Beta Doradus

β Doradus

Location of β Doradus (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Dorado
Right ascension	05^h 33^m 37.51253^s[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)	3.14 ± 0.16 mas[6]
Distance	1,040 ± 50 ly (320 ± 20 pc)
Absolute magnitude (MV)	−3.91±0.11[7]
Details
Mass	7.7±0.2[8] M☉
Radius	67.8±0.7[9] R☉
Luminosity	3,200[7] L☉
Surface gravity (log g)	1.3[10] cgs
Temperature	5,445[7] K
Metallicity [Fe/H]	–0.13[10] dex
Rotational velocity (v sin i)	0[3] km/s
Age	42.5±2.7[8] 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[11]
Database references
SIMBAD	data

Beta Doradus, Latinized from β Doradus, is the second brightest star in the southern constellation of Dorado.[12] It is a Classical Cepheid variable, with an apparent magnitude that varies between 3.46 to 4.08.[2] 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]

Characteristics

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 R_☉ around a mean of 67.8 R_☉.[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 × 10^29 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. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
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 Archived 2017-06-20 at the Wayback Machine, 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", Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, vol. 30, University of Toronto: International Astronomical Union, p. 57, Bibcode:1967IAUS...30...57E
6. Benedict, G. Fritz; et al. (April 2007), "Hubble Space Telescope Fine Guidance Sensor Parallaxes of Galactic Cepheid Variable Stars: Period-Luminosity Relations", Astronomical Journal, 133 (4): 1810–1827, arXiv:astro-ph/0612465, Bibcode:2007AJ....133.1810B, doi:10.1086/511980, S2CID 16384267.
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, S2CID 119264970
8. 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, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873
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, S2CID 16955805
11. "V* bet Dor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 9, 2008.
12. Kaler, James B., "Beta Doradus", Stars, University of Illinois, retrieved 2012-01-01
13. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
14. Plachy, E.; et al. (2021), "TESS Observations of Cepheid Stars: First Light Results", The Astrophysical Journal Supplement Series, 253 (1): 11, arXiv:2012.09709, Bibcode:2021ApJS..253...11P, doi:10.3847/1538-4365/abd4e3, S2CID 229297708
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, vol. 1135, pp. 192–197, arXiv:0902.3449, Bibcode:2009AIPC.1135..192E, doi:10.1063/1.3154048, S2CID 16635363