Messier 30
{{short description|Globular cluster in the constellation Capricornus}}
{{Use dmy dates|date=February 2021}}
{{Infobox globular cluster
| name = Messier 30
| image = File:M30 NASA.jpg
| caption = Open cluster Messier 30 in Capricornus
| epoch = J2000
| dist_ly = {{cvt|27.14|+/-|0.65|kly|kpc|lk=on|sigfig=2}}
| appmag_v = 7.2{{cite web |url=http://www.messier.seds.org/m/m030.html |title=Messier 30 |access-date=22 July 2024 |website=SEDS Messier Catalog}}
| size_v = 12'.0
| constellation = Capricornus
| radius_ly =
| v_hb =
| age = 12.93 Gyr
| notes =
| names = M30, NGC 7099, GCl 122
}}
Messier 30 (also known as M30, NGC 7099, or the Jellyfish Cluster) is a globular cluster of stars in the southeast of the southern constellation of Capricornus, at about the declination of the Sun when the latter is at December solstice.{{efn|Thus, its northern limit for good visibility is a few degrees south of the Arctic Circle, all year}} It was discovered by the French astronomer Charles Messier in 1764, who described it as a circular nebula without a star. In the New General Catalogue, compiled during the 1880s, it was described as a "remarkable globular, bright, large, slightly oval." It can be easily viewed with a pair of 10×50 binoculars, forming a patch of hazy light some 4 arcminutes wide that is slightly elongated along the east–west axis. With a larger instrument, individual stars can be resolved and the cluster will cover an angle of up to 12 arcminutes across graduating into a compressed core about one arcminute wide that has further star density within.
It is longest observable (opposed to the Sun) in the first half of August.{{efn|This is when it is risen, throughout the night, so culminates about midnight. The Earth's orbit means the sun leaves Capricornus, as if it heads east a few degrees NNE, on about 15 or 16 February, having figured in the constellation for a month.}}
M30 is centered 27,100 light-years away from Earth with a roughly 2.5% margin of error, and is about 93 light-years across. The estimated age is roughly 12.9 billion years and it forms a mass of about 160,000 times the mass of the Sun ({{solar mass}}). The cluster is following a retrograde orbit (against the general flow) through the inner galactic halo, suggesting that it was acquired from a satellite galaxy rather than forming within the Milky Way. It is in this epoch {{cvt|22.2|kly|kpc}}, from the center of the galaxy, compared to an estimated {{cvt|26|kly|kpc}} for the Sun.
The cluster has passed through a dynamic process called core collapse and now has a concentration of mass at its core of about a million times the Sun's mass per cubic parsec. This makes it one of the highest density regions in the Milky Way galaxy. Stars in such close proximity will experience a high rate of interactions that can create binary star systems, as well as a type of star called a blue straggler that is formed by mass transfer. A process of mass segregation may have caused the central region to gain a greater proportion of higher mass stars, creating a color gradient with increasing blueness toward the middle of the cluster.
See also
References and footnotes
{{reflist|refs=
{{citation | first1=Stephen James | last1=O'Meara | title=The Messier objects | series=Deep-sky companions | publisher=Cambridge University Press | year=1998 | isbn=978-0-521-55332-2 | url=https://books.google.com/books?id=jis4evHuuzUC&pg=PA108 | page=108 }}
{{citation | last1=Forbes | first1=Duncan A. | last2=Bridges | first2=Terry | title=Accreted versus in situ Milky Way globular clusters | journal=Monthly Notices of the Royal Astronomical Society | volume=404 | issue=3 | pages=1203–1214 |date=May 2010 | doi=10.1111/j.1365-2966.2010.16373.x | doi-access=free | bibcode=2010MNRAS.404.1203F |arxiv = 1001.4289 | s2cid=51825384 }}
{{cite simbad | title=M 30 | access-date=2006-11-16}}
}}
Notes
{{notelist}}
External links
{{Commons category|Messier 30}}
- [http://www.messier.seds.org/m/m030.html Globular Cluster M30 @ SEDS Messier pages]
- [http://gclusters.altervista.org/cluster_4.php?ggc=M+30 Messier 30, Galactic Globular Clusters Database page]
- {{cite web|last=Gray|first=Meghan|title=M30 – Globular Cluster|url=http://www.deepskyvideos.com/videos/messier/M30_globular_cluster.html|work=Deep Sky Videos|publisher=Brady Haran}}
- {{WikiSky}}
{{Sky|21|40|22.03|-|23|10|44.6|26000}}
{{Messier objects}}
{{Ngc75}}
{{Capricornus}}
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