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.[5] 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[7] of the galaxy at about 8,500 light-years' distance.[8]
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.[7]
^ abcDucati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
^Walborn, Nolan R.; Howarth, Ian D.; Evans, Christopher J.; Crowther, Paul A.; Moffat, Anthony F. J.; St-Louis, Nicole; Fariña, Cecilia; Bosch, Guillermo L.; Morrell, Nidia I.; Barbá, Rodolfo H.; Van Loon, Jacco Th. (2010). "The Onfp Class in the Magellanic Clouds". The Astronomical Journal. 139 (3): 1283. arXiv:1001.4032. Bibcode:2010AJ....139.1283W. doi:10.1088/0004-6256/139/3/1283. S2CID119297513.
^ abMoore, B. D.; Walter, D. K.; Hester, J. J.; Scowen, P. A.; Dufour, R. J.; Buckalew, B. A. (2002). "Hubble Space Telescope Observations of the Windblown Nebula NGC 7635". The Astronomical Journal. 124 (6): 3313. Bibcode:2002AJ....124.3313M. doi:10.1086/344596. S2CID117009444.
^ abcAnand, M. Y.; Kagali, B. A.; Murthy, Jayant (2009). "Study of Bubble nebula using IUE high resolution spectra". Bulletin of the Astronomical Society of India. 37 (1): 1. arXiv:0903.2828. Bibcode:2009BASI...37....1A.