Give a young star two or three million years and planets are likely to emerge from the dust and gas surrounding it. But note the wild card shown in the image below, the danger of proximity to more massive stars. In the image, several stars not so different from our Sun at that stage of its evolution are shown with streams of material flowing away from them. We're seeing their outer disk material blown away by nearby class O stars, while inner materials might still survive to form rocky, terrestrial worlds close to the parent star. Image: This image from NASA's Spitzer Space Telescope shows the nasty effects of living near a group of massive stars: radiation and winds from the massive stars (white spot in center) are blasting planet-making material away from stars like our Sun. The planetary material can be seen as comet-like tails behind three stars near the center of the picture. The tails are pointing away from the massive stellar furnaces that are blowing them outward. Credit:...

Brown dwarfs raise plenty of questions, not the least of which is how they form. Work up to some fifteen times Jupiter's mass and the planet in question starts to look more like a brown dwarf, a 'failed star' that cannot sustain fusion at its core. Somewhere around 75 Jupiter masses long-term fusion ignites and you're in the territory of a true star. This brown dwarf zone between the two poles makes these objects provocative -- do they form the way most planets seem to do by collecting more and more rocky materials and eventually a gas envelope? Or does a brown dwarf form, like a star, through the gravitational collapse of a gas cloud? The latter idea gets a boost from recent work from the Harvard-Smithsonian Center for Astrophysics. Astronomers have now found a stream of carbon monoxide flowing out from a young brown dwarf known as ISO-Oph 102. This gets interesting at several levels, the first being that the outflow from the dwarf resembles what happens in larger stars as they...

It hasn't been all that long since Hanny van Arkel, a Dutch school teacher, lent her name to the anomalous object since known as 'Hanny's Voorwerp.' Working with data from the Galaxy Zoo project, van Arkel was scanning galaxy images when she ran across what seemed to be a green blob of extremely hot gas with a hole in its center. That hole turned out to be 16000 light years across, its cause unknown, and the object itself seemed to be lit by an unseen source. Theories abounded, including a 'light echo' from a defunct quasar in a nearby galaxy. And then there was the fact that the remarkably hot object (15000 degrees Celsius or more) was not only enormous but also empty of stars. Baffling astronomers for the past year, Hanny's Voorwerp may now be swimming into sharper focus. An international team has been observing both the object and the nearby galaxy IC2497 using the Westerbork Synthesis Radio Telescope, with results that indicate the presence of a jet coming from a massive black...

As we learn more about cosmic rays, it becomes clear that these incoming particles -- protons and electrons accelerated to high energy levels -- do not reach us uniformly. Just a few days ago we saw that the ATIC (Advanced Thin Ionization Calorimeter) experiment had revealed a source of cosmic rays relatively close to the Earth. Now the Milagro Gamma-Ray Observatory, based at Los Alamos National Laboratory, has found two such cosmic ray 'hot spots.' Again we are looking at a source of high energy cosmic rays not terribly far (in galactic terms) from our planet. Jordan Goodman (University of Maryland) is principal investigator for Milagro: "These two results may be due to the same, or different, astrophysical phenomenon. However, they both suggest the presence of high-energy particle acceleration in the vicinity of the earth. Our new findings point to general locations for the localized excesses of cosmic-ray protons observed with the Milagro observatory." Milagro has been monitoring...

Ponder the image below, which scientists at Tel Aviv University are interpreting in terms of the structure of the universe itself. The work draws on the well established notion that large galaxies are found on bubble-like structures -- the soap bubble analogy is inevitable -- with smaller dwarf galaxies scattered along the bubble surface. The Tel Aviv team thinks it has discovered visible traces of a filament of dark matter around which galaxies form. Filaments would be found at the juncture of two bubbles where the membrane is presumably thickest. Thus the image, which shows fourteen galaxies studied at the university's Wise Observatory. Here the galaxies are thought to stretch along a line extending from the lower right to the upper left corner. In its paper, the team calls the grouping "...a single kinematically well-behaved ensemble." The area studied is intriguing not only because the galaxies found here seem to be forming in a line, but also because thirteen of them show new...

Asteroseismology is the science of looking inside a star by studying the oscillations made by sound waves as they move throughout its interior. A recent news release from the COROT team calls these 'Sun-quakes' when they occur on our own star, and points out that the effect can be compared to seismic waves on Earth, whose examination can tell us much about what is happening below the surface. The Solar and Heliospheric Observatory (SOHO) mission, launched in 1995, studies our Sun's oscillations, but COROT is now extending the science to other stars. All three of the stars the mission has studied for this purpose -- HD49933, HD181420 and HD181906 -- are main sequence stars hotter than the Sun. And while stellar oscillations can be studied by ground observatories, moving to space offers serious advantages. So says Malcolm Fridlund, ESA project scientist for COROT, who notes the limitations of such observations when made from Earth: "Adverse weather conditions, plus the fact that you...

Again and again I'm amazed by our growing ability to tease information out of apparent noise. Consider the problem of viewing celestial objects from Earth's surface. The image below demonstrates the latest way to remove atmospheric blur that would otherwise bedevil a ground-based telescope. We're looking at Jupiter through a prototype instrument called the Multi-Conjugate Adaptive Optics Demonstrator (MAD). This is a form of adaptive optics that uses two guide stars (or in this case, two of Jupiter's moons) instead of one as references, allowing a wider field of view. Adaptive optics involves real-time corrections made at high speed, feeding a computer-controlled deformable mirror that interprets the atmospheric distortion by examining light from the chosen guide stars. Normally, the method works with a single guide star, but that allows for atmospheric corrections only in a tiny region of sky. The new MAD methods significantly overcome this limitation. The false-color infrared...

Hubble's ACS Nearby Galaxy Survey Treasury (ANGST) has everything going for it but the right acronym. One thing the spectacular images returned from this work definitely do not lead to is a deep, philosophical fear or, as 'angst' is defined by the American Heritage Dictionary, "A feeling of anxiety or apprehension often accompanied by depression." Quite the contrary, the results of ANGST are all but euphoric in their celebration of stars in the galaxies we see around us, fully sixty nine galaxies in the so-called 'Local Volume.' The euphoria comes from Hubble's sharp vision. The Local Volume encompasses galaxies beyond the Local Group, with distances in the survey ranging from 6.5 million light years to 13 million light years from Earth. That's actually close enough that the right tools for seeing -- Hubble's Advanced Camera for Surveys and Wide Field Planetary Camera 2 -- can pull individual stars out of what had been an indistinct galactic background. Out of that we stand to learn...

Seeing things that are otherwise invisible means looking for their effect on the things we can see. Examples abound: The presence of dark matter was originally inferred from the shape of galaxies, and the fact that the mass of what we could see couldn't explain how these cities of stars held together. Dark energy turned up through minute examination of supernovae, shaping the idea that the acceleration of the universe is an ongoing phenomenon. And now we have another unusual effect suggesting the presence of matter beyond the observable universe. The work grows out of the study of some 700 galactic clusters whose X-rays, emitted by hot gases, cause measurable effects on photons from the cosmic microwave background. This is the Sunyaev-Zel'dovich effect, in which high energy electrons impart some of their energy to the CMB. A variant of the SZ effect helps us study galactic clusters in ways that now suggest the presence of inflation in the early universe. Thus Alexander Kashlinsky...

Most Centauri Dreams readers will be familiar with the concept of interferometry by now. The idea is to combine light from multiple telescopes, allowing the combined array to act like a single telescope with a diameter equivalent to the distance between the telescopes. Thus we have the European Southern Observatory's VLTI (Very Large Telescope Interferometer), which uses two telescope elements some 200 meters apart. The VLTI has now put a new instrument called PRIMA into operation, with useful exoplanetary implications. PRIMA (Phase Referenced Imaging and Microarcsecond Astrometry) is designed to pick out the tiny motions a star makes as it is influenced by unseen planetary companions. We've long studied such wobbles in stars through radial velocity methods -- these analyze the light from the star, determining through Doppler shifts in the star's spectrum how a companion object may be influencing it. But PRIMA will find the wobbles through actual imaging, using incredibly precise...

Segue 1 is one of the tiny satellite galaxies orbiting the Milky Way whose dark matter component has caused great astronomical interest. As we saw in this post a couple of weeks ago, these ultra-faint objects have been turning up in Sloan Digital Sky Survey data, surprising astronomers by their mass, which indicates they're dominated by dark matter. Consider them top-heavy with the stuff: Segue 1 turns out to be a billion times fainter than the Milky Way, yet a study by members of the same team shows that it is a thousand times more massive than would be expected by its visible stars. The new regime of faint galaxies offers intriguing observational clues to galaxy formation while putting dark matter's properties on display. Thus Marla Geha (Yale University): "These dwarf galaxies tell us a great deal about galaxy formation. For example, different theories about how galaxies form predict different numbers of dwarf galaxies versus large galaxies. So just comparing numbers is...

A massive gamma-ray burst detected last March, believed to be the brightest ever seen, turns out to have been aimed directly at the Earth. A narrow jet that drove material toward us at 99.99995 of the speed of light is revealed in the data, itself wrapped within a somewhat slower and wider jet. The best estimates are that an alignment like this occurs only once every ten years. Says Paul O'Brien (University of Leicester, and a member of the team working on the Swift satellite): "We normally detect only the wide jet of a GRB as the inner jet is very narrow, equivalent to not much more than 1/100th the angular size of the full Moon. It seems that to see a very bright GRB the narrow jet has to be pointing precisely at the Earth. We would expect that to happen only about once per decade. On March 19th, we got lucky." It could be said that any information we get about GRBs is in a sense lucky, given how tricky are the constraints for observing them. And indeed, another GRB just degrees...

Although we often talk about the Magellanic Clouds as satellites of the Milky Way, recent research seems to point to a different conclusion. The dwarf galaxies may be moving too fast to be bound to our own, cities of stars simply flowing past us in the night. Be that as it may, the Milky Way still has over twenty other dwarf galaxies in orbit around it, eighteen of which have been the subject of recent work aimed at calculating their masses. The odd results have striking implications for dark matter. For the dwarf galaxies around us vary greatly in brightness, from a thousand times the luminosity of the Sun to a billion times that amount. You would assume that the brightest dwarf galaxy would have the greatest mass, while the faintest would show the least. The surprise is that all the dwarf galaxies have roughly the same mass, some ten million times the mass of the Sun within their central 300 parsecs. Here's Manoj Kaplinghat (University of California at Irvine) with a helpful...

Keeping our eyes open over a whole range of wavelengths makes priceless science possible. Thus the new data on dark matter, culled from observations of the galactic cluster known as MACSJ0025.4-1222. The Hubble Space Telescope offered up images in the visual light range, sufficient to provide astronomers (thanks to the effects of gravitational lensing) with a map of dark matter associated with the cluster. The Chandra X-Ray Observatory provided a balancing map of ordinary matter by showing us the distribution of hot gas in the cluster, the latter readily visible in the X-ray wavelengths Chandra works at. The result is the beautiful, if color-coded, image at the left. Here the dark matter is shown in blue, the ordinary matter in pink. The assumption is this: The two galactic clusters that formed MACSJ0025.4-1222 (each a quadrillion times the mass of the Sun) merged at titanic speeds, causing the hot gas (ordinary matter) within each to collide and slow. The dark matter, however, seems...

I like the logo for the Fermi Gamma-Ray Space Telescope, shown at the right. It's appropriately stylish and, with that 'beamed' F emerging out of a galactic core, reminds us that the instrument will be opening a data window on the supermassive black holes found in such places. Fermi was until yesterday known as GLAST (Gamma-Ray Large Area Space Telescope), so the change of name moves us out of acronym territory and personalizes the instrument in favor of one of the true pioneers of high-energy physics, as well as the author of the ever intriguing Fermi paradox. We've talked about the latter in the context of the search for extraterrestrial life, wondering how Fermi's famous 'where are they?' question might be answered. But the Fermi telescope, in space for just two and a half months, is giving signs of being quite a newsmaker itself, if perhaps less controversial. The image below presents a map put together from 95 hours of observation, an all-sky view showing the glow of gas and...

Simulations showing how giant gas clouds evolve -- clouds as large as 100,000 times the mass of the Sun -- have demonstrated that stars can form in the neighborhood of supermassive black holes, the kind of black holes found at the center of galaxies. As you would expect, the clouds are disrupted when they move close to the black hole, but only part of the cloud is captured, with the rest contributing to the formation of massive stars that move about the black hole in eccentric orbits. Usefully, the results match what we see near the center of the Milky Way. These are short-lived stars, says Ian Bonnell (St Andrews University), which in itself may be telling us something: "That the stars currently present around the Galaxy's supermassive black hole have relatively short lifetimes of ~10 million years, suggests that this process is likely to be repetitive. Such a steady supply of stars into the vicinity of the black hole, and a diet of gas directly accreted by the black hole, may...

by Larry Klaes It's been a tough weekend, not only with the loss of the SpaceX Falcon booster but also the NanoSail-D sail experiment that flew aboard it. I'll have more on the loss of the sail tomorrow, but this may be a good day to look back and reflect on some of the titans of astronomical history, including the Hale instrument whose views of the heavens gave so many of us early inspiration. Tau Zero journalist Larry Klaes has been pondering these matters, and offers us a look at some of the people and instruments that proved essential in changing our view of the universe. Sixty years ago, on June 3, 1948, the most massive astronomical tool of the era was dedicated on Palomar Mountain near Pasadena, California. Known as the Hale Telescope, this instrument was much bigger than any telescope that had ever come before it. In its nearly three decades as the reigning largest telescope on Earth, the "Giant Eye" of the Palomar Observatory revealed new vistas of the heavens ranging from...

If dark energy is accelerating the expansion of the universe, how can we identify its signature? Researchers at the University of Hawaii have been using microwaves to detect what they believe to be dark energy at work. If their work stands up, it will be a useful step for cosmology, but also a potential boon for those of us with interstellar travel in mind. We obviously want to understand a force that may one day have propulsion implications, and it's possible that the universe is offering a set of useful clues. Here cosmology and propulsion science share a common interest. Led by István Szapudi, the researchers zeroed in on galactic superclusters -- the largest structures in the universe -- and so-called 'supervoids,' vast areas with few galaxies in them. Remember the prefix 'super' here, for conventional galactic clusters are some ten times smaller and held together by gravity, while the Hawaii team believes galaxies in the supervoids and superclusters are more affected by dark...

How does a planet full of amateur and professional astronomers miss an exploding star that was one of the brightest novae in the past ten years? The fact that the event called V598 Puppis (the brightening of the star USNO-A2.0 0450-03360039) was only spotted days after its explosive appearance by an orbiting space observatory that was turning from one target to another seems remarkable, but maybe it's a salutary reminder that with resources limited on the professional level, amateurs are still needed to track such interesting events. The observatory in question was ESA's XMM-Newton, an X-ray observatory whose data is recorded even as the satellite moves between different objects. That 'slewing' data revealed that the star in question had brightened by more than 600 times, as verified by later observers at Las Campanas Observatory in Chile. The evident cause: A white dwarf drawing off gas from a companion star, building sufficient quantities that a nuclear reaction released the...