View Laura K. Kinoshita's profileLast year, Dr. Andrea Prestwich of the Harvard-Smithsonian Center for Astrophysics announced the discovery of the largest stellar-mass black hole ever found. It was so large, the team claimed, that it was almost double the size of the previous record holder, which was located in M33.
But some scientists questioned the results because part of the data had been affected by a defective CCD. Plus, the conclusions were only based on a few spectra.
Now, new data taken with the Keck I telescope on Mauna Kea confirms that Prestwich did, in fact, find the largest "stellar-mass" black hole, in the galaxy IC-10, located in Cassiopia.
Stellar-mass black holes are different from those at the center of galaxies because they are created during supernovae explosions. Unlike galactic black holes, stellar-mass black holes were once thought to top out at 20 solar masses.
Prestwich estimates the progenitor star was extremely massive -- at least 60 times the size of the Sun. When the core collapsed, it left behind a singularity that contains as much mass as 33 stars. The results indicate that giant stars may not shed as much material during the final stages of their life as once believed.
Astronomers calculated the size of the black hole by measuring the orbit of its companion -- a highly evolved star known as a Wolf-Rayet -- and plugged the values into Kepler's fundamental laws of orbital motion. The Wolf-Rayet star will also explode as a supernova someday.
A paper describing the most massive known stellar-mass black hole is located at:
http://arxiv.org/PS_cache/arxiv/pdf/0802/0802.2716v2.pdf
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