HD 40409

HD 40409 is a suspected astrometric binary[6] star system in the southern constellation of Dorado. It is a faint system but visible to the naked eye with an apparent visual magnitude of 4.65.[2] Based upon an annual parallax shift of 36.96 mas,[1] it is located 88 light years away from the Sun. It is moving further away with a heliocentric radial velocity of +25 km/s.[2] The system has a relatively high proper motion, traversing the celestial sphere at the rate of 0.57 arcseconds per year along a position angle of 14.51°.[7]

HD 40409
Observation data
Epoch J2000      Equinox J2000
Constellation Dorado
Right ascension  05h 54m 06.05633s[1]
Declination −63° 05′ 23.1963″[1]
Apparent magnitude (V) 4.65[2]
Characteristics
Spectral type K2 III[3]
B−V color index 1.022±0.045[2]
Astrometry
Radial velocity (Rv)+25.1±0.8[2] km/s
Proper motion (μ) RA: +118.57[1] mas/yr
Dec.: +572.93[1] mas/yr
Parallax (π)36.9551 ± 0.2499[1] mas
Distance88.3 ± 0.6 ly
(27.1 ± 0.2 pc)
Absolute magnitude (MV)2.56[2]
Details[4]
Mass1.12 M☉
Radius4.79 R☉
Luminosity11.2 L☉
Surface gravity (log g)3.27 cgs
Temperature4,858 K
Metallicity [Fe/H]+0.07 dex
Age7.91 Gyr
Other designations
CD−63° 218, FK5 2452, GJ 9194, HD 40409, HIP 27890, HR 2102, SAO 249390[5]
Database references
SIMBADdata

The visible component is an evolved K-type giant star, based upon a stellar classification of K2 III assigned by Gray et al. (2006).[3] In contrast, Keenan and McNeil (1989) gave it a somewhat less evolved classification of K2 III–IV.[8] It is about eight billion years old with 12% more mass than the Sun, and has expanded to 4.8 times the Sun's radius. The star is radiating 11 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,858 K.[4]

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.
  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. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
  4. Wittenmyer, Robert A.; Liu, Fan; Wang, Liang; Casagrande, Luca; Johnson, John Asher; Tinney, C. G. (July 2016), "The Pan-Pacific Planet Search. V. Fundamental Parameters for 164 Evolved Stars", The Astronomical Journal, 152 (1): 15, arXiv:1605.00323, Bibcode:2016AJ....152...19W, doi:10.3847/0004-6256/152/1/19, 19.
  5. "HD 40409". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-16.
  6. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  7. Bakos, Gáspár Á.; et al. (July 2002), "Revised Coordinates and Proper Motions of the Stars in the Luyten Half-Second Catalog", The Astrophysical Journal Supplement Series, 141 (1): 187–193, arXiv:astro-ph/0202164, Bibcode:2002ApJS..141..187B, doi:10.1086/340115.
  8. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
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