Anemic Galaxy NGC 4921 at the Edge
Explanation:
How far away is spiral galaxy NGC 4921?
Although presently estimated to be about 320 million
light years distant, a more precise determination
could be coupled with its known
recession speed to help humanity better calibrate the
expansion rate of the entire visible universe.
Toward this goal, this image was taken by the
Hubble
Space Telescope in order to help identify key stellar distance
markers know as
Cepheid
variable stars.
Since
NGC 4921
is a member of the
Coma Cluster of Galaxies,
refining its distance would also allow a better
distance determination to one of the largest
nearby clusters in the local universe.
The magnificent spiral
NGC 4921
has been informally dubbed
anemic
because of its low rate of star formation and
low surface brightness.
The remarkably sharp image was made with Hubble's
Advanced
Camera for Surveys, currently in need of repair.
Visible in
the
image are, from the center, a bright nucleus, a bright
central bar, a prominent
ring of dark
dust, blue
clusters of recently formed stars, several
smaller
companion galaxies, unrelated
galaxies in the far distant universe,
and unrelated stars in our
Milky Way
Galaxy.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
