9 Cephei
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Cepheus |
Right ascension | 21h 37m 55.22469s[1] |
Declination | +62° 04′ 54.9825″[1] |
Apparent magnitude (V) | 4.69 - 4.78[2] |
Characteristics | |
Spectral type | B2 Ib[3] |
U−B color index | −0.54[4] |
B−V color index | +0.30[4] |
Variable type | α Cyg[2] |
Astrometry | |
Radial velocity (Rv) | −13.50 ± 0.8[5] km/s |
Proper motion (μ) | RA: −1.64 ± 0.17[1] mas/yr Dec.: −3.02 ± 0.16[1] mas/yr |
Parallax (π) | 0.00 ± 0.17 mas[1] |
Distance | 950[6] pc |
Absolute magnitude (MV) | −6.44[3] |
Details | |
Searle et al 2008[3] | |
Mass | 21 M☉ |
Radius | 39.8 R☉ |
Luminosity | 151,000 L☉ |
Surface gravity (log g) | 2.50 cgs |
Temperature | 18,000 K |
Rotational velocity (v sin i) | 73 km/s |
Markova & Puls 2008[7] | |
Mass | 12 M☉ |
Radius | 32 R☉ |
Luminosity | 129,000 L☉ |
Surface gravity (log g) | 2.50 cgs |
Temperature | 19,200 K |
Rotational velocity (v sin i) | 45 km/s |
Other designations | |
Database references | |
SIMBAD | data |
9 Cephei (9 Cep), also known as V337 Cephei, is a variable star in the constellation Cepheus.
9 Cephei was given the name V337 Cephei and classified as an α Cygni variable in 1967.[8] It varies irregularly between magnitude 4.69 and 4.78.[2] A study of the Hipparcos satellite photometry showed an amplitude of 0.56 magnitudes, but could find no periodicity.[9]
9 Cephei is considered to be a member of the Cepheus OB2 stellar association, a scattering of massive bright stars around a thousand parsecs away in the southern part of the constellation Cepheus.[3]
Calculations of the physical properties of 9 Cephei vary considerably even from broadly similar observational data. Modelling using the non-LTE line-blanketed CMFGEN atmospheric code gives a temperature of 18,000 K, radius of 40 R☉, luminosity of 151,000 L☉, and mass of 21 M☉.[3] Calculations using the FASTWIND model give gives a temperature of 19,200 K, radius of 32 R☉, luminosity of 129,000 L☉, and mass of 12 M☉.[7]
References
- ^ a b c d e van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.Vizier catalog entry
- ^ a b c Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
- ^ a b c d e Searle, S. C.; Prinja, R. K.; Massa, D.; Ryans, R. (2008). "Quantitative studies of the optical and UV spectra of Galactic early B supergiants. I. Fundamental parameters". Astronomy and Astrophysics. 481 (3): 777. arXiv:0801.4289. Bibcode:2008A&A...481..777S. doi:10.1051/0004-6361:20077125. S2CID 1552752.
- ^ a b Ducati, 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.
- ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
- ^ Pan, K.; Federman, S. R.; Cunha, K.; Smith, V. V.; Welty, D. E. (2004). "Cloud Structure and Physical Conditions in Star-forming Regions from Optical Observations. I. Data and Component Structure". The Astrophysical Journal Supplement Series. 151 (2): 313. arXiv:astro-ph/0312095. Bibcode:2004ApJS..151..313P. doi:10.1086/381805. S2CID 17367021.
- ^ a b Markova, N.; Puls, J. (2008). "Bright OB stars in the Galaxy. IV. Stellar and wind parameters of early to late B supergiants". Astronomy and Astrophysics. 478 (3): 823. arXiv:0711.1110. Bibcode:2008A&A...478..823M. doi:10.1051/0004-6361:20077919. S2CID 14510634.
- ^ Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (1979). "64th Name-List of Variable Stars". Information Bulletin on Variable Stars. 1581: 1. Bibcode:1979IBVS.1581....1K.
- ^ Lefèvre, L.; Marchenko, S. V.; Moffat, A. F. J.; Acker, A. (2009). "A systematic study of variability among OB-stars based on HIPPARCOS photometry". Astronomy and Astrophysics. 507 (2): 1141. Bibcode:2009A&A...507.1141L. doi:10.1051/0004-6361/200912304.