R Doradus

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**R Doradus A / B / C**
Observation data Epoch J2000
R Doradus
Constellation (pronunciation)	Dorado
Right ascension	04h 36m 45.5923s
Declination	-62° 04' 37.756"'
Apparent magnitude (V)	5.73 / 11.9 / 11
Characteristics
Spectral type	M8III
U-B color index	0.86
B-V color index	1.58
Variable type	Mira, pulsating variable star
Astrometry
Radial velocity (R_v)	26.1 km/s
Proper motion (μ)	RA: -68.46 mas/yr Dec.: -71.22 mas/yr
Parallax (π)	16.02 ± 0.69 mas
Distance	204 ± 9 ly (62 ± 3 pc)
Absolute magnitude (M_V)	6.97
Visual binary orbit
Companion	R Doradus B
Semimajor axis (a)	38.4"
Inclination (i)	13°
Visual binary orbit
Companion	R Doradus C
Semimajor axis (a)	34.5"
Inclination (i)	124°
Details
Mass	? M_☉
Radius	185 ± 25 R_☉
Surface gravity (log g)	?
Luminosity	6500 ± 1400 L_☉
Temperature	2740 ± 190 K
Metallicity	?
Rotation	340 days
Age	? years
Other designations
R Dor, GC 5661, HR 1492, P Dor, GCRV 2726, IDS 04356-6216 A, TYC 8880-1071-1, CCDM J04368-6205A, IRAS 04361-6210, UBV M 10273, CD-62° 175, GSC 08880-01071, JP11 913, CPC 20.1 1002, HD 29712, N30 980, [[ CPD]]-62° 372, HIC 21479, PPM 354226, AAVSO 0435-62, CSI-62° 372 41, HIP 21479, SAO 249066, HJ 3679.
Database references
SIMBAD	data

R Doradus (also called HD 29712) is the name of a red giant Mira variable star in the far-southern constellation Dorado, although visually it appears more closely associated with the constellation Reticulum. Its distance from Earth is 200 ± 25 light-years. Having an angular diameter of 0.057 ± 0.005 arcsec, and given its distance, it is currently believed to be the star with the largest apparent size as viewed from Earth (except for the sun). The diameter of R Doradus is 515 ± 70 million km or 370 ± 50 times the diameter of the Sun. If placed at the center of the Solar System, the orbit of Mars would be entirely contained within the star.

The visible magnitude of R Doradus varies between 4.8 and 6.6, which makes it just about visible to the naked eye, but in the infrared it is one of the brightest stars in the sky. Thus, even though its mass is about one solar mass, its total luminousity is 6500 ± 1400 times that of the sun.^[1]