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Beta Doradus

Coordinates: Sky map 05h 33m 37.5177s, −62° 29′ 23.371″
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β Doradus
Diagram showing star positions and boundaries of the Dorado constellation and its surroundings
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 mas[6]
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 (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]

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. ^ a b c d 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. ^ a b c 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. ^ a b c d 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. ^ a b c 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 {{citation}}: Unknown parameter |book-title= ignored (help)
  6. ^ a b 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. ^ a b c 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. ^ a b Kaler, James B., "Beta Doradus", Stars, University of Illinois, retrieved 2012-01-01
  9. ^ a b 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. ^ a b 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. ^ a b 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, vol. 1135, pp. 192–197, arXiv:0902.3449, Bibcode:2009AIPC.1135..192E, doi:10.1063/1.3154048
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