Alpha Doradus

Alpha Doradus
Diagram showing star positions and boundaries of the Dorado constellation and its surroundings


Location of α Doradus (circled)

Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
ConstellationDorado
ComponentAB
Right ascension04h 33m04h 33m
 59.778s59.782s
Declination−55° 02′[1]−55° 02′[2]
 41.91″42.39″
Apparent magnitude (V)3.8[3]4.3[3]
Characteristics
Spectral typeA0IIIp[3]B9IV[3]
U-B color index−0.35[3]
B-V color index−0.10[3]
R-I color index−0.09[3]
Variable typeACV[4]
Astrometry
Radial velocity (Rv)25.6 ± 0.9[5] km/s
Proper motion: 
RA (μα cos δ) 58.06[1] mas/yr 42.83[2] mas/yr 
Dec. (μδ) 12.73[1] mas/yr 12.94[2] mas/yr 
Parallax (π)19.34 ± 0.31[6] mas
Distance169 ± 3 ly
(51.7 ± 0.8 pc)
Details
Mass3.33 ± 0.10[7] M☉2.7[8] M☉
Radius3.5 ± 0.3[7] R☉1.9[8] R☉
Surface gravity (log g)4.02 ± 0.07[7]
Luminosity (bolometric)195[7] L☉70[8] L☉
Temperature11,588[7] K12,200[8] K
Rotation2.94 days[7]
Orbit[9]
Period (P)12.1 y
Semimajor axis (a)0.18″
Eccentricity (e)0.80
Inclination (i)31°
Longitude of node (Ω)140°
Periastron epoch (T)B1986
Argument of periastron (ω)
(secondary)		193°
Database references
SIMBADdata
Other designations
α Dor, Alpha Doradus, Alpha Dor, B 2092, CCDM J04340-5503AB, CD−55 916, CPD−55 663, FK5 171, GC 5600, HD 29305, HIP 21281, HR 1465, IDS 04318-5515 AB, PPM 333592, SAO 233564, WDS 04340-5503AB.[5]

Alpha Doradus (Alpha Dor, α Doradus, α Dor) is the brightest star in the southern constellation of Dorado. The distance to this system, as measured using the parallax method, is about 169 light-years (52 parsecs).[6]

This is a binary star system[8] with an overall apparent visual magnitude that varies between 3.26 and 3.30,[4] making this one of the brightest binary stars.[10] The system consists of a subgiant star of spectral type B revolving around a giant star with spectral type A in an eccentric orbit with a period of about 12 years.[3][9] The orbital separation varies from 2 astronomical units at periastron to 17.5 astronomical units at apastron. The primary, α Doradus A, is a chemically peculiar star whose atmosphere displays an abnormally high abundance of silicon, making this an Si star.[7]

Alpha Doradus has an optical companion, CCDM J04340-5503C, located 77 arcseconds away along a position angle of 94°. It has no physical relation to the other two stars.[3][11]

References

  1. ↑ 1.0 1.1 1.2 HIP 21281, record for component 1, Hipparcos catalogue; CDS ID I/239.
  2. ↑ 2.0 2.1 2.2 HIP 21281, record for component 2, Hipparcos catalogue; CDS ID I/239.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 HR 1465, 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 3, 2008.
  4. ↑ 4.0 4.1 alf 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 3, 2008.
  5. ↑ 5.0 5.1 V* alf Dor -- Variable Star, database entry, SIMBAD. Accessed on line September 3, 2008.
  6. ↑ 6.0 6.1 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.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 North, P. (June 1998), "Do SI stars undergo any rotational braking?", Astronomy and Astrophysics 334: 181–187, arXiv:astro-ph/9802286, Bibcode:1998A&A...334..181N
  8. ↑ 8.0 8.1 8.2 8.3 8.4 Kaler, James B., Alpha Dor, retrieved 2012-03-04
  9. ↑ 9.0 9.1 "Entry 04340-5503", Sixth Catalog of Orbits of Visual Binary Stars (United States Naval Observatory), retrieved 2008-09-03
  10. ↑ Heintz, W. D. (April 1984), "Note on the orbit of alpha Doradus", The Observatory 104: 88–89, Bibcode:1984Obs...104...88H
  11. ↑ "Entry 04340-5503, discoverer code HJ3668, components AB-C", The Washington Double Star Catalog (United States Naval Observatory), retrieved 2008-09-03