars in our Galaxy -...

Brown dwarfs offer exciting prospects for exoplanet work. Not only are we learning that they can have planets of their own, but brown dwarfs themselves are a useful bridge between planets and stars. We also know that there are a lot of them out there. According to data from the WISE (Wide-field Infrared Survey Explorer) mission, there is about one brown dwarf for every six main sequence stars. That’s plenty of brown dwarfs, but it actually represents a reduction in estimates, which once went as high as a brown dwarf for every star. Moreover, WISE could identify about 200 brown dwarfs relatively near the Sun, with 33 within 26 light years. 211 stars are found in that same volume, incidentally. If we extrapolate this out to the galaxy at large, we should have about 33 billion brown dwarfs, assuming a galactic total of 200 billion stars. These numbers have a certain flexibility in them, especially given how hard it can be to track the coolest Y-dwarfs. Added to this is the fact that...

Those of you who have been following the controversy over the dimming of KIC 8462852 (Tabby's Star) may remember an interesting note at the end of Bradley Schaefer's last post on Centauri Dreams. Schaefer (Louisiana State University) had gone through his reasoning for finding a long-term dimming of the star in the DASCH (Digital Access to a Sky Century@Harvard) database. His third point about the star had to do with the work of Ben Montet (Caltech) and Joshua Simon (Carnegie Observatories). Montet and Simon's work relied on an interesting premise. Tabby's Star had been discovered because it was in the Kepler field, and thus we had high-quality data on its behavior, the unusual light curves that the Planet Hunters team brought to the attention of Tabetha Boyajian. As the researchers note in a new paper, Kepler found ten significant dips in the light curve over the timespan of the Kepler mission, dips that were not only aperiodic but irregular in shape, and that varied enormously, from...

A large part of the fascination of astronomy is the discovery of objects that don't fit our standard definitions. KIC 8462852 -- 'Tabby's Star' -- is deeply mysterious and high on my watchlist. But yesterday we also looked at CX330, a so-called FUor of the kind that brightens enormously over years of observation. Today we have another strange one, a system called AR Scorpii, where a white dwarf star in a binary system is releasing a blast of radiation onto a nearby red dwarf. The entire system brightens and fades every 1.97 minutes, a phenomenon that has only recently been properly understood. "AR Scorpii was discovered over 40 years ago, but its true nature was not suspected until we started observing it in June 2015," says Tom Marsh (University of Warwick), lead author of the paper on this work. "We realised we were seeing something extraordinary the more we progressed with our observations." Those observations proceeded with data from the European Southern Observatory's Very Large...

Given that we have fewer than a dozen examples, highly variable stars like the recently discovered CX330 have much to teach us. These stars have been nicknamed FUors, after FU Orionis, a pre-main sequence star that has shown huge variations in magnitude over the past century. Eruptions like these may be common, as Alan Boss argued last year (see A Disruptive Pathway for Planet Formation), but as we learn more about them, we have to account for dramatic changes, as when the star V1057 Cyg increased in brightness by 5.5 magnitudes over the course of a few years. What does this do to an associated circumstellar disk? As we ponder these questions, we also have to account for CX330, which comes into the news this week because of its odd isolation. Star-forming clouds packed with young stars are rich in gas and dust, and it is in these that we find all other examples in the FU Orionis category. But CX330 is a thousand light years away from the closest region of star formation, and because...

Because we want to learn more about how stars form, we study the so-called Initial Mass Function, which tells us, for a given population of stars, the distribution of their initial masses. As one recent reference (the Encyclopedia of Astrobiology, Springer, 2011) puts it: "The initial mass function is the relative number of stars, as a function of their individual initial mass, that forms during a single star forming episode." Figuring out the IMF for places like the Orion Nebula, visible from Earth with the naked eye as a patch in Orion's sword, is a start in learning how this grouping of stars formed. About 1350 light years from Earth, the Orion Nebula is known as an H II region, a reference to the fact that it contains ionized hydrogen in its star-forming, gaseous depths. A surprise emerged when the European Southern Observatory put its HAWK-I infrared instrument on the Very Large Telescope to work on the nebula. What turned up were faint brown dwarfs and isolated objects of...

Accurate distances are critical for understanding the physical properties of brown dwarfs and low-mass stars. We need to know the intrinsic brightness of these objects to proceed, but we can’t know that until we have an idea of their distance. After all, a relatively faint star can seem much brighter if nearer to us, while a distant bright star can appear deceptively dim. Intrinsic brightness is a measure of how stars would appear if observed at a common distance. Enter an exoplanet search that began at the Carnegie Institution for Science in 2007, using the Carnegie Astrometric Planet Search Camera (CAPSCam) to look for gas giant planets and brown dwarfs orbiting nearby low-mass stars. A new report from the program tells us that it has measured the distance to 134 low-mass stars and brown dwarfs, 38 of which have had no previously measured trigonometric parallax. These are all stars considered too faint for inclusion in the European Space Agency’s Hipparcos survey, but as the report...

It’s not often that I get the chance to back up and take a broad look at the universe, the kind of thing that reinforces my interest in cosmology and structure at the grandest scale. But today I’ll take my cue from the Royal Astronomical Society’s annual meeting, now underway in Nottingham UK, which gives me the chance to look at a new catalog from the European Space Agency’s Herschel Space Observatory. On offer is a guide to hidden sources of energy in the universe, on a scale at which the Milky Way itself is but a bit of froth on a cosmic wave. As presented by Haley Gomez (Cardiff University) at the National Astronomy Meeting, the project known as the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) is offering a deep look at galaxies through time. Because about half the light emitted by stars and galaxies is absorbed by interstellar dust grains, Herschel’s ability to work in the far-infrared can reveal that light re-emitted, showing us the sources of energy that...

The second detection of gravitational waves by the LIGO (Laser Interferometer Gravitational-Wave Observatory) instruments reminds us how much we gain when we move beyond the visible light observations that for so many millennia determined what people thought of the universe. In the electromagnetic spectrum, it took data at long radio wavelengths to show us the leftover radiation from the Big Bang, and we've used radio ever since to study everything from quasars and supernovae to interesting molecules in interstellar space. Infrared helps us penetrate dust clouds and see not only into star-forming areas but the galactic center. So much is learned by taking advantage of the enormous width of the electromagnetic spectrum, wide enough that, as Gregory Benford points out, visible light is a mere one octave on a keyboard fifteen meters wide. Ultraviolet tells us about the gaseous halo around the Milky Way and shows us active galaxies and quasars while helping us analyze interstellar gas...

In his novel The Twilight of Briareus (John Day, 1974), Richard Cowper, who in reality was John Middleton Murry, Jr., wrote about a fictitious star called Delta Briareus that goes supernova (true, there is no constellation called Briareus, but bear with me). Because it is only 130 light years out, the supernova showers the Earth with radiation, with consequences that are in some cases obvious, in others imaginative in the extreme. It's a good read, one that at least one critic, Brian Stableford, has compared to J. G. Ballard's early disaster novels. The novel contrasts an earthy domesticity with the celestial display that soon shatters it. It's worth quoting a patch of the book: It so happened that I, in common, no doubt, with several million others -- was among the first in England to observe that 'majestic effulgence' within seconds of its arrival. At about twenty past nine on the Tuesday evening I switched off the telly and suggested to Laura that we could do worse than saunter...

Debris disks around young stars are keys to understanding how planets form. But what about debris around older stars? We now have the best view ever achieved of the dusty disk around an aging star -- a red giant -- and we’re forced to ask whether such a debris disk, so similar to what we see around young stars, could itself form a second generation of planets. The star in question is a binary designated IRAS 08544-4431, first detected by the Infrared Astronomical Satellite in the 1980s. Some 4000 light years from Earth in the direction of the southern constellation Vela (The Sails), the system contains a red giant (the source of the material in the surrounding disk) and a much smaller, less evolved companion star. Image: The dusty ring around the aging double star IRAS 08544-4431. Credit: ESO. Here we’re working with data from the Very Large Telescope Interferometer at the European Southern Observatory’s Paranal Observatory (Chile) using the PIONIER (Precision Integrated-Optics...

You probably recall how tricky it was to find 2014 MU69, the small Kuiper Belt Object that will be the next destination for our New Horizons probe. The actual extended mission to 2014 MU69 awaits a summer 2016 review within NASA, but because trajectory changes to get there could not be delayed, the New Horizons craft performed four maneuvers late last year to set the course. The search for a suitable KBO began in 2011 and it was not until 2014, working with data from the Hubble Space Telescope, that scientists were able to find their best candidate. Now consider that 2014 MU69 has a diameter of about 45 kilometers, making it ten times larger than the average comet. How difficult, then, to assess the true population of smaller Kuiper Belt Objects. We'd like to know a lot more about much smaller KBOs, because assessing the abundance and collisional processes of these objects is way of understanding the debris disks we're seeing around other stars. Current theory suggests that KBOs...

A new paper in Nature offers further information about Fast Radio Bursts (FRBs), which we last looked at only a few days back. The February 24 post examined work on FRBs that were consistent with what has been seen before -- transient pulses lasting mere milliseconds, while emitting huge amounts of energy (see Fast Radio Bursts: First Distance Measurement). Now we have further work out of the Max Planck Institute for Radio Astronomy (MPIfR) in Germany that describes the detection of the first source of repeating bursts, an object outside our own galaxy that is producing multiple short bursts. Lead author Laura Spitler (MPIfR) explains that a McGill University graduate student named Paul Scholz, using data from the Arecibo radio telescope in Puerto Rico, discovered the repeat signals last November. Scholz found a total of 10 new bursts. "Not only does this source repeat, but the brightness and spectra of the bursts also differs from those of other FRBs," adds Spitler. We may be...

Have we finally traced a Fast Radio Burst to its place of origin? News from the CSIRO (Commonwealth Scientific and Industrial Research Organisation) radio telescopes in eastern Australia, along with confirming data from the Japanese Subaru instrument in Hawaii, suggests the answer is yes. Fast Radio Bursts (FRBs) are transient radio pulses that last scant milliseconds. In that amount of time, they have been known to emit as much energy as the Sun emits in 10,000 years. And exactly what causes FRBs is still a mystery. Take the so-called 'Lorimer Burst' ( FRB 010724) which was discovered in archival data from 2001 at the Parkes radio telescope in New South Wales. Here we're dealing with a 30-jansky dispersed burst that was less than 5 milliseconds in duration. Although the burst appeared roughly in the direction of the Small Magellanic Cloud, the FRB is not thought to be associated with our galaxy at all. A 2015 event, FRB 110523, was discovered in data from the Green Bank dish in West...

“Einstein would be beaming,” said National Science Foundation director France Córdova as she began this morning’s news conference announcing the discovery of gravitational waves. I can hardly disagree, because we have in this discovery yet another confirmation of the reality of General Relativity. Caltech’s Kip Thorne, who discussed black hole mergers way back in 1994 in his book Black Holes and Time Warps, said at the same news conference that Einstein must have been frustrated by the lack of available technologies to detect the gravitational waves his theory predicted, a lack that it took a century to remedy with the LIGO collaboration. Thorne believes that if he had been armed with the right tools, Einstein himself would have made the detection. But of course the tools weren’t there. Somehow that thought produced an odd echo of the very decade of General Relativity’s emergence, one that shows how much GR changed the nature of our view of the universe. It was in 1911, just four...

Somewhere a decade or so back in these pages a Centauri Dreams commenter described the event that formed our Moon as ‘the big whack.’ Although I hadn't run across it before, the phrase turns out to have been common parlance for what is now thought to be a massive collision between the Earth and an early planetesimal. But whatever the case, we know a bit more about the cataclysm thanks to new work out of UCLA, as reported in the journal Science. The impactor, which struck about 4.5 billion years ago, is commonly called Theia. So how do we analyze such a remote event? The key, as discussed in this UCLA news release, is oxygen, which makes up 90 percent of the volume of lunar rocks the team of geochemists studied, and 50 percent of their weight. Usefully, oxygen can manifest itself in various isotopes, the most common on Earth being O-16, meaning each atom holds eight protons and eight neutrons. Image: Light image of a lunar rock from the Apollo 17 mission. Credit: NASA. Heavier...

If you're looking for detailed imagery of a distant astronomical object, VLBI (Very Long Baseline Interferometry) can deliver the goods. As witness the image below, which the National Radio Astronomy Observatory (NRAO) is calling "the highest resolution astronomical image ever made." Here we see radio emission from a jet of particles moving close to the speed of light. The particles are being accelerated by a supermassive black hole at the core of the galaxy BL Lacertae, a highly variable 'active galaxy' some 900 million light years from the Earth. Image (click to enlarge): Signals from 15 ground-based radio telescopes, combined with data from the RadioAstron orbiting satellite, produced the highest resolution astronomical image ever made. Credit: Gomez, et al., Bill Saxton, NRAO/AUI/NSF. What fascinates me about this work is the technique. Very Long Baseline Interferometry works by collecting a signal at multiple radio telescopes, the distance between them being calculated from the...

About 1.4 million years from now, the K-class star Gliese 710, now 64 light years distant in the constellation Serpens, will brush past our Solar System. Moving to within 50,000 AU, the star could be expected to have an unsettling effect on cometary orbits in the Oort Cloud, perhaps dislodging some of these comets to cause them to move into our inner planetary system. An interesting scenario, particularly remembering speculation that comets were a source of water for the early Earth, and may perform a similar function in other young systems. So just how common are such celestial encounters? We may have one at our very doorstep in the form of Proxima Centauri. The Pale Red Dot campaign that began yesterday is focusing on a red dwarf that is roughly 15,000 AU from the close binary stars Centauri A and B. If you think about what our system would look like with a red dwarf at the inner edge of the Oort Cloud, you can see that Proxima may play a large role in the evolution of the...