HD 131664

HD 131664 is an 8th magnitude star in the southern constellation of Apus with an orbiting brown dwarf companion. Parallax measurements by the Gaia space observatory provide an estimated distance of 172.5 light years from the Earth. The system is moving further away with a baseline heliocentric radial velocity of +35 km/s.[1]

HD 131664
Observation data
Epoch J2000      Equinox J2000
Constellation Apus
Right ascension 15h 00m 06.07997s[1]
Declination −73° 32′ 07.2265″[1]
Apparent magnitude (V) 8.13[2]
Characteristics
Spectral type G3 V[3]
B−V color index 0.667[4]
Astrometry
Radial velocity (Rv)+35.31±0.14[1] km/s
Proper motion (μ) RA: +8.046[1] mas/yr
Dec.: +24.666[1] mas/yr
Parallax (π)18.9059 ± 0.0349[1] mas
Distance172.5 ± 0.3 ly
(52.89 ± 0.10 pc)
Absolute magnitude (MV)4.41[4]
Details[5]
Mass1.10 M☉
Radius1.16[4] R☉
Luminosity1.60[2] L☉
Surface gravity (log g)4.50 cgs
Temperature5,901 K
Metallicity [Fe/H]0.281[6] dex
Rotation25[7] days
Rotational velocity (v sin i)3.01 km/s
Age2.32 Gyr
Other designations
CD–73° 1031, HD 131664, HIP 73408[8]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

The stellar component is an ordinary G-type main-sequence star with a stellar classification of G3 V.[3] The star is particularly metal-rich ([Fe/H] = 0.28)[6] in comparison with the mean metallicity of the solar neighborhood. It is about 2.3 billion years old with a projected rotational velocity of 3 km/s.[5] The star has 110% of the mass of the Sun and 116%[4] times the Sun's radius. It is radiating 160%[2] of the Sun's luminosity from its photosphere at an effective temperature of 5,901 K.[5]

The discovery of a planet in orbit around HD 131664 was announced on October 26, 2008 and designated HD 131664 b.[9] The object was detected from Doppler measurements of the host star between 2004 and 2008.[4] This planet or brown dwarf has mass of at least 18.15[4] times that of Jupiter and orbits in a long-period, eccentric orbit that completely overlaps the star's habitable zone.[10] This period (1,951 days or 5.34 years) is among the dozen longest exoplanet periods known, as of 2009.[4] Follow-up studies with the Hipparcos satellite further constrained the predicted mass of the companion, providing a best estimate of 23+26
−5 MJ.[11][12]

The HD 131664 planetary system[4]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥18.15±0.35 MJ 3.17±0.03 1,951±41 0.638±0.02 149.3–171.9°[11]° —

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.
  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. Houk, Nancy (1978). "Michigan catalogue of two-dimensional spectral types for the HD stars". 1. Ann Arbor: Dept. of Astronomy, University of Michigan. Bibcode:1975mcts.book.....H. Cite journal requires |journal= (help)
  4. Moutou, C.; et al. (2009). "The HARPS search for southern extra-solar planets XVII. Six long-period giant planets around BD -17 0063, HD 20868, HD 73267, HD 131664, HD 145377, HD 153950". Astronomy and Astrophysics. 496 (2): 513–519. arXiv:0810.4662. Bibcode:2009A&A...496..513M. doi:10.1051/0004-6361:200810941.
  5. Delgado Mena, E.; et al. (April 2015). "Li abundances in F stars: planets, rotation, and Galactic evolution". Astronomy & Astrophysics. 576: 24. arXiv:1412.4618. Bibcode:2015A&A...576A..69D. doi:10.1051/0004-6361/201425433. A69.
  6. Ramírez, I.; et al. (January 2014). "Chemical signatures of planets: beyond solar-twins". Astronomy & Astrophysics. 561: 16. arXiv:1310.8581. Bibcode:2014A&A...561A...7R. doi:10.1051/0004-6361/201322558. A7.
  7. Arriagada, Pamela (June 2011). "Chromospheric Activity of Southern Stars from the Magellan Planet Search Program". The Astrophysical Journal. 734 (1): 6. arXiv:1104.3186. Bibcode:2011ApJ...734...70A. doi:10.1088/0004-637X/734/1/70. 70.
  8. "HD 131664". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 19, 2018.
  9. "Planet HD 131664 b". exoplanet.eu. Retrieved 11 October 2018.
  10. Agnew, Matthew T.; et al. (November 2017). "Stable habitable zones of single Jovian planet systems". Monthly Notices of the Royal Astronomical Society. 471 (4): 4494−4507. arXiv:1706.05805. Bibcode:2017MNRAS.471.4494A. doi:10.1093/mnras/stx1449.
  11. Reffert, S.; Quirrenbach, A. (2011). "Mass constraints on substellar companion candidates from the re-reduced Hipparcos intermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs". Astronomy & Astrophysics. 527. id.A140. arXiv:1101.2227. Bibcode:2011A&A...527A.140R. doi:10.1051/0004-6361/201015861.
  12. Sozzetti, A.; Desidera, S. (January 2010), "Hipparcos preliminary astrometric masses for the two close-in companions to HD 131664 and HD 43848. A brown dwarf and a low-mass star", Astronomy and Astrophysics, 509, arXiv:0909.4454, Bibcode:2010A&A...509A.103S, doi:10.1051/0004-6361/200912717, A103
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