Astronomy:WR 137
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[1] mas |
| Distance | 6,700 ± 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 | |
| Mass | 4.4 ± 1.5[6] M☉ |
| Radius | 3.8 ± 1[4] R☉ |
| Luminosity | 398,000[7] L☉ |
| Temperature | 60,000 ± 5,000[4] K |
| O | |
| Mass | 20 ± 2[6] M☉ |
| Radius | 7.7 ± 1[4] R☉ |
| Luminosity | 158,000[7] L☉ |
| Surface gravity (log g) | 4.0 ± 0.3[4] cgs |
| Temperature | 32,000 ± 2,000[4] K |
| Rotational velocity (v sin i) | 220 ± 20[4] km/s |
| Age | 4.1[7] Myr |
| Other designations | |
V1679 Cygni, WR 137, HD 192641, HIP 99769, BD+35°4001, Hen 3-1839 | |
| Database references | |
| SIMBAD | data |
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]
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
- ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 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.
- ↑ 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. doi:10.1051/0004-6361/201220095. Bibcode: 2012A&A...548A..79A.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Richardson, Noel D.; Shenar, Tomer; Roy-Loubier, Olivier; Schaefer, Gail; Moffat, Anthony F. J.; St-Louis, Nicole; Gies, Douglas R.; Farrington, Chris et al. (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. doi:10.1093/mnras/stw1585. Bibcode: 2016MNRAS.461.4115R.
- ↑ Samus, N. N. 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.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Lefèvre, L.; Marchenko, S. V.; Lépine, S.; Moffat, A. F. J.; Acker, A.; Harries, T. J.; Annuk, K.; Bohlender, D. A. et al. (2005). "Spectroscopic study of the long-period dust-producing WC7pd+O9 binary HD192641". Monthly Notices of the Royal Astronomical Society 360 (1): 141–152. doi:10.1111/j.1365-2966.2005.09017.x. Bibcode: 2005MNRAS.360..141L.
- ↑ 7.0 7.1 7.2 7.3 7.4 St-Louis, N.; Piaulet, C.; Richardson, N. D.; Shenar, T.; Moffat, A F J.; Eversberg, T.; Hill, G. M.; Gauza, B. 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. doi:10.1093/mnras/staa2214. Bibcode: 2020MNRAS.497.4448S.
- ↑ Murdin, P. (2001). "Wolf, Charles J E (1827-1918)". The Encyclopedia of Astronomy and Astrophysics. pp. 4101. doi:10.1888/0333750888/4101. ISBN 0333750888. Bibcode: 2000eaa..bookE4101..
- ↑ Hiltner, W. A.; Schild, R. E. (1966). "Spectral Classification of Wolf-Rayet Stars". Astrophysical Journal 143: 770. doi:10.1086/148556. Bibcode: 1966ApJ...143..770H.
- ↑ 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. doi:10.1051/0004-6361/201117830. Bibcode: 2012A&A...540A.144S.
- ↑ 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. Bibcode: 2000A&A...355..607P. https://ui.adsabs.harvard.edu/abs/2000A&A...355..607P. Retrieved 29 December 2021.
- ↑ Gervais, Simon; St-Louis, Nicole (1999). "A Large H I Shell surrounding the Wolf-Rayet Star HD 191765". The Astronomical Journal 118 (5): 2394. doi:10.1086/301065. Bibcode: 1999AJ....118.2394G.
External links
- Wolf-Rayet shells showing a spectrum of WR 135
- WR134 Ring Nebula with WR 135 visible in the top left corner
 |  |
