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 mas[1]
Distance172.5 ± 0.3 ly
(52.89 ± 0.10 pc)
Absolute magnitude (MV)4.41[4]
Orbit[5]
CompanionHD 131664 b
Period (P)5.424±0.004 yr
Semi-major axis (a)3.2±0.1 AU
Eccentricity (e)0.693±0.002
Inclination (i)170.7±1.5°
Longitude of the node (Ω)348.3±6.4°
Periastron epoch (T)2452023±2
Argument of periastron (ω)
(primary)		151.8±0.3°
Semi-amplitude (K1)
(primary)		0.4337±0.0031 km/s
Details[6]
HD 131664 A
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[7] dex
Rotation25[8] days
Rotational velocity (v sin i)3.01 km/s
Age2.32 Gyr
HD 131664 b
Mass127.8±17.9[5] MJup
Other designations
CD–73° 1031, HD 131664, HIP 73408[9]
Database references
SIMBADdata
Exoplanet Archivedata

HD 131664 is an 8th magnitude star in the southern constellation of Apus with an orbiting brown dwarf or stellar 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]

The primary 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)[7] 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.[6] 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.[6]

The discovery of a brown dwarf in orbit around HD 131664 was announced on October 26, 2008 and designated HD 131664 b.[10] The object was detected from Doppler measurements of the host star between 2004 and 2008.[4] This object has a minimum mass of 18.15[4] times that of Jupiter and orbits in a long-period, eccentric orbit that completely overlaps the star's habitable zone.[11] As of 2009, this period (1,951 days or 5.34 years) was among the dozen longest exoplanet periods known.[4] Follow-up studies with data from the Hipparcos and Gaia satellites further constrained the predicted mass of the companion, providing a best estimate of 127.8±17.9 MJ, or about 0.12 times the mass of the Sun.[5]

References

  1. 1 2 3 4 5 6 7 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. 1 2 3 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. 1 2 Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 1. Ann Arbor: Dept. of Astronomy, University of Michigan. Bibcode:1975mcts.book.....H.
  4. 1 2 3 4 5 6 7 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. S2CID 116707055.
  5. 1 2 3 Feng, Fabo; Butler, R Paul; Jones, Hugh R A.; Phillips, Mark W.; Vogt, Steven S.; Oppenheimer, Rebecca; Holden, Bradford; Burt, Jennifer; Boss, Alan P. (2021). "Optimized modelling of Gaia–Hipparcos astrometry for the detection of the smallest cold Jupiter and confirmation of seven low-mass companions". Monthly Notices of the Royal Astronomical Society. 507 (2): 2856–2868. arXiv:2107.14056. Bibcode:2021MNRAS.507.2856F. doi:10.1093/mnras/stab2225.
  6. 1 2 3 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. S2CID 56051637. A69.
  7. 1 2 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. S2CID 21698677. A7.
  8. ↑ 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. S2CID 118384591. 70.
  9. ↑ "HD 131664". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 19, 2018.
  10. ↑ "Planet HD 131664 b". Extrasolar Planets Encyclopaedia. Retrieved 11 October 2018.
  11. ↑ 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.
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