Alpha Doradus information

Alpha Doradus
	Location of α Doradus (circled)
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Dorado
	A
Right ascension	04h 33m 59.778s
Declination	−55° 02′ 41.91″
Apparent magnitude (V)	3.27
	B
Right ascension	04h 33m 59.782s
Declination	−55° 02′ 42.39″
Apparent magnitude (V)	4.3
Characteristics
U−B color index	−0.35
B−V color index	−0.10
R−I color index	−0.09
A
Spectral type	A0IIIp
Variable type	ACV
B
Spectral type	B9IV
Astrometry
A
Radial velocity (Rv)	25.6 ± 0.9 km/s
Proper motion (μ)	RA: 58.06 mas/yr ; Dec.: 12.73 mas/yr
Parallax (π)	19.34 ± 0.31 mas
Distance	169 ± 3 ly ; (51.7 ± 0.8 pc)
B
Proper motion (μ)	RA: 42.83 mas/yr ; Dec.: 12.94 mas/yr
Orbit
Period (P)	12.1 y
Semi-major axis (a)	0.18″
Eccentricity (e)	0.80
Inclination (i)	31°
Longitude of the node (Ω)	140°
Periastron epoch (T)	B1986
Argument of periastron (ω); (secondary)	193°
Details
A
Mass	3.33 ± 0.10 M☉
Radius	3.5 ± 0.3 R☉
Luminosity (bolometric)	195 L☉
Surface gravity (log g)	4.02 ± 0.07 cgs
Temperature	11,588 K
Rotation	2.94 days
B
Mass	2.7 M☉
Radius	1.9 R☉
Luminosity (bolometric)	70 L☉
Temperature	12,200 K
Other designations
	α Dor, Alpha Doradus, Alpha Dor, CD−55 916, CPD−55 663, FK5 171, GC 5600, HD 29305, HIP 21281, HR 1465, SAO 233564, PPM 333592, CCDM J04340-5503AB, WDS 04340-5503AB
Database references
SIMBAD	data

Alpha Doradus, Latinized from α Doradus, 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]

A light curve for Alpha Doradus, plotted from *TESS* data^[10]^[11]

This is a binary star system^[9] with an overall apparent visual magnitude that varies between 3.26 and 3.30,^[4] making this one of the brightest binary stars.^[12] 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.^[2]^[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 displays an abnormally high abundance of silicon, making this an Si star.^[8]

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.^[2]^[13]

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Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Location of α Doradus (circled)
Constellation	Dorado
A
Right ascension	04^h 33^m 59.778^s
Declination	−55° 02′ 41.91″^[1]
Apparent magnitude (V)	3.27^[2]
B
Right ascension	04^h 33^m 59.782^s
Declination	−55° 02′ 42.39″^[3]
Apparent magnitude (V)	4.3^[2]
Characteristics
U−B color index	−0.35^[2]
B−V color index	−0.10^[2]
R−I color index	−0.09^[2]

A
Spectral type	A0IIIp^[2]
Variable type	ACV^[4]

B
Spectral type	B9IV^[2]
Astrometry
A
Radial velocity (R_v)	25.6 ± 0.9^[5] km/s
Proper motion (μ)	RA: 58.06^[1] mas/yr Dec.: 12.73^[1] mas/yr
Parallax (π)	19.34 ± 0.31 mas^[6]
Distance	169 ± 3 ly (51.7 ± 0.8 pc)
B
Proper motion (μ)	RA: 42.83^[3] mas/yr Dec.: 12.94^[3] mas/yr
Orbit^[7]
Period (P)	12.1 y
Semi-major axis (a)	0.18″
Eccentricity (e)	0.80
Inclination (i)	31°
Longitude of the node (Ω)	140°
Periastron epoch (T)	B1986
Argument of periastron (ω) (secondary)	193°
Details
A
Mass	3.33 ± 0.10^[8] `M`_☉
Radius	3.5 ± 0.3^[8] `R`_☉
Luminosity (bolometric)	195^[8] `L`_☉
Surface gravity (log g)	4.02 ± 0.07^[8] cgs
Temperature	11,588^[8] K
Rotation	2.94 days^[8]
B
Mass	2.7^[9] `M`_☉
Radius	1.9^[9] `R`_☉
Luminosity (bolometric)	70^[9] `L`_☉
Temperature	12,200^[9] K
Other designations
α Dor, Alpha Doradus, Alpha Dor, CD−55 916, CPD−55 663, FK5 171, GC 5600, HD 29305, HIP 21281, HR 1465, SAO 233564, PPM 333592, CCDM J04340-5503AB, WDS 04340-5503AB^[5]
Database references
SIMBAD	data

Alpha Doradus information

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