Gliese 86

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Gliese 86 is a star system in the constellation Eridanus 35.9 ly away. The star system has three known members: an orange main sequence star of spectral type K which is orbited by an extrasolar planet, and a white dwarf companion.

Contents

[edit] Gliese 86 A

Gliese 86 A
Observation data
Epoch J2000
Constellation
(pronunciation)		 Eridanus
Right ascension 2h 10m 14s
Declination -50° 50' 00"
Apparent magnitude (V) 6.17
Distance 35.9 ly
(11 pc)
Spectral type K1V
Other designations
HD 13445, HIP 10138, HR 637

The primary companion Gliese 86 A is an orange dwarf star of spectral type K1V. The characteristics in comparison to our Sun are 79% the mass, 86% the radius, and 35% the luminosity. The star has a close-orbiting massive gas giant planet.

[edit] Gliese 86 b

Gliese 86 b
Extrasolar planet List of extrasolar planets
Orbital elements
Semimajor axis (a) 0.113[1] AU
Eccentricity (e) 0.0416 ± 0.0072[1]
Orbital period (P) 15.76491 ± 0.00039[1] d
Angular distance (θ) 10 mas
Longitude of
periastron		 (ω) 269 ± 16[1]°
Time of periastron (T0) 2451903.36 ± 0.59[1] JD
Semi-amplitude (K) 376.7 ± 2.9[1] m/s
Physical characteristics
Mass (m) >3.91[1] MJ
Discovery information
Discovery date 2000
Discoverer(s) Mayor, Queloz, Udry et al.
Detection method Doppler spectroscopy
Discovery site California, United States
Discovery status Published
Other designations
HD 13445 b

Gliese 86 b (sometimes referred to as Gliese 86 Ab to distinguish it from the white dwarf Gliese 86 B) is a planet around the primary star Gliese 86 A. It is a superjovian planet that orbits very close to the star (0.11 AU), completing an orbit for 15.77 days.

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.[2] 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.[3]

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 star.

[edit] Gliese 86 B

Gliese 86 B
Observation data
Epoch J2000
Constellation
(pronunciation)		 Eridanus
Right ascension 2h 10m 26s
Declination -50° 49' 25"
Distance 35.9 ly
(11 pc)
Spectral type D

Gliese 86 B is a white dwarf star located around 21 AU from the primary star, making the Gliese 86 system one of the tightest binaries known to host an extrasolar planet.[4] It was discovered in 2001 and initially suspected to be a brown dwarf,[5] however high contrast observations in 2005 suggested that the object is probably a white dwarf star, as its spectrum does not exhibit molecular absorption features which are typical of brown dwarfs.[6] 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.[7]

[edit] References

  1. ^ a b c d e f g Butler, R. et al. (2007). Planets Table. Catalog of Nearby Exoplanets. Retrieved on 2007-08-02.
  2. ^ Han et al. (2001). "Preliminary astrometric masses for proposed extrasolar planetary companions". The Astrophysical Journal 548 (1): L57 – L60. doi:10.1086/318927. 
  3. ^ Pourbaix, D. and Arenou, F. (2001). "Screening the Hipparcos-based astrometric orbits of sub-stellar objects". Astronomy and Astrophysics 372: 935 – 944. doi:10.1051/0004-6361:20010597. 
  4. ^ Raghavan, D. et al. (2006). "Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems". The Astrophysical Journal 646 (1): 523 – 542. doi:10.1086/504823. 
  5. ^ 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: L1 – L4. doi:10.1051/0004-6361:20010298. 
  6. ^ Mugrauer, M. and Neuhäuser, R. (2005). "Gl86B: a white dwarf orbits an exoplanet host star". Monthly Notices of the Royal Astronomical Society: Letters 361 (1): L15 – L19. doi:10.1111/j.1745-3933.2005.00055.x. 
  7. ^ 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. doi:10.1051/0004-6361:20054710. 

[edit] See also

[edit] External links

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