# HD 37124

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**HD 37124** is a [star](/source/Star) in the [equatorial](/source/Celestial_equator) [constellation](/source/Constellation) of [Taurus](/source/Taurus_(constellation)) (the Bull), positioned about a half degree to the SSW of the bright star [Zeta Tauri](/source/Zeta_Tauri).[1] The [apparent visual magnitude](/source/Apparent_visual_magnitude) of this star is 7.68,[2] which is too dim to be visible to the naked eye. It is located at a distance of 103 [light years](/source/Light_year) from the [Sun](/source/Sun) based on [parallax](/source/Stellar_parallax), but is drifting closer with a [radial velocity](/source/Radial_velocity) of −23 km/s.[2] Three [extrasolar planets](/source/Extrasolar_planet) have been found to orbit the star.

The [stellar classification](/source/Stellar_classification) of HD 37124 is G4IV-V, showing a spectrum with blended traits of a [main sequence](/source/Main_sequence) star and a more [evolved](/source/Stellar_evolution) [subgiant star](/source/Subgiant_star). It is a [quiet star](/source/Magnetic_activity) with a low [activity index](/source/Chromospheric_activity_index).[3] This star is smaller than the Sun, with 81–92% of the [mass of the Sun](/source/Mass_of_the_Sun) and around 92% of the [Sun's radius](/source/Sun's_radius). It is an older, [thick disk](/source/Thick_disk)[4] star with an age of around 11 billion years, and is spinning with a [projected rotational velocity](/source/Projected_rotational_velocity) of 3.6 km/s.[5] The [metallicity](/source/Metallicity) of the star, what astronomers term the abundance of heavier elements, is much lower than in the Sun with an iron abundance of 35–41%. It is radiating 77–84% of the [Sun's luminosity](/source/Sun's_luminosity) from its [photosphere](/source/Photosphere) at an [effective temperature](/source/Effective_temperature) of 5,763 K.

## Planetary system

As of 2011, three [extrasolar planets](/source/Extrasolar_planet) have been found to orbit the star. The first planet, [HD 37124 b](/source/HD_37124_b), was detected by the [Keck observatory](/source/Keck_observatory) through the [radial velocity](/source/Radial_velocity) method; its discovery was announced on 1 November 1999.[6][7] HD 37124 b was discovered orbiting its parent star around the inner edge of the habitable zone, causing the planet to have a somewhat similar [insolation](/source/Insolation) to that of [Venus](/source/Venus). A second planet became apparent by 2003, thought to orbit in a 1940 days on an eccentric orbit,[8] but this was subsequently found to be unstable.[9] Solving this, a three-planet solution was announced in 2005:[10] this contained a second planet ([HD 37124 c](/source/HD_37124_c)) orbiting at the outer edge of the habitable zone with an insolation similar to that of [Mars](/source/Mars), and a third planet, ([HD 37124 d](/source/HD_37124_d)). While not obviously in any [orbital resonances](/source/Orbital_resonance) in 2005, an updated solution announced in 2011 found planets c and d to likely be in a 2:1 resonance.[11]

## See also

- [Upsilon Andromedae](/source/Upsilon_Andromedae)
- [HIP 14810](/source/HIP_14810)

## References

1. Sinnott, Roger W. & Perryman, Michael A. C. (1997). *Millennium Star Atlas*. Vol. 1. Sky Publishing Corporation and the European Space Agency. p. 182. ISBN 0-933346-84-0.

1. Goździewski, Krzysztof et al. (July 2006). "Orbital Configurations and Dynamical Stability of Multiplanet Systems around Sun-like Stars HD 202206, 14 Herculis, HD 37124, and HD 108874". *The Astrophysical Journal*. **645** (1): 688–703. [arXiv:astro-ph/0511463](https://arxiv.org/abs/astro-ph/0511463). [Bibcode:2006ApJ...645..688G](https://ui.adsabs.harvard.edu/abs/2006ApJ...645..688G). [doi:10.1086/504030](https://doi.org/10.1086/504030). [S2CID 15012577](https://api.semanticscholar.org/CorpusID:15012577)

1. Gonzalez, Guillermo (October 2009). "Stars with planets and the thick disc". *Monthly Notices of the Royal Astronomical Society: Letters*. **399** (1): L103–L107. [Bibcode:2009MNRAS.399L.103G](https://ui.adsabs.harvard.edu/abs/2009MNRAS.399L.103G). [doi:10.1111/j.1745-3933.2009.00734.x](https://doi.org/10.1111/j.1745-3933.2009.00734.x)

1. Luck, R. Earle (January 2017). "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants". *The Astronomical Journal*. **153** (1): 19. [arXiv:1611.02897](https://arxiv.org/abs/1611.02897). [Bibcode:2017AJ....153...21L](https://ui.adsabs.harvard.edu/abs/2017AJ....153...21L). [doi:10.3847/1538-3881/153/1/21](https://doi.org/10.3847/1538-3881/153/1/21). [S2CID 119511744](https://api.semanticscholar.org/CorpusID:119511744). 21.

1. ["Astronomers discover six new planets orbiting nearby stars"](https://web.archive.org/web/20181202013046/http://keckobservatory.org/astronomers_discover_six_new_planets_orbiting_nearby_stars/). Kamuela, Hawaii: W. M. Keck Observatory. November 1, 1999. Archived from [the original](http://www.keckobservatory.org/astronomers_discover_six_new_planets_orbiting_nearby_stars/) on December 2, 2018. Retrieved December 19, 2017.

1. Vogt, Steven S. et al. (2000). "Six New Planets from the Keck Precision Velocity Survey". *The Astrophysical Journal*. **536** (2): 902–914. [arXiv:astro-ph/9911506](https://arxiv.org/abs/astro-ph/9911506). [Bibcode:2000ApJ...536..902V](https://ui.adsabs.harvard.edu/abs/2000ApJ...536..902V). [doi:10.1086/308981](https://doi.org/10.1086/308981). [S2CID 119375519](https://api.semanticscholar.org/CorpusID:119375519)

1. Butler, R. Paul et al. (2003). "Seven New Keck Planets Orbiting G and K Dwarfs". *The Astrophysical Journal*. **582** (1): 455–466. [Bibcode:2003ApJ...582..455B](https://ui.adsabs.harvard.edu/abs/2003ApJ...582..455B). [CiteSeerX 10.1.1.7.6988](https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.7.6988). [doi:10.1086/344570](https://doi.org/10.1086/344570). [S2CID 17608922](https://api.semanticscholar.org/CorpusID:17608922)

1. Goźdiewski, K. (2003). "A dynamical analysis of the HD 37124 planetary system". *Astronomy and Astrophysics*. **398** (1): 315–325. [Bibcode:2003A&A...398..315G](https://ui.adsabs.harvard.edu/abs/2003A%26A...398..315G). [doi:10.1051/0004-6361:20021602](https://doi.org/10.1051/0004-6361:20021602)

1. Vogt, Steven S. et al. (2005). ["Five New Multicomponent Planetary Systems"](https://authors.library.caltech.edu/36250/1/0004-637X_632_1_638.pdf). *The Astrophysical Journal*. **632** (1): 638–658. [Bibcode:2005ApJ...632..638V](https://ui.adsabs.harvard.edu/abs/2005ApJ...632..638V). [doi:10.1086/432901](https://doi.org/10.1086/432901). [S2CID 16509245](https://api.semanticscholar.org/CorpusID:16509245). Retrieved 2020-12-11.

1. Wright, J. T. et al. (2011). "The California Planet Survey. III. A Possible 2:1 Resonance in the Exoplanetary Triple System HD 37124". *The Astrophysical Journal*. **730** (2): 61–145. [arXiv:1101.1097](https://arxiv.org/abs/1101.1097). [Bibcode:2011ApJ...730...93W](https://ui.adsabs.harvard.edu/abs/2011ApJ...730...93W). [doi:10.1088/0004-637X/730/2/93](https://doi.org/10.1088/0004-637X/730/2/93). [S2CID 119273897](https://api.semanticscholar.org/CorpusID:119273897)

## External links

- Jianghui Ji et al. (2003-05-23). "The Librating Companions in HD 37124, HD 12661, HD 82943, 47 Uma and GJ 876: Alignment or Antialignment?". *The Astrophysical Journal*. **591** (1): L57–L60. [arXiv:astro-ph/0305448](https://arxiv.org/abs/astro-ph/0305448). [Bibcode:2003ApJ...591L..57J](https://ui.adsabs.harvard.edu/abs/2003ApJ...591L..57J). [doi:10.1086/377038](https://doi.org/10.1086/377038). [S2CID 12743267](https://api.semanticscholar.org/CorpusID:12743267)
- ["Notes for star HD 37124"](https://web.archive.org/web/20071106055841/http://exoplanet.eu/star.php?st=HD+37124). *[Extrasolar Planets Encyclopaedia](/source/Extrasolar_Planets_Encyclopaedia)*. Archived from [the original](http://exoplanet.eu/star.php?st=HD+37124) on November 6, 2007. Retrieved 2008-06-22.

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