Theta Doradus

Theta Doradus, Latinized from θ Doradus, is a solitary^[10] star in the southern constellation of Dorado. Based upon an annual parallax shift of 6.64 mas as seen from Earth, it is located around 540 light years from the Sun. With an apparent visual magnitude of +4.82,^[2] the star is bright enough to be faintly visible to the naked eye.

Theta Doradus

Location of θ Doradus (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Dorado
Right ascension	05h 13m 45.45571s[1]
Declination	−67° 11′ 06.9298″[1]
Apparent magnitude (V)	+4.82[2]
Characteristics
Spectral type	K2/3 III CNIb/II[3]
U−B color index	+1.38[2]
B−V color index	+1.28[2]
Astrometry
Radial velocity (Rv)	+10.5±0.8[4] km/s
Proper motion (μ)	RA: +18.485[1] mas/yr Dec.: +38.123[1] mas/yr
Parallax (π)	6.0186±0.1209 mas[1]
Distance	540 ± 10 ly (166 ± 3 pc)
Absolute magnitude (MV)	−0.56[5]
Details
Mass	2.23[6] M☉
Radius	35.6[1] R☉
Luminosity	427[6] L☉
Surface gravity (log g)	2.5[7] cgs
Temperature	4,320±59[6] K
Metallicity [Fe/H]	−0.16[5] dex
Rotational velocity (v sin i)	2.2[8] km/s
Age	1.17[6] Gyr
Other designations
θ Dor, Theta Dor, CPD−67°401, FK5 196, HD 34649, HIP 24372, HR 1744, SAO 249225[9]
Database references
SIMBAD	data

This is an evolved orange-hued K-type giant star with a stellar classification of K2/3 III CNIb/II,^[3] where the suffix indicates it is a CN star, a cool giant showing unusually strong CN bands in its spectrum.^[11] With an age of around 1.17 billion years, it has an estimated 2.23 times the mass of the Sun and has expanded to about 36 times the Sun's radius. It is radiating 427 times the solar luminosity from its photosphere at an effective temperature of 4,320 K.^[6]

Naming

In the Chinese astronomical adaptation of the European southern hemisphere constellations, 夾白 (Jiá Bái), meaning White Patches Attached, refers to an asterism consisting of θ Doradus and α Reticuli. Consequently, θ Doradus itself is known as 夾白一 (Jiá Bái yī, English: the First Star of White Patches Attached.)^[12]