Messier 31 - M31
Credit: X-ray (NASA/CXC/SAO/R.Barnard, Z.Lee et
al.), Optical (NOAO/AURA/NSF/REU Prog./B.Schoening, V.Harvey; Descubre
Fndn./CAHA/OAUV/DSA/V.Peris)
Data from NASA's Chandra X-ray Observatory have been used to discover 26 black hole candidates in the Milky Way's galactic neighbor, Andromeda, as described in our latest press release. This is the largest number of possible black holes found in a galaxy outside of our own.
A team of researchers, led by Robin Barnard of the
Harvard-Smithsonian Center for Astrophysics, used 152 observations of
Chandra spanning over 13 years to find the 26 new black hole candidates.
Nine were known from earlier work. These black holes belong to the stellar-mass black hole category, which means they were created when a massive star collapsed and are about 5 to 10 times the mass of the Sun.
This wide-field view of Andromeda contains optical data from the
Burrell Schmidt telescope of the Warner and Swansey Observatory on Kitt
Peak in Arizona. Additional detail of the core and dust in the spiral
arms comes from an image taken by astrophotographer Vicent Peris using
data from two of his personal telescopes. In this combined optical
image, red, green, and blue show different bands from the visible light
portion of the electromagnetic spectrum.
The inset contains X-ray data from multiple Chandra observations of
the central region of Andromeda. This Chandra image shows 28 of the 35
black hole candidates in this view, visible by mousing over the image.
The other seven candidates can be seen in this Chandra image with a larger field of view.
Chandra X-ray close-up of M31's core, with sources circled
(Credit: X-ray (NASA/CXC/SAO/R.Barnard, Z.Lee et
al.), Optical (NOAO/AURA/NSF/REU Prog./B.Schoening, V.Harvey; Descubre
Fndn./CAHA/OAUV/DSA/V.Peris)
Seven of the 35 black hole candidates are within only 1,000 light years
of the Andromeda Galaxy's center (mouse over the image for the dotted
circle enclosing these sources). This is more than the number of black
hole candidates with similar properties located near the center of our own Galaxy.
This, however, does not take astronomers by surprise, since the bulge
of stars in the middle of Andromeda is bigger, allowing more black holes
to form.
Eight of the nine black hole candidates that were previously identified are associated with globular clusters,
the ancient concentrations of stars distributed in a spherical pattern
about the center of the galaxy. This also differentiates Andromeda from
the Milky Way as astronomers have yet to find a similar black hole in
one of the Milky Way's globular clusters.
Andromeda, also known as Messier 31 (M31), is a spiral galaxy located
about 2.5 million light years away. It is thought that the Milky Way
and Andromeda will collide
several billion years from now. The black holes located in both
galaxies will then reside in the large, elliptical galaxy that results
from this merger.
These results are available online
and will be published in the June 20th issue of The Astrophysical
Journal. Many of the Andromeda observations were made within Chandra's
Guaranteed Time Observer program.
Fast Facts for M31:
Category: Normal Galaxies & Starburst Galaxies, Black Holes
Coordinates (J2000): RA 00h 40m 27s | Dec +40° 40' 12
Constellation: Andromeda
Observation Date: 152 pointings between 1999 and 2012
Observation Time: 55 hours 30 min (2 days 7 hours 30 min)
Instrument: ACIS
Also Known As: Andromeda
References: Barnard, R. et al, 2013, ApJ 770, 148; arXiv:1304.7780
Color Code: X-ray (Purple); Optical (Red, Green, Blue)
Distance Estimate: About 2.5 million light years
