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Messier 80 - a globular cluster and the minor planet Ceres
in the constellation Scorpion |
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Object description:
Messier 80and
Ceres
Our image of
Messier 80 is actually a byproduct. In the night the image was taken there were
three minor planets - Ceres, Dione and Katyusha - in the field of view
which were the actual target of the image. In the upper
right corner of the image there are two small and faint galaxies, IC 4596 and
IC 4600.
Messier 80 (NGC 6093) is a small bright globular
cluster in the constellation Scorpio. It is about 33,000 light-years from Earth
and contains over 100,000 stars in a volume of space about 90 light-years
across. The age of the stars is estimated to be 13 billion years. M 80 is
cataloged as Class II according to Shapley, making
it one of the densest globular clusters in the Milky Way.
M 80 contains
a surprisingly large number of hot blue stars ("blue stragglers"), normally
found only in regions where star formation has occurred until recently. Until
recently, the nature of the "blue stragglers" was a mystery, but they are now
believed to be formed by the collision of two smaller stars. In normal regions
of the galaxy, where the distances between stars are millions of times greater,
such collisions are considered essentially impossible. In globular clusters,
however, where the stars are clustered thousands or tens of thousands of times
more densely, such collisions can certainly occur. M80 hosts more than twice as
many "blue stragglers" than any other globular cluster in the Milky Way. M80
was discovered by Charles Messier on January 4, 1781. |
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Ceres
In addition to the globular
cluster, an object from our solar system is also in the image. The labeled
version of our image marks the position of the dwarf planet Ceres, which orbits
the Sun in an orbit between Mars and Jupiter. Ceres, with a diameter of just
under 1000 kilometers, is the largest object in the asteroid belt and the
smallest of the dwarf planets. The distance to Ceres at the time the image was
taken was only 22 light minutes, or 397 million kilometers.
Ceres was
discovered on January 1, 1801 by Giuseppe Piazzi at the Palermo Observatory.
« Click here or the thumbnail to load a large annoted image
and a size comparison to the full moon. |
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All Images and all Content are ©
by Franz Hofmann + Wolfgang Paech |