Gliese 754

Gliese 754 is a dim star in the southern constellation of Telescopium. It has an apparent visual magnitude of 12.25,[2] which requires a telescope to view. The star is located at a distance of 19.3 light-years from the Sun based on parallax,[1] and it is drifting further away with a radial velocity of +7 km/s.[3] It is one of the hundred closest stars to the Solar System. Calculations of its orbit around the Milky Way showed that it is eccentric, and indicate that it might be a thick disk object.[7]

Gliese 754
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Telescopium
Right ascension 19h 20m 47.98349s[1]
Declination −45° 33′ 29.6292″[1]
Apparent magnitude (V) 12.25[2]
Characteristics
Spectral type M4V[2]
Astrometry
Radial velocity (Rv)+6.8[3] km/s
Proper motion (μ) RA: +659.330[1] mas/yr
Dec.: −2,897.035[1] mas/yr
Parallax (π)169.0921 ± 0.2165[1] mas
Distance19.29 ± 0.02 ly
(5.914 ± 0.008 pc)
Details[3]
Mass0.173 M☉
Radius0.205 R☉
Luminosity0.005[4] L☉
Temperature3,202±100[5] K
Metallicity [Fe/H]−0.169[5] dex
Rotation132.651 days
Other designations
GJ 754, L 347-14, LHS 60, LTT 7652[6]
Database references
SIMBADdata

The stellar classification of Gliese 754 is M4V,[2] indicating that this is a small red dwarf star on the core hydrogen fusing main sequence. It has 17% of the mass of the Sun and 21% of the Sun's radius.[3] The star is fully convective and is a source of X-ray emission.[8] It is rotating slowly with a period of about 133 days.[3] The metallicity is sub-solar,[5] indicating it has a lower abundance of heavy elements compared to the Sun. It is radiating just 0.5%[4] of the luminosity of the Sun from its photosphere at an effective temperature of around 3,202 K.[5]

Planetary System

In June 2019 a candidate exoplanet was reported in orbit around Gliese 754. It was detected using the Doppler method and is orbiting at a distance of 0.28 AU with a period of 78 days. The orbit is essentially circular, to within the margin of error.[9] The habitable zone for this star ranges from 0.05 AU to 0.14 AU;[4] inside the orbit of this proposed companion.

The Gliese 754 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b (unconfirmed) ≥9.8+4.6
−5.2 M⊕		 0.277+0.025
−0.028		 78.37+0.55
−0.47		 0.03+0.20
−0.03		 — —

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. Henry, Todd J.; et al. (2018). "The Solar Neighborhood XLIV: RECONS Discoveries within 10 parsecs". The Astronomical Journal. 155 (6): 265. arXiv:1804.07377. Bibcode:2018AJ....155..265H. doi:10.3847/1538-3881/aac262. S2CID 53983430.
  3. Newton, Elisabeth R.; et al. (November 2018). "New Rotation Period Measurements for M Dwarfs in the Southern Hemisphere: An Abundance of Slowly Rotating, Fully Convective Stars". The Astronomical Journal. 156 (5): 11. arXiv:1807.09365. Bibcode:2018AJ....156..217N. doi:10.3847/1538-3881/aad73b. 217.
  4. Mayor, M.; et al. (2009). "The HARPS search for southern extra-solar planets. XIII. A planetary system with 3 Super-Earths (4.2, 6.9, & 9.2 Earth masses)". Astronomy and Astrophysics. 493 (2): 639–644. arXiv:0806.4587. Bibcode:2009A&A...493..639M. doi:10.1051/0004-6361:200810451.
  5. Houdebine, E. R.; et al. (May 2016). "Rotation-Activity Correlations in K and M Dwarfs. I. Stellar Parameters and Compilations of v sin I and P/sin I for a Large Sample of Late-K and M Dwarfs". The Astrophysical Journal. 822 (2): 38. arXiv:1604.07920. Bibcode:2016ApJ...822...97H. doi:10.3847/0004-637X/822/2/97. 97.
  6. "L 347-14". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-12.
  7. Innanen, K.A.; Flynn, C. (2010). "The Radial Velocity, Space Motion, and Galactic Orbit of GJ 754". Journal of the Royal Astronomical Society of Canada. 104 (6): 223–24. Bibcode:2010JRASC.104..223I.
  8. Wright, Nicholas J.; et al. (September 2018). "The stellar rotation-activity relationship in fully convective M dwarfs". Monthly Notices of the Royal Astronomical Society. 479 (2): 2351–2360. arXiv:1807.03304. Bibcode:2018MNRAS.479.2351W. doi:10.1093/mnras/sty1670.
  9. Barnes, J. R.; et al. (June 2019). "Frequency of planets orbiting M dwarfs in the Solar neighbourhood". arXiv:1906.04644. Bibcode:2019arXiv190604644T. Cite journal requires |journal= (help)
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