A Stellar Close Encounter at the Core of Globular Cluster M15
The sky is ablaze with several hundred thousand stars in the imaginary view from the surface of a hypothetical planet at the center if the globular star cluster called M15 (located 30,000 light- years away in the constellation Pegasus). The average distance between stars is a fraction of a light-year.
A new population of extremely hot and blue stars - recently discovered by NASA's Hubble Space Telescope - stand out like diamonds on black velvet. At the center of the image, a bypassing star gravitationally pulls the outer envelop of gas from a red giant star. This process will expose the giant's core - the nuclear fusion "engine" that powers the star.
This stellar cannibalism could only take place where stars are so crowded together, that chances for close encounters are exceptionally high. This new class of blue star is possibly fossil evidence that the center of the globular cluster has contracted to an extremely dense condition called "core collapse."
This research, by DeMarchi and Dr. Francesco Paresce of the Space Telescope Science Institute and the European Space Agency, is being announced at a press conference at the meeting of the American Astronomical Society in Berkeley, California.
Illustration by: G. Dana Berry, STSCI