Star formation is probably one of the more sublime processes to watch in our universe. That is, of course, if you could be around for thousands to millions of years to watch it happen. But if you could, you would see vast amounts of gas collapsing, coalescing, and rotating to form a brand new star to be counted in the galaxy. Because we only get a snapshot in time in the birth of a star to observe, astronomers are still fuzzy on the details, especially when it comes to the birth of the most massive stars.
Astronomers, led by Peter Barnes of the University of Florida, used radio telescopes in Australia and Chile to study massive star formation. In the midst of a survey called CHaMP (Census of High and Medium-mass Protostars), they discovered what appears to be the largest gravitational collapse of gas into a massive cluster ever seen.
Infrared and millimeter wave light give us a window into the dusty star forming regions through which optical light cannot penetrate. Many gas molecules also produce light of these wavelengths, and these trace the movements of dense gas give us temperature information, and more. For this "clump" of gas called BYF73, astronomers tracked the molecules HCO+ and H13CO+.
This clump of material is approximately 20,000 times the mass of the sun. The amount of gas falling into the center is 3% of the sun's mass per year. That may not seem like a lot, but in human terms, this is on the order of 1028 kilograms per year (1 with 28 zeros!) for a process that takes tens of thousands of years. This is going to be one huge cluster of stars when it is finished!
Astronomers are still not sure whether massive stars form in a scaled up version of the way that lower mass stars like our sun formed, with material falling into the protostar over time, or by some collective, massive collapse. This new study certainly gives us a clue for one case.
Massive stars exert great influence over their environments, which include stars of all sizes, and seed the galaxy with all of the elements needed for planets and life when they die. The better we understand how these behemoths are born, the better we understand our origins.
Image: Mid-infrared image of BYF 73 from NASA's Spitzer Space Telescope. The yellowish wisps to the right are remnants of gas that have been heated and are being driven off by the massive young stars within them (seen in blue). NASA/JPL-Caltech