Cygnus OB9

Cygnus OB9
Observation data (J2000.0 epoch)
Right ascension	20h 21m 00.0s [1]
Declination	39° 54′ 00″
Distance	5,000 ly
Apparent magnitude  (V)	7.7
Physical characteristics
Associations
Constellation	Cygnus
See also: Open cluster, List of open clusters

Cygnus OB9 is an OB association in Cygnus. ^[2] It is near to the Cygnus OB2 association. The region is embedded within a wider one of star formation known as Cygnus X, which is one of the most luminous objects in the sky at radio wavelengths. The region is approximately 5,000 light years from Earth in the constellation of Cygnus. ^[3]

Although Cygnus OB9 has many O and B type stars, Cygnus OB9 is also hidden behind a massive dust cloud known as the Cygnus Rift like Cygnus OB2.

Prominent stars ^[4]

Star name	Spectral type	MV	Temperature (K)	Mass (M☉)
V2245 Cygni (HD 229196)	O5	−6.19	40,862	61.6
ALS 11244	O5If	−5.42	38,612	40.1
BD+39 4177	O6.5	−5.51	37,870	39.3
HD 229250	O7	−5.28	36,872	33.9
BD+39 4168	O7	−5.40	36,872	37.3
HD 229202	O8V	−4.66	34,877	25.0
HD 228929	B0.5Ib	−5.60	22,537	20.5
HD 193945	B0Vnn	−5.11	30,110	23.8
RIC 13431720	B1Ia	−5.91	19,979	20.5
HD 193426	B9Ia	−6.71	10,500	15.4

See also

• List of most massive stars

References

1. "Ass Cyg OB 9". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2021-01-02.
2. Pickett, Daniel Edward (1993). Photoelectric UBV photometry of Cygnus OB3 and Cygnus OB9 (M.Sc. thesis). University of Montana. p. 39. Bibcode:1993PhDT.......160P.
3. Zakirov, M. M.; Eshankulova, M. U. (2008). "Close binary systems in regions of OB associations. VI. V498 Cyg in Cyg OB9". Kinematics and Physics of Celestial Bodies. 24 (2): 77–88. Bibcode:2008KPCB...24...77Z. doi:10.3103/S0884591308020037. S2CID   121799853.
4. Comerón, F.; Pasquali, A. (2012). "New members of the massive stellar population in Cygnus". Astronomy & Astrophysics. 110: 2715. Bibcode:2012A&A...543A.101C. doi: 10.1051/0004-6361/201219022 .