Astronomy:HD 162020
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Scorpius |
| Right ascension | 17h 50m 38.35575s[1] |
| Declination | −40° 19′ 06.0723″[1] |
| Apparent magnitude (V) | 9.10[2] |
| Characteristics | |
| Spectral type | K3V[3] |
| B−V color index | 0.964±0.066[2] |
| Astrometry | |
| Radial velocity (Rv) | −26.55±2.30[4] km/s |
| Proper motion (μ) | RA: +19.412[1] mas/yr Dec.: −25.799[1] mas/yr |
| Parallax (π) | 31.8624 ± 0.0622[1] mas |
| Distance | 102.4 ± 0.2 ly (31.38 ± 0.06 pc) |
| Absolute magnitude (MV) | 6.76[2] |
| Orbit[5] | |
| Period (P) | 8.4282388+0.0000014 −0.0000026 d |
| Semi-major axis (a) | 0.0859±0.0010 astronomical unit|AU |
| Eccentricity (e) | 0.28126±0.00057 |
| Inclination (i) | 177.273+0.030 −0.027° |
| Longitude of the node (Ω) | 288.93+0.67 −0.73° |
| Periastron epoch (T) | 2457393.1874+0.0026 −0.0023 |
| Argument of periastron (ω) (secondary) | 28.70+0.13 −0.12° |
| Semi-amplitude (K1) (primary) | 1.8112+0.0013 −0.0016 km/s |
| Details[5] | |
| Mass | 0.797±0.042 M☉ |
| Radius | 0.770±0.017 R☉ |
| Luminosity | 0.413+0.056 −0.050 L☉ |
| Surface gravity (log g) | 4.567±0.028 cgs |
| Temperature | 5,270+190 −180 K |
| Metallicity [Fe/H] | −0.18+0.17 −0.19 dex |
| Rotational velocity (v sin i) | 1.9[6] km/s |
| Age | 5.7±4.7 Gyr[7] 3.1±2.7[8] Gyr |
| HD 162020 b | |
| Mass | 0.39±0.02[9] M☉ |
| Mass | 410.8+5.8 −5.3 MJup |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 162020 is a star in the southern constellation of Scorpius with a likely red dwarf companion. It has an apparent visual magnitude of 9.10,[2] which is too faint to be visible to the naked eye. The distance to this system is 102 light-years (31 parsecs) based on stellar parallax.[1] It is drifting closer to the Sun with a radial velocity of −27 km/s,[4] and is predicted to come to within ~18 light-years in 1.1 million years.[11]
This is an ordinary K-type main-sequence star with a stellar classification of K3V.[3] The age estimate is poorly constrained but it appears to have an intermediate age of several billion years. However, the activity level suggests a younger star; the rotation rate of the star may have been increased through synchronization with the companion, resulting in a higher than normal activity for its age.[6] X-ray emission has been detected from this star.[12]
HD 162020 has 74%[7] of the mass of the Sun and 73%[4] of the Sun's radius. The abundance of iron is roughly the same as the Sun, suggesting a similar metallicity. It is radiating just 25.8% of the luminosity of the Sun from its photosphere at an effective temperature of 4,801 K.[4] The star is spinning with a projected rotational velocity of 1.9 km/s.[6]
Companion
HD 162020 b is a companion, initially thought to be a brown dwarf, with a minimum mass of 15.0 |♃|J}}}}}}. At the time of discovery, the actual mass was undetermined since the orbital inclination was not known. This object orbits very close to the star at a distance of 0.075 astronomical unit|AU with an eccentricity (ovalness) of 0.277. The object's distance from the star ranges from 0.054 to 0.096 AU. It has an extremely high semi-amplitude of 1,813 m/s. The discovery was announced on April 15, 2000 by the Geneva Extrasolar Planet Search Team.[13][6]
Despite the presence of this massive object in an eccentric orbit around the star, computer modelling done in 2017 (when the object was still thought to be a brown dwarf) showed it is still theoretically possible for an Earth-mass exoplanet to be occupying a dynamically-stable orbit in the habitable zone of this star.[14]
An astrometric measurement of this object's true mass was published in 2022 as part of Gaia DR3, revealing it to be 0.39 M☉ and thus likely a red dwarf star.[9] A full orbital solution was published in 2023.[5]
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 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 3.0 3.1 Torres, C. A. O. et al. (December 2006). "Search for associations containing young stars (SACY). I. Sample and searching method". Astronomy and Astrophysics 460 (3): 695–708. doi:10.1051/0004-6361:20065602. Bibcode: 2006A&A...460..695T.
- ↑ 4.0 4.1 4.2 4.3 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 5.0 5.1 5.2 Unger, N. et al. (December 2023). "Exploring the brown dwarf desert with precision radial velocities and Gaia DR3 astrometric orbits". Astronomy & Astrophysics 680: A16. doi:10.1051/0004-6361/202347578. Bibcode: 2023A&A...680A..16U.
- ↑ 6.0 6.1 6.2 6.3 Udry, M. et al. (2002). "The CORALIE survey for southern extra-solar planets VIII. The very low-mass companions of HD 141937, HD 162020, HD 168443, HD 202206: Brown dwarfs or "superplanets"?". Astronomy and Astrophysics 390 (1): 267–279. doi:10.1051/0004-6361:20020685. Bibcode: 2002A&A...390..267U. http://www.aanda.org/articles/aa/full/2002/28/aa2416/aa2416.html.
- ↑ 7.0 7.1 Delgado Mena, E. et al. (April 2019). "Abundance to age ratios in the HARPS-GTO sample with Gaia DR2. Chemical clocks for a range of [Fe/H]". Astronomy & Astrophysics 624: 24. doi:10.1051/0004-6361/201834783. A78. Bibcode: 2019A&A...624A..78D.
- ↑ Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics 585: A5, 14 pp. doi:10.1051/0004-6361/201527297. Bibcode: 2016A&A...585A...5B.
- ↑ 9.0 9.1 Gaia Collaboration et al. (June 2023). "Gaia Data Release 3: Stellar multiplicity, a teaser for the hidden treasure". Astronomy & Astrophysics 674: A34. doi:10.1051/0004-6361/202243782. Bibcode: 2023A&A...674A..34G.
- ↑ "HD 162020". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+162020.
- ↑ Bailer-Jones, C.A.L. et al. (2018). "New stellar encounters discovered in the second Gaia data release". Astronomy & Astrophysics 616: A37. doi:10.1051/0004-6361/201833456. Bibcode: 2018A&A...616A..37B.
- ↑ Poppenhaeger, K.; Schmitt, J. H. M. M. (July 2011). "A Correlation Between Host Star Activity and Planet Mass for Close-in Extrasolar Planets?". The Astrophysical Journal 735 (1): 5. doi:10.1088/0004-637X/735/1/59. 59. Bibcode: 2011ApJ...735...59P.
- ↑ "Exoplanets Galore!" (Press release). Garching, Germany: European Southern Observatory. April 15, 2000. Retrieved December 30, 2012.
- ↑ Agnew, Matthew T.; Maddison, Sarah T.; Thilliez, Elodie; Horner, Jonathan (2017). "Stable habitable zones of single Jovian planet systems". Monthly Notices of the Royal Astronomical Society 471 (4): 4494–4507. doi:10.1093/mnras/stx1449. Bibcode: 2017MNRAS.471.4494A.
External links
- "Notes for star HD 162020". Extrasolar Planets Encyclopaedia. http://exoplanet.eu/star.php?st=HD+162020. Retrieved December 21, 2007.
- "Notes for planet HD 162020 b". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/hd_162020_b--20/. Retrieved December 21, 2007.
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