HD 93250

From Wikipedia, the free encyclopedia
Jump to: navigation, search
HD 93250
Carina Nebula by ESO.jpg
HD 93250 is the bright star just above and left of the centre of this image of the Carina Nebula.
Credit: ESO
Observation data
Epoch J2000      Equinox J2000
Constellation Carina
Right ascension 10h 44m 45.026s[1]
Declination −59° 33′ 54.68″[1]
Apparent magnitude (V) 7.41[2]
Characteristics
Spectral type O4III(fc)[3]
U−B color index −0.85[2]
B−V color index +0.17[2]
Astrometry
Radial velocity (Rv) 11.6[4] km/s
Proper motion (μ) RA: −7.27[1] mas/yr
Dec.: +2.45[1] mas/yr
Parallax (π) 0.53 ± 0.42[1] mas
Distance 2,350[5] pc
Absolute magnitude (MV) −6.14[6]
Details[6]
Mass 83.3 (65[7]M
Radius 15.9 R
Luminosity 1,000,000 L
Surface gravity (log g) 3.96 cgs
Temperature 46,000 K
Rotational velocity (v sin i) 130 km/s
Age 1.3 Myr
Other designations
1E 104248-5918.0, XMMU J104444.8-593354, ALS 1859, 2E 2317, HIP 52558, CD-58°3537, GC 14791, CGO 246, GCRV 25947, PPM 339400, Trumpler 16 180, SAO 238423, Trumpler 14 101, TYC 8626-2075-1, CPC 20°3140, GOS G287.51-00.54 01, CPD−58°2661, GSC 08626-02075
Database references
SIMBAD data

HD 93250 is a highly luminous hot blue binary star in the Carina Nebula in the constellation Carina.

Location[edit]

HD 93250 is marked above centre in this mosaic of the Carina Nebula region

HD 93250 is one of the brightest stars in the region of the Carina Nebula. It is only 7.5 arc-minutes from the famous Eta Carinae[5] and HD 93250 is considered to be a member of the same loose open cluster Trumpler 16, although it is appears closer to the more compact Trumpler 14.[8]

HD 93250 is in a region of the Carina Nebula with several bright stars, for example HD 93268 and HDE 303311, but relatively few faint stars. It has been proposed that these bright stars are the core of a separate cluster called Collinder 232, but the lack of any concentration of fainter stars in the area makes it more likely that Collinder 232 is not a real cluster and HD 93250 is just an outlying member of one of the more obvious clusters.[9]

Membership of Trumpler 16 constrains the distance and likely age of HD 93250.[6]

Binary[edit]

HD 93250 is the brightest x-ray source in the Carina Nebula.[5] It has long been suspected that this is due to colliding winds in a close pair of hot luminous stars, but investigations have failed to show any significant radial velocity variations to support this.[4]

In 2010, AMBER interferometry resolved HD 93250 into two separate stars. No relative motion or radial velocity variations could be detected and so the orbit and properties of the two stars is still uncertain. The projected separation of the stars is 1.5 mas, approximately 3.5 astronomical units. The two stars show no measurable colour difference and are both likely to be hot O stars with masses within 10% of each other.[5]

Properties[edit]

The physical properties of HD 93250 have only been calculated on the assumption that it is a single star. The temperature is around 50,000 K and its luminosity around 1,000,000 L Calculations of the mass have shown discrepancies between spectroscopic models and evolutionary models, which may be resolved by analysis of two separate stars in the system.[7]

References[edit]

  1. ^ a b c d e van Leeuwen, F. (2007). "Validation of the New Hipparcos Reduction". Astronomy and Astrophysics. 474 (2): 653–64. arXiv:0708.1752free to read. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Antokhin, I. I.; Rauw, G.; Vreux, J.-M.; Van Der Hucht, K. A.; Brown, J. C. (2008). "XMM-Newton X-ray study of early type stars in the Carina OB1 association". Astronomy and Astrophysics. 477 (2): 593. arXiv:0711.3612free to read. Bibcode:2008A&A...477..593A. doi:10.1051/0004-6361:20065711. 
  3. ^ Sota, A.; Maíz Apellániz, J.; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J. (2014). "The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars". The Astrophysical Journal Supplement. 211: 10. arXiv:1312.6222free to read. Bibcode:2014ApJS..211...10S. doi:10.1088/0067-0049/211/1/10. 
  4. ^ a b Rauw, G.; Nazé, Y.; Fernández Lajús, E.; Lanotte, A. A.; Solivella, G. R.; Sana, H.; Gosset, E. (2009). "Optical spectroscopy of X-Mega targets in the Carina nebula - VII. On the multiplicity of Tr16-112, HD93343 and HD93250". Monthly Notices of the Royal Astronomical Society. 398 (3): 1582. arXiv:0906.2681free to read. Bibcode:2009MNRAS.398.1582R. doi:10.1111/j.1365-2966.2009.15226.x. 
  5. ^ a b c d Sana, H.; Le Bouquin, J.-B.; De Becker, M.; Berger, J.-P.; De Koter, A.; Mérand, A. (2011). "The Non-thermal Radio Emitter HD 93250 Resolved by Long Baseline Interferometry". The Astrophysical Journal Letters. 740 (2): L43. arXiv:1110.0831free to read. Bibcode:2011ApJ...740L..43S. doi:10.1088/2041-8205/740/2/L43. 
  6. ^ a b c Repolust, T.; Puls, J.; Herrero, A. (2004). "Stellar and wind parameters of Galactic O-stars. The influence of line-blocking/blanketing". Astronomy and Astrophysics. 415: 349. Bibcode:2004A&A...415..349R. doi:10.1051/0004-6361:20034594. 
  7. ^ a b Weidner, C.; Vink, J. S. (2010). "The masses, and the mass discrepancy of O-type stars". Astronomy and Astrophysics. 524: A98. arXiv:1010.2204free to read. Bibcode:2010A&A...524A..98W. doi:10.1051/0004-6361/201014491. 
  8. ^ Smith, Nathan (2006). "A census of the Carina Nebula - I. Cumulative energy input from massive stars". Monthly Notices of the Royal Astronomical Society. 367 (2): 763. arXiv:astro-ph/0601060free to read. Bibcode:2006MNRAS.367..763S. doi:10.1111/j.1365-2966.2006.10007.x. 
  9. ^ Tapia, Mauricio; Roth, Miguel; Vázquez, Rubén A.; Feinstein, Alejandro (2003). "Imaging study of NGC 3372, the Carina nebula - I. UBVRIJHK photometry of Tr 14, Tr 15, Tr 16 and Car I". Monthly Notices of the Royal Astronomical Society. 339: 44. Bibcode:2003MNRAS.339...44T. doi:10.1046/j.1365-8711.2003.06186.x.