Star in the constellation Orion
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 E and 200.0 M E .[ 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 toe 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]
The HD 34445 planetary system[ 2]
Companion(in order from star)
Mass
Semimajor axis (AU )
Orbital period (days )
Eccentricity
Inclination
Radius
e (unconfirmed)
≥0.0529 ± 0.0089 M J
0.2687 ± 0.0019
49.175 ± 0.045
0.090 ± 0.062
—
—
d (unconfirmed)
≥0.097 ± 0.13 M J
0.4817 ± 0.0033
117.87 ± 0.18
0.027 ± 0.051
—
—
c (unconfirmed)
≥0.168 ± 0.016 M J
0.7181 ± 0.0049
214.67 ± 0.45
0.036 ± 0.071
—
—
f (unconfirmed)
≥0.119 ± 0.021 M J
1.543 ± 0.016
676.8 ± 7.9
0.031 ± 0.057
—
—
b
≥0.629 ± 0.028 M J
2.075 ± 0.016
1056.7 ± 4.7
0.014 ± 0.035
—
—
g (unconfirmed)
≥0.38 ± 0.13 M J
6.36 ± 1.02
5700 ± 1500
0.032 ± 0.080
—
—
See also
References
^ a b c d e Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties" . Astronomy & Astrophysics . 616 . A1. arXiv :1804.09365 . Bibcode :2018A&A...616A...1G . doi :10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR .
^ a b c d e f g h i j k l m n o p q r Vogt, Steven S.; et al. (2017). "A Six-planet System around the Star HD 34445" . The Astronomical Journal . 154 (5): 181. arXiv :1710.07337 . Bibcode :2017AJ....154..181V . doi :10.3847/1538-3881/aa8b61 . S2CID 119182115 .
^ a b Soubiran, C.; et al. (2013). "The catalogue of radial velocity standard stars for Gaia. I. Pre-launch release". Astronomy and Astrophysics . 552 . A64. arXiv :1302.1905 . Bibcode :2013A&A...552A..64S . doi :10.1051/0004-6361/201220927 . S2CID 56094559 .
^ a b 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. Bibcode :2006A&A...458..873S . doi :10.1051/0004-6361:20065658 .
^ a b Howard, Andrew W.; et al. (2010). "The California Planet Survey. I. Four New Giant Exoplanets". The Astrophysical Journal . 721 (2): 1467–1481. arXiv :1003.3488 . Bibcode :2010ApJ...721.1467H . doi :10.1088/0004-637X/721/2/1467 . S2CID 14147776 .
^ a b Rosenthal, Lee J.; Fulton, Benjamin J.; Hirsch, Lea A.; Isaacson, Howard T.; Howard, Andrew W.; Dedrick, Cayla M.; Sherstyuk, Ilya A.; Blunt, Sarah C.; Petigura, Erik A.; Knutson, Heather A.; Behmard, Aida; Chontos, Ashley; Crepp, Justin R.; Crossfield, Ian J. M.; Dalba, Paul A.; Fischer, Debra A.; Henry, Gregory W.; Kane, Stephen R.; Kosiarek, Molly; Marcy, Geoffrey W.; Rubenzahl, Ryan A.; Weiss, Lauren M.; Wright, Jason T. (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. arXiv :2105.11583 . Bibcode :2021ApJS..255....8R . doi :10.3847/1538-4365/abe23c . S2CID 235186973 .
^ "HD 34445" . SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 19 November 2017 .
^ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters . 38 (5): 331. arXiv :1108.4971 . Bibcode :2012AstL...38..331A . doi :10.1134/S1063773712050015 . S2CID 119257644 .
^ 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. arXiv :1907.05495 . Bibcode :2019MNRAS.488.3818G . doi :10.1093/mnras/stz1945 .