Each of the two light-peaks contains a few million densely packed stars. The brighter object is the "classic'' nucleus as studied from the ground. However, HST reveals that the true center of the galaxy is really the dimmer component.
One possible explanation is that the brighter cluster is the leftover remnant of a galaxy cannibalized by M31. Another idea is that the true center of the galaxy has been divided in two by deep dust absorption across the middle, creating the illusion of two peaks.
This green-light image was taken with HST's Wide Field and Planetary Camera (WF/PC), in high resolution mode, on July 6, 1991. The two peaks are separated by 5 light years, The Hubble image is 40 light years across.
The background of the present picture is dark only because the contrast has been adjusted to show the full detail in the nucleus, which is much brighter than the surrounding bulge.
Credit: T. R. Lauer (NOAO), NASA
Last Modification: January 31, 2001