The star cluster NGC 3293 in the constellation of Carina
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In this striking new image from ESO’s La
Silla Observatory in Chile young stars huddle together against a
backdrop of clouds of glowing gas and lanes of dust. The star cluster,
known as NGC 3293, would have been just a cloud of gas and dust itself
about ten million years ago, but as stars began to form it became the
bright group of stars we see here. Clusters like this are celestial
laboratories that allow astronomers to learn more about how stars
evolve.
This beautiful star cluster, NGC 3293,
is found 8000 light-years from Earth in the constellation of Carina
(The Keel). This cluster was first spotted by the French astronomer
Nicolas-Louis de Lacaille in 1751, during his stay in what is now South
Africa, using a tiny telescope with an aperture of just 12 millimetres.
It is one of the brightest clusters in the southern sky and can be
easily seen with the naked eye on a dark clear night.
Star clusters like NGC 3293 contain stars that all formed at the same
time, at the same distance from Earth and out of the same cloud of gas
and dust, giving them the same chemical composition. As a result
clusters like this are ideal objects for testing stellar evolution
theory.
Most of the stars seen here are very young, and the cluster itself is
less than 10 million years old. Just babies on cosmic scales if you
consider that the Sun is 4.6 billion years old and still only
middle-aged. An abundance of these bright, blue, youthful stars is
common in open clusters like NGC 3293, and, for example, in the better
known Kappa Crucis cluster, otherwise known as the Jewel Box or NGC 4755.
These open clusters each formed from a giant cloud of molecular gas
and their stars are held together by their mutual gravitational
attraction. But these forces are not enough to hold a cluster together
against close encounters with other clusters and clouds of gas as the
cluster’s own gas and dust dissipates. So, open clusters will only last a
few hundred million years, unlike their big cousins, the globular
clusters, which can survive for billions of years, and hold on to far
more stars.
Despite some evidence suggesting that there is still some ongoing
star formation in NGC 3293, it is thought that most, if not all, of the
nearly fifty stars in this cluster were born in one single event. But
even though these stars are all the same age, they do not all have the
dazzling appearance of a star in its infancy; some of them look
positively elderly, giving astronomers the chance to explore how and why
stars evolve at different speeds.
Take the bright orange star at the bottom right of the cluster. This
huge star, a red giant, would have been born as one of the biggest and
most luminous of its litter, but bright stars burn out fast. As the star
used up the fuel at its core its internal dynamics changed and it began
to swell and cool, becoming the red giant we now observe. Red giants
are reaching the end of their life cycle, but this red giant’s sister
stars are still in what is known as the pre-main-sequence — the period
before the long, stable, middle period in a star’s life. We see these
stars in the prime of their life as hot, bright and white against the
red and dusty background.
This image was taken with the Wide Field Imager (WFI) installed on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in northern Chile.
More information
ESO is the foremost intergovernmental
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programme focused on the design, construction and operation of powerful
ground-based observing facilities enabling astronomers to make
important scientific discoveries. ESO also plays a leading role in
promoting and organising cooperation in astronomical research. ESO
operates three unique world-class observing sites in Chile: La Silla,
Paranal and Chajnantor. At Paranal, ESO operates the Very Large
Telescope, the world’s most advanced visible-light astronomical
observatory and two survey telescopes. VISTA works in the infrared and
is the world’s largest survey telescope and the VLT Survey Telescope is
the largest telescope designed to exclusively survey the skies in
visible light. ESO is the European partner of a revolutionary
astronomical telescope ALMA, the largest astronomical project in
existence. ESO is currently planning the 39-metre European Extremely
Large optical/near-infrared Telescope, the E-ELT, which will become “the
world’s biggest eye on the sky”.
Links
- Photos of the MPG/ESO 2.2-metre telescope
- Other photos taken with the MPG/ESO 2.2-metre telescope
- Photos of La Silla
Contacts
Richard Hook
ESO education and Public Outreach Department
Garching bei München, Germany
Tel: +49 89 3200 6655
Email: rhook@eso.org
Source: ESO
