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α Doradus
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Dorado
Component A B
Right ascension 04h 33m 04h 33m
  59.778s 59.782s
Declination −55° 02′[1] −55° 02′[2]
  41.91″ 42.39″
Apparent magnitude (V) 3.8[3] 4.3[3]
Characteristics
Spectral type A0IIIp[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 type ACV[4]
Astrometry
Radial velocity (Rv) 25.6 ± 0.9[5] km/s
Proper motion:  
RA α cos δ)  58.06[1] mas/yr  42.83[2] mas/yr 
Dec. δ)  12.73[1] mas/yr  12.94[2] mas/yr 
Parallax (π) 18.56 ± 0.46[5] mas
Distance 176 ± 4 ly
(54 ± 1 pc)
Details
Mass 3.0[6] M 2.7[6] M
Radius 2.8[6] R 1.9[6] R
Luminosity (bolometric) 160[6] L 70[6] L
Temperature 12200[6] K 12200[6] K
Orbit[7]
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
SIMBAD data
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 constellation of Dorado. It is actually a binary system of two stars,[6] and has an overall apparent visual magnitude which varies between 3.26 and 3.30.[4] The binary star consists of a subgiant with spectral type B revolving around a giant star with spectral type A in an eccentric orbit with a period of about 12 years.[3][7] 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 has a high concentration of silicon.[6]

Visual companion

CCDM J04340-5503C
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Dorado
Right ascension 04h 34m 08.7251s[8]
Declination −55° 02′ 47.754″[8]
Apparent magnitude (V) 10.1[8]
Characteristics
B-V color index 1.2[8]
Astrometry
Proper motion (μ) RA: 63.50[8] mas/yr
Dec.: 144.30[8] mas/yr
Position (relative to α Doradus AB)
Epoch of observation 1999
Angular distance 77.2 [9]
Position angle 94° [9]
Other designations
HJ 3668C, CD−55 917, CPD−55 664, IDS 04318-5515 C, PPM 333595, SAO 233565, WDS 04340-5503C.[8][9]
Database references
SIMBAD data

The binary star has an optical visual companion, CCDM J04340-5503C, located 77 arcseconds away. It has no physical relation to the other two stars.[9][3]

References

  1. ^ a b c HIP 21281, record for component 1, Hipparcos catalogue; CDS ID I/239.
  2. ^ a b c HIP 21281, record for component 2, Hipparcos catalogue; CDS ID I/239.
  3. ^ a b c d e f g h i 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. ^ a b 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. ^ a b c V* alf Dor -- Variable Star, database entry, SIMBAD. Accessed on line September 3, 2008.
  6. ^ a b c d e f g h i j Alpha Dor, Jim Kaler, Stars. Accessed on line September 3, 2008.
  7. ^ a b Entry 04340-5503, Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory. Accessed on line September 3, 2008.
  8. ^ a b c d e f g CD-55 917 -- Star in double system, database entry, SIMBAD. Accessed on line September 3, 2008.
  9. ^ a b c d Entry 04340-5503, discoverer code HJ3668, components AB-C, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line September 3, 2008.
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