NML Cygni

NML Cygni

NML Cygni, seen as the deep red star at the center, from the Sloan Digital Sky Survey DR9. Note the green circumstellar nebula surrounding the star.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cygnus
Right ascension 20h 46m 25.54s[1]
Declination +40° 06′ 59.5″[1]
Apparent magnitude (V) 16.60 (variable)[2]
Characteristics
Evolutionary stage OH/IR[3] red hypergiant[4]
Spectral type M4.5–M7.9 Ia–III[5]
Apparent magnitude (K) 0.791±0.204[1]
Apparent magnitude (G) 11.148[1]
Apparent magnitude (J) 4.877±0.037[1]
Apparent magnitude (H) 2.389±0.2[1]
B−V color index +2.04[2]
Variable type Semiregular variable star[6]
Astrometry
Proper motion (μ) RA: −1.55[4] mas/yr
Dec.: −4.59[4] mas/yr
Parallax (π)0.620 ± 0.047 mas[4]
Distance5,250+420
−360 ly
(1,610+130
−110[4] pc)
Details
Mass25[4] (initial) M☉
Radius<1,350+195
−229[7][a] R☉
Luminosity229,000+40,000
−41,000[9] L☉
Age8[4] Myr
Other designations
NML Cyg, V1489 Cyg, RAFGL 2650, IRC +40448, 2MASS J20462554+4006594, AAVSO 2042+39
Database references
SIMBADdata

NML Cygni or V1489 Cygni (abbreviated to NML Cyg or V1489 Cyg) is a red hypergiant[4] or red supergiant (RSG) in the constellation Cygnus. It is possibly one of the largest known stars currently known, and is also possibly one of the most luminous and massive cool hypergiants, as well as one of the most luminous stars in the Milky Way.

The distance of NML Cygni from Earth is estimated to be around 1.6 kpc, about 5,300 light-years.[10] It is a part of the Cygnus OB2 association, one of the closest massive associations to the Sun, spanning nearly 2° on the sky or ~30 pc in radius at the distance of 1.74±0.2 kpc.[11] Based on the estimated distance and a measurement of its angular diameter of 7.8±0.64 milliarcseconds,[8] NML Cygni's physical radius is of 1,350 R☉. If placed at the center of the Solar System, its surface would potentially extend past the orbit of Jupiter.

  1. ^ a b c d e f "NML Cyg". SIMBAD. Centre de données astronomiques de Strasbourg.
  2. ^ a b Johnson, Harold L.; Eugenio E., Mendoza V.; Wisniewski, Weislaw Z. (October 1965). "Observations of "Infrared Stars."". The Astrophysical Journal. 142: 1249. Bibcode:1965ApJ...142.1249J. doi:10.1086/148393. ISSN 0004-637X.{{cite journal}}: CS1 maint: date and year (link)
  3. ^ Cite error: The named reference michael was invoked but never defined (see the help page).
  4. ^ a b c d e f g h Zhang, B.; Reid, M. J.; Menten, K. M.; Zheng, X. W.; Brunthaler, A. (August 2012). "The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry". Astronomy & Astrophysics. 544: A42. arXiv:1207.1850. Bibcode:2012A&A...544A..42Z. doi:10.1051/0004-6361/201219587. ISSN 0004-6361.
  5. ^ Cite error: The named reference gcvs was invoked but never defined (see the help page).
  6. ^ De Beck, E.; Decin, L.; De Koter, A.; Justtanont, K.; Verhoelst, T.; Kemper, F.; Menten, K. M. (2010). "Probing the mass-loss history of AGB and red supergiant stars from CO rotational line profiles. II. CO line survey of evolved stars: Derivation of mass-loss rate formulae". Astronomy and Astrophysics. 523: A18. arXiv:1008.1083. Bibcode:2010A&A...523A..18D. doi:10.1051/0004-6361/200913771. S2CID 16131273.
  7. ^ Cite error: The named reference lang2006 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference CHARM2 was invoked but never defined (see the help page).
  9. ^ Davies, Ben; Beasor, Emma R. (March 2020). "The 'red supergiant problem': the upper luminosity boundary of Type II supernova progenitors". MNRAS. 493 (1): 468–476. arXiv:2001.06020. Bibcode:2020MNRAS.493..468D. doi:10.1093/mnras/staa174. S2CID 210714093.
  10. ^ Schuster, Michael Thomas (2007). Investigating the Circumstellar Environments of the Cool Hypergiants. University of Minnesota. ISBN 978-0-549-32782-0.
  11. ^ Cite error: The named reference Schuster2008 was invoked but never defined (see the help page).


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