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Messier 38

Messier 38
M38 open cluster
Observation data (J2000.0 epoch)
Right ascension05h 28m 43s[1]
Declination+35° 51′ 18″[1]
Distance3,480 ly (1.066 kpc)[2]
Apparent magnitude (V)7.4
Apparent dimensions (V)21′
Physical characteristics
Radius4pc. (13 ly.)
Estimated age250[2] Myr
Other designationsNGC 1912[3]
Associations
ConstellationAuriga
See also: Open cluster, List of open clusters

Messier 38 or M38, also known as NGC 1912 or Starfish Cluster,[4] is an open cluster of stars in the constellation of Auriga. It was discovered by Giovanni Batista Hodierna before 1654 and independently found by Le Gentil in 1749. The open clusters M36 and M37, also discovered by Hodierna, are often grouped together with M38.[5] Distance is about 1.066 kpc (3,480 ly) away from Earth.[2] The open cluster NGC 1907 lies nearby on the sky, but the two are most likely just experiencing a fly-by, having originated in different parts of the galaxy.[1]

The cluster's brightest stars form a pattern resembling the Greek letter Pi or, according to Webb, an "oblique cross". Walter Scott Houston described its appearance as follows:[6]

Photographs usually show a departure from circularity, a feature quite evident to visual observers. Older reports almost always mention a cross shape, which seems more pronounced with small instruments. A view with a 24-inch reflector on a fine Arizona night showed the cluster as irregular, and the host of stars made fruitless any effort to find a geometrical figure.

At its distance of 1066 pc., its angular diameter of about 20 arc minutes corresponds to about 4.0 parsecs (13 light years), similar to that of its more distant neighbor M37. It is of intermediate age at about 290 million years.[2] From the population of about 100 stars,[7] this open cluster features a prominent yellow giant with the apparent magnitude +7.9 and spectral type G0 as its brightest member. This corresponds to an absolute magnitude of -1.5, or a luminosity of 900 Suns. For comparison, the Sun would appear as a faint magnitude +15.3 star from the distance of M38.

Components

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Map
NAME Right
ascension		 Declination Spectral
Type
HD 35519 05h 26m 54.32s +35° 27' 26.2 K2
NGC 1912 HOAG 2 B5II-III
NGC 1912 HOAG 3
NGC 1912 HOAG 4 05h 28m 35.39s +35° 52' 51.2' A0V
NGC 1912 HOAG 5 05h 28m 50.73s +35° 46' 47.2 A0Vn
NGC 1912 HOAG 6 05h 28m 10.46s +35° 55' 26.0 A0:V
NGC 1912 HOAG 7 05h 28m 34.25s +35° 53' 29.7 A2V
NGC 1912 HOAG 11
NGC 1912 HOAG 19 K2IIIb
NGC 1912 HOAG 104 G5III
NGC 1912 SS G2
NGC 1912 HOAG 128 K0III
NGC 1912 SS G4 A5:V
NGC 1912 HOAG 153 K0V
NGC 1912 SS G3 A3V
NGC 1912 HOAG 160 K1IV
NGC 1912 HOAG 161 G5V
NGC 1912 HOAG 171 G7IV
NGC 1912 HOAG 172

See also

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References

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  1. ^ a b c de Oliveira, M. R.; Fausti, A.; Bica, E.; Dottori, H. (July 2002), "NGC 1912 and NGC 1907: A close encounter between open clusters?", Astronomy and Astrophysics, 390: 103–108, arXiv:astro-ph/0205100, Bibcode:2002A&A...390..103D, doi:10.1051/0004-6361:20020679, S2CID 898638
  2. ^ a b c d "WEBDA page for open cluster NGC 1912". Department of Theoretical Physics and Astrophysics of the Masaryk University. Retrieved 18 February 2018.
  3. ^ "Messier 38". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-12-10.
  4. ^ Carter, J. (2015). March: The Plane Truth. In A Stargazing Program for Beginners (pp. 57-85). Springer, Cham.
  5. ^ Majaess, D. J.; et al. (2007). "In Search of Possible Associations between Planetary Nebulae and Open Clusters". Publications of the Astronomical Society of the Pacific. 119 (862): 1349–1360. arXiv:0710.2900. Bibcode:2007PASP..119.1349M. doi:10.1086/524414. S2CID 18640979.
  6. ^ Houston, Walter Scott (2005). Deep-Sky Wonders. Sky Publishing Corporation. ISBN 978-1-931559-23-2.
  7. ^ "WEBDA page Lynga catalogue data". Department of Theoretical Physics and Astrophysics of the Masaryk University. Retrieved 18 February 2018.
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