HR Carinae

From Wikipedia, the free encyclopedia
Jump to: navigation, search
HR Car

Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Carina
Right ascension 10h 22m 53.84074s
Declination −59° 37′ 28.3774″
Apparent magnitude (V) 7.57 (variable)
Characteristics
Spectral type LBV
U−B color index 0.73
B−V color index 0.94
Variable type LBV
Astrometry
Proper motion (μ) RA: -6.87 mas/yr
Dec.: +2.33 mas/yr
Parallax (π) 1.69 ± 0.82 mas
Distance 5.2k[1] pc
Absolute magnitude (MV) -8.4[2]
Details
Mass 25[3] M
Radius 100[2] R
Luminosity 416,000-790,000[1] L
Temperature 7,900-21,900 (variable)[1] K
Rotational velocity (v sin i) 150[3] km/s
Other designations
HR Car, HD 90177, HIP 50843, SAO 238005.
Database references
SIMBAD data

HR Carinae is a supergiant, luminous blue variable star located in the constellation Carina. It is surrounded by a vast nebula of ejected nuclear-processed material because this star has a multiple shell expanding atmosphere. This star is among the most luminous stars in our galaxy. It has very broad emission wings on the Balmer lines, reminiscent from the broad lines observed in the spectra of O and Wolf-Rayet stars. A distance 5 kpc and a bolometric magnitude of -9.4 put HR Car among the most luminous stars of the galaxy.

Brightness variation[edit]

HR Carinae undergoes spectral variations apparently correlated with the light variations similarly to other luminous blue variables. It has undergone several outbursts during which the visual brightness increases and the temperature drops, but the bolometric luminosity remains approximately constant. The visual brightness increased erratically but consistently during the later decades of the 20th century to a record peak of mag 6.8, then dropped straight to a record minimum of mag 8.8 by 2010.[4]

Characteristics[edit]

HR Carinae has a temperature around 21,000K when quiescent and the spectrum is of an early B hypergiant,[5] but in outburst it cools to below 8,000K.

HR Carinae is a lot like Eta Carinae, both luminous blue variables, and both surrounded by ejected material. HR Carinae is also likely to be a binary system with a similar separation, period, and ratio of component sizes to Eta Carinae.[6] However, the Eta Carinae system is more massive and more luminous.

References[edit]

  1. ^ a b c Nazé, Y.; Rauw, G.; Hutsemékers, D. (2012). "The first X-ray survey of Galactic luminous blue variables". Astronomy & Astrophysics 538: A47. arXiv:1111.6375. Bibcode:2012A&A...538A..47N. doi:10.1051/0004-6361/201118040.  edit
  2. ^ a b Hutsemekers, D. & van Drom, E. (1991). "HR Carinae - A luminous blue variable surrounded by an arc-shaped nebula". Astronomy and Astrophysics 281: 141–149. Bibcode:1991A&A...248..141H. 
  3. ^ a b Groh, J. H. (2009). "BONA FIDE, STRONG-VARIABLE GALACTIC LUMINOUS BLUE VARIABLE STARS ARE FAST ROTATORS: DETECTION OF A HIGH ROTATIONAL VELOCITY IN HR CARINAE". The Astrophysical Journal 705 (1): L25–L30. doi:10.1088/0004-637X/705/1/L25.  edit
  4. ^ "AAVSO - query form". result for HR Carinae. Retrieved 12 August 2014. 
  5. ^ Clampin, M. (1995). "High Resolution Coronographic Imaging and Spectropolarimetry of the HR Carinae Nebula". The Astronomical Journal 110: 251. doi:10.1086/117514.  edit
  6. ^ Rivinius, Th.; Boffin, H. M. J.; de Wit, W. J.; Mehner, A.; Martayan, Ch.; Guieu, S.; Le Bouquin, J. -B. (2014). "Binarity of the LBV HR Car". arXiv:1408.0511v1 [astro-ph.SR].