HD 136118

HD 136118 is a star in the Serpens Caput section of the Serpens constellation. The star is too dim to be readily visible to the naked eye, having an apparent visual magnitude of 6.93.[2] It is located at a distance of 165 light years from the Sun based on parallax,[1] and is drifting closer with a radial velocity of −3 km/s.[2]

HD 136118

Telescope image of HD 136118
Observation data
Epoch J2000      Equinox J2000
Constellation Serpens
Right ascension 15h 18m 55.47227s[1]
Declination −01° 35′ 32.5926″[1]
Apparent magnitude (V) 6.93[2]
Characteristics
Evolutionary stage main sequence[3]
Spectral type F7V[4]
B−V color index 0.553±0.007[2]
Astrometry
Radial velocity (Rv)−3.07±0.13[1] km/s
Proper motion (μ) RA: −123.024(31) mas/yr[1]
Dec.: 22.180(30) mas/yr[1]
Parallax (π)19.8116 ± 0.0341 mas[1]
Distance164.6 ± 0.3 ly
(50.48 ± 0.09 pc)
Absolute magnitude (MV)3.60[5]
Details
Mass1.84±0.23[6] M☉
Radius1.70±0.02[7] R☉
Luminosity3.717±0.018[7] L☉
Surface gravity (log g)4.08[5] cgs
Temperature6,148+38
−43[7] K
Metallicity [Fe/H]−0.06±0.01[2] dex
Rotational velocity (v sin i)8.5[5] km/s
Age3.5±0.4[2] Gyr
Other designations
BD−01° 3045, HD 136118, HIP 74948, SAO 140452[8]
Database references
SIMBADdata

This object is an F-type main-sequence star with a stellar classification of F7V.[4] The absolute visual magnitude of this star suggests that it has begun to evolve away from the main sequence.[3] The abundances of the stellar atmosphere are similar to the Sun, and it has only a modest level of chromospheric activity.[9] HD 136118 has 84% more mass compared to the Sun,[6] and is 70%[7] larger in radius. The star is an estimated 3.5[2] billion years old and is spinning with a projected rotational velocity of 8.5 km/s.[5]

Brown dwarf companion

The astronomer Debra Fischer discovered a substellar companion, originally thought to be a very massive exoplanet, which was announced on February 7, 2002.[3] Designated HD 136118 b, it is orbiting the host star with a period of 3.25 years.[9] This object has a minimum mass of 11.9 MJ.[3] On November 25, 2009, its inclination was calculated to be 163.1° and its true mass 42 MJ, classifying it as a brown dwarf.[9] Later studies in 2022 and 2023 found true masses of about 13-16 MJ, closer to the minimum mass, but still classifying the companion as a brown dwarf by most definitions.[10][11]

Due to its high mass the object is likely to be very hot and possibly glowing faintly. The orbit of the object has a semimajor axis of 1.45 astronomical units from the parent star, taking 1,188 days (3.25 years) to complete one eccentric orbit.

The HD 136118 planetary system[11]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(years)		 Eccentricity Inclination Radius
b 16.5+1.7
−1.8 MJ		 2.353+0.046
−0.045		 3.262+0.053
−0.051		 0.35+0.027
−0.026		 134.0+4.7
−7.5°		 —

See also

References
  1. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  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. S2CID 119257644.
  3. Fischer, Debra A.; et al. (2002). "Planetary Companions to HD 136118, HD 50554, and HD 106252". Publications of the Astronomical Society of the Pacific. 114 (795): 529–535. Bibcode:2002PASP..114..529F. doi:10.1086/341677. JSTOR 10.1086/341677.
  4. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  5. Luck, R. Earle (January 2017). "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants". The Astronomical Journal. 153 (1): 19. arXiv:1611.02897. Bibcode:2017AJ....153...21L. doi:10.3847/1538-3881/153/1/21. S2CID 119511744. 21.
  6. Stassun, Keivan G.; et al. (2017). "Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes". The Astronomical Journal. 153 (3): 136. arXiv:1609.04389. Bibcode:2017AJ....153..136S. doi:10.3847/1538-3881/aa5df3. S2CID 119219062.
  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. Gaia DR2 record for this source at VizieR.
  8. "HD 81040". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-13.
  9. Martioli, Eder; et al. (January 2010). "The Mass of the Candidate Exoplanet Companion to HD 136118 from Hubble Space Telescope Astrometry and High-Precision Radial Velocities". The Astrophysical Journal. 708 (1): 625–634. arXiv:0911.4645. Bibcode:2010ApJ...708..625M. doi:10.1088/0004-637X/708/1/625. S2CID 119183677.
  10. Feng, Fabo; Butler, R. Paul; et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series. 262 (21): 21. arXiv:2208.12720. Bibcode:2022ApJS..262...21F. doi:10.3847/1538-4365/ac7e57. S2CID 251864022.
  11. Xiao, Guang-Yao; Liu, Yu-Juan; et al. (May 2023). "The Masses of a Sample of Radial-Velocity Exoplanets with Astrometric Measurements". Research in Astronomy and Astrophysics. 23 (5): 055022. arXiv:2303.12409. Bibcode:2023RAA....23e5022X. doi:10.1088/1674-4527/accb7e.
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