HD 4308

HD 4308 is a single^[2] star with an orbiting exoplanet in the southern constellation of Tucana.^[9] It has a yellow hue and is a challenge to view with the naked eye even under good seeing conditions, having an apparent visual magnitude of 6.54.^[2] This object is located at a distance of 72 light years, as determined from parallax measurements. It is a population II star^[2] and is considered to be a member of the thick disk.^[10] The star is receding from the Sun with a radial velocity of +95 km/s.^[6]

HD 4308

Observation data Epoch J2000      Equinox J2000
Constellation	Tucana
Right ascension	00h 44m 39.2675s[1]
Declination	–65° 38′ 58.2825″[1]
Apparent magnitude (V)	6.544±0.005[2]
Characteristics
Evolutionary stage	main sequence
Spectral type	G6VFe-0.9[3]
Apparent magnitude (B)	7.193[4]
Apparent magnitude (V)	6.552[4]
Apparent magnitude (J)	5.366±0.024[5]
Apparent magnitude (H)	5.101±0.016[5]
Apparent magnitude (K)	4.945±0.020[5]
Astrometry
Radial velocity (Rv)	+95.251±0.0162[6] km/s
Proper motion (μ)	RA: 157.504±0.041[1] mas/yr Dec.: −741.599±0.040[1] mas/yr
Parallax (π)	45.3930±0.0220 mas[1]
Distance	71.85 ± 0.03 ly (22.03 ± 0.01 pc)
Details[7]
Mass	0.95±0.05 M☉
Radius	1.04±0.03 R☉
Luminosity	1.03±0.01 L☉
Surface gravity (log g)	4.38±0.02 cgs
Temperature	5,714±61 K
Metallicity [Fe/H]	−0.35±0.07[2] dex
Rotational velocity (v sin i)	1.0±1.0[2] km/s
Age	1.6±4.0[7] or 10.0+0.5 −1.0[8] Gyr
Other designations
BD−27°223, GC 897, GJ 31.5, GJ 9028, HD 4308, HIP 3497, SAO 248244, PPM 352003, LFT 71, LHS 1139, LPM 40, LTT 416, TYC 8847-598-1, GCRV 50662, 2MASS J00443925-6538581[9]
Database references
SIMBAD	data
ARICNS	data

This is a Sun-like G-type main-sequence star with a stellar classification of G6VFe-0.9,^[3] where the suffix notation indicates an underabundance of iron in the spectrum. The age of the star is poorly constrained, with estimated ranging from 1.6^[7] billion years up to 10 billion.^[8] It has 95% of the mass of the Sun but 104% of the Sun's radius. The star is radiating nearly the same luminosity as the Sun from its photosphere at an effective temperature of 5,714 K.^[7]

Planetary system

In 2005, a low-mass planet was found in orbit around this star using the radial velocity method with the HARPS spectrograph. It is following a circular orbit close to its host star with a period of just 15.6 days. Unusual for a star with planets, HD 4308 has a metallicity lower than that of the Sun.^[11]

The HD 4308 planetary system^[11]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	>0.0442 MJ	0.115	15.56±0.02	0.00±0.01	—	—

See also

• HARPS spectrograph
• HD 4203
• HD 4208
• List of extrasolar planets