Untitled Document
NASA/Chandra/Palomar Obs.
A compact group of galaxies
known as Stephan's Quintet was nearly demoted to a quartet recently, but as
you'll soon learn, its status has remained intact.
This unusual photo of the
group combines X-ray and optical observations into one image to better illustrate
the dynamics of the system. Blue areas represent X-ray observations of gas heated
by shock to about 10.8 million degrees Fahrenheit (6 million Celsius).
The heat is produced by
the rapid motion of a spiral galaxy that is intruding on the system (it's labeled
B in the wider-field optical image at the bottom right -- you'll need to enlarge
the image to see the labels). As galaxies move through the hot gas and are affected
by the gravity of each other, cool gas is stripped out of them. This deprives
the galaxies of raw material needed to form new stars.
The group is about 280 million
light-years from Earth.
When the image was released
earlier this month, astronomers said the galaxy marked F is actually in the
foreground, closer to Earth and not part of the quintet, as previously thought.
Galaxy C, however, has now been found to be in the group, so it is still a quintet.
The spiral galaxies will
probably become elliptical galaxies in a few billion years. The X-ray data was
gathered by NASA's Chandra X-ray Observatory. The optical image was provided
by the Palomar Observatory and the Digitized Sky Survey.
-- Robert
| 
