Steve Roy
Marshall Space Flight Center January 14, 2000
Huntsville, AL
Phone: 256-544-6535
Barbara Kennedy
Penn State PIO
University Park, PA.
Phone: 814-863-4682
Dr. Wallace Tucker
Chandra X-ray Observatory Center, CfA.
Cambridge, MA
Phone: 617-496-7998
Teresa Thomas
Carnegie Mellon University PIO
Pittsburgh, PA
412-268-3580
CXC PR: 00-02
Chandra Images the Seething Cauldron of Starburst Galaxy
NASA’s Chandra X-ray Observatory has imaged the core of the nearest starburst galaxy, Messier 82
(M82). The observatory has revealed a seething cauldron of exploding stars, neutron stars, black holes,
100 million degree gas, and a powerful galactic wind.
The discovery will be presented by a team of scientists from Carnegie Mellon University, Pittsburgh, Penn.,
Pennsylvania State University, University Park, and the University of Michigan, Ann Arbor, on January 14
at the 195th national meeting of the American Astronomical
Society.
“In the disk of our Milky Way Galaxy, stars form and die in a relatively calm fashion like burning embers in
a campfire,” said Richard Griffiths, Professor of Astrophysics at Carnegie Mellon University. “But in a
starburst galaxy, star birth and death are more like explosions in a fireworks factory.”
Short-lived massive stars in a starburst galaxy produce supernova explosions, which heat the interstellar
gas to millions of degrees, and leave behind neutron stars and black holes. These explosions emit light in
the X rays rather than in visible light.
Because the superhot components inside starburst galaxies are
complex and sometimes confusing, astronomers need an X-ray-
detecting telescope with the highest focusing power (spatial
resolution) to clearly discriminate the various structures.
“NASA’s Chandra X-ray Observatory is the perfect tool for studying starburst galaxies since it has the
critical combination of high- resolution optics and good sensitivity to penetrating X rays,” said Gordon
Garmire, the Evan Pugh Professor of Astronomy and
Astrophysics at Pennsylvania State University, and head of the
team that conceived and built Chandra’s Advanced CCD Imaging
Spectrograph (ACIS) X-ray camera, which acquired the data.
Many intricate structures missed by earlier satellite observatories are now visible in the ACIS image,
including more than twenty
powerful X-ray binary systems that contain a normal star in a close orbit around a neutron star or a
black hole. “Several sources are so bright that they are probably black holes, perhaps left over from
past starburst episodes,” Garmire explained.
The astronomers report that the X-ray emitting gas in the galaxy’s core region has a surprisingly hot
temperature. “Determining the source of high energy X rays from M82 may elucidate whether
starburst galaxies throughout the Universe contribute significantly to the X-ray background radiation
that pervades intergalactic space,” said Griffiths. “The image also shows a chimney-like structure at the
base of the galactic wind, which may help us understand how
metal-rich starburst gas is dispersed into intergalactic space.”
“What we don’t see may be as important as what we do see,” said Garmire. “There is no indication of a
single, high luminosity, compact X-ray source from a supermassive black hole at the very center of the
galaxy, although considerable evidence exists that such central black holes are present in many or most
galaxies.”.
The astronomers note that recent optical and infrared data suggest most galaxies were starbursts
when the Universe was young and that their galactic winds may have distributed carbon, oxygen, iron
and other heavy atoms that now pervade the Universe. The starburst in M82 is thought to have been
caused by a near collision with a large spiral galaxy, M81, about 100 million years ago. At a distance of
11 million light years, M82 is the closest starburst galaxy to our Milky Way Galaxy and provides the best
view of this type of galactic
structure, which may have played a critical role in the early history of the Universe.
The Chandra image was taken with the Advanced CCD Imaging
Spectrometer (ACIS) on September 20, 1999 in an observation that lasted about 13 hours. ACIS was
built by Penn State Univ. and
Massachusetts Institute of Technology, Cambridge.
To follow Chandra’s progress or download images visit the Chandra sites at
AND
NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. TRW, Inc.,
Redondo Beach, CA, is the prime contractor for the spacecraft. The Smithsonian’s Chandra X-ray Center
controls science and flight operations from Cambridge, MA.
High resolution digital versions of the X-ray image (JPG, 300 dpi TIFF) are available at the Internet site
listed above.
Additional Contacts:
Dr. Richard Griffiths, Carnegie Mellon University
Pittsburgh, Penn.
412-268-1886, griffith@astro.phys.cmu.edu
Dr. Gordon Garmire, Penn State Univ.
814-865-1117, ggarmire@astro.psu.edu
IMAGE CAPTION:
Chandra X-ray Image of M82
M82, at a distance of 11 million light years from Earth, is the nearest starburst galaxy. Massive stars
are forming and expiring in M82 at a rate ten times higher than in our galaxy. The bright spots in the
center are supernova remnants and X-ray binaries. These are some of the brightest such objects known.
The luminosity of the X-ray binaries suggests that most contain a black hole. The diffuse X-ray light in the
image extends over several thousand light years, and is caused by multimillion degree gas flowing out of
M82. A close encounter with a large galaxy, M81, in the last 100 million years is thought to be the cause
of the starburst activity.
Image made with the Advanced CCD Imaging Spectrometer (ACIS)
Credit: NASA/CXC/SAO/PSU/CMU
