WR 120
 A near-infrared (2.033 micron) light curve for V462 Scuti, adapted from Chené and St-Louis (2007). The left-most point shows the 3 sigma error bar. | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Scutum |
| Right ascension | 18h 41m 00.86701s |
| Declination | −04° 26′ 14.4841″ |
| Apparent magnitude (V) | 11.93 |
| Characteristics | |
| Evolutionary stage | Wolf–Rayet |
| Spectral type | WN7w + WN3/4 |
| U−B color index | 0.13 |
| B−V color index | 1.04 |
| Astrometry | |
| Proper motion (μ) | RA: −0.489 mas/yr Dec.: −2.524 mas/yr |
| Parallax (π) | 0.3246±0.0541 mas |
| Distance | approx. 10,000 ly (approx. 3,100 pc) |
| Absolute magnitude (MV) | −3.81 |
| Details | |
| Mass | 7 M☉ |
| Radius | 3.78 R☉ |
| Luminosity | 83,200 L☉ |
| Temperature | 50,100 K |
| Other designations | |
| MR 89, V462 Scuti, 2MASS J18410086-0426145 | |
| Database references | |
| SIMBAD | data |
WR 120 is a binary containing two Wolf–Rayet stars in the constellation of Scutum, around 10,000 light years away. The primary is a hydrogen-free weak-lined WN7 star, the secondary is a hydrogen-free WN3 or 4 star, and the system is a possible member of the cluster Dolidze 33. From our point of view, WR 120 is reddened by 4.82 magnitudes.
Photometric observations obtained in 1995 by Sergey V. Marchenko et al. showed that WR 120 is a variable star. For that reason it was given its variable star designation, V462 Scuti, in the year 2000.
Properties
Analysis of the primary's spectrum with PoWR shows that it has a temperature of around 50,000 Kelvins, and is losing mass at a rate of 10−4.9 M☉/year, or 1 solar mass every 80,000 years, which is being carried away from the surface at a speed of 1,225 kilometres per second. Taking its close distance into account, WR 120 A's luminosity turns out to be a mere 83,200 L☉, which would make it one of the dimmest WN stars known, and one of the only WN stars with a luminosity below 100,000 L☉. Using the Stefan-Boltzmann Law, a radius of 3.78 R☉ is derived, and a "transformed" radius at an optical depth of 2/3, more comparable to other types of stars, is about 6 R☉. Using the WR luminosity-mass ratio, WR 120 may have a mass of just 7 M☉, one of the lowest masses of any WR star. WR 120's absolute magnitude is −3.8, which is also relatively faint for a Wolf–Rayet star.
WR 120 is thought to be a member of Dolidze 33, an open cluster nearly 3,000 pc away.
Binarity
In 2021, WR 120 was found to have a close companion. Previously, it was thought to be a single WR star. The companion is thought to be a WN3/4 WR star and would be located at least 1,700 AU from the primary WN7 WR star. It is about two magnitudes fainter than WR 120.
References
- ↑ Chené, André-Nicolas (2007). "The First Determination of the Rotation Rates of Wolf-Rayet Stars". Massive Stars as Cosmic Engines, Proceedings IAU Symposium. 250: 139–144. doi:10.1017/S1743921308020425.
- ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
- 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ↑ Zacharias, N. (2012). "The fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)". VizieR On-line Data Catalog. Bibcode:2012yCat.1322....0Z.
- 1 2 3 Shara, Michael M.; Howell, Steve B.; Furlan, Elise; Gnilka, Crystal L.; Moffat, Anthony F. J.; Scott, Nicholas J.; Zurek, David (2022-01-01). "A speckle-imaging search for close and very faint companions to the nearest and brightest Wolf-Rayet stars". Monthly Notices of the Royal Astronomical Society. 509 (2): 2897–2907. arXiv:2109.06975. Bibcode:2022MNRAS.509.2897S. doi:10.1093/mnras/stab2666. ISSN 0035-8711.
- 1 2 3 4 5 6 7 8 Hamann, W.-R.; Gräfener, G.; Liermann, A.; Hainich, R.; Sander, A. A. C.; Shenar, T.; Ramachandran, V.; Todt, H.; Oskinova, L. M. (2019-05-01). "The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters". Astronomy and Astrophysics. 625: A57. arXiv:1904.04687. Bibcode:2019A&A...625A..57H. doi:10.1051/0004-6361/201834850. ISSN 0004-6361. S2CID 104292503.
- 1 2 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". VizieR Online Data Catalog. 2237. Bibcode:2002yCat.2237....0D.
- 1 2 Rate, Gemma; Crowther, Paul A.; Parker, Richard J. (2020-06-01). "Unlocking Galactic Wolf-Rayet stars with Gaia DR2 - II. Cluster and association membership". Monthly Notices of the Royal Astronomical Society. 495 (1): 1209–1226. arXiv:2005.02533. Bibcode:2020MNRAS.495.1209R. doi:10.1093/mnras/staa1290. ISSN 0035-8711.
- ↑ Marchenko, S. V.; Moffat, A. F. J.; Eversberg, T.; Morel, T.; Hill, G. M.; Tovmassian, G. H.; Seggewiss, W. (March 1998). "A comprehensive variability study of the enigmatic WN8 stars: final results". Monthly Notices of the Royal Astronomical Society. 294 (4): 642–656. Bibcode:1998MNRAS.294..642M. doi:10.1111/j.1365-8711.1998.01174.x.
- ↑ Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V. (March 2000). "The 75th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 4870: 1–47. Bibcode:2000IBVS.4870....1K. Retrieved 14 September 2025.
