BD+40° 4210

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BD+40° 4210

Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cygnus
Right ascension 20h 31m 4.6s[1]
Declination +40° 30′ 57.05″[1]
Apparent magnitude (V) 10.45[2]
Spectral type B1III:e[3]
Apparent magnitude (K) 4.466[4]
Apparent magnitude (J) 5.469[4]
Apparent magnitude (H) 4.833[4]
B−V color index 1.68[2]
Variable type candidate LBV[3]
Proper motion (μ) RA: -3.8[2] mas/yr
Dec.: -2.8[2] mas/yr
Distance 4,700[3] ly
(1,450 pc)
Absolute magnitude (MV) -7.66
Mass 54[3] M
Luminosity (bolometric) 630,000[5] L
Temperature 21,353[3] K
Age 3.5[3] Myr
Other designations
BD+40° 4210, IRAS 20292+4020, 2MASS J20310464+4030568, TYC 3157-679-1, PPM 60064
Database references

BD+40° 4210 is a hot luminous star located in the constellation Cygnus


BD+40° 4210, heavily reddened and extinguished by the interstellar dust of the Milky Way and little studied until now, has turned out to be one of the most luminous stars of the Cygnus OB2 association, with an absolute magnitude of -7.66 and a bolometric luminosity more than 600,000 times that of our Sun. It has been assigned a B1III spectral classification, but with peculiarities including unusually shallow lines and broad emission. Despite the giant luminosity class, the luminosity appears to be extremely high, placing it on or near the S Doradus instability strip occupied by quiescent luminous blue variables.[3]

BD+40° 4210 is located at a projected 4.8 parsecs from the candidate luminous blue variable G79.29+0.46 and probably at a similar distance since both are assumed members of Cygnus OB2; however, unlike the latter which is surrounded by an extensive ring-shaped nebulosity, no nebula has been found around this star.[3]


  1. ^ a b . Bibcode:1988A&AS...74..449R.  Missing or empty |title= (help)
  2. ^ a b c d . Bibcode:2000A&A...355L..27H.  Missing or empty |title= (help)
  3. ^ a b c d e f g h 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. 
  4. ^ a b c . Bibcode:-2003yCat.2246....0C.  Missing or empty |title= (help)
  5. ^ In and around the rich association Cygnus OB2