Beta Doradus

Beta Doradus (Beta Dor, β Doradus, β Dor) is the second brightest star in the southern constellation of Dorado.[8] It has a variable apparent visual magnitude,[4] visible to the naked eye from the southern hemisphere. Based upon parallax measurements with the Hubble Space Telescope, it is located at a distance of 1,040 light-years (320 parsecs) from Earth.[6]

β Doradus
Location of β Doradus (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Dorado
Right ascension 05h 33m 37.51729s[1]
Declination −62° 29′ 23.3692″[1]
Apparent magnitude (V) 3.46 to 4.08[2]
Characteristics
Spectral type F4-G4Ia-II[3]
U−B color index +0.55[3]
B−V color index +0.70[4]
R−I color index +0.48[4]
Variable type δ Cephei[2]
Astrometry
Radial velocity (Rv)+7.2[5] km/s
Proper motion (μ) RA: +0.79[1] mas/yr
Dec.: +12.74[1] mas/yr
Parallax (π)3.14 ± 0.16[6] mas
Distance1,040 ± 50 ly
(320 ± 20 pc)
Absolute magnitude (MV)−3.91 ± 0.11[7]
Details
Mass6.5[8] M☉
Radius67.8 ± 0.7[9] R☉
Luminosity3,200[7] L☉
Surface gravity (log g)1.3[10] cgs
Temperature5,445[7] K
Metallicity [Fe/H]–0.13[10] dex
Rotational velocity (v sin i)0[3] km/s
Other designations
β Dor, Beta Doradus, Beta Dor, CD−62 214, CPD−62 487, FK5 212, GC 6944, HD 37350, HIP 26069, HR 1922, PPM 354837, SAO 249311.[11]
Database references
SIMBADdata

Beta Doradus is a Cepheid variable that regularly changes magnitude from a low of 4.08 to a high of 3.46[2] over a period of 9.84318 days.[12] The light curve of this magnitude change follows a nearly regular saw-tooth pattern, with average amplitude variations period to period about 0.005 magnitude from average amplitude of 0.62 magnitude.[12] During each radial pulsation cycle, the radius of the star varies by ±3.9 times the Sun's radius around a mean of 67.8.[9] Its spectral type and luminosity class are likewise variable, from F-type to G-type and from a supergiant to a bright giant.[3]

Far ultraviolet emissions have been detected from this star with the Far Ultraviolet Spectroscopic Explorer, while X-ray emissions were detected with the XMM-Newton space telescope. The X-ray luminosity is about 1 × 1029 erg/s and the emission varies with the pulsation period, suggesting a connection with the pulsation process. The peak X-ray emissions are in the 0.6–0.8 keV energy range, which occurs for plasmas with temperatures of 7–10 million K.[13]

References
  1. 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. bet Dor, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line September 9, 2008.
  3. HR 1922, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 9, 2008.
  4. Turner, D. G. (April 1980), "The reddening of Beta Doradus", Journal of the Royal Astronomical Society of Canada, 74: 64–69, Bibcode:1980JRASC..74...64T
  5. Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), The Revision of the General Catalogue of Radial Velocities, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E
  6. McArthur, Barbara E.; et al. (May 2011), "Astrometry with the Hubble Space Telescope: Trigonometric Parallaxes of Selected Hyads", The Astronomical Journal, 141 (5): 172, arXiv:1103.2094, Bibcode:2011AJ....141..172M, doi:10.1088/0004-6256/141/5/172
  7. Turner, David G. (April 2010), "The PL calibration for Milky Way Cepheids and its implications for the distance scale", Astrophysics and Space Science, 326 (2): 219–231, arXiv:0912.4864, Bibcode:2010Ap&SS.326..219T, doi:10.1007/s10509-009-0258-5
  8. Kaler, James B., "Beta Doradus", Stars, University of Illinois, retrieved 2012-01-01
  9. Taylor, Melinda M.; Booth, Andrew J. (August 1998), "The bright southern Cepheid beta Doradus: the radial velocity curve, distance and size", Monthly Notices of the Royal Astronomical Society, 298 (2): 594–600, Bibcode:1998MNRAS.298..594T, doi:10.1046/j.1365-8711.1998.01670.x
  10. Romaniello, M.; et al. (September 2008), "The influence of chemical composition on the properties of Cepheid stars. II. The iron content", Astronomy and Astrophysics, 488 (2): 731–747, arXiv:0807.1196, Bibcode:2008A&A...488..731R, doi:10.1051/0004-6361:20065661
  11. "V* bet Dor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 9, 2008.
  12. TESS observations of Cepheid stars: first light results, 2020, arXiv:2012.09709
  13. Engle, Scott G.; et al. (May 2009), "The Secret XUV Lives of Cepheids: FUV/X-ray observations of Polaris and β Dor", Future Directions in Ultraviolet Spectroscopy: A Conference Inspired by the Accomplishments of the Far Ultraviolet Spectroscopic Explorer Mission, AIP Conference Proceedings, 1135, pp. 192–197, arXiv:0902.3449, Bibcode:2009AIPC.1135..192E, doi:10.1063/1.3154048

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