Messier 93
| Messier 93 | |
|---|---|
 | |
| Observation data (J2000.0 epoch) | |
| Right ascension | 07h 44m 30.0s[1] |
| Declination | −23° 51′ 24″[1] |
| Distance | 3.38 kly (1.037 kpc)[1] |
| Apparent magnitude (V) | 6.2[2] |
| Apparent dimensions (V) | 10′[2] |
| Physical characteristics | |
| Mass | 723[3] M☉ |
| Radius | 5[2] |
| Estimated age | 387.3 Myr[1] |
| Other designations | NGC 2447, Cr 160, OCl 649.0 [4] |
| Associations | |
| Constellation | Puppis |
Messier 93 or M93, also known as NGC 2447, is an open cluster in the constellation Puppis. It was discovered by Charles Messier then added to his catalogue of comet-like objects on March 20, 1781.[5] Caroline Herschel, the younger sister of William Herschel, independently discovered M93 in 1783, thinking it had not yet been catalogued by Messier.[6] Walter Scott Houston described its appearance as follows:[7]
Some observers mention the cluster as having the shape of a starfish. With a fair-sized telescope, this is its appearance on a dull night, but [a four-inch refractor] shows it as a typical star-studded galactic cluster.
It has a Trumpler class of I 3 r, indicating it is strongly concentrated (I) with a large range in brightness (3) and is rich in stars (r).[8]
M93 is at a distance of about 3,380[1] light years from Earth and has a spatial radius of some 5 light years,[2] a tidal radius of 13.1±2.3 ly,[3] and a core radius of 4.2 ly.[9] Its age is estimated at 387.3 million years.[1] The cluster is positioned nearly on the galactic plane and it is following an orbit that varies between 28–29 kly (8.5–8.9 kpc) from the Galactic Center over a period of 242.7±7.9 Myr.[1]
54 variable stars have been found in M93, including one slowly pulsating B-type star, one rotating ellipsoidal variable, seven Delta Scuti variables, six Gamma Doradus variables, and one hybrid δ Sct/γ Dor pulsator.[10] Four spectroscopic binary systems in M93 include a yellow straggler component.[11]
References
- ^ a b c d e f g Wu, Zhen-Yu; et al. (November 2009), "The orbits of open clusters in the Galaxy", Monthly Notices of the Royal Astronomical Society, 399 (4): 2146–2164, arXiv:0909.3737, Bibcode:2009MNRAS.399.2146W, doi:10.1111/j.1365-2966.2009.15416.x.
- ^ a b c d Finlay, Warren H. (2014), Concise Catalog of Deep-Sky Objects: Astrophysical Information for 550 Galaxies, Clusters and Nebulae, The Patrick Moore Practical Astronomy Series (2nd ed.), Springer, p. 120, ISBN 978-3319031705
- ^ a b Piskunov, A. E.; et al. (January 2008), "Tidal radii and masses of open clusters", Astronomy and Astrophysics, 477 (1): 165–172, Bibcode:2008A&A...477..165P, doi:10.1051/0004-6361:20078525.
- ^ "NGC 2447". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-12-06.
- ^ Frommert, Hartmut; Kronberg, Christine (September 2, 2007), "Messier 93", SEDS Messier pages, Students for the Exploration and Development of Space (SEDS), retrieved 2018-12-07.
- ^ Hoskin, Michael (February 1, 2016), "Gazing at the starry heavens", Astronomy & Geophysics, 57 (1): 1.22–1.25, Bibcode:2016A&G....57a1.22H, doi:10.1093/astrogeo/atw038
- ^ Houston, Walter Scott (2005). Deep-Sky Wonders. Sky Publishing Corporation. ISBN 978-1-931559-23-2.
- ^ Maitzen, H. M. (November 1993), "Photoelectric Search for Peculiar Stars in Open Clusters - Part Fourteen - NGC1901 NGC2169 NGC2343 CR:132 NGC2423 and NGC2447", Astronomy and Astrophysics Supplement, 102 (1): 1, Bibcode:1993A&AS..102....1M.
- ^ Piskunov, A. E.; et al. (June 2007), "Towards absolute scales for the radii and masses of open clusters", Astronomy and Astrophysics, 468 (1): 151–161, arXiv:astro-ph/0702517, Bibcode:2007A&A...468..151P, doi:10.1051/0004-6361:20077073.
- ^ Eyer, L.; Eggenberger, P.; Greco, C.; Saesen, S.; Anderson, R. I.; Mowlavi, N. (September 2010), "Time resolved surveys of stellar clusters", JENAM 2010, Joint European and National Astronomy Meeting held 6-10 September, 2010 in Lisbon Portugal, p. 212, Bibcode:2010jena.confE.212E, 212.
- ^ da Silveira, M. D.; et al. (June 2018), "Red giants and yellow stragglers in the young open cluster NGC 2447", Monthly Notices of the Royal Astronomical Society, 476 (4): 4907–4931, Bibcode:2018MNRAS.476.4907D, doi:10.1093/mnras/sty265
External links
- SEDS: Open Star Cluster M93
- Messier 93 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
- Gray, Meghan; Zarnecki, John. "M93 – Open Cluster". Deep Sky Videos. Brady Haran. Retrieved 2018-12-05.
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