Nobody has been anticipating the results from WISE -- the Wide-field Infrared Survey Explorer -- any more than I have. Speculations about the number of brown dwarfs in the galaxy have been all over the map, with some suggesting they might be as plentiful as M-dwarfs, which make up perhaps 80 percent of the stellar population. But the latest results from our infrared scan of the sky argue a much different result: Brown dwarfs turn out to be considerably more rare than stars, with an initial tally of the WISE data showing just one brown dwarf for every six stars. Thus Davy Kirkpatrick, a member of the WISE science team at NASA's Infrared Processing and Analysis Center at Caltech: "This is a really illuminating result. Now that we're finally seeing the solar neighborhood with keener, infrared vision, the little guys aren't as prevalent as we once thought." Ouch. The nice thing about a sky full of undiscovered brown dwarfs was that it might serve up interstellar destinations closer than...

Back in 1997, astronaut John Grunsfeld pulled off one of the great radio gags of all time by calling in to National Public Radio's 'Car Talk' program while orbiting the Earth aboard Atlantis in STS-81. He had called to complain about his vehicle's performance which, as he told the show's hosts -- known as 'Click and Clack, the Tappet Brothers' -- was driving him crazy. His troublesome ride would buck and rattle and run loud for four minutes, then get much quieter for another ten, and then the engine would quit. Odd behavior for any vehicle but the Space Shuttle, as Click and Clack eventually realized, and a memorable exploit for Grunsfeld's second Shuttle mission. Image: A bumpy ride to orbit -- liftoff of STS-81 on January 12, 1997. Credit: NASA. Grunsfeld is more commonly remembered as a repairman for the Hubble Space Telescope, a task he performed on three subsequent missions without the help of 'Car Talk.' Now the astronaut, with over 58 days in space and eight space-walks, is in...

We now know that the vast collection of radio dishes and antennae that will become the Square Kilometer Array (SKA) will be built on two sites, with the majority of dishes in Phase 1 (beginning in 2016) being constructed in South Africa, and further dishes added in Australia as the project develops. The SKA is to be a radio telescope of unprecedented sensitivity capable of sky surveys at frequencies from 70 MHz to 10 GHz. A SKA news release notes that "All the dishes and the mid-frequency aperture arrays for Phase II of the SKA will be built in Southern Africa while the low-frequency aperture array antennas for Phase I and II will be built in Australia." Combining the signals from the project's dishes, mid-frequency aperture arrays and low-frequency aperture arrays will offer a telescope with a collecting area equivalent to a dish with an area of one square kilometer, a truly formidable observing platform. Phase 1 construction will involve about 10 percent of the array and will...

Long-time Centauri Dreams readers know I love the idea of ‘deep time,’ an interest that cosmology provokes on a regular basis these days. Avi Loeb’s new work at Harvard tweaks these chords nicely as the theorist examines what we know and when we won’t be able to study it any longer. For an accelerating universe means that galaxies are moving outside our light horizon, to become forever unknown to us. Using tools like the Wilkinson Microwave Anisotropy Probe, we’ve been able to learn how density perturbations in the early universe, thought to have been caused by quantum fluctuations writ large by a period of cosmic inflation, emerged as the structures we see today. But are there limits to cosmological surveys? Start with that period of inflation after the Big Bang, which would have boosted the scale of things by more than 26 orders of magnitude, helping to account for the fact that the cosmic microwave background (CMB) appears so uniform in all directions. We can tease out the...

Can we tell something about the planets around another star by examining that star's atmosphere? A new study out of the University of Warwick makes a strong case for the method in the study of white dwarfs, following up on a landmark 2007 paper by Benjamin Zuckerman (UCLA) that looked at pollution in white dwarf photospheres. 'Pollution' as in metals that shouldn't be there, which suggests an accretion disk of material feeding the star, which itself would have collapsed from a red giant stage and is perhaps now absorbing planetary material around it. What we would expect to find in the atmosphere of a white dwarf is little more than hydrogen and helium -- heavy elements should quickly sink to the core and not be observable. But white dwarfs with metal-contamination in their atmospheres have been observed for almost a century now. Let me Boris Gänsicke and colleagues on this, from the paper on the University of Warwick work (internal references deleted for brevity): ...the rapidly...

Having just re-read Arthur C. Clarke's The City and the Stars for the first time in a couple of decades, I've been preoccupied by the idea of 'deep time,' and astronomical events that play out over billions of years. The fictional trick, of course, is to pair human observation with events that take aeons to unfold. In Clarke's novel, the city of Diaspar is a place that is almost outside of time, a self-contained and beautiful place whose very inwardness ultimately becomes stultifying. But the vision of this glowing jewel of a city surviving amidst the dunes of an ancient Earth is one of those science fiction images that stick with you over a lifetime of reading. New work out of Vanderbilt University now suggests other deep time images, but they're likely to be more fantasy than science fiction. Imagine a star moving fast enough to escape the galaxy, living out its life on a long trajectory that will take it into intergalactic space. Kelly Holley-Bockelmann and Lauren Palladino think...

Alpha Centauri is irresistible, a bright beacon in the southern skies that captures the imagination because it is our closest interstellar target. If we learn there are no planets in the habitable zones around Centauri A and B, we then have to look further afield, where the next candidate is Barnard's Star, at 5.9 light years. Centauri A and B are far enough at 4.3 light years -- that next stretch adds a full 1.6 light years, and takes us to a red dwarf that may or may not have planets. Still further out are Tau Ceti (11.88 light years) with its problematic cometary cloud, and Epsilon Eridani (10.48 light years), a young system though one thought to have at least one planet. A warm and cozy planet around the K-class Centauri B would be just the ticket, and the planet hunt continues. One thing we've learned in the past decade is that neither Centauri A or B is orbited by a gas giant -- planets of this size should have shown up in the data by now. We've also learned that stable orbits...

As promised, we now have the infrared sky at a new level of detail thanks to the labors of the Wide-Field Infrared Survey Explorer (WISE) mission, which has now mapped (with a few slight glitches) more than half a billion objects, from galaxies to stars to asteroids and comets. We can now expect a new wave of papers from the more than 2.7 million images WISE has delivered at four infrared wavelengths and can explore the WISE atlas of some 18,000 images ourselves. The Big Picture But first, I want to step back and look at astronomical discovery in context, a thought spurred by Larry Klaes, who sent me a note originally posted on the HASTRO-L mailing list (by Rich Sanderson, of the Springfield Science Museum in Massachusetts). Every now and then I read something that wraps back into the past and yet implies future things, generating a sense of connection with what the enterprise is all about. Such is the case in this passage Sanderson quotes from an 1875 book by Richard Proctor that...

HLX-1 (Hyper-Luminous X-ray source 1) is thought to be a black hole, one that's a welcome discovery for astronomers trying to puzzle out the mysteries of black hole formation. Located roughly 290 million light years from Earth and situated toward the edge of a galaxy called ESO 243-49, this black hole looks to be some 20,000 times the mass of the Sun, which makes it mid-sized when compared with the supermassive black holes at the center of many galaxies. The latter can have masses up to billions of times more than the Sun -- the black hole at the center of our own galaxy is thought to comprise about four million solar masses. Just how a supermassive black hole forms remains a subject for speculation, but study of HLX-1 is giving us clues that point in the direction of a series of mergers of small and mid-sized black holes. For it turns out that HLX-1, discovered by Sean Farrell (Sydney Institute for Astronomy in Australia and University of Leicester, UK) and team at X-ray...

Luminous Blue Variables are large, bright stars that give rise to periodic eruptions, like the so-called “Great Eruption” of Eta Carinae that was first noted in 1837 and continued to be observed for an additional 21 years. Things must have been lively around the companion star thought to orbit in the nebula around Eta Carinae, for the LBV blew off about 20 solar masses in this era, mimicking a supernova as it became the second brightest star in the sky. We’ve witnessed similar ‘supernova impostor’ events in other galaxies, but at 7500 light years, the Eta Carinae system is relatively nearby, allowing close study by Hubble and other telescopes. What brings Eta Carinae’s 1837 event back into the news is the use of so-called ‘light echoes’ to study what happened at a time when astronomy was in a much earlier state. Armin Rest (Space Telescope Science Institute) notes how useful the work is turning out to be: "When the eruption was seen on Earth 170 years ago, there were no cameras...

The Planck mission continues to peel the layers off the onion as it probes the early universe. Planck is all about the Cosmic Microwave Background (CMB), that radiation left over from the era of recombination around 380,000 years after the Big Bang. As electrons and protons began to form neutral atoms, light was freed to stream through the universe, an afterglow of the Big Bang that missions like the Wilkinson Microwave Anisotropy Probe have studied in detail, and which Planck will now observe at still better sensitivity, angular resolution and frequency range. But the initial job for researchers is to remove sources of foreground emission to reveal the CMB itself, and that process is turning up interesting findings in its own right. The latest announcement from the European Space Agency involves a haze of microwaves that is not yet understood. Coming from the region around galactic center, the haze appears to be synchrotron emission, produced as electrons accelerated in supernovae...

Given yesterday's post on wandering planets, otherwise known as 'rogue' planets or 'nomads,' today's topic falls easily into place. For even as we ponder the possibility of 105 rogue planets at Pluto's mass or above for every main sequence star in the galaxy, we confront the fact that we still have much to learn about objects much closer to home in our own Kuiper Belt. We have yet, for example, to have a flyby, although it's possible the New Horizons spacecraft will line up on a useful target after its encounter with Pluto/Charon (and yes, it's conceivable that Triton is a captured KBO, and thus we have had a Voyager flyby). The discovery of objects like Sedna, Makemake and Eris makes it clear how much we may yet uncover. We can think of the broader category of Trans-Neptunian Objects (TNOs) in terms of potential mission targets, but we should also ponder the fact that their strong dynamical connection with the planets can help us gain insight into the mechanics of Solar System and...

Not long ago we looked at comet C/2011 N3 (SOHO), discovered last July just two days before it plunged into the Sun, evaporating some 100,000 kilometers above the solar surface. It was startling to learn that the SOHO observatory is tracking numerous ‘Sun-grazers,’ comets whose fatal encounters with our star are occurring roughly once every three days. Now comes news that Sagittarius A*, the supermassive black hole at the center of the Milky Way, is producing X-ray flares about once a day, thought by some to be the result of similar debris in the process of destruction. The flares last just a few hours, according to researchers working with data from the Chandra X-Ray Observatory, and can reach brightness levels up to 100 times what is normally observed in the black hole region. Kastytis Zubovas (University of Leicester) thinks we’re seeing asteroids and comets passing within 160 million kilometers of the black hole (roughly 1 AU), at which point they would likely be broken apart by...

Gravitational lensing always gets my attention not only because of its growing use in astronomy but because of its potential for deep space missions like FOCAL, Claudio Maccone's concept for a deep space probe that would be sent beyond the Sun's 550 AU gravitational lensing distance to make observations of astronomical targets. FOCAL is an interstellar precursor mission that could give us detailed information about any system to which we might send a future probe. And, as Maccone has shown, lensing could also be used to create the kind of robust communications relay that would function with little data loss over huge distances. But we don't have to wait for FOCAL to exploit the potential of lensing for studying distant exoplanets. As Centauri Dreams readers know, gravitational microlensing has developed into a potent tool. A foreground star distorts the light from a background object when the alignment is right, and that magnification is likewise affected by planets orbiting the...

Imagine what we could do if we could attain speeds of 640 kilometers per second. That's the velocity of a comet recently tracked just before passing across the face of the Sun and apparently disintegrating in the low solar corona. I'm just musing here, but it's always fun to muse about such things. 640 kilometers per second drops the Alpha Centauri trip from 74,600 years-plus (Voyager-class speeds) to less than 2000 years. A long journey, to be sure, but moving in the right direction, and in any case, these are speeds that would allow exploration deep into the outer system. We're a long way from such capabilities, but they're a rational goal. But back to the comet. The object was discovered on July 4, 2011 and designated C/2011 N3 (SOHO), the latter a reference to the ESA/NASA Solar and Heliospheric Observatory, whose Large Angle and Spectrometric Coronagraph made the catch. On July 6, NASA's Solar Dynamics Observatory was able to pick up the comet some 0.2 solar radii off the Sun,...

Cygnus X-1 is one of the strongest X-ray sources we can detect from Earth and the first widely thought to be a black hole. In fact, when Stephen Hawking bet against X-1 being a black hole back in 1975, he was more or less setting up a hedge, for black holes have been a crucial part of Hawking's work. Hawking writes about his wager with Kip Thorne entertainingly in the first edition of his A Brief History of Time (1988): This was a form of insurance policy for me. I have done a lot of work on black holes, and it would all be wasted if it turned out that black holes do not exist. But in that case, I would have the consolation of winning my bet, which would win me four years of the magazine Private Eye. If black holes do exist, Kip will get one year of Penthouse. When we made the bet in 1975, we were 80% certain that Cygnus was a black hole. By now, I would say that we are about 95% certain, but the bet has yet to be settled. Not long afterwards, the bet would be settled. If you go on...

The Laser Interferometer Space Antenna mission (LISA), slated for launch later this decade, will go about testing one of Einstein's key predictions, that gravitational waves should emanate from exotic objects like black holes. Detectors like the Laser Interferometer Gravitational Wave Observatory (LIGO) have operated on Earth's surface but are subject to seismic noise that disturbs the observations in some of the key frequency ranges. The hope is that the space-based LISA will be able to go after the low-frequency gravitational wave spectrum to detect such things as the collision of black holes, the merger of galaxies or the interactions of neutron star binary systems. The good news out of the European Space Agency is that the LISA Pathfinder precursor mission, planned for a 2014 launch, is showing the accuracy needed to demonstrate what the more sophisticated LISA mission should be able to do. LISA Pathfinder is a small spacecraft unable to make a direct detection of gravitational...

?It was Gregory Benford who used the wonderful phrase ‘the first hard science fiction convention’ to describe what happened at the 100 Year Starship Symposium. It was an apt choice of words. ‘Hard’ science fiction refers to SF that goes out of its way to get the science right, and in which the scientific and technical details play a major role in the development of the plot. Science fiction critic P. Schuyler Miller evidently coined the term in one of his reviews for Astounding Science Fiction back in the 1950s. In many ways, the Symposium operated under a science fictional meme. Science fiction at its best exists to paint possibilities for us. Some scientific speculations may be remarkable in their own right but only become vivid when portrayed by writers who can make the background science into a scenario that plays out in fictional terms. An obvious case is the classic Isaac Asimov tale “Nightfall,” published in Astounding’s September, 1941 issue. Asimov took us to a place that...

Planetary migration can play a huge role in the evolution of a solar system, as witness the thinking that it was a migration of the gas giants Jupiter and Saturn that brought about the Late Heavy Bombardment, a time four billion years ago when impacts from space pock-marked the Moon and inner planets. The migration model, first proposed at the Observatoire de la Côte d'Azur and thus known as the Nice model, posits a long-lasting cometary bombardment caused when gravitational effects of the migration scattered icy bodies in the Kuiper Belt. Most of these would have been ejected from the system, but others would have been sent on planet-intersecting paths. If the Nice model is correct, then we may have an explanation for at least part of the water that wound up on our blue and green planet today, with obvious consequences for the development of life. That makes events similar to the Late Heavy Bombardment of considerable interest when we can find them in other solar systems, and new...

About a month ago we were looking at the work of Ray Jayawardhana and team on the brown dwarf 2MASS 2139, an interesting case because Jayawardhana (University of Toronto) thinks he has spotted a giant storm raging on the object, or perhaps holes in the cloud deck that allow a glimpse of deeper layers of the atmosphere within. At issue is the striking 30 percent change in brightness of the star within a mere eight hours, seeming to indicate atmospheric changes we can pick up as the brown dwarf rotates. Unlike a normal star, a brown dwarf is hot when young but gradually cools to the point where it has an atmosphere similar to that of a gas giant. All this is part of a survey program called SONYC - Substellar Objects in Nearby Young Clusters - that uses data from the Subaru Telescope in Hawaii and the Very Large Telescope (VLT) in Chile. SONYC may change the way we look at brown dwarfs, and now it is back in the news. The latest word is that the same team has found over two dozen...