M31:
Chandra Images Heart of Andromeda Galaxy

[Please note: Additional observations of M31 that alter the conclusions in this release were announced on October 12, 2001. View the updated Chandra results on the Andromeda galaxy.]

This Chandra X-ray image shows the central portion of the Andromeda Galaxy. The blue dot in the center of the image is an unusually "cool" million degree X-ray source of unknown nature. Just above this cool source is a source (yellow) that is thought to be due to X-rays from matter swirling toward a supermassive black hole in the nucleus of the galaxy. This black hole contains the mass of 30 million suns. Numerous other X-ray sources are also apparent. Most of these are probably due to X-ray binary systems, in which a neutron star or black hole is in a close orbit around a normal star.

Fast Facts for M31: Credit  NASA/CXC/SAO Scale  Image is 1 arcmin across. Category  Normal Galaxies & Starburst Galaxies Coordinates (J2000)  RA 00h 40m 27s | Dec +40° 40' 12" Constellation  Andromeda Observation Dates  October 13, 1999 Observation Time  3 hours Obs. IDs  303 Color Code  Cool blue dot - the rest is intensity Instrument  ACIS Also Known As  Andromeda Distance Estimate  2.9 million light years Release Date  January 14, 2000