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The star Antares, Messier 4 and NGC 6144 in the
constellation of Scorpion |
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Object description:
Antares, the
major star in the constellation Scorpio, illuminates the surrounding gas and
dust masses and produces a rare yellow-orange reflection nebula. Along the line
of sight, but far behind Antares, are two globular clusters,
M 4 and NGC
6144.
Messier 4 (NGC 6121) is
a globular cluster of concentration class IX (weak
concentration). At a distance of only 7000 light-years, M4 is the closest
globular cluster to the solar system and correspondingly well studied.
It has a physical diameter of 75 light-years and contains about 100 000
stars. A special study of more than 600 white dwarf stars suggests an age of
about 12.7 billion years. First observed by Swiss astronomer Jean-Philippe Loys
de Chéseaux in 1746, Messier 4 was described by Charles Messier in 1764
as "a cluster of very small stars, which with smaller
telescopes appears more like a nebula". |
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NGC 6144 is a small globular
cluster of concentration class XI. It is located
just under 28 000 light years from the solar system. NGC 6144 was first
observed by William Herschel on May 22, 1784. John Dreyer, a Danish-Irish
astronomer, described it "as of considerable size,
strongly concentrated, brightening toward the center, and readily resolvable
into single stars."
Johan Ludvig Emil Dreyer created the NGC
catalog, a list of more than 7000 star clusters, nebulae and galaxies and later
as a supplement the IC catalog.
Information and images of the star
Antares
can be found here.
« 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 |