Astronomy:Messier 30

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Short description: Globular cluster in the constellation Capricornus
Messier 30
M30 NASA.jpg
Open cluster Messier 30 in Capricornus
Observation data (J2000 epoch)
ClassV[1]
ConstellationCapricornus
Right ascension 21h 40m 22.12s[2]
Declination–23° 10′ 47.5″[2]
Distance27.14 ± 0.65 kly (8.3 ± 0.20 kpc)[3][4]
Apparent magnitude (V)7.2[5]
Apparent dimensions (V)12'.0
Physical characteristics
Mass1.6×105[6] M☉
Metallicity[math]\displaystyle{ \begin{smallmatrix}\left[\ce{Fe}/\ce{H}\right]\end{smallmatrix} }[/math] = –2.27[7] dex
Estimated age12.93 Gyr[8]
Other designationsM30, NGC 7099, GCl 122[9]
See also: Globular cluster, List of globular clusters

Messier 30 (also known as M30 or NGC 7099) 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.[lower-alpha 1] 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,[10] forming a patch of hazy light some 4 arcminutes wide that is slightly elongated along the east–west axis.[10] 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.[11]

It is longest observable (opposed to the Sun) in the first half of August.[lower-alpha 2][10]

M30 is centered 27,100 light-years away from Earth with a roughly 2.5% margin of error,[4] and is about 93 light-years across.[11] The estimated age is roughly 12.9 billion years[8] and it forms a mass of about 160,000 times the mass of the Sun (M☉).[6] 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.[8] It is in this epoch 22.2 kly (6.8 kpc), from the center of the galaxy, compared to an estimated 26 kly (8.0 kpc) for the Sun.[12]

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.[3] 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.[13]

See also

References and footnotes

  1. ↑ Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin 849 (849): 11–14, Bibcode: 1927BHarO.849...11S. 
  2. ↑ 2.0 2.1 Goldsbury, Ryan et al. (December 2010), "The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters", The Astronomical Journal 140 (6): 1830–1837, doi:10.1088/0004-6256/140/6/1830, Bibcode: 2010AJ....140.1830G. 
  3. ↑ 3.0 3.1 Lugger, Phyllis M. et al. (March 2007), "Chandra X-Ray Sources in the Collapsed-Core Globular Cluster M30 (NGC 7099)", The Astrophysical Journal 657 (1): 286–301, doi:10.1086/507572, Bibcode: 2007ApJ...657..286L 
  4. ↑ 4.0 4.1 Kains, N. et al. (2016), "Estimating the parameters of globular cluster M 30 (NGC 7099) from time-series photometry", Astronomy and Astrophysics 555 (1): 36–50, doi:10.1051/0004-6361/201321819, Bibcode: 2013A&A...555A..36K 
  5. ↑ "Messier 30". https://messier.seds.org/m/m030.html. 
  6. ↑ 6.0 6.1 Vande Putte, D.; Cropper, Mark (January 2009), "Detecting the effect of globular cluster impacts on the disc of the Milky Way", Monthly Notices of the Royal Astronomical Society 392 (1): 113–124, doi:10.1111/j.1365-2966.2008.14072.x, Bibcode: 2009MNRAS.392..113V 
  7. ↑ Boyles, J. et al. (November 2011), "Young Radio Pulsars in Galactic Globular Clusters", The Astrophysical Journal 742 (1): 51, doi:10.1088/0004-637X/742/1/51, Bibcode: 2011ApJ...742...51B. 
  8. ↑ 8.0 8.1 8.2 Forbes, Duncan A.; Bridges, Terry (May 2010), "Accreted versus in situ Milky Way globular clusters", Monthly Notices of the Royal Astronomical Society 404 (3): 1203–1214, doi:10.1111/j.1365-2966.2010.16373.x, Bibcode: 2010MNRAS.404.1203F 
  9. ↑ "M 30". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=M+30. 
  10. ↑ 10.0 10.1 10.2 Bone, N. M. (August 2008), "Sky notes, 2008 August & September", Journal of the British Astronomical Association 118 (4): 231–232, Bibcode: 2008JBAA..118..231B 
  11. ↑ 11.0 11.1 O'Meara, Stephen James (1998), The Messier objects, Deep-sky companions, Cambridge University Press, p. 108, ISBN 978-0-521-55332-2, https://books.google.com/books?id=jis4evHuuzUC&pg=PA108 
  12. ↑ Dinescu, Dana I. et al. (January 1999), "Space Velocities of Southern Globular Clusters. II. New Results for 10 Clusters", The Astronomical Journal 117 (1): 277–285, doi:10.1086/300699, Bibcode: 1999AJ....117..277D 
  13. ↑ Howell, Justin H.; Guhathakurta, Puragra; Tan, Amy (March 2000), "Radial Color Gradient and Main-Sequence Mass Segregation in M30 (NGC 7099)", The Astronomical Journal 119 (3): 1259–1267, doi:10.1086/301270, Bibcode: 2000AJ....119.1259H 
  1. ↑ Thus, its northern limit for good visibility is a few degrees south of the Arctic Circle, all year
  2. ↑ 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.
Masp showing the location of M30

External links

Coordinates: Sky map 21h 40m 22.03s, −23° 10′ 44.6″



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