Gliese 86

Gliese 86 (13 G. Eridani, HD 13445) is a K-type main-sequence star approximately 35 light-years away in the constellation of Eridanus. It has been confirmed that a white dwarf orbits the primary star. In 1998 the European Southern Observatory announced that an extrasolar planet was orbiting the star.[13]

Gliese 86
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Eridanus
Gliese 86 A
Right ascension 02h 10m 25.9191s[1]
Declination −50° 49′ 25.4672″[1]
Apparent magnitude (V) 6.17[2]
Gliese 86 B
Right ascension 02h 10m 26s
Declination −50° 49′ 25″
Apparent magnitude (V)
Characteristics
Spectral type K1V[3] + D?[4]
U−B color index 0.45
B−V color index 0.812[5]
V−R color index 0.45
R−I color index 0.40
Astrometry
Radial velocity (Rv)56.7[6] km/s
Proper motion (μ) RA: 2,124.853±0.075[1] mas/yr
Dec.: 638.092±0.063[1] mas/yr
Parallax (π)92.7042 ± 0.0454[1] mas
Distance35.18 ± 0.02 ly
(10.787 ± 0.005 pc)
Absolute magnitude (MV)5.95[7]
Details[8]
Gliese 86 A
Mass0.83±0.05 M☉
Radius0.79±0.03 R☉
Surface gravity (log g)4.56±0.10 cgs
Temperature5180±80 K
Metallicity [Fe/H]−0.27±0.07 dex
Rotational velocity (v sin i)2.0±1.0 km/s
Age10±1 Gyr
Gliese 86 B
Mass0.49[9] M☉
Temperature8180[10] K
Other designations
Gliese 86A: CD−51°532, HD 13445, HIP 10138, HR 637, SAO 232658, WDS J02104-5049A[11]
Gliese 86B: GJ 86 B, HD 13445B, WDS J02104-5049B, WD 0208-510[12]
Database references
SIMBADdata
Exoplanet Archivedata
ARICNSdata
Extrasolar Planets
Encyclopaedia		data

Stellar components

The primary companion (Gliese 86 A) is a K-type main-sequence star of spectral type K1V. The characteristics in comparison to our Sun are 83% the mass, 79% the radius, and 50% the luminosity. The star has a close-orbiting massive Jovian planet.

Gliese 86 B is a white dwarf located around 21 AU from the primary star, making the Gliese 86 system one of the tightest binaries known to host an extrasolar planet.[14] It was discovered in 2001 and initially suspected to be a brown dwarf,[15] but high contrast observations in 2005 suggested that the object is probably a white dwarf, as its spectrum does not exhibit molecular absorption features which are typical of brown dwarfs.[4] Assuming the white dwarf has a mass about half that of our Sun and that the linear trend observed in radial velocity measurements is due to Gliese 86 B, a plausible orbit for this star around Gliese 86 A has a semimajor axis of 18.42 AU and an eccentricity of 0.3974.[16] More precise measurements for the white dwarf give it a mass of 59% the mass of the Sun and a temperature of 8180K. [10]

Planetary system

The preliminary astrometric measurements made with the Hipparcos space probe suggest the planet has an orbital inclination of 164.0° and a mass 15 times Jupiter, which would make the object a brown dwarf.[17] However, further analysis suggests the Hipparcos measurements are not precise enough to reliably determine astrometric orbits of substellar companions, thus the orbital inclination and true mass of the candidate planet remain unknown.[18] It was discovered by the Swiss 1.2 m Leonhard Euler Telescope operated by the Geneva Observatory.[19]

The radial velocity measurements of Gliese 86 show a linear trend once the motion due to this planet are taken out. This may be associated with the orbital motion of the white dwarf companion.

The Gliese 86 planetary system[20]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥6.588±0.018 MJ 0.114340±0.000001 15.76480±0.00004 0.048±0.002 — —

See also

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. C. Cincunegui; P. J. D. Mauas (2004). "Library of flux-calibrated echelle spectra of southern late-type dwarfs with different activity levels". Astronomy and Astrophysics. 414 (2): 699–706. Bibcode:2004A&A...414..699C. doi:10.1051/0004-6361:20031671.
  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. Mugrauer, M.; Neuhäuser, R. (2005). "Gl86B: a white dwarf orbits an exoplanet host star". Monthly Notices of the Royal Astronomical Society: Letters. 361 (1): L15–L19. arXiv:astro-ph/0506311. Bibcode:2005MNRAS.361L..15M. doi:10.1111/j.1745-3933.2005.00055.x. S2CID 16904466.
  5. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
  6. Ramírez, I.; et al. (February 2013), "Oxygen abundances in nearby FGK stars and the galactic chemical evolution of the local disk and halo", The Astrophysical Journal, 764 (1): 78, arXiv:1301.1582, Bibcode:2013ApJ...764...78R, doi:10.1088/0004-637X/764/1/78.
  7. Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191.
  8. Fuhrmann, K.; et al. (2014). "On the Age of Gliese 86". The Astrophysical Journal. 785 (1). 68. Bibcode:2014ApJ...785...68F. doi:10.1088/0004-637X/785/1/68.
  9. Quarles, Billy; Li, Gongjie; Kostov, Veselin; Haghighipour, Nader (2020), "Orbital Stability of Circumstellar Planets in Binary Systems", The Astronomical Journal, 159 (3): 80, arXiv:1912.11019, doi:10.3847/1538-3881/ab64fa, S2CID 209444271
  10. http://www.openexoplanetcatalogue.com/planet/Gliese%2086%20b/
  11. "HD 13445". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-08-14.
  12. "HD 13445B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-08-14.
  13. "Extrasolar Planet in Double Star System Discovered from La Silla" (Press release). Garching, Germany: European Southern Observatory. November 24, 1998. Retrieved December 29, 2012.
  14. Raghavan, Deepak; et al. (2006). "Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems". The Astrophysical Journal. 646 (1): 523–542. arXiv:astro-ph/0603836. Bibcode:2006ApJ...646..523R. doi:10.1086/504823.
  15. Els, S. G.; et al. (2001). "A second substellar companion in the Gliese 86 system. A brown dwarf in an extrasolar planetary system". Astronomy and Astrophysics. 370 (1): L1–L4. Bibcode:2001A&A...370L...1E. doi:10.1051/0004-6361:20010298.
  16. Lagrange, A.-M.; et al. (2006). "New constrains on Gliese 86 B. VLT near infrared coronographic imaging survey of planetary hosts". Astronomy and Astrophysics. 459 (3): 955–963. Bibcode:2006A&A...459..955L. doi:10.1051/0004-6361:20054710.
  17. Han; Black, David C.; Gatewood, George (2001). "Preliminary astrometric masses for proposed extrasolar planetary companions". The Astrophysical Journal Letters. 548 (1): L57–L60. Bibcode:2001ApJ...548L..57H. doi:10.1086/318927.
  18. Pourbaix, D.; Arenou, F. (2001). "Screening the Hipparcos-based astrometric orbits of sub-stellar objects". Astronomy and Astrophysics. 372 (3): 935–944. arXiv:astro-ph/0104412. Bibcode:2001A&A...372..935P. doi:10.1051/0004-6361:20010597. S2CID 378792.
  19. "Southern Sky extrasolar Planet search Programme".
  20. Wittenmyer, Robert A.; et al. (2020). "Cool Jupiters greatly outnumber their toasty siblings: occurrence rates from the Anglo-Australian Planet Search". Monthly Notices of the Royal Astronomical Society. 492 (1): 377–383. arXiv:1912.01821. Bibcode:2020MNRAS.492..377W. doi:10.1093/mnras/stz3436. S2CID 208617606.

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