BD+60°2522

BD+60°2522 is a bright O-type star that has produced the Bubble Nebula (NGC 7635) with its stellar wind. The exact classification of the star is uncertain, with a number of spectral peculiarities and inconsistencies between the appearance of the star itself and the effects on the nearby nebulosity, but it is undoubtedly a highly luminous hot massive star.^[7] Direct spectroscopy yields a spectral class of O6.5 and an effective temperature around 39,500 K. It is a member of the Cassiopeia OB2 stellar association in the Perseus Arm^[9] of the galaxy at about 8,500 light-years' distance.^[10]

BD+60°2522

NGC 7635 surrounding BD+60 2522 Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Observation data Epoch J2000      Equinox J2000
Constellation	Cassiopeia[1]
Right ascension	23h 20m 44.5135s[2]
Declination	+61° 11′ 40.531″[2]
Apparent magnitude (V)	8.67[3]
Characteristics
Evolutionary stage	main sequence[4]
Spectral type	O6.5(f)(n)p[5]
U−B color index	−0.62[3]
B−V color index	+0.41[3]
Astrometry
Radial velocity (Rv)	−26[6] km/s
Proper motion (μ)	RA: −2.662[2] mas/yr Dec.: 0.388[2] mas/yr
Parallax (π)	0.3341±0.0152 mas[2]
Distance	9,800 ± 400 ly (3,000 ± 100 pc)
Absolute magnitude (MV)	−5.5[7]
Details
Mass	45[4] M☉
Radius	15[8] R☉
Luminosity	457,088[4] L☉
Temperature	39,500[4] K
Rotational velocity (v sin i)	178 - 240[8] km/s
Age	2[9] Myr
Other designations
SAO 20575 IRAS 23185+6055 2MASS J23204452+6111404
Database references
SIMBAD	data

Although BD+60°2522 is around two million years old, the surrounding nebula is apparently only about 40,000 years old. The bubble is expected to be formed as a shock front where the stellar wind meets interstellar material at supersonic speeds. The wind from BD+60°2522 is travelling outwards at 1,800–2,500 km/s, causing the star to lose over a millionth of the mass of the Sun every year.^[9] It has already lost approximately 25% of its initial mass and is roughly halfway through its main sequence life.^[4]