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HD 33636

HD 33636
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Orion
Right ascension 05h 11m 46.44941s[1]
Declination +04° 24′ 12.7421″[1]
Apparent magnitude (V) 7.00[2]
Characteristics
Spectral type G0V_CH-0.3[3]
B−V color index 0.588 ± 0.016[2]
Astrometry
Radial velocity (Rv)5.66±0.13[1] km/s
Proper motion (μ) RA: 181.259(45) mas/yr[1]
Dec.: −138.193(29) mas/yr[1]
Parallax (π)33.7982 ± 0.0529 mas[1]
Distance96.5 ± 0.2 ly
(29.59 ± 0.05 pc)
Absolute magnitude (MV)4.71[2]
Orbit[4]
CompanionHD 33636 B
Period (P)5.807+0.016
−0.017 yr
Semi-major axis (a)3.329+0.022
−0.023 AU
Eccentricity (e)0.483±0.0063
Inclination (i)7.07+0.62
−0.54°
Longitude of the node (Ω)109.9+4.9
−5.0°
Periastron epoch (T)2455442+12
−13
Argument of periastron (ω)
(secondary)		338.2±1.3°
Details
Mass1.01 ± 0.02[5] M☉
Radius0.97 ± 0.01[5] R☉
Luminosity1.08 ± 0.003[5] L☉
Surface gravity (log g)4.46 ± 0.02[5] cgs
Temperature5979 ± 28[5] K
Age2.5 ± 1.1[5] Gyr
Other designations
BD+04 858, HD 33636, HIP 24205, SAO 112506, G 97-25[3]
Database references
SIMBADdata

HD 33636 is a G-type main-sequence star located approximately 96.5 light-years away in the Orion constellation. It is a 7th magnitude star with a metallicity of −0.05 ± 0.07. A likely substellar companion was discovered in 2002.[6][7]

Companion

HD 33636 b was discovered in 2002 by the Keck telescope in Hawaii using the radial velocity method.[6] It was independently detected at the Haute-Provence Observatory in France.[2] With this method it showed a minimum mass of 9.28 Jupiter masses, and was initially assumed to be a planet and labelled "HD 33636 b" (lower-case).[8]

In 2007, Bean et al. used the Hubble Space Telescope (HST) astrometry to find that this body has an inclination as little as 4.1 ± 0.1°, which yielded a true mass of 142 MJ. This is too high to be a planet. It was classified by this study as an M-dwarf star of likely spectral type M6V, "HD 33636 B" (upper-case).[9]

This picture was further revised in the 2020s. A 2023 study using astrometry from Hipparcos and Gaia found that the mass had likely been overestimated, and found a lower true mass of about 77.8 MJ. This would place HD 33636 b near the borderline between stars and brown dwarfs.[4] A 2024 study using Gaia astrometry even excluded the possibility of a companion mass greater than 40 MJ, instead finding a mass range more compatible with the initial minimum mass estimate. This study estimated a mass of about 15.4 MJ, near the borderline between brown dwarfs and planets.[7]

This object takes 2121 days or 5.807 years to orbit at a semimajor axis of 3.33 astronomical units (AU).[4]

References

  1. ^ a b c d e 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. ^ a b c d Perrier, C.; et al. (2003). "The ELODIE survey for northern extra-solar planets. I. Six new extra-solar planet candidates". Astronomy and Astrophysics. 410 (3): 1039–1049. arXiv:astro-ph/0308281. Bibcode:2003A&A...410.1039P. doi:10.1051/0004-6361:20031340. S2CID 6946291.
  3. ^ a b "HD 33636". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 26 September 2024.
  4. ^ a b c 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. S2CID 257663647.
  5. ^ a b c d e f Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575. A18. arXiv:1411.4302. Bibcode:2015A&A...575A..18B. doi:10.1051/0004-6361/201424951. S2CID 54555839.
  6. ^ a b Vogt, Steven S.; et al. (2002). "Ten Low-Mass Companions from the Keck Precision Velocity Survey". The Astrophysical Journal. 568 (1): 352–362. arXiv:astro-ph/0110378. Bibcode:2002ApJ...568..352V. doi:10.1086/338768. S2CID 2272917.
  7. ^ a b Kiefer, Flavien; Lagrange, Anne-Marie; Rubini, Pascal; Philipot, Florian (September 2024). "Searching for substellar companion candidates with Gaia. II. A catalog of 9,698 planet candidate solar-type hosts". Astronomy & Astrophysics. arXiv:2409.16993.
  8. ^ Butler, R. P.; Wright, J. T.; et al. (July 2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701.
  9. ^ Bean, Jacob L.; et al. (2007). "The Mass of the Candidate Exoplanet Companion to HD 33636 from Hubble Space Telescope Astrometry and High-Precision Radial Velocities". The Astronomical Journal. 134 (2): 749–758. arXiv:0705.1861. Bibcode:2007AJ....134..749B. doi:10.1086/519956. S2CID 119599833.
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