Astronomy:Beta Doradus

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Short description: Variable star in the constellation Dorado
β Doradus
Dorado constellation map.svg
Red circle.svg
Location of β Doradus (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Dorado
Right ascension  05h 33m 37.51253s[1]
Declination −62° 29′ 23.3231″[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: +0.800[1] mas/yr
Dec.: +9.458[1] mas/yr
Parallax (π)3.1119 ± 0.2845[1] mas
Distance1,050 ± 100 ly
(320 ± 30 pc)
Absolute magnitude (MV)−3.91±0.11[6]
Details
Mass7.7±0.2[7] M☉
Radius67.8±0.7[8] R☉
Luminosity3,200[6] L☉
Surface gravity (log g)1.3[9] cgs
Temperature5,445[6] K
Metallicity [Fe/H]–0.13[9] dex
Rotational velocity (v sin i)0[3] km/s
Age42.5±2.7[7] Myr
Other designations
β Dor, Beta Doradus, Beta Dor, CD−62 214, CPD−62 487, FK5 212, GC 6944, HD 37350, HIP 26069, HR 1922, SAO 249311, PPM 354837[10]
Database references
SIMBADdata

Beta Doradus, Latinized from β Doradus, is the second brightest star in the southern constellation of Dorado.[11] It has a variable apparent visual magnitude,[4] and is 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.[12]

A light curve for Beta Doradus, plotted from TESS data[13]

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.[14] 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.[14] 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.[8] 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.[15]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 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. ↑ 3.0 3.1 3.2 3.3 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. ↑ 4.0 4.1 4.2 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", Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 (University of Toronto: International Astronomical Union) 30: p. 57, Bibcode: 1967IAUS...30...57E 
  6. ↑ 6.0 6.1 6.2 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, doi:10.1007/s10509-009-0258-5, Bibcode: 2010Ap&SS.326..219T 
  7. ↑ 7.0 7.1 Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society 410 (1): 190–200, doi:10.1111/j.1365-2966.2010.17434.x, Bibcode: 2011MNRAS.410..190T 
  8. ↑ 8.0 8.1 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, doi:10.1046/j.1365-8711.1998.01670.x, Bibcode: 1998MNRAS.298..594T 
  9. ↑ 9.0 9.1 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, doi:10.1051/0004-6361:20065661, Bibcode: 2008A&A...488..731R 
  10. ↑ "V* bet Dor". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V%2A+bet+Dor. 
  11. ↑ Kaler, James B., "Beta Doradus", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/betador.html, retrieved 2012-01-01 
  12. ↑ McArthur, Barbara E. et al. (May 2011), "Astrometry with the Hubble Space Telescope: Trigonometric Parallaxes of Selected Hyads", The Astronomical Journal 141 (5): 172, doi:10.1088/0004-6256/141/5/172, Bibcode: 2011AJ....141..172M 
  13. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  14. ↑ 14.0 14.1 Plachy, E. et al. (2021), "TESS Observations of Cepheid Stars: First Light Results", The Astrophysical Journal Supplement Series 253 (1): 11, doi:10.3847/1538-4365/abd4e3, Bibcode: 2021ApJS..253...11P 
  15. ↑ 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, doi:10.1063/1.3154048, Bibcode: 2009AIPC.1135..192E 

Coordinates: Sky map 05h 33m 37.5177s, −62° 29′ 23.371″



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