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WR 137

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WR 137
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 20h 14m 31.76669s[1]
Declination 36° 39′ 39.5982″[1]
Apparent magnitude (V) 7.91[2] (7.86 - 7.93[3])
Characteristics
Evolutionary stage Wolf-Rayet
Spectral type WC7pd + O9V[4]
U−B color index −0.40[2]
B−V color index +0.29[2]
Variable type WR[5]
Astrometry
Proper motion (μ) RA: −2.681[1] mas/yr
Dec.: −5.739[1] mas/yr
Parallax (π)0.4898 ± 0.0172 mas[1]
Distance6,700 ± 200 ly
(2,040 ± 70 pc)
Absolute magnitude (MV)−5.7[6] (−4.18 + −4.34)[4]
Orbit[6]
Period (P)4,766 ± 66
Semi-major axis (a)16 AU
Eccentricity (e)0.178 ± 0.042
Inclination (i)67°
Semi-amplitude (K1)
(primary)		27.9 ± 1.2 km/s
Semi-amplitude (K2)
(secondary)		6.1 ± 1.3 km/s
Details
WR
Mass4.4 ± 1.5[6] M☉
Radius3.8 ± 1[4] R☉
Luminosity398,000[7] L☉
Temperature60,000 ± 5,000[4] K
O
Mass20 ± 2[6] M☉
Radius7.7 ± 1[4] R☉
Luminosity158,000[7] L☉
Surface gravity (log g)4.0 ± 0.3[4] cgs
Temperature32,000 ± 2,000[4] K
Rotational velocity (v sin i)220 ± 20[4] km/s
Age4.1[7] Myr
Other designations
V1679 Cygni, WR 137, HD 192641, HIP 99769, BD+35°4001, Hen 3-1839
Database references
SIMBADdata
Spectrum of WR 137 showing the prominent emission lines of ionised Carbon and Helium

WR 137 is a variable Wolf-Rayet star located around 6,000 light years away from Earth in the constellation of Cygnus.

WR 137, together with WR 134 and WR 135, was one of three stars in Cygnus observed in 1867 to have unusual spectra consisting of intense emission lines rather than the more normal continuum and absorption lines. These were the first members of the class of stars that came to be called Wolf-Rayet stars (WR stars) after Charles Wolf and Georges Rayet who discovered their unusual appearance.[8] It is a member of the carbon sequence of WR stars, indicated by the lack of nitrogen lines and the strength of carbon emission. WR 137 has a spectrum with CIII emission weaker than CIV and OV weaker still, leading to the assignment of a WC7 spectral type. The spectrum also shows emission lines of HeII and OIV.[9][10]

A blue band light curve for V1679 Cygni, plotted from data published by Panov et al. (2000)[11]

WR 137 is a binary system, with an O9 main sequence or giant companion. The two stars orbit every thirteen years in a mildly eccentric orbit, and there is an episode of dust production near periastron. The inclination of the orbit is uncertain, most likely near 67° but with some analyses suggesting values around 23°.[6] The O star is visually brighter and more massive, but the WR star dominates the spectrum and has a higher bolometric luminosity. Visible in the spectrum are absorption lines and some narrow emission lines, each thought to originate from the secondary star. The line profiles suggest a decretion disc around the star, produced by its rapid rotation, which would make it the only known system containing a WR star and an Oe star.[7]

WR 137 is about a degree away from WR 135 and the two are believed to lie at approximately the same distance from Earth within the Cygnus OB3 association.[12] Its properties are uncertain because of the presence of the hot luminous companion. A pseudo-fit of the combined spectrum yielded a temperature of 56,000 K, a luminosity of 537,000 L☉, and a radius of 10 R☉. A more typical radius for a WC7 star would be 4.5 R☉, implying a hotter temperature.[6]

Evolutionary modelling of the WR 137 pair suggest an initial mass for the primary of 60 M☉ and for the secondary of 30 M☉, with an age of 4.1 million years. The initial orbital period would have been around 1,580 days. Around three M☉ have been transferred from the primary to the secondary.[7]

References

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  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b c 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. ^ Alfonso-Garzón, J.; Domingo, A.; Mas-Hesse, J. M.; Giménez, A. (2012). "The first INTEGRAL-OMC catalogue of optically variable sources". Astronomy & Astrophysics. 548: A79. arXiv:1210.0821. Bibcode:2012A&A...548A..79A. doi:10.1051/0004-6361/201220095. S2CID 118428054.
  4. ^ a b c d e f g h Richardson, Noel D.; Shenar, Tomer; Roy-Loubier, Olivier; Schaefer, Gail; Moffat, Anthony F. J.; St-Louis, Nicole; Gies, Douglas R.; Farrington, Chris; Hill, Grant M.; Williams, Peredur M.; Gordon, Kathryn; Pablo, Herbert; Ramiaramanantsoa, Tahina (2016). "The CHARA Array resolves the long-period Wolf–Rayet binaries WR 137 and WR 138". Monthly Notices of the Royal Astronomical Society. 461 (4): 4115–4124. arXiv:1606.09586. Bibcode:2016MNRAS.461.4115R. doi:10.1093/mnras/stw1585. S2CID 35333968.
  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. ^ a b c d e f Lefèvre, L.; Marchenko, S. V.; Lépine, S.; Moffat, A. F. J.; Acker, A.; Harries, T. J.; Annuk, K.; Bohlender, D. A.; Demers, H.; Grosdidier, Y.; Hill, G. M.; Morrison, N. D.; Knauth, D. C.; Skalkowski, G.; Viti, S. (2005). "Spectroscopic study of the long-period dust-producing WC7pd+O9 binary HD192641". Monthly Notices of the Royal Astronomical Society. 360 (1): 141–152. arXiv:astro-ph/0504475. Bibcode:2005MNRAS.360..141L. doi:10.1111/j.1365-2966.2005.09017.x. S2CID 14511057.
  7. ^ a b c d e St-Louis, N.; Piaulet, C.; Richardson, N. D.; Shenar, T.; Moffat, A F J.; Eversberg, T.; Hill, G. M.; Gauza, B.; Knapen, J. H.; Kubát, J.; Kubátová, B.; Sablowski, D. P.; Simón-Díaz, S.; Bolduan, F.; Dias, F. M.; Dubreuil, P.; Fuchs, D.; Garrel, T.; Grutzeck, G.; Hunger, T.; Küsters, D.; Langenbrink, M.; Leadbeater, R.; Li, D.; Lopez, A.; Mauclaire, B.; Moldenhawer, T.; Potter, M.; Dos Santos, E. M.; et al. (2020). "An extensive spectroscopic time series of three Wolf–Rayet stars – II. A search for wind asymmetries in the dust-forming WC7 binary WR137". Monthly Notices of the Royal Astronomical Society. 497 (4): 4448–4458. arXiv:2007.09239. Bibcode:2020MNRAS.497.4448S. doi:10.1093/mnras/staa2214. S2CID 220646604.
  8. ^ Murdin, P. (2001). "Wolf, Charles J E (1827-1918)". The Encyclopedia of Astronomy and Astrophysics. p. 4101. Bibcode:2000eaa..bookE4101.. doi:10.1888/0333750888/4101. ISBN 0333750888.
  9. ^ Hiltner, W. A.; Schild, R. E. (1966). "Spectral Classification of Wolf-Rayet Stars". Astrophysical Journal. 143: 770. Bibcode:1966ApJ...143..770H. doi:10.1086/148556.
  10. ^ Sander, A.; Hamann, W.-R.; Todt, H. (2012). "The Galactic WC stars. Stellar parameters from spectral analyses indicate a new evolutionary sequence". Astronomy & Astrophysics. 540: A144. arXiv:1201.6354. Bibcode:2012A&A...540A.144S. doi:10.1051/0004-6361/201117830. S2CID 119182468.
  11. ^ Panov, Kiril P.; Altmann, Martin; Seggewiss, Wilhelm (March 2000). "Long-term photometry of the Wolf-Rayet stars WR 137, WR 140, WR 148, and WR 153". Astronomy and Astrophysics. 355: 607–616. arXiv:astro-ph/0002221. Bibcode:2000A&A...355..607P. Retrieved 29 December 2021.
  12. ^ Gervais, Simon; St-Louis, Nicole (1999). "A Large H I Shell surrounding the Wolf-Rayet Star HD 191765". The Astronomical Journal. 118 (5): 2394. Bibcode:1999AJ....118.2394G. doi:10.1086/301065.
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