标题: IMAGES OF A GALAXY IN THE FORNAX CLUSTER OF GALAXIES [打印本页] 作者: 夜空 时间: 2006-3-12 01:09 标题: IMAGES OF A GALAXY IN THE FORNAX CLUSTER OF GALAXIES EMBARGOED UNTIL: 1:00 P.M. (EDT) May 9, 1996
PHOTO RELEASE NO.: STScI-PRC96-21a
IMAGES OF A GALAXY IN THE FORNAX CLUSTER OF GALAXIES
This color image from the Hubble Space Telescope shows a region in NGC
1365, a barred spiral galaxy located in a cluster of galaxies called
Fornax. A barred spiral galaxy is characterized by a "bar" of stars,
dust and gas across its center. The black and white photograph from a
ground-based telescope shows the entire galaxy, which is visible from
the Southern Hemisphere. Members of the Key Project team, who have
been measuring the distance to the Fornax cluster, have estimated it to
be 60 million light-years from Earth. The team arrived at their
preliminary estimate by using Cepheids, bright, young stars that are
used as milepost markers to calculate distances to nearby galaxies.
The line of small blue dots in the color image shows the formation of
stars in the galaxy's spiral arms, making them ideal targets for the
discovery of Cepheids. The group has discovered about 50 Cepheids in
the galaxy. The team also has used the Fornax cluster to calibrate and
compare many secondary distance methods. Cepheids are accurate
distance markers for nearby galaxies, but astronomers need secondary
methods to measure distances to faraway galaxies. An accurate value
for the Hubble Constant is dependent on reliable secondary distance
methods.
Credit: W. Freedman (Carnegie Observatories), the Hubble Space
Telescope Key Project team, and NASA
Image files in GIF and JPEG format and captions may be accessed on
Internet via anonymous ftp from oposite.stsci.edu in /pubinfo.
GIF JPEG
PRC96-21a NGC 1365 gif/NGC1365.gif jpeg/NGC1365.jpg
