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    HD 196885

    From Wikipedia - Reading time: 5 min
    HD 196885
    Observation data
    Epoch J2000      Equinox J2000
    Constellation Delphinus
    Right ascension 20h 39m 51.87531s[1]
    Declination +11° 14′ 58.7029″[1]
    Apparent magnitude (V) 6.39[2]
    Characteristics
    Spectral type F8V[3] + M1±1V[4]
    B−V color index 0.559±0.006[2]
    Astrometry
    Radial velocity (Rv)−30.13±0.09[2] km/s
    Proper motion (μ) RA: +71.470±0.066[1] mas/yr
    Dec.: +89.165±0.076[1] mas/yr
    Parallax (π)29.2372 ± 0.0486 mas[1]
    Distance111.6 ± 0.2 ly
    (34.20 ± 0.06 pc)
    Absolute magnitude (MV)3.76[2]
    Orbit[5]
    Period (P)72.06±4.59 yr
    Semi-major axis (a)21.00±0.86 AU
    Eccentricity (e)0.42±0.03
    Inclination (i)116.8±0.7°
    Longitude of the node (Ω)79.8±0.1°
    Argument of periastron (ω)
    (secondary)    		−118.1±3.1°
    Details[6]
    A
    Mass1.33 M☉
    Radius1.45+0.02
    −0.05    [1] R☉
    Luminosity2.695±0.006[1] L☉
    Surface gravity (log g)4.46±0.02 cgs
    Temperature6,340±39 K
    Metallicity [Fe/H]0.29±0.05 dex
    Rotation15 days
    Rotational velocity (v sin i)7.3±1.5 km/s
    Age2.0±0.5 Gyr
    B
    Mass0.45±0.01[5] M☉
    Other designations
    BD+10° 4351, GC 28784, HD 196885, HIP 101966, HR 7907, SAO 106360, WDS J20399+1115, GCRV 12946[7]
    Database references
    SIMBADdata

    HD 196885 is a binary star system in the northern constellation of Delphinus. It is near the lower limit of visibility to the naked eye with an apparent visual magnitude of 6.39.[2] According to its parallax of 29.24 mas, it is located at a distance of 112 light years from the Sun. It is drifting closer with a radial velocity of −30 km/s, and is expected to come to within 52.5 light-years in 836,000 years.[2] The absolute magnitude of the system is 3.76.[2]

    The primary, component A, is an F-type main-sequence star with a stellar classification of F8V[3] It is about two billion years old and is spinning with a projected rotational velocity, for a rotation period of around 15 days. The star has 1.33[6] times the mass of the Sun and 1.45 times the Sun's radius.[1] The metallicity of this star – what astronomers term the abundance of elements with higher atomic number than helium – is nearly double that in the Sun. It is radiating 2.7 times the luminosity of the Sun from its photosphere at an effective temperature of 6,340 K.[6]

    In 2004, a planet was announced to be orbiting the star in a 386-day orbit.[8] Follow-up work published in 2008 did not confirm the original candidate but instead found evidence of a planet in a 3.63 years.[6] This object has a minimum estimated mass at least three times that of the planet Jupiter.[5] Perturbation by the secondary star in this system may have driven the planet into a high inclination orbit.[9]

    The secondary, component B, is a red dwarf star separated by 0.6 arcseconds from the primary star that was discovered in 2006 with NaCo at VLT.[10][4] derive the orbital elements of the pair give an orbital period of 72 years, a semimajor axis of 21 AU, and an eccentricity of 0.42.[5] It has a class in the range M1V to M3V[4] with 45% of the Sun's mass.[5]

    The star BD+10 4351B, located 192 arcseconds away from HD 196885 is located at the same distance and may be a physically bound companion star, in which case HD 196885 is a triple system.[11] If it is bound, then the separation is at least 6,600 AU (the separation along the line-of-sight is unknown, so this value represents a lower limit on the true separation).[citation needed]

    The HD 196885 planetary system[5]
    Companion
    (in order from star)     		Mass Semimajor axis
    (AU)     		Orbital period
    (days)     		Eccentricity Inclination Radius
    b ≥2.98±0.05 MJ 2.6±0.1 1,326.0±3.7 0.48±0.02 — —

    See also[edit]

    • Epsilon Reticuli
    • GJ 3021

    References[edit]

    1. ^ a b c d e f g h 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. ^ a b c d e f g 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. ^ a b Gray, R. O.; et al. (2001), "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars", The Astronomical Journal, 121 (4): 2148, Bibcode:2001AJ....121.2148G, doi:10.1086/319956
    4. ^ a b c Chauvin, G.; et al. (2007). "Characterization of the long-period companions of the exoplanet host stars: HD 196885, HD 1237 and HD 27442". Astronomy and Astrophysics. 475 (2): 723–727. arXiv:0710.5918. Bibcode:2007A&A...475..723C. doi:10.1051/0004-6361:20067046.
    5. ^ a b c d e f Chauvin, G.; et al. (2011). "Planetary systems in close binary stars: the case of HD 196885" (abstract). Astronomy and Astrophysics. 528: A8. arXiv:1009.5851. Bibcode:2011A&A...528A...8C. doi:10.1051/0004-6361/201015433.
    6. ^ a b c d Correia, A. C. M.; et al. (2008). "The ELODIE survey for northern extra-solar planets. IV. HD 196885, a close binary star with a 3.7-year planet". Astronomy and Astrophysics. 479 (1): 271–275. arXiv:0711.3343. Bibcode:2008A&A...479..271C. doi:10.1051/0004-6361:20078908. S2CID 119261807.
    7. ^ "HD 196885". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-08-08.
    8. ^ "The Planet Around HD 196885". California & Carnegie Planet Search Team (Internet Archive link). Archived from the original on 2004-12-27. Retrieved 2008-08-19.
    9. ^ Satyal, S.; Hinse, T. C.; Quarles, B.; Noyola, J. P. (September 2014). "Chaotic dynamics of the planet in HD 196885 AB". Monthly Notices of the Royal Astronomical Society. 443 (2): 1310–1318. arXiv:1401.1268. Bibcode:2014MNRAS.443.1310S. doi:10.1093/mnras/stu1221. S2CID 119189415.
    10. ^ Chauvin, G.; et al. (2006). "Probing long-period companions to planetary hosts. VLT and CFHT near infrared coronographic imaging surveys". Astronomy and Astrophysics. 456 (3): 1165–1172. arXiv:astro-ph/0606166. Bibcode:2006A&A...456.1165C. doi:10.1051/0004-6361:20054709. S2CID 15611548.
    11. ^ "HD 196885 A page". Geneva Observatory. Retrieved 2008-08-19.

    Coordinates: Sky map 20h 39m 51.8756s, +11° 14′ 58.737″

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    Original source: https://en.wikipedia.org/wiki/HD 196885
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