HD 9446

HD 9446 is a star located about 164^[1] light-years away in the constellation of Triangulum, near the southwestern constellation border with Pisces. This object can be viewed with binoculars or a telescope, but it is too faint to be seen with the naked eye at its apparent visual magnitude of 8.35.^[2] It is drifting further away from the Sun with a radial velocity of +21 km/s.^[2]

HD 9446

Observation data Epoch J2000      Equinox J2000
Constellation	Triangulum
Right ascension	01h 33m 20.1847s[1]
Declination	+29° 15′ 54.539″[1]
Apparent magnitude (V)	8.35[2]
Characteristics
Spectral type	G5V[3]
B−V color index	+0.680±0.015[2]
Astrometry
Radial velocity (Rv)	+21.2±3.1[2] km/s
Proper motion (μ)	RA: 190.343(28) mas/yr Dec.: −53.675(31) mas/yr
Parallax (π)	19.9200±0.0413 mas[1]
Distance	163.7 ± 0.3 ly (50.2 ± 0.1 pc)
Absolute magnitude (MV)	4.76[2]
Details
Mass	1.07±0.18 [4] M☉
Radius	0.984±0.01 [4] R☉
Luminosity	1.1[3] L☉
Surface gravity (log g)	4.53±0.16[3] cgs
Temperature	5,793±22[3] K
Metallicity [Fe/H]	0.09±0.05[3] dex
Rotational velocity (v sin i)	4±1 km/s
Age	2.0±1.5[5] Gyr
Other designations
BD+28°253, HD 9446, HIP 7245, SAO 74788[6]
Database references
SIMBAD	data
Exoplanet Archive	data

This object is a G-type main sequence star with a stellar classification of G5V.^[3] The physical properties this star appear similar to the Sun, making it a candidate solar analog. However, the measured abundance of elements with more mass than helium is outside the accepted range.^[7] It is roughly two billion years in age and has an active chromosphere. The amount of activity measured in the chromosphere corresponds to a star with a rotation period of about 10 days.^[3]

On 5 January 2010, scientists announced the discovery of two planets orbiting around HD 9446.^[3] In addition, another exoplanet candidate is detected by astrometry in 2024.^[8]

The HD 9446 planetary system^[3][4][8]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥ 0.687±0.0056 MJ	0.1892±0.0065	30.0608+0.0034 −0.0033	0.20±0.06	—	—
c	≥ 1.71±0.13 MJ	0.646±0.022	189.6±0.13	0.06±0.06	—	—
d (unconfirmed)	1.5 MJ	7.0	—	—	—	—

See also

• List of extrasolar planets