NGC 3310 A 'Starburst' Spiral Galaxy
Most galaxies form new stars at a fairly slow rate, but
members of a rare class known as "starburst" galaxies blaze
with extremely active star formation. The galaxy NGC 3310 is
forming clusters of new stars at a prodigious rate. There are
several hundred star clusters in NGC 3310, visible in the
Heritage image as the bright blue diffuse objects that trace
the galaxy's spiral arms. Each of these star clusters
represents the formation of up to about a million stars, a
process that takes less than 100,000 years. In addition,
hundreds of individual young, luminous stars can be seen
throughout the galaxy.
Once formed, the star clusters become redder with age as
the most massive and bluest stars exhaust their fuel and burn
out. Measurements in this image of the wide range of cluster
colors show that they have ages ranging from about one million
up to more than one hundred million years. This suggests that
the starburst "turned on" over 100 million years ago. It may
have been triggered when a companion galaxy collided with NGC
These observations may change astronomers' view of
starbursts. Starbursts were once thought to be brief episodes,
resulting from catastrophic events like a galactic collision.
However, the wide range of cluster ages in NGC 3310 suggests
that the starbursting can continue for an extended interval,
Located in the direction of the constellation Ursa Major,
NGC 3310 has a distance of about 59 million light-years.
Hubble's Wide Field Planetary Camera 2 was used to make
observations of NGC 3310 in March 1997 and again in September
2000. The color rendition of the combined images was created
by the Hubble Heritage Team.