WR 42e

WR 42e (2MASS J11144550-115001) is a Wolf–Rayet star in the massive H II region NGC 3603 in the constellation of the Carina. It is around 25,000 light-years or 7,600 parsec from the Sun. WR 42e is one of the most massive and most luminous stars known.

WR 42e

WR 42e (circled) near HD 97950 in NGC 3603
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Carina
Right ascension	11h 14m 45.513s[1]
Declination	−61° 15′ 00.30″[1]
Apparent magnitude (V)	14.53[2]
Characteristics
Spectral type	O3If*/WN6[3]
Apparent magnitude (U)	16.31[2]
Apparent magnitude (B)	16.05[2]
Apparent magnitude (V)	14.53[2]
Apparent magnitude (I)	12.05[2]
Apparent magnitude (J)	10.177[4]
Apparent magnitude (H)	9.466[4]
Apparent magnitude (K)	9.037[4]
U−B color index	+0.26[2]
B−V color index	+1.52[2]
Astrometry
Proper motion (μ)	RA: −5.679[1] mas/yr Dec.: +1.908[1] mas/yr
Parallax (π)	0.1053 ± 0.0157 mas[1]
Distance	25,000 ly (7,600[2] pc)
Absolute magnitude (MV)	−6.92[3]
Details
Mass	123[3] M☉
Luminosity	3,200,000[2] L☉
Temperature	43,652[3] K
Age	1-2[2][5][3] Myr
Other designations
2MASS J11144550-115001, SB04 #954, WR 42-1[6]
Database references
SIMBAD	data

WR 42e was first catalogued in 2004 as a member of NGC 3603, numbered 954. It was noted as having x-ray and H_α emission.^[7] A detailed study published in 2012 showed that the faint red star was actually a highly obscured (6.4 magnitudes in the visual) hot blue Wolf Rayet star and gave it the name WR 42e.^[2] Subsequent changes to the naming conventions for new galactic Wolf–Rayet stars mean it is also called WR 42-1.^[6]

WR 42e is located 2.7 arcmin west-northwest of the massive open cluster HD 97950 at the heart of NGC 3603,^[5] corresponding to 6 parsecs at the distance of NGC 3603.^[2] This is outside the compact core of the cluster where similar massive luminous stars are found. It is speculated that WR 42e was ejected in an unusual three-body encounter possibly involving the merger of two of the stars and the ejection of both the resulting objects.^[5]

The spectrum of WR 42e shows many characteristics of an OIf^* star, such as hydrogen Balmer series absorption lines and emission lines of ionised nitrogen and helium. The relative strengths of the nitrogen emission lines and the lack of absorption in the 468.4 nm helium line indicate a spectral class of O3 If^*. However, the H_β line shows a distinct emission wing. A P Cygni profile for this line is a defining character of the OIf^*/WN class and so WR 42e is assigned the type O3If^*/WN6.^[3]

See also

• Initial mass function

References

1. 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.
2. Roman, A.; Lopes (2012). "A Galactic O2 If*/WN6 star possibly ejected from its birthplace in NGC 3603". Monthly Notices of the Royal Astronomical Society: Letters. 427 (1): L65. arXiv:1209.1598. Bibcode:2012MNRAS.427L..65R. doi:10.1111/j.1745-3933.2012.01346.x. S2CID 118453639.
3. Roman-Lopes, A.; Franco, G. A. P.; Sanmartim, D. (2016). "SOAR Optical and Near-infrared Spectroscopic Survey of Newly Discovered Massive Stars in the Periphery of Galactic Massive Star Clusters I-NGC 3603". The Astrophysical Journal. 823 (2): 96. arXiv:1604.01096. Bibcode:2016ApJ...823...96R. doi:10.3847/0004-637X/823/2/96. S2CID 119204619.
4. Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
5. Gvaramadze, V. V.; Kniazev, A. V.; Chené, A. -N.; Schnurr, O. (2012). "Two massive stars possibly ejected from NGC 3603 via a three-body encounter". Monthly Notices of the Royal Astronomical Society: Letters. 430: L20–L24. arXiv:1211.5926. Bibcode:2013MNRAS.430L..20G. doi:10.1093/mnrasl/sls041. S2CID 56103308.
6. Rosslowe, C. K.; Crowther, P. A. (2014). "Spatial distribution of Galactic Wolf–Rayet stars and implications for the global population". Monthly Notices of the Royal Astronomical Society. 447 (3): 2322. arXiv:1412.0699. Bibcode:2015MNRAS.447.2322R. doi:10.1093/mnras/stu2525. S2CID 28747394.
7. Sung, H.; Bessell, M. S. (2004). "The Initial Mass Function and Stellar Content of NGC 3603". Astronomy & Astrophysics. 127 (2): 1014. Bibcode:2004AJ....127.1014S. doi:10.1086/381297.