The star cluster NGC 2367 in the constellation of Canis Major
Wide-field view of the sky around the bright star cluster NGC 2367
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This rich view of an array of colourful stars and gas was captured by the Wide Field Imager (WFI) camera, on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. It shows a young open cluster of stars known as NGC 2367, an infant stellar grouping that lies at the centre of an immense and ancient structure on the margins of the Milky Way.
Discovered from England by the tireless observer Sir William Herschel on 20 November 1784, the bright star cluster NGC 2367 lies about 7000 light-years from Earth in the constellation Canis Major.
Having only existed for about five million years, most of its stars are
young and hot and shine with an intense blue light. This contrasts
wonderfully in this new image with the silky-red glow from the
surrounding hydrogen gas.
Open clusters like NGC 2367 are a common sight in spiral galaxies
like the Milky Way, and tend to form in their host’s outer regions. On
their travels about the galactic centre, they are affected by the
gravity of other clusters, as well as by large clouds of gas that they
pass close to. Because open clusters are only loosely bound by gravity
to begin with, and because they constantly lose mass as some of their
gas is pushed away by the radiation of the young hot stars, these
disturbances occur often enough to cause the stars to wander off from
their siblings, just as the Sun is believed to have done many years ago.
An open cluster is generally expected to survive for a few hundred
million years before it is completely dispersed.
In the meantime, clusters serve as excellent case studies for stellar
evolution. All the constituent stars are born at roughly the same time
from the same cloud of material, meaning they can be compared alongside
one another with greater ease, allowing their ages to be readily
determined and their evolution mapped.
Like many open clusters, NGC 2367 is embedded within an emission nebula,
from which its stars were born. The remains show up as wisps and clouds
of hydrogen gas, ionised by the ultraviolet radiation being emitted by
the hottest stars. What is more unusual is that, as you begin to pan out
from the cluster and its nebula, a far more expansive structure is
revealed: NGC 2367 and the nebula containing it are thought to be the
nucleus of a larger nebula, known as Brand 16, which in turn is only a
small part of a huge supershell, known as GS234-02.
The GS234-02 supershell lies towards the outskirts of our galaxy, the
Milky Way. It is a vast structure, spanning hundreds of light-years. It
began its life when a group of particularly massive stars, producing
strong stellar winds,
created individual expanding bubbles of hot gas. These neighbouring
bubbles eventually merged to form a superbubble, and the short life
spans of the stars at its heart meant that they exploded as supernovae
at similar times, expanding the superbubble even further, to the point
that it merged with other superbubbles, which is when the supershell was
formed. The resulting formation ranks as one of the largest possible
structures within a galaxy.
This concentrically expanding system, as ancient as it is enormous,
provides a wonderful example of the intricate, interrelated structures
that are sculpted in galaxies by the lives and deaths of stars.
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Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Source: ESO
