Chandra X-Ray Observatory image of M82
Nasa's Chandra X-ray Observatory has images nearby irregular starburst galaxy M82 in the x-ray part of the spectrum. As massive stars are orming and expiring in M82 at a rate ten times higher than in our galaxy, there is a large number of supernova remnants and X-ray binaries in this galaxy, which can be seen as bright spots in this image. Some of these spots are probably among the brightest X-ray binaries known. The diffuse glow of X-ray light is caused by very hot gas with a temperature of several million degress; this gas extends over several thousands of light years and is flowing out of the galaxy. It is thought that the starburst activity in M82 has been caused by a close encounter with its larger neighbor, M81, a few tens of million years ago.
Images were obtained with Chandra's Advanced CCD Imaging Spectrometer (ACIS).
Chandra image of the central region of M82, colorized for X-ray energy: In this image, red represents the low energy band, green intermediate, and blue the highest observed energies. The white and yellow sources are those that emit significant amounts of both low- and high-energy X-rays. The image was created from data collected with Chandra's ACIS X-ray camera on September 29, 1999 over 13 hours.
The ultraluminous sources emit ten to several hundred times more X-ray power than similar sources in our Galaxy; the brightest point-like source, located near the center of the image, is the most powerful ultraluminous source detected in any galaxy to date. Their enormous X-ray luminosity can be either intrinsically, or caused by the effect that they are beaming energy toward Earth. Many astronomers believe that these sources may be considerably massive black holes.
Observations of M82 and other starburst galaxies suggest that the origin of ultraluminous sources is related to a burst of star formation triggered by a collision with another galaxy, in case of M82, the presumable close encounter with its larger neighbor galaxy, M81, within the last 100 million years.
The diffuse red cloud in the image is caused by multi-million degree gas flowing out of the central region of M82.
Chandra has captured dramatical variations of a strong X-ray source near, but offset the center of irregular starburst galaxy M82. This source was seen to increase dramatically in intensity over a period of three months (compare left and right panels) after which it decreased in intensity. Some astronomers believe that the pattern of variability such as this indicates that the source is a black hole.
Last Modification: 7 Jun 2001, 21:40 MET