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HD 34445 is a star in the equatorial constellation of Orion. With an apparent visual magnitude of 7.31,[2] it is a 7th magnitude star that is too dim to be readily visible to the naked eye. The system is located at a distance of 150.5 light years from the Sun based on parallax measurements, but is drifting closer with a high radial velocity of −79 km/s.[3] It is expected to draw as close as 57.5 light-years in ~492,000 years.[8]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 17m 40.9804s[1] |
| Declination | +07° 21′ 12.0548″[1] |
| Apparent magnitude (V) | 7.31±0.03[2] |
| Characteristics | |
| Spectral type | G0 V[2] |
| B−V color index | 0.661 ± 0.015[2] |
| Astrometry | |
| Radial velocity (Rv) | −78.906±0.0082[3] km/s |
| Proper motion (μ) | RA: −0.811±0.076[1] mas/yr Dec.: −146.997±0.061[1] mas/yr |
| Parallax (π) | 21.6675 ± 0.0464 mas[1] |
| Distance | 150.5 ± 0.3 ly (46.15 ± 0.10 pc) |
| Absolute magnitude (MV) | 4.04±0.10[2] |
| Details | |
| Mass | 1.07±0.02[2] M☉ |
| Radius | 1.38±0.08[2] R☉ |
| Luminosity | 2.01 ± 0.2[2] L☉ |
| Surface gravity (log g) | 4.21 ± 0.08[2] cgs |
| Temperature | 5836 ± 44[2] K |
| Metallicity [Fe/H] | +0.14±0.04 dex[2] +0.24±0.04[4] dex |
| Rotation | ~22 d,[5] ~52 d[6] |
| Rotational velocity (v sin i) | 2.7±0.5[2] km/s |
| Age | 8.5±2.0[2] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
This is an ordinary G-type main-sequence star with a stellar classification of G0 V,[2] which means it is a Sun-like star that is generating energy through core hydrogen fusion. It is considered a metal-rich star,[4] showing a much higher metallicity compared to the Sun. Despite this it is an older star and chromospherically quiet, lying about 0.8 magnitudes above the main sequence. This star is larger, hotter, brighter, and more massive than the Sun. It is spinning with a projected rotational velocity of ~3 km/s, giving it a rotation period of around 22 days.[2]
In 2004, a gas giant was found in orbit around the star, but it was not until 2009 that this planet was confirmed.[5] In 2017, five more planets were found.[2] All have minimum masses significantly greater than that of the Earth, between 16.8 ME and 200.0 ME.[2] The system as configured appears to be dynamically stable.[9]
A 2021 study was only able to confirm HD 34445 b as a planet. HD 34445 e was found to likely be an artifact of the stellar rotation, as its orbital period closely matched to the rotation period of the star, HD 34445 c & d were also found to likely be false positives having orbital periods of around 1⁄4 and 1⁄3 of a year, and HD 34445 f was not detected.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| e (unconfirmed) | ≥0.0529 ± 0.0089 MJ | 0.2687 ± 0.0019 | 49.175 ± 0.045 | 0.090 ± 0.062 | — | — |
| d (unconfirmed) | ≥0.097 ± 0.13 MJ | 0.4817 ± 0.0033 | 117.87 ± 0.18 | 0.027 ± 0.051 | — | — |
| c (unconfirmed) | ≥0.168 ± 0.016 MJ | 0.7181 ± 0.0049 | 214.67 ± 0.45 | 0.036 ± 0.071 | — | — |
| f (unconfirmed) | ≥0.119 ± 0.021 MJ | 1.543 ± 0.016 | 676.8 ± 7.9 | 0.031 ± 0.057 | — | — |
| b | ≥0.629 ± 0.028 MJ | 2.075 ± 0.016 | 1056.7 ± 4.7 | 0.014 ± 0.035 | — | — |
| g (unconfirmed) | ≥0.38 ± 0.13 MJ | 6.36 ± 1.02 | 5700 ± 1500 | 0.032 ± 0.080 | — | — |
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