NML Cygni information

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
Declination	+40° 06′ 59.5″
Apparent magnitude (V)	16.60 (variable)
Characteristics
Evolutionary stage	OH/IR red hypergiant
Spectral type	M4.5–M7.9 Ia–III
Apparent magnitude (K)	0.791±0.204
Apparent magnitude (G)	11.148
Apparent magnitude (J)	4.877±0.037
Apparent magnitude (H)	2.389±0.2
B−V color index	+2.04
Variable type	Semiregular variable star
Astrometry
Proper motion (μ)	RA: −1.55 mas/yr ; Dec.: −4.59 mas/yr
Parallax (π)	0.620 ± 0.047 mas
Distance	5,250+420; −360 ly ; (1,610+130; −110 pc)
Details
Mass	40 M☉
Radius	<1,350 R☉
Luminosity	229,000+40,000; −41,000 L☉
Temperature	3,300 – 3,440 K
Age	8 Myr
Other designations
	NML Cyg, V1489 Cyg, RAFGL 2650, IRC +40448, 2MASS J20462554+4006594, AAVSO 2042+39
Database references
SIMBAD	data

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.^[12] 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.^[13] Based on the estimated distance and a measurement of its angular diameter of 7.8±0.64 milliarcseconds,^[9] 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.

^ ^a ^b ^c ^d ^e ^f "NML Cyg". SIMBAD. Centre de données astronomiques de Strasbourg.
^ ^a ^b Johnson, Harold L.; Mendoza v., Eugenio E.; Wisniewski, Weislaw Z. (1965). "Observations of "Infrared Stars."". Astrophysical Journal. 142: 1249. Bibcode:1965ApJ...142.1249J. doi:10.1086/148393.
^ ^a ^b Cite error: The named reference michael was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e ^f ^g Zhang, B.; Reid, M. J.; Menten, K. M.; Zheng, X. W.; Brunthaler, A. (2012). "The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry" (PDF). Astronomy & Astrophysics. 544: A42. arXiv:1207.1850. Bibcode:2012A&A...544A..42Z. doi:10.1051/0004-6361/201219587. S2CID 55509287.
^ Cite error: The named reference gcvs was invoked but never defined (see the help page).
^ 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.
^ Cite error: The named reference singh2021 was invoked but never defined (see the help page).
^ Cite error: The named reference lang2006 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference CHARM2 was invoked but never defined (see the help page).
^ 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.
^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ Schuster, Michael Thomas (2007). Investigating the Circumstellar Environments of the Cool Hypergiants. p. 57. ISBN 978-0-549-32782-0. Retrieved 27 August 2012.^{[permanent dead link]}
^ Cite error: The named reference Schuster2008 was invoked but never defined (see the help page).

Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).

[SIMBAD-1] ^ ^a ^b ^c ^d ^e ^f "NML Cyg". SIMBAD. Centre de données astronomiques de Strasbourg.

[johnson-2] Johnson, Harold L.; Mendoza v., Eugenio E.; Wisniewski, Weislaw Z. (1965). "Observations of "Infrared Stars."". Astrophysical Journal. 142: 1249. Bibcode:1965ApJ...142.1249J. doi:10.1086/148393.

[michael-3] Cite error: The named reference michael was invoked but never defined (see the help page).

[zhang-4] ^ ^a ^b ^c ^d ^e ^f ^g Zhang, B.; Reid, M. J.; Menten, K. M.; Zheng, X. W.; Brunthaler, A. (2012). "The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry" (PDF). Astronomy & Astrophysics. 544: A42. arXiv:1207.1850. Bibcode:2012A&A...544A..42Z. doi:10.1051/0004-6361/201219587. S2CID 55509287.

[gcvs-5] Cite error: The named reference gcvs was invoked but never defined (see the help page).

[debeck-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.

[singh2021-7] Cite error: The named reference singh2021 was invoked but never defined (see the help page).

[lang2006-8] Cite error: The named reference lang2006 was invoked but never defined (see the help page).

[CHARM2-9] Cite error: The named reference CHARM2 was invoked but never defined (see the help page).

[Davies2020-11] 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.

[12] Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[Schuster2007-13] Schuster, Michael Thomas (2007). Investigating the Circumstellar Environments of the Cool Hypergiants. p. 57. ISBN 978-0-549-32782-0. Retrieved 27 August 2012.^{[permanent dead link]}

[Schuster2008-14] Cite error: The named reference Schuster2008 was invoked but never defined (see the help page).

Observation data Epoch J2000.0 Equinox J2000.0
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.
Constellation	Cygnus
Right ascension	20^h 46^m 25.54^s^[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]
Distance	5,250+420 −360 ly (1,610+130 −110^[4] pc)

Details

Mass	40^[7] `M`_☉
Radius	<1,350^[8]^[a] `R`_☉
Luminosity	229,000+40,000 −41,000^[10] `L`_☉
Temperature	3,300^[3] – 3,440^[11] K
Age	8^[4] Myr

Other designations
NML Cyg, V1489 Cyg, RAFGL 2650, IRC +40448, 2MASS J20462554+4006594, AAVSO 2042+39
Database references
SIMBAD	data

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