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Chandra X-ray
Observatory Center
Harvard-Smithsonian Center for Astrophysics
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M101: A spiral galaxy about 20 million light years from Earth.
(Credit: NASA/CXC/SAO/R.DiStefano et al.)

Caption: This Chandra image of M101 shows numerous "quasisoft" X-ray sources (marked with green diamonds) that may represent a new class of objects. The quasisoft sources have temperatures in the range of one to four million degrees Celsius, significantly less than the ten to a hundred million degree gas associated with "hard" X-ray sources, such as neutron stars or stellar-mass black holes. The power output of quasisoft sources is comparable to or greater than that of neutron stars or stellar-mass black holes fueled by the infall of matter from companion stars. It is not known how quasisoft sources are produced; one possibility is that they are due to hot gas swirling around intermediate-mass black holes with masses a hundred or more times greater than the mass of the Sun.

Scale: Image is 14 arcmin per side

Chandra X-ray Observatory ACIS Image

CXC operated for NASA by the Smithsonian Astrophysical Observatory