WR 9

WR 9 is a spectroscopic binary in the constellation Puppis consisting of a Wolf-Rayet star and a class O star. It is around 4,800 light years away.

WR 9
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Puppis
Right ascension  07h 45m 50.39754s[1]
Declination −34° 19′ 48.5067″[1]
Apparent magnitude (V) 10.50[2]
Characteristics
Spectral type WC4 + O7[3]
Apparent magnitude (J) 8.452[4]
Apparent magnitude (K) 7.545[4]
U−B color index +0.04[2]
B−V color index +0.93[2]
Variable type Eclipsing + WR[5]
Astrometry
Radial velocity (Rv)321 ± 12[6] km/s
Proper motion (μ) RA: −4.43[1] mas/yr
Dec.: +2.76[1] mas/yr
Parallax (π)0.94 ± 1.48[1] mas
Distance1,470[7] pc
Absolute magnitude (MV)WR: −3.34
O: −4.01[7]
Orbit[6]
Period (P)14.305
Semi-major axis (a)123 R☉[8]
Eccentricity (e)0
Inclination (i)55 ± 34°
Semi-amplitude (K1)
(primary)		186 ± 19 km/s
Semi-amplitude (K2)
(secondary)		56 ± 28 km/s
Details
WR
Mass9[9] M☉
Radius5[8] R☉
Luminosity500,000[10] L☉
Temperature139,700[10] K
O
Mass32[9] M☉
Other designations
V443 Puppis, CD−34° 3879, HD 63099, HIP 37876
Database references
SIMBADdata

WR 9 is a binary with two components in a circular 14-day orbit. The Wolf-Rayet component is often identified as the primary because it dominates the spectrum with its broad emission lines, although it is less massive, less luminous, and less visually bright than its companion. The companion is an approximately O7 star.

The spectrum is dominated by broad emission lines, those of CIV being the strongest, followed by HeII. CIII lines are seen but much weaker. OV lines are also stronger than CIII. The classification is usually given as WC4, although it has previously been assigned as WC5. By comparison, the absorption lines of the secondary star are narrower and weaker, although at blue and shorter wavelengths they become stronger than the WR lines. The spectral type of the secondary can be set at O7.[3] The luminosity class cannot be determined clearly, although it has been suggested to be a supergiant.[11] The Wolf-Rayet star shows no hydrogen in its spectrum and is thought to be hydrogen-free. It is calculated to consist of 42% helium and 58% heavier elements, mostly carbon and oxygen.[10]

WR 9 is listed as an eclipsing binary in the General Catalogue of Variable Stars, as well as having the more irregular brightness changes frequently seen in Wolf Rayet stars. The total amplitude is only 0.04 magnitudes.[5] The eclipses are so shallow because only the atmosphere of the WR star eclipses the O star on each orbit.[8]

References
  1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. 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.
  3. Bartzakos, P.; Moffat, A. F. J.; Niemela, V. S. (2001). "Magellanic Cloud WC/WO Wolf-Rayet stars - I. Binary frequency and Roche lobe overflow formation". Monthly Notices of the Royal Astronomical Society. 324: 18. Bibcode:2001MNRAS.324...18B. doi:10.1046/j.1365-8711.2001.04126.x.
  4. Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; Carpenter, J. M.; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; Huchra, J.; Jarrett, T.; Kopan, E. L.; Kirkpatrick, J. D.; Light, R. M.; Marsh, K. A.; McCallon, H.; Schneider, S.; Stiening, R.; Sykes, M.; Weinberg, M.; Wheaton, W. A.; Wheelock, S.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog: II/246. Originally Published in: 2003yCat.2246....0C. 2246. Bibcode:2003yCat.2246....0C.
  5. 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.
  6. Bartzakos, P.; Moffat, A. F. J.; Niemela, V. S. (2001). "Magellanic Cloud WC/WO Wolf-Rayet stars - II. Colliding winds in binaries". Monthly Notices of the Royal Astronomical Society. 324: 33. Bibcode:2001MNRAS.324...33B. doi:10.1046/j.1365-8711.2001.04127.x.
  7. Van Der Hucht, Karel A. (2001). "The VIIth catalogue of galactic Wolf-Rayet stars". New Astronomy Reviews. 45 (3): 135. Bibcode:2001NewAR..45..135V. doi:10.1016/S1387-6473(00)00112-3.
  8. Lamontagne, Robert; Moffat, Anthony F. J.; Drissen, Laurent; Robert, Carmelle; Matthews, Jaymie M. (1996). "Photometric Determination of Orbital Inclinations and Mass Loss Rates for Wolf-Rayet Stars in WR+O Binaries". Astronomical Journal. 112: 2227. Bibcode:1996AJ....112.2227L. doi:10.1086/118175.
  9. Petrovic, J.; Langer, N.; Van Der Hucht, K. A. (2005). "Constraining the mass transfer in massive binaries through progenitor evolution models of Wolf-Rayet+O binaries". Astronomy and Astrophysics. 435 (3): 1013. arXiv:astro-ph/0504242. Bibcode:2005A&A...435.1013P. doi:10.1051/0004-6361:20042368.
  10. Nugis, T.; Lamers, H. J. G. L. M. (2000). "Mass-loss rates of Wolf-Rayet stars as a function of stellar parameters". Astronomy and Astrophysics. 360: 227. Bibcode:2000A&A...360..227N.
  11. Niemela, V. S.; Massey, P.; Conti, P. S. (1984). "The WC5 + O7 binary system HD 63099". Astronomical Society of the Pacific. 96: 549. Bibcode:1984PASP...96..549N. doi:10.1086/131377.
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