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. Direct spectroscopy yields a spectral class of O6.5 and an effective temperature around 37,500 K. It is a member of the Cassiopeia OB2 stellar association in the Perseus Arm of the galaxy at about 8,500 light-years' distance.
NGC 7635 surrounding BD+60 2522 Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 23h 20m 44.5135s |
| Declination | +61° 11′ 40.531″ |
| Apparent magnitude (V) | 8.67 |
| Characteristics | |
| Spectral type | O6.5(f)(n)p |
| U−B color index | −0.62 |
| B−V color index | +0.41 |
| Astrometry | |
| Radial velocity (Rv) | −26 km/s |
| Proper motion (μ) | RA: −2.662 mas/yr Dec.: 0.388 mas/yr |
| Parallax (π) | 0.3341 ± 0.0152 mas |
| Distance | 9,800 ± 400 ly (3,000 ± 100 pc) |
| Absolute magnitude (MV) | −5.5 |
| Details | |
| Mass | 44 M☉ |
| Radius | 15 R☉ |
| Luminosity | 398,000 L☉ |
| Temperature | 37,500 K |
| Rotational velocity (v sin i) | 178 - 240 km/s |
| Age | 2 Myr |
| Other designations | |
| 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.