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HD 40979 is a triple star system in the northern constellation of Auriga. The combined brightness of this group lies below the typical limit of visibility to the naked eye at an apparent visual magnitude of 6.74. It is located at a distance of approximately 108 light years from the Sun based on parallax. The system is receding with a radial velocity of +32 km/s. It has a relatively high rate of proper motion, traversing the celestial sphere at the rate of 0.182″ per year.

The primary, designated component A, is an F-type main-sequence star with a stellar classification of F7V. It is an estimated 2.51 billion years old and is spinning with a projected rotational velocity of 9.1 km/s. The star has 1.21 times the mass of the Sun and 1.26 times the Sun's radius. It has a higher metallicity than the Sun – what astronomers term the relative abundance of elements with a higher atomic number than helium. The star is radiating 1.96 times the luminosity of the Sun from its photosphere at an effective temperature of 6,077 K. As of 2002, there is one extrasolar planet known to be orbiting around this star. An infrared excess suggests a debris disk is orbiting the star at a separation of 16.10 AU with a mean temperature of 80 K.

The magnitude 9.11 secondary, component B, is a co-moving companion at an angular separation of 192.5″ from the primary, which corresponds to a projected separation of around 6,400 AU. It has 83% of the mass of the Sun. This star in turn has a magnitude 12.00 companion, component C, at a separation of 3.877″±0.013″ along a position angle of 37.969°±0.178°, as of 2015. This equates to a projected separation of 129 AU. The star has an estimated 0.38 times the Sun's mass.

Planetary system

In 2003, the detection of a giant planet orbiting the primary was announced. It was discovered using the radial velocity method, which allow selected orbital elements of this object to be determined.

See also

• List of extrasolar planets

References

1. ^ 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.
2. ^ 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.
3. ^ Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
4. ^ Abt, Helmut A. (November 2004). "Spectral Classification of Stars in A Supplement to the Bright Star Catalogue". The Astrophysical Journal Supplement Series. 155 (1): 175–177. Bibcode:2004ApJS..155..175A. doi:10.1086/423803.
5. ^ Mugrauer, M.; et al. (July 2007). "The multiplicity of exoplanet host stars. Spectroscopic confirmation of the companions GJ 3021 B and HD 27442 B, one new planet host triple-star system, and global statistics". Astronomy and Astrophysics. 469 (2): 755–770. arXiv:astro-ph/0703795. Bibcode:2007A&A...469..755M. doi:10.1051/0004-6361:20065883. S2CID 204926851.
6. Stassun, Keivan G.; et al. (March 2017). "Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes". The Astronomical Journal. 153 (3): 20. arXiv:1609.04389. Bibcode:2017AJ....153..136S. doi:10.3847/1538-3881/aa5df3. S2CID 119219062. 136.
7. ^ 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. Bibcode:2017AJ....153...21L. doi:10.3847/1538-3881/153/1/21. S2CID 119511744. 21.
8. ^ 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.
9. ^ Guillout, P.; et al. (September 2009). "A spectroscopic survey of the youngest field stars in the solar neighbourhood. I. The optically bright sample". Astronomy and Astrophysics. 504 (3): 829–843. arXiv:0907.1157. Bibcode:2009A&A...504..829G. doi:10.1051/0004-6361/200811313. S2CID 15723883.
10. "HD 40979". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-01-01.
11. Lépine, Sébastien; Shara, Michael M. (March 2005). "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)". The Astronomical Journal. 129 (3): 1483–1522. arXiv:astro-ph/0412070. Bibcode:2005AJ....129.1483L. doi:10.1086/427854. S2CID 2603568.
12. ^ Fischer, Debra A.; et al. (April 2003). "A Planetary Companion to HD 40979 and Additional Planets Orbiting HD 12661 and HD 38529". The Astrophysical Journal. 586 (2): 1394–1408. Bibcode:2003ApJ...586.1394F. doi:10.1086/367889.
13. Cotten, Tara H.; Song, Inseok (July 2016). "A Comprehensive Census of Nearby Infrared Excess Stars". The Astrophysical Journal Supplement Series. 225 (1): 24. arXiv:1606.01134. Bibcode:2016ApJS..225...15C. doi:10.3847/0067-0049/225/1/15. S2CID 118438871. 15.
14. Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. S2CID 119067572.

v t e Constellation of Auriga
Auriga in Chinese astronomy List of stars in Auriga
Stars	Bayer α (Capella) β (Menkalinan) γ (Elnath) δ ε (Almaaz) ζ (Saclateni) η (Haedus) θ (Mahasim) ι (Hassaleh) κ λ (Alhurr) μ ν ξ ο π ρ σ τ υ φ χ ψ ψ ψ ψ ψ ψ ψ ψ ψ ω Flamsteed 2 5 6 9 12 14 16 18 19 22 26 28 36 38 39 40 41 42 43 45 47 49 51 53 54 59 60 62 63 64 65 66 35 Cam Variable R T RT (48) RW SU UU WW AB AE AR (17) EO IQ IU LY MZ NO NY PU QZ V352 V361 V394 V420 V433 V538 HR 1558 1615 1738 1752 1794 1795 1822 1825 1866 1884 1938 1945 2028 2096 2137 HD 33203 33463 35619 43691 45350 (Lucilinburhuc) 49674 (Nervia) Other Gliese 268 HAT-P-9 (Tevel) KELT-2 MWC 480 SGR 0501+4516 UGPS J0521+3640 WASP-12
Exoplanets HAT-P-9b (Alef) HD 40979 b HD 43691 b HD 45350 b HD 49674 b KELT-2Ab WASP-12b
Star clusters	NGC 1664 1893 1907 1931 2240 2281 Other Messier 36 Messier 37 Messier 38 Palomar 2
Nebulae	NGC 1985 2242 Other IC 405 IC 2149 Westbrook Nebula
Galaxies 3C 147 4C +41.17 DA 193 MCG +08-11-011
Galaxy clusters MACS J0717.5+3745
Category

• F-type main-sequence stars
• Planetary systems with one confirmed planet
• Circumstellar disks
• Multi-star planetary systems
• Auriga
• Durchmusterung objects
• Henry Draper Catalogue objects
• Hipparcos objects