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...

The image below is striking enough that I would have run it even without the interesting story it tells about the presence of organic materials in Messier 101. Viewed at infrared wavelengths and color-coded, the Pinwheel galaxy's spiral arms are visible, as is an outer zone, marked by a coral color, in which the organic molecules called polycyclic aromatic hydrocarbons disappear. These hydrocarbons are typically found in areas of star formation, with interesting implications for the appearance of life. So what does an organic-free zone tell us about the Pinwheel galaxy? "If you were going look for life in Messier 101, you would not want to look at its edges," said Karl Gordon of the Space Telescope Science Institute in Baltimore, Md. "The organics can't survive in these regions, most likely because of high amounts of harsh radiation." Image: The Pinwheel galaxy, otherwise known as Messier 101, sports bright reddish edges in this new infrared image from NASA's Spitzer Space Telescope....

By Larry Klaes Just how dangerous a place is our universe? As Larry Klaes notes, the apparent calm of a quiet summer sky masks events that can dwarf the imagination. New instruments, particularly those in space, are now giving us an unprecedented look at stellar flares and exploding stars, allowing us to observe the earliest phases of their activity. The implications for life are also striking, as flaring red dwarfs and titanic supernova can attest. When we look up at the night sky with our eyes alone, everything about it seems calm and even peaceful. Aside from a passing airplane or satellite, only the occasional meteor or twinkling star indicate any natural activities up there. Otherwise, the Universe seems almost immobile and permanent, even when we watch the stars for a long while. Recent news by the astronomy community shows just how much of an illusion this perception actually is. On May 14, NASA announced the discovery of the youngest local supernova remnant yet known, an...

Figuring out what makes up 74 percent of the universe is no small matter. But the late 20th Century discovery that the rate of expansion of the universe is not slowing but accelerating makes the research all but imperative. The Dark Energy Survey is behind the construction of an extraordinarily sensitive camera that will be installed on the Cerro Tololo Inter-American Observatory (CTIA) 4-meter telescope in Chile, with the aim of creating an unprecedented sky survey to probe these questions. I'm looking at the original proposal for the DES survey as submitted to the National Optical Astronomy Observatory office (NOAO controls the Cerro Tololo site). The document calls the discovery of accelerated expansion 'arguably the most important discovery in cosmology since the serendipitous detection of the cosmic microwave background radiation by Penzias and Wilson in 1965' (it's hard to argue with that!). And it goes on to state the challenge posed by dark energy in stark terms: According to...

Have the laws of physics stayed the same throughout the history of the cosmos? It's an interesting question because even minute changes to physical constants could imply the existence of extra dimensions, of the sort posited by string theorists. But that's a big 'could', because despite earlier controversial findings, at least one cornerstone constant -- the ratio of a proton's mass to that of an electron -- looks to be exactly the same in a galaxy some 6 billion light years away as it is when we measure it on Earth. A study led by Michael Murphy (Swinburne University) presents the result in a recent issue of Science. The constant, known as mu, determines the value of the strong nuclear force, so it has everything to do with how atomic nuclei hold themselves together. No one can say why the mass of a proton should be 1836 times that of an electron. All we know is that it is. To be more precise, the value is 1836.15. The recently published research studied light from the quasar...

Start thinking about large telescopes on the Moon and the imagination quickly runs riot. With no atmosphere to contend with, a 50-meter instrument of the sort now under discussion would be able to dwarf what telescopes can do on Earth. Exoplanet detections would be commonplace, but that's only a beginning, for this kind of telescope could take the spectra of the planets it finds and search for biomarkers. Ponder this: Even a twenty-meter telescope would be seventy times more sensitive than Hubble, and able to detect objects 100 times fainter than what the James Webb Space Telescope will be able to see. Now think about putting two telescopes on the Moon. Space them widely to take advantage of interferometry, creating an instrument that can, in essence, act as a single collecting surface. Mixing such possibilities with current work on detecting exoplanetary oceans and continents, we would be able to move quickly from the indirect signature of planets found by radial velocity,...

The feeling I have when deciding what to discuss next about this year's American Astronomical Society meeting is like what I get in a good used bookstore. Where to turn next? We've already looked at several stories with exoplanetary significance, but the arrival of a new type of star entirely seems to vault past even these in significance. If, of course, the so-called 'quark star' is real, a question sure to remain controversial as the study of extremely bright supernovae continues. When I say bright, I'm talking about three events in particular, each of which produced one hundred times more light energy than normal supernovae. The events, designated SN2006gy, SN2005gj and SN2005ap, have been under intense scrutiny, among the researchers a team from the University of Calgary, who point to the lack of a satisfactory explanation of these events. The hypothesis they defended at AAS is that neutron stars are not the most compact solid objects known to exist. That honor belongs to still...

Following up on yesterday's post on EPOCh, the extended exoplanet mission of the Deep Impact spacecraft, I want to mention that principal investigator Drake Deming (NASA GSFC) will be in my old home town of St. Louis on June 2 as part of the 212th meeting of the American Astronomical Society. Deming will be giving an update on the search for 'super Earths' of the sort that EPOCh may be able to spot during its investigations, while David Bennett (Notre Dame) as well as Michael Liu and Trent Dupuy (University of Hawaii) will be discussing other developments related to the exoplanet hunt and the study of brown dwarfs. We'll keep an eye out for EPOCh results, particularly re GJ 436. Also of relevance to future exoplanet as well as other astronomical studies is an upcoming report by Paul Chen (Catholic University) on work at NASA Goddard on inexpensive ways to make giant telescope mirrors on the Moon. That session will take place at the AAS on June 4 under the heading 'Speculative...

If you want to understand the size of the Milky Way, you have to know something about how fast stars move. Measuring the velocities of stars in the galaxy's stellar halo -- a spherical halo of old stars and globular clusters surrounding the disk -- you can figure out the mass of the whole by examining the gravity needed to keep these stars in their orbits. The Milky Way's stars are a part of that mass, of course, but so is the extended distribution of dark matter, about which we know all too little. This is where the so-called 'blue horizontal branch' stars (BHB) come into play. These ancient objects have evolved past their red giant phase and now burn helium. Because they tend to be both distant and bright (BHB stars are generally of spectral class B or A), they make useful markers for measuring stellar velocities out to a distance of 180,000 light years from the Sun, far beyond the confines of the primary galaxy. The huge star survey called SEGUE (a part of the Sloan Digital Sky...

If the pace of discovery seems to be accelerating, that's surely because of the network of tools we're putting into place, able to work with each other both in space and on the ground to ferret out new information. Thus the collaborative effort that followed the remarkable observation of a new supernova, one caught so early in the process that it was found before visible light from the blast had begun to become apparent. We have such tools as the Swift satellite to thank for this. Its ongoing observations of a supernova in the spiral galaxy NGC 2770, ninety million light years from Earth in the constellation called the Lynx, caught a three-minute, 40 second x-ray burst from the same galaxy, another supernova in the process of happening. What Swift seems to have uncovered was the shock wave of kinetic energy heating gas in the star's outer layers to the temperatures that produce X-ray emissions. Such an event would be undetectable at optical wavelengths, which is where most supernovae...

By Larry Klaes An alternative title for Larry's new story might be "Toward a Science of Galactic Archaeology." For the vast cities of stars we see in the night sky are in a constant, if extremely long-term, process of re-shaping themselves through encounters with other galaxies, an activity whose traces in the distant past may still be detectable. In fact, astronomers hoping to learn more about such collisions may have a interesting remnant close at hand. As Larry writes, Omega Centauri offers some characteristics that set it apart from the average globular cluster, and point to a much different origin. Just days ago, the team that operates the Hubble Space Telescope (HST) released a large collection of images on the eighteenth anniversary of the astronomical instrument's deployment into Earth orbit that show dozens of galaxies doing what the team called "interactions" with each other, but which can just as easily be described as collisions. The new Hubble images show massive islands...

A tricky aspect of modern astronomy is keeping all the wavelengths straight. Take the case of G1.9+0.3, a supernova remnant (SNR) near the center of the Milky Way. If you look at an X-ray image of this object made with the Chandra satellite in 2007, you'll see clear signs of growth compared to what the Very Large Array saw in 1985. But the VLA was working at radio wavelengths, making the image comparison problematic. Scientists studying G1.9+0.3 therefore went back to the VLA to observe the object for a second time in order to verify their initial impression. The later study confirmed that this supernova remnant -- consisting of the materials ejected by the vast explosion -- really is growing at what seems to be an unprecedented pace. Fifteen percent growth in 23 years is no small matter in astronomical terms, and the growth also makes it possible to work backwards in time to arrive at the time the supernova went off, now pegged at 150 years ago. That makes G1.9+0.3 the youngest of...

With the GLAST mission near launch, keep in mind the possibilities of this unique observatory in terms of findings that could revolutionize our view of distant events. GLAST (Gamma-Ray Large Area Space Telescope) will be looking at things we've only recently learned about, such as the enigmatic gamma-ray bursts (GRBs) now flagged by the Swift satellite and quickly pinpointed for the use of Earth-based observatories. We know we're pushing into uncharted waters given that GLAST represents a major step forward over all previous satellites designed to study gamma ray events. And major new instruments usually deliver new classes of objects. Because of the increase in GLAST's sensitivity over earlier tools like the EGRET instrument on NASA's Compton Gamma-ray Observatory (CGRO), the satellite may find thousands of new point sources. And we have plenty of questions already on the table. Gamma-ray bursts, for example, may be the result of black hole mergers, or the merger of a black hole and...

It's hard enough to figure out what dark energy and dark matter are, a task that will occupy physicists for a long time to come. But even if we confine ourselves to 'normal' or 'baryonic' matter (accounting only for some four or five percent of the universe), we're still left with a problem. Baryons are heavy subatomic particles like protons and neutrons that experience the strong nuclear force, and the problem is that even these relatively familiar particles are only partially accounted for. So where is the missing baryonic matter? The answer may lie in a thin haze of hot, low-density gas that connects galactic clusters. Call it WHIM, for warm-hot intergalactic medium. Dutch and German scientists now think they have uncovered a filament of such gas that connects the clusters Abell 222 and Abell 223. The properties of the gas, visible primarily in the far ultraviolet and X-ray bands, fit with simulations in terms of density and temperature. The scientists used the XMM-Newton X-ray...

Just how different were things in the early universe? One answer comes from a study of galaxies whose light has taken eleven billion years to reach us. In this early era -- the universe would have been less than three billion years old -- researchers have found galaxies so unusually compact that they compress a galaxy's worth of stars into a space only five thousand light years across. Such objects would be able to fit into the central hub of the Milky Way. What's more, these ultra-dense galaxies may account for as much as half the number of all galaxies of their mass that existed at this time. "In the Hubble Deep Field, astronomers found that star-forming galaxies are small," said Marijn Franx of Leiden University, The Netherlands. "However, these galaxies were also very low in mass. They weigh much less than our Milky Way. Our study, which surveyed a much larger area than in the Hubble Deep Field, surprisingly shows that galaxies with the same weight as our Milky Way were also very...