Cygnus OB2-12

The correct title of this article is " Cyg OB2 # 12 ". This notation is not possible in Wikipedia due to technical restrictions .

Database links to Cyg OB2 # 12

Star Cyg OB2 # 12
AladinLite
Observation dates equinox :  J2000.0 , epoch : J2000.0
Constellation	swan
Right ascension	20 h 32 m 40.96 s
declination	+ 41 ° 14 ′ 29.3 ″
Apparent brightness	12.54 mag
Typing
B − V color index	(1.91)
U − B color index	(1.65)
Spectral class	B3-4 Ia +
Astrometry
parallax	(1.175 ± 0.129)  mas
distance	(2750 ± 300)  ly (850)  pc
Proper movement
Rec. Share:	(−1.87 ± 0.22)  mas / a
Dec. portion:	(−3.21 ± 0.24)  mas / a
Physical Properties
Dimensions	110   +23−31 M ☉
radius	246  R ☉
Luminosity	1.9 million  L ☉
Effective temperature	13,700   +800−500 K
Other names and catalog entries
Hipparcos catalog HIP 101364 [1] 2MASS catalog 2MASS J20324096 + 4114291 [2] Other names Schulte 12

Cygnus OB2 # 12 is one of the most massive stars currently known. Its mass is currently around 110 M _☉ . Cyg OB2 # 12 is a hypergiant of the spectral class B3-4 Ia +. Cyg OB2 # 12 is located in the constellation Swan in a cluster of stars called Cyg OB2 .

mystery

The physical properties of Cyg OB2 # 12 pose the following puzzles:

• Cyg OB2 # 12 crosses the Humphreys-Davidson limit , but is also below the Eddington limit . The two limits provide clues for the maximum luminosity and the maximum mass a star can have.

• The physical properties of Cyg OB2 # 12 are difficult to reconcile with the prevailing doctrinal opinion regarding the evolution of the stars, since one does not expect such low temperatures with such massive stars (with correspondingly high luminosity).

Surname

The name Cyg OB2 # 12 is composed as follows:

• Cyg : ( Latin : Cygnus , swan '), as the star is in the constellation Swan .
• OB2 : a collection of stars of spectral classes O and B.
• # 12 : a serial number

See also

• List of stars
• List of the most massive stars

Individual evidence

1. ↑ ^{a b c d e f} Schulte 12. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed August 26, 2018 . 
2. ↑ ^{a b c d e f} J. S. Clark et al .: On the nature of the galactic early-B hypergiants . In: Astronomy & Astrophysics . 541, 2012. arxiv : 1202.3991 . bibcode : 2012A & A ... 541A.145C . doi : 10.1051 / 0004-6361 / 201117472 .