HD 9446
Star with a planetary system in the constellation Triangulum
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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]
| 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]
| 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 | — | — | — | — |