NGC 6121 (Globular Cluster, M4)

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NGC 6121, M4
Globular Cluster (球状星団)

別名 (Other names)
GCL 41, ESO 517-SC1, Messier 4

明るさ (Brightness)

星座 (Constellation)
さそり座 (Sco) (Scopius)

距離 (Distance)
7,000光年 (7,000 light-years)





NGC 6121 (M4) is a globular cluster located 7,000 light years from the Earth in the constellation Scopius.

NGC 6121 (Globular Cluster, M4) : Picture

M4: The Closest Known Globular Cluster
M4: The Closest Known Globular Cluster
(C) NASA, T2KA, KPNO 0.9-m Telescope, NOAO, AURA, NSF
M4 is a globular cluster visible in dark skies about one degree west of the bright star Antares in the constellation Scorpius. M4 is perhaps the closest globular cluster at 7,000 light years, meaning that we see M4 only as it was 7,000 years ago, near the dawn of recorded human history. Although containing hundreds of thousands of stars and spanning over 50 light-years, M4 is one of the smallest and sparsest globular clusters known. A particularly unusual aspect for a globular cluster is M4's central bar of stars. M4, pictured above, is one of the oldest objects for which astronomers can estimate age directly. Cluster white dwarfs appear to be at least nine billion years old - so ancient they limit the youth of our entire universe.

Globular cluster M4
Globular cluster M4
In July 2003, Hubble helped make the astounding discovery of a planet called PSR B1620-26 b, 2.5 times the mass of Jupiter, which is located in this cluster. Its age is estimated to be around 13 billion years — almost three times as old as the Solar System! It is also unusual in that it orbits a binary system of a white dwarf and a pulsar (a type of neutron star).

Amateur stargazers may like to track M 4 down in the night sky. Use binoculars or a small telescope to scan the skies near the orange-red star Antares in Scorpius. M 4 is bright for a globular cluster, but it won’t look anything like Hubble’s detailed image: it will appear as a fuzzy ball of light in your eyepiece.

The Planet, the White Dwarf, and the Neutron Star
The Planet, the White Dwarf, and the Neutron Star
(C) H. Richer (Univ. British Columbia), et al. NASA, NOAO
A planet, a white dwarf, and a neutron star orbit each other in the giant globular star cluster M4, some 5,600 light-years away. The most visible member of the trio is the white dwarf star, indicated above in an image from the Hubble Space Telescope, while the neutron star is detected at radio frequencies as a pulsar. A third body was known to be present in the pulsar/white dwarf system and a detailed analysis of the Hubble data has indicated it is indeed a planet with about 2.5 times the mass of Jupiter. In such a system, the planet is likely to be about 13 billion years old. Compared to our solar system's tender 4.5 billion years and other identified planets of nearby stars, this truly ancient world is by far the oldest planet known, almost as old as the Universe itself. Its discovery as part of an evolved cosmic trio suggests that planet formation spans the age of the Universe and that this newly discovered planet is likely only one of many formed in the crowded environs of globular star clusters.

Globular cluster M4
Globular cluster M4
(C) NASA and H. Richer (University of British Columbia), credit for ground-based photo: NOAO/AURA/NSF
Globular cluster M4 Globular cluster M4
Globular cluster M4
Globular cluster M4

NGC 6121 (Globular Cluster, M4) : Movie

Zooming in on the globular star cluster Messier 4
This video starts with a broad view of the spectacular central parts of the Milky Way. We close in on the constellation of Scorpius. Close to its brightest star, Antares, lies the globular star cluster Messier 4, one of the closest of these rich stellar systems to the Earth. The final detailed views of the cluster come from the Wide Field Imager attached to the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile followed by a close up of the central region from the NASA/ESA Hubble Space Telescope.

Panning across the globular star cluster Messier 4
This video gives a close-up view of a new image from the Wide Field Imager attached to the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory showing the spectacular globular star cluster Messier 4. This great ball of ancient stars is one of the closest such stellar systems to the Earth and appears in the constellation of Scorpius close to the bright red star Antares.
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M4 (天体). (2012, November 2). In Wikipedia. ブログパーツ