HD 40979

HD 40979 is a triple star[5] 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.[2] It is located at a distance of approximately 108 light years from the Sun based on parallax.[1] The system is receding with a radial velocity of +32 km/s.[1] It has a relatively high rate of proper motion, traversing the celestial sphere at the rate of 0.182″ per year.[11]

HD 40979
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension  06h 04m 29.94293s[1]
Declination +44° 15′ 37.5977″[1]
Apparent magnitude (V) 6.74[2] + 9.11 + 12.00[3]
Characteristics
Spectral type F7V[4]
B−V color index 0.573±0.007[2]
Astrometry
Radial velocity (Rv)+32.47±0.23[1] km/s
Proper motion (μ) RA: +95.210[1] mas/yr
Dec.: −152.903[1] mas/yr
Parallax (π)30.20 ± 0.44[1] mas
Distance108 ± 2 ly
(33.1 ± 0.5 pc)
Absolute magnitude (MV)4.14[2]
Details
A
Mass1.21[5] or 1.45[6] M☉
Radius1.26±0.03[1] R☉
Luminosity1.960+0.003
−0.004[1] L☉
Surface gravity (log g)4.35[7] cgs
Temperature6,077+82
−72[1] K
Metallicity [Fe/H]1.14[7] dex
Rotational velocity (v sin i)9.1[7] km/s
Age2.51[7] Gyr
B
Mass0.833±0.011[5] M☉
Radius0.78[8] R☉
Luminosity0.301[8] L☉
Surface gravity (log g)4.35[9] cgs
Temperature4,992[9] K
Rotational velocity (v sin i)3.3±2.2[9] km/s
Other designations
BD+44°1353, GC 7670, HD 40979, HIP 28767, SAO 40830, PPM 48712, WDS J06045+4416A, GSC 02937-01747, 2MASS J06042993+4415379[10]
Database references
SIMBADdata
Extrasolar Planets
Encyclopaedia		data

The primary, designated component A, is an F-type main-sequence star with a stellar classification of F7V.[4] It is an estimated 2.51[7] billion years old and is spinning with a projected rotational velocity of 9.1[7] km/s. The star has 1.21[5] times the mass of the Sun and 1.26[1] times the Sun's radius. It has a higher metallicity than the Sun[7] – what astronomers term the relative abundance of elements with a higher atomic number than helium. The star is radiating 1.96[1] times the luminosity of the Sun from its photosphere at an effective temperature of 6,077 K.[1] As of 2002, there is one extrasolar planet known to be orbiting around this star.[12] 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.[13]

The magnitude 9.11[3] 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.[5] This star in turn has a magnitude 12.00[3] 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.[5] The star has an estimated 0.38 times the Sun's mass.[5]

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.[12]

The HD 40979A planetary system[14]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥3.83±0.36 MJ 0.855±0.049 263.84±0.71 0.269±0.034 — —
gollark: One of the classes is Mine, but you don't know which.
gollark: Imagine Minesweeper but with a UML diagram instead of a grid.
gollark: Over skynet though, so maybe HTTP weirdness.
gollark: monday shouldn't cause horrible lag, it just runs programs in a loop and reports crashes.
gollark: I hope none of the laggifying computers were mine!

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.
  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.
  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. 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. 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.
  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.
  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. 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.

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