Chandra captures spiral galaxy's violent, restless nature (Forwarded)

Steve Roy
Media Relations Dept.
Marshall Space Flight Center, Huntsville, AL

(256) 544-0034

Megan Watzke
Chandra X-ray Observatory Center, CFA, Cambridge, MA

(617) 496-7998

For release: 10-28-03

Photo release no.: 03-192

Chandra captures spiral galaxy's violent, restless nature
[http://www1.msfc.nasa.gov/NEWSROOM/n...os03-192.html]

A series of NASA Chandra X-ray Observatory images of the spiral galaxy NGC 1637
has provided a dramatic view of a violent, restless nature that belies the
galaxy's serene optical image. Over a span of 21 months, intense neutron star
and black hole X-ray sources flashed on and off, giving the galaxy the
appearance of a cosmic Christmas tree.

Erratic, volatile behavior is a common characteristic of neutron stars or black
holes that orbit normal companion stars. Gas ripped off the normal star falls
toward the compact star where the gas is compressed and heated by gravitational
fields billions of times stronger than on the surface of the Sun. This process
generates powerful X-radiation that can flare up and subside in a matter of seconds.

The X-ray view is in marked contrast to the view with an optical telescope.
Optically, the galaxy is a stately spiral lit by the glow of about fifty billion
stars slowly evolving over millions and billions of years.

This tranquil scene is interrupted about once a century with a supernova that
signals the death of a star, and, in many cases, the formation of a neutron star
or black hole. It was the detection of such a supernova in 1999 that triggered
the subsequent series of Chandra observations.

The supernova appears in the panels on days four and 49 as the faint source at
the five o'clock position just below the diffuse glow in the center of the
image. The supernova faded in a few months, but the Chandra observations
continued on five more occasions in coordination with the Hubble Space Telescope
and the Very Large Array radio telescope. This collaboration produced a valuable
data set of long-term radio, optical and X-ray observations of the galaxy.

Of particular note is an extremely bright (white) X-ray source that appears in
all panels at the nine o'clock position. This source is located in a group of
massive stars in one of the outer spiral arms of the galaxy. It is likely a
black hole formed relatively recently, in the last million years or so, when a
massive star exhausted its nuclear fuel, exploded as a supernova, and left
behind a black hole which is now pulling in gas from a companion star.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra
program.

Credits: NASA/CXC/Penn State/S. Immler et al.