Astronomy:HD 33636
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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)[1] mas/yr Dec.: −138.193(29)[1] mas/yr |
| Parallax (π) | 33.7982 ± 0.0529[1] mas |
| Distance | 96.5 ± 0.2 ly (29.59 ± 0.05 pc) |
| Absolute magnitude (MV) | 4.71[2] |
| Orbit[4] | |
| Companion | HD 33636 B |
| Period (P) | 5.807+0.016 −0.017 yr |
| Semi-major axis (a) | 3.329+0.022 −0.023 astronomical unit|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 | |
| Mass | 1.01 ± 0.02[5] M☉ |
| Radius | 0.97 ± 0.01[5] R☉ |
| Luminosity | 1.08 ± 0.003[5] L☉ |
| Surface gravity (log g) | 4.46 ± 0.02[5] cgs |
| Temperature | 5979 ± 28[5] K |
| Age | 2.5 ± 1.1[5] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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 |♃|J}}}}}}. 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
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 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. doi:10.1051/0004-6361:20031340. Bibcode: 2003A&A...410.1039P.
- ↑ 3.0 3.1 "HD 33636". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+33636.
- ↑ 4.0 4.1 4.2 Xiao, Guang-Yao et al. (May 2023). "The Masses of a Sample of Radial-velocity Exoplanets with Astrometric Measurements". Research in Astronomy and Astrophysics 23 (5): 055022. doi:10.1088/1674-4527/accb7e. Bibcode: 2023RAA....23e5022X.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Bonfanti, A. et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics 575: A18. doi:10.1051/0004-6361/201424951. Bibcode: 2015A&A...575A..18B. http://www.aanda.org/articles/aa/full_html/2015/03/aa24951-14/aa24951-14.html.
- ↑ 6.0 6.1 Vogt, Steven S. et al. (2002). "Ten Low-Mass Companions from the Keck Precision Velocity Survey". The Astrophysical Journal 568 (1): 352–362. doi:10.1086/338768. Bibcode: 2002ApJ...568..352V.
- ↑ 7.0 7.1 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. doi:10.1051/0004-6361/202451745.
- ↑ Butler, R. P. et al. (July 2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646 (1): 505–522. doi:10.1086/504701. Bibcode: 2006ApJ...646..505B.
- ↑ 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. doi:10.1086/519956. Bibcode: 2007AJ....134..749B.
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