Gliese 317

Gliese 317 is a small red dwarf star with two exoplanetary companions[3][8] in the southern constellation of Pyxis. It is located at a distance of 49.6 light-years from the Sun based on parallax measurements,[1] and is drifting further away with a radial velocity of +87.8 km/s.[3] This star is too faint to be viewed with the naked eye, having an apparent visual magnitude of 11.98[2] and an absolute magnitude of 11.06.[3]

Gliese 317
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pyxis
Right ascension 08h 40m 59.2056s[1]
Declination −23° 27′ 22.5986″[1]
Apparent magnitude (V) 11.98[2]
Characteristics
Spectral type M2.5V[3]
V−R color index 0.338[2]
Astrometry
Radial velocity (Rv)87.8[3] km/s
Proper motion (μ) RA: −461.162±0.139 mas/yr[1]
Dec.: 805.571±0.126 mas/yr[1]
Parallax (π)65.7744 ± 0.0557 mas[1]
Distance49.59 ± 0.04 ly
(15.20 ± 0.01 pc)
Absolute magnitude (MV)11.06±0.04[3]
Details
Mass0.42±0.05[3] M☉
Radius0.4170±0.0013[4] R☉
Luminosity0.02175±0.00034[4] L☉
Temperature3,510±50[3] K
Metallicity [Fe/H]+0.3[3][5] dex
Rotation69 days[6]
Age~5[3] Gyr
Other designations
GJ 317, LFT 538, LHS 2037, LPM 296, LTT 3215[7]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

This is an M-type main-sequence star with a stellar classification of M2.5V.[3] Photometric calibrations and infrared spectroscopic measurements indicate that the star is enriched in heavy elements compared to the Sun.[5] The star is estimated to be roughly five billion years old and has a low activity level for a star of its class.[3] It has 42%[3][4] of the mass and radius of the Sun and is spinning with a rotation period of 69 days.[6] The star is radiating 2.2%[4] of the Sun's luminosity from its photosphere at an effective temperature of 3,510 K.[3]

Planetary system

In 2007, a jovian planet (designated Gliese 317 b) was announced to orbit the star.[8] The planet orbits about 95% the distance between Earth to the Sun. Despite this, it takes about 1.9 years, due to the lower mass of the central M dwarf. Astrometric measurements on Gliese 317 provided a significant update to the distance, putting the star at 15.3 pc, which is 65% further out than previously assumed.[3] Using mass-luminosity calibrations, the new distance implies the star is significantly more massive and so are the planet candidates. The same astrometric measurements allowed to constrain the orbital inclination and put an upper limit to the mass of Gliese 317 b (98% confidence level) of 2.5 MJ.

The second planet in the system was also confirmed with the additional new RV measurements, but the period and orbital parameters of Gliese 317 c were very uncertain (P>2000 days).[3] A stability analysis on this putative system suggest that the pair of gas giant planets are in a 4:1 mean motion resonance.[9] The second planet, remote from its host star, is a good candidate for direct imaging.[3] Revised elements of this companion were presented in 2020, demonstrating this is a Jupiter analog.[6]

The Gliese 317 planetary system[6]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥1.75±0.06 MJ 1.151±0.018 695.660±0.355 0.07±0.01 — —
c ≥1.64±0.06 MJ 5.230±0.111 6739.323±143.106 0.17±0.02 — —

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. Zacharias, N.; et al. (1 February 2013), "The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)", The Astronomical Journal, 145 (2): 44, arXiv:1212.6182, Bibcode:2013AJ....145...44Z, doi:10.1088/0004-6256/145/2/44, ISSN 0004-6256, S2CID 119299381.
  3. Anglada-Escude, Guillem; et al. (2012), "Astrometry and radial velocities of the planet host M dwarf Gliese 317: new trigonometric distance, metallicity and upper limit to the mass of Gliese 317 b", The Astrophysical Journal, 764 (1): 37A, arXiv:1111.2623, Bibcode:2012ApJ...746...37A, doi:10.1088/0004-637X/746/1/37, S2CID 118526264.
  4. Schweitzer, A.; et al. (May 2019), "The CARMENES search for exoplanets around M dwarfs. Different roads to radii and masses of the target stars", Astronomy & Astrophysics, 625: 16, arXiv:1904.03231, Bibcode:2019A&A...625A..68S, doi:10.1051/0004-6361/201834965, S2CID 102351979, A68.
  5. Terrien, Ryan C.; et al. (2012), "An H-band Spectroscopic Metallicity Calibration for M Dwarfs", The Astrophysical Journal, 747 (2): L38, arXiv:1202.1800, Bibcode:2012ApJ...747L..38T, doi:10.1088/2041-8205/747/2/L38, S2CID 118403568.
  6. Feng, Fabo; et al. (October 2020), "Search for Nearby Earth Analogs .III. Detection of 10 New Planets, 3 Planet Candidates, and Confirmation of 3 Planets around 11 Nearby M Dwarfs", The Astrophysical Journal Supplement Series, 250 (2): 22, arXiv:2008.07998, Bibcode:2020ApJS..250...29F, doi:10.3847/1538-4365/abb139, S2CID 221150644, 29.
  7. "L 675-81". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 20 November 2021.
  8. Johnson, J. A.; et al. (2007), "A New Planet Around an M Dwarf: Revealing a Correlation between Exoplanets and Stellar Mass", The Astrophysical Journal, 670 (1): 833–840, arXiv:0707.2409, Bibcode:2007ApJ...670..833J, doi:10.1086/521720, S2CID 9135084.
  9. Barnes, Rory; Greenberg, Richard (2008), "Extrasolar Planet Interactions", Proceedings of the International Astronomical Union, 3: 469–478, arXiv:0801.3226v1, Bibcode:2008IAUS..249..469B, doi:10.1017/S1743921308016980, S2CID 17096607.
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