Fireworks of star birth light up nearby galaxy
Galaxy NGC 4214
January 11, 2000
Web posted at: 10:17 a.m. EST (1517 GMT)
(CNN) -- Bursting in brilliant yellows, reds and blues, the
formation of stars in a nearby galaxy presents some
spectacular celestial fireworks, as illustrated in a recently
released image taken by NASA's Hubble Space Telescope.
Located 13 million light-years from Earth, the galaxy NGC
4214 is forming clusters of new stars from its
interstellar gas and dust, according to NASA, which released
the image this month. The Hubble snapshot reveals a sequence
of steps in the evolution of stars and star clusters.
NGC 4214 contains a multitude of faint stars covering most of
the frame, but the picture is dominated by clouds of glowing
gas surrounding bright stellar clusters.
| MESSAGE BOARD|
The youngest of these star clusters are located at the lower
right of the picture, where they appear as about half a dozen
bright clumps of glowing gas. Inside the clouds, young stars,
formed due to gravitational collapse of the gas, emit strong
The young, hot stars have a whitish to bluish color because
of their high surface temperatures, ranging from 10,000 to
50,000 degrees Celsius.
In addition to pouring out ultraviolet light, these hot stars
eject fast "stellar winds," moving at thousands of kilometers
per second, which plow out into the surrounding gas.
The radiation and wind forces from the young stars literally
blow bubbles in the gas. Over millions of years, the bubbles
increase in size as the stars inside them grow older.
To the lower left of the youngest clusters is an older star
cluster, around which a gas bubble has inflated to the point
that there is an obvious cavity around the central cluster.
The most spectacular feature in the Hubble picture lies near
the center of the galaxy. This object is a cluster of
hundreds of massive blue stars, each of them more than 10,000
times brighter than the sun.
A vast heart-shaped bubble, inflated by the combined stellar
winds and radiation pressure, surrounds the cluster. The
expansion of the bubble is augmented as the most massive
stars in the center reach the ends of their lives and explode
Deprived of gas, the cluster at the center of NGC 4214 will
be unable to form further new stars, and its luminous stars
will continue to go supernova and disappear.
Elsewhere in the galaxy, however, gas will start to collapse
and form another generation of stars, even as the clusters
currently visible gradually fade.
The faint stars covering most of the picture are much older
than the bright blue supergiants and indicate that episodes
of star birth have been occurring in the galaxy for billions
The picture was created from exposures taken in several color
filters with a Hubble camera in 1997.
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The Hubble Space Telescope
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