Beta Doradus

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 and 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]

β Doradus

Location of β Doradus (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Dorado
Right ascension	05h 33m 37.51253s[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

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 × 10²⁹ 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]