Just how common are brown dwarfs? The answer is still up for debate, for stars like these (with masses less than 0.05 that of the Sun) are so small that they do not burn hydrogen, and as they age, they become more and more difficult to detect. But we'd like to know more, especially in understanding our local interstellar neighborhood. Red dwarfs are common throughout the galaxy, and we know that they can support planetary systems and even worlds in the habitable zone. Is it possible that brown dwarfs are even more numerous than red dwarfs? Asking questions like these takes us into what is known as the initial mass function (IMF), which involves the number of stars versus their masses at the time of their formation. The place to study the issue is a star forming region like the one shown in the image below. This Subaru Telescope composite shows the W3 Main region, about 6,000 light years away in the constellation Cassiopeia. A region like this is helpful because the majority of stars...

A familiar scenario from the early universe is getting a tune-up. It's long been believed that cosmic dust was first produced by supernovae, becoming the essential building block for the formation of planets. New work using the Spitzer Space Telescope suggests a second mechanism that complements the first. So-called 'carbon stars,' stars late in their lives and similar to red giants but containing more carbon than oxygen, may have played as significant a role as supernovae themselves. The work focused on the carbon star MAG 29, some 280,000 light years away in the Sculptor Dwarf galaxy. Says Albert Zijlstra (Jodrell Bank Centre for Astrophysics): "All the elements heavier than helium were made after the Big Bang in successive generations of stars. We came up with the idea of looking at nearby galaxies poor in heavier elements to get a close-up view of how stars live and die in conditions similar to those in the first galaxies." Image (click to enlarge): The star MAG 29, shown in...

Finding something unexpected adds immeasurably to the pleasure of doing science. Yesterday we looked at an anomalous transient in Boötes, one that has already spawned a number of theories to explain it. Today let's look at some of the radio noise that pervades the cosmos, and an intriguing experiment that discovered more of it than expected. The story makes this writer marvel again at how the universe continues to change the game. I like how Philip M. Lubin (UCSB) puts it: "It seems as though we live in a darkened room and every time we turn the lights on and explore, we find something new. The universe continues to amaze us and provide us with new mysteries. It is like a large puzzle that we are slowly given pieces to so that we can eventually see through the fog of our confusion." Indeed. Lubin is on the team behind the NASA balloon-borne experiment called ARCADE (Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission), which discovered this particular static back in...

We continue to follow the American Astronomical Society's meeting in Long Beach with fascination. This has, indeed, become AAS week in these pages. But amidst the news of brown dwarf discoveries, a more massive Milky Way than previously thought, and asteroids around white dwarf stars, the story of a genuine mystery stands out. Such a mystery is the optical transient known as SCP 06F6, a flash of light picked up by the Hubble Space Telescope back in 2006. Have a look at the images below: Image: This pair of NASA Hubble Space Telescope pictures shows the appearance of a mysterious burst of light that was detected on February 21, 2006. The event was detected serendipitously in a Hubble search for supernovae in a distant cluster of galaxies. The light-signature of this event does not match the behavior of a supernova or any previously observed astronomical transient phenomenon in the universe. Credit: : NASA, ESA, and K. Barbary (University of California, Berkeley/Lawrence Berkeley...

On my walk this morning, I was musing about the ongoing AAS meeting in Long Beach when I found myself having one of those epiphanies that seem to open a window into the heart of things. The day was unusually warm but gusts of wind tossed the trees and low clouds laced with rain scudded past. And suddenly I was no longer walking along a quiet street but became aware that I walking a planet within a star system, within a cloud of stars, and that by being made up of elements from those stars, I was in some sense an expression of that universe as it observed itself. It's hardly an original notion, but the sense of it was palpable, an almost physical awareness that translated something known factually into something experienced. It was spurred by the recent news that the Milky Way is fifty percent more massive than we thought, maybe the twin of the Andromeda Galaxy. Increasing our sense of scale adds to the grandeur. The punch of the Fermi Paradox comes from the sheer size of galaxies --...