Astronomy:HD 34445
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[1] mas |
| 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 |
| Extrasolar Planets Encyclopaedia | data |
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]
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]
Planetary companions
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 M⊕ and 200.0 M⊕.[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, HD 34445 c & d were also found to likely be false positives, 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 | — | — |
See also
- HD 126614
- HD 24496
- HD 13931
- Gliese 179
- QS Virginis
- List of extrasolar planets
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. 3241295308714904960 Gaia DR2 record for this source at VizieR.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 Vogt, Steven S. et al. (2017). "A Six-planet System around the Star HD 34445". The Astronomical Journal 154 (5): 181. doi:10.3847/1538-3881/aa8b61. Bibcode: 2017AJ....154..181V.
- ↑ 3.0 3.1 Soubiran, C. et al. (2013). "The catalogue of radial velocity standard stars for Gaia. I. Pre-launch release". Astronomy and Astrophysics 552: A64. doi:10.1051/0004-6361/201220927. Bibcode: 2013A&A...552A..64S.
- ↑ 4.0 4.1 Sousa, S. G. et al. (November 2006). "Spectroscopic parameters for a sample of metal-rich solar-type stars". Astronomy and Astrophysics 458 (3): 873–880. doi:10.1051/0004-6361:20065658. Bibcode: 2006A&A...458..873S.
- ↑ 5.0 5.1 Howard, Andrew W. et al. (2010). "The California Planet Survey. I. Four New Giant Exoplanets". The Astrophysical Journal 721 (2): 1467–1481. doi:10.1088/0004-637X/721/2/1467. Bibcode: 2010ApJ...721.1467H.
- ↑ 6.0 6.1 Rosenthal, Lee J.; Fulton, Benjamin J.; Hirsch, Lea A.; Isaacson, Howard T.; Howard, Andrew W.; Dedrick, Cayla M.; Sherstyuk, Ilya A.; Blunt, Sarah C. et al. (2021). "The California Legacy Survey. I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades". The Astrophysical Journal Supplement Series 255 (1): 8. doi:10.3847/1538-4365/abe23c. Bibcode: 2021ApJS..255....8R.
- ↑ "HD 34445". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+34445.
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ Georgakarakos, Nikolaos; Dobbs-Dixon, Ian (September 2019). "Do the planets in the HD 34445 system really exist?". Monthly Notices of the Royal Astronomical Society 488 (3): 3818–3825. doi:10.1093/mnras/stz1945. Bibcode: 2019MNRAS.488.3818G.
Coordinates: 
05h 17m 40.9786s, +07° 21′ 12.036″
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