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FOR RELEASE: June 11, 1998

PHOTO NO.: STScI-PRC98-21


A BRIGHT RING OF STAR BIRTH AROUND A GALAXY'S CORE

An image from NASA's Hubble Space Telescope reveals clusters of infant
stars that formed in a ring around the core of the barred-spiral galaxy
NGC 4314. This stellar nursery, whose inhabitants were created within the
past 5 million years, is the only place in the entire galaxy where new stars
are being born. The Hubble image is being presented today (June 11) at the
American Astronomical Society meeting in San Diego, Calif.

This close-up view by Hubble also shows other interesting details in
the galaxy's core: dust lanes, a smaller bar of stars, dust and gas
embedded in the stellar ring, and an extra pair of spiral arms packed
with young stars. These details make the center resemble a miniature
version of a spiral galaxy. While it is not unusual to have dust
lanes and rings of gas in the centers of galaxies, it is uncommon to
have spiral arms full of young stars in the cores. NGC 4314 is one of
the nearest (only 40 million light-years away in the constellation
Coma Berenices) examples of a galaxy with a ring of infant stars close
to the core. This stellar ring - whose radius is 1,000 light-years -
is a great laboratory to study star formation in galaxies.



The image shows Hubble's close-up view of the galaxy's core,
taken in December 1995 by the Wide Field and Planetary Camera 2. The
bluish-purple clumps that form the ring are the clusters of infant stars.
Two dark, wispy lanes of dust and a pair of blue spiral arms are just
outside the star-forming ring. The lanes of dust are being shepherded
into the ring by the longer, primary stellar bar seen in the ground-based
(left-hand) image. The gas is trapped inside the ring through the stars'
gravitational attraction.

The two spiral arms outside the ring are probably unrelated to the
dust lanes, and seem to contain very little dust or gas. The stars in
these spiral arms are bluer than most of the galaxy, indicating that
many of them are relatively young, less than 200 million years
old. However, they are older than those in the ring. This information
suggests that the neighborhood of star formation is moving closer to
the galaxy's core. Another interpretation has the arms formed through
the gravitational interaction of the embedded bar and ring of stars,
causing them to spray outward.

This picture was created by combining images taken in ultraviolet, blue,
visible, infrared, and H-alpha. The purple color represents hydrogen gas
being excited by hot, young star clusters.

Credits: G. Fritz Benedict, Andrew Howell, Inger Jorgensen,
David Chapell (University of Texas), Jeffery Kenney (Yale University),
and Beverly J. Smith (CASA, University of Colorado), and NASA.

We gratefully acknowledge the support of the Hubble Space Telescope
Astrometry Science Team: Principal Investigator W.H. Jefferys,
R. Duncombe, P. Shelus, B. McArthur (University of Texas),
P. Hemenway (University of Rhode Island), O. Franz (Lowell Observatory),
A. Whipple (Allied-Signal Corp.), Wm. van Altena (Yale University), and,
L. Fredrick (University of Virginia).