R Doradus

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R Doradus
R Doradus ESO.jpg
Infrared image of the star
Credit: ESO
Observation data
Epoch J2000      Equinox J2000
Constellation Dorado
Right ascension 04h 36m 45.59127s[1]
Declination −62° 04′ 37.7974″[1]
Apparent magnitude (V) 4.8 - 6.6[2]
5.40[3]
Characteristics
Spectral type M8IIIe
Apparent magnitude (J) -2.6[4]
Apparent magnitude (K) -4.2[4]
U−B color index +0.86[1]
B−V color index +1.58[1]
Variable type Mira variable
Astrometry
Radial velocity (Rv) +26.1[5] km/s
Proper motion (μ) RA: -69.36[1] mas/yr
Dec.: -75.78[1] mas/yr
Parallax (π) 18.31 ± 0.99[1] mas
Distance 178 ± 10 ly
(55 ± 3 pc)
Details
Mass 1.2[6] M
Radius 370 ± 50[7] R
Luminosity 6,500 ± 1400[7] L
Temperature 2,740 ± 190[7] K
Rotation 340 days
Other designations
P Dor, R Dor, CD-62 175, HD 29712, HIP 21479, HR 1492, GSC 08880-01071, SAO 249066.
Database references
SIMBAD data

R Doradus (also called HD 29712) is the name of a red giant Mira variable star in the far-southern constellation Dorado, although visually it appears more closely associated with the constellation Reticulum. Its distance from Earth is 178 ± 10 light-years (54.6 ± 3.1 parsecs).[1] Having a uniform disk diameter of 0.057 ± 0.005 arcsec,[8] it is currently believed to be the star with the second largest apparent size as viewed from Earth (right after the Sun). The estimated diameter of R Doradus is 515 ± 70 million km (3.46 AU) or 370 ± 50[7] times the diameter of the Sun. If placed at the centre of the Solar System, the orbit of Mars and most of the main asteroid belt would be contained within the star.

The visible magnitude of R Doradus varies between 4.8 and 6.6, which makes it usually just visible to the naked eye, but in the infrared it is one of the brightest stars in the sky and its total luminosity is 6500 ± 1400 times that of the Sun.[9] With a near-infrared J band magnitude of −2.6,[4] only Betelgeuse at −2.9 is brighter.

References[edit]

  1. ^ a b c d e f g h van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ "GCVS Query=R Dor". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2012-08-22. 
  3. ^ Nicolet, B. (1978). "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System". Astronomy and Astrophysics Supplement Series 34: 1–49. Bibcode:1978A&AS...34....1N. 
  4. ^ a b c Skrutskie, M. F.; Cutri, R. M.; Stiening, R.; Weinberg, M. D.; Schneider, S.; Carpenter, J. M.; Beichman, C.; Capps, R.; Chester, T.; Elias, J.; Huchra, J.; Liebert, J.; Lonsdale, C.; Monet, D. G.; Price, S.; Seitzer, P.; Jarrett, T.; Kirkpatrick, J. D.; Gizis, J. E.; Howard, E.; Evans, T.; Fowler, J.; Fullmer, L.; Hurt, R.; Light, R.; Kopan, E. L.; Marsh, K. A.; McCallon, H. L.; Tam, R.; Van Dyk, S. (2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal 131 (2): 1163. Bibcode:2006AJ....131.1163S. doi:10.1086/498708.  edit
  5. ^ Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953QB901.W495..... 
  6. ^ Jacob, A. P. et al. (March 2004), "Multiwavelength visibility measurements of Miras: observations of R Dor and R Leo with MAPPIT", Monthly Notices of the Royal Astronomical Society 349 (1): 303–312, Bibcode:2004MNRAS.349..303J, doi:10.1111/j.1365-2966.2004.07503.x 
  7. ^ a b c d Bedding, T. R. et al. (April 1997), "The angular diameter of R Doradus: a nearby Mira-like star", Monthly Notices of the Royal Astronomical Society 286 (4): 957–962, arXiv:astro-ph/9701021, Bibcode:1997MNRAS.286..957B 
  8. ^ Richichi; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039 
  9. ^ "The Biggest Star in the Sky" (Press release). European Southern Observatory. 1997-03-11. Retrieved 2006-09-05. 

External links[edit]