R Doradus

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R Doradus
R Doradus ESO.jpg
Infrared interferometric 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]
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
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
Distance178 ± 10 ly
(55 ± 3 pc)
Mass1.2[6] M
Radius370 ± 50[7] R
Luminosity6,500 ± 1400[7] L
Temperature2,740 ± 190[7] K
Rotation340 days
Other designations
P Dor, R Dor, AAVSO 0435-62, CCDM J04368-6205A CD−62°175, CPC 20.1 1002, CPD−62°372, GCRV 2726, GSC 08880-01071, HD 29712, HIC 21479, HIP 21479, HR 1492, 2MASS J04364544-6204379, PPM 354226, SAO 249066, WDS J04368-6205A
Database references

R Doradus[8] (HD 29712[8] or P Doradus[8]) is the name of a Mira-variable red giant star in the far-southern constellation Dorado. (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,[9] it is currently believed to be the extrasolar star with the largest apparent size as viewed from Earth.[7] 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 bolometric luminosity is 6500 ± 1400 times that of the Sun.[10] With a near-infrared J band magnitude of −2.6,[4] only Betelgeuse at −2.9 is brighter.

R Doradus starmap.png
R Doradus exists on the constellation boundaries of Dorado and Reticulum, also close between the bright stars Canopus and Achernar.


  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.
  5. ^ Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W.
  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 e 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, doi:10.1093/mnras/286.4.957
  8. ^ a b c "* P Dor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2015-03-05.
  9. ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039
  10. ^ "The Biggest Star in the Sky" (Press release). European Southern Observatory. 1997-03-11. Retrieved 2017-12-24.

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