HD 162020

Last updated
HD 162020
Observation data
Epoch J2000       Equinox J2000
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  mas/yr [1]
Dec.: −25.799  mas/yr [1]
Parallax (π)31.8624 ± 0.0622  mas [1]
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  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
CD−40°11894, HD  162020, HIP  87330, PPM  763039 [10]
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]

Contents

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  MJ. 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  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]

Related Research Articles

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HD 114729 is a Sun-like star with an orbiting exoplanet in the southern constellation of Centaurus. Based on parallax measurements, it is located at a distance of 124 light years from the Sun. It is near the lower limit of visibility to the naked eye, having an apparent visual magnitude of 6.68 The system is drifting further away with a heliocentric radial velocity of 26.3 km/s. The system has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.373″·yr−1.

HD 121504 is a star with an orbiting exoplanet in the southern constellation of Centaurus. It is located at a distance of 136 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 19.6 km/s. With an apparent visual magnitude of 7.54, this star is too faint to be visible to the naked eye. It shows a high proper motion, traversing the celestial sphere at an angular rate of 0.270 arcsec yr−1.

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HD 142 is a wide binary star system in the southern constellation of Phoenix. The main component has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.7. The system is located at a distance of 85.5 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +6 km/s.

NGC 2423-3 is a red giant star approximately 3,040 light-years away in the constellation of Puppis. The star is part of the NGC 2423 open cluster. The star has an apparent magnitude of 10 and an absolute magnitude of zero, with a mass of 2.4 times the Sun. In 2007, it was proposed that an exoplanet orbits the star, but this is now doubtful.

HD 4113 is a dual star system in the southern constellation of Sculptor. It is too faint to be viewed with the naked eye, having an apparent visual magnitude of 7.88. The distance to this star, as estimated by parallax measurements, is 137 light years. It is receding away from the Sun with a radial velocity of +5 km/s.

HD 190228 is a star with an orbiting substellar companion in the northern constellation of Vulpecula. Its apparent magnitude is 7.30 – too faint to be seen with the naked eye – and the absolute magnitude is 3.34. Based on parallax measurements, it is located at a distance of 205 light-years from the Sun. The system is drifting closer with a radial velocity of −50 km/s.

HD 213240 is a possible binary star system in the constellation Grus. It has an apparent visual magnitude of 6.81, which lies below the limit of visibility for normal human sight. The system is located at a distance of 133.5 light years from the Sun based on parallax. The primary has an absolute magnitude of 3.77.

HD 60532 is a star with two orbiting exoplanets in the southern constellation of Puppis. The designation HD 60532 takes its name from the Henry Draper Catalogue. The system is located at a distance of 85.5 light years from the Sun, and is drifting further away with a radial velocity of 61 km/s. At that distance, the star has an apparent visual magnitude of 4.45, which is bright enough to be faintly visible to the naked eye. The motion of this system through space brought it within 10.3 light-years of the Sun some 408,600 years ago.

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HD 86226 is a star with a pair of orbiting exoplanet companions, found in the constellation of Hydra. With an apparent visual magnitude of 7.93, it is too dim to be visible with the naked eye. The distance to this system has been determined by the parallax method, yielding a range of 149 light years. It is receding with a heliocentric radial velocity of +19.6 km/s. A survey in 2015 has ruled out the existence of any stellar companions at projected distances above 12 astronomical units.

HD 152079 is a star with an orbiting exoplanet in the southern constellation of Ara. It is located at a distance of 287 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −21 km/s. At that distance the star is much too faint to be visible with the naked eye, having an apparent visual magnitude of 9.18.

HD 175167 is a star with an exoplanet companion in the southern constellation of Pavo. It is too faint to be visible with the naked eye at an apparent visual magnitude of 8.01. The system is located at a distance of 232 light-years from the Sun based on parallax measurements, and it is drifting further away with a radial velocity of 5 km/s. It shows a high proper motion, traversing the celestial sphere at an angular rate of 0.190 arcsec yr−1.

HD 175167 b is an exoplanet orbiting HD 175167, which is a G type star within the Pavo constellation 232 light-years away from the Earth. The planet was discovered by the Magellan Planet Search Program as the astronomical object fit the Keplerian orbital model. During the observations 13 doppler velocity tests were conducted, which showed this object's mass was at least 7.8 Jovian-masses and its orbit has a high eccentricity. The exoplanet takes 3.53 years to complete a full stellar orbit.

HD 220689 is a single star in the equatorial constellation of Aquarius. It is a challenge to view with the naked eye, having an apparent visual magnitude of +7.74, but is readily viewed with a pair of binoculars. The star is located at a distance of 153 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +12 km/s. A survey in 2015 has ruled out the existence of any additional stellar companions at projected distances from 26 to 305 astronomical units.

HD 106515 is a binary star in the constellation of Virgo.

HD 109271 is a wide binary star system in the constellation of Virgo. The brighter member of the binary has a pair of orbiting exoplanets. With an apparent visual magnitude of 8.05, it cannot be seen with the naked eye. Parallax measurements made by Gaia put the star at a distance of 181 light-years away from the Sun, but it is drifting closer with a radial velocity of −5 km/s. The system shows a high proper motion, traversing the celestial sphere at an angular rate of 0.232 arcsec yr−1.

<span class="mw-page-title-main">HD 189567</span> Star in the constellation Pavo

HD 189567 is a star with a pair of orbiting exoplanets, located in the southern constellation of Pavo. It is also known as Gliese 776, CD-67 2385, and HR 7644. The star has an apparent visual magnitude of 6.07, which is bright enough for it to be dimly visible to the naked eye. It lies at a distance of 58 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −10.5 km/s.

References

  1. 1 2 3 4 5 6 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. 1 2 3 4 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. 1 2 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. arXiv: astro-ph/0609258 . Bibcode:2006A&A...460..695T. doi:10.1051/0004-6361:20065602. S2CID   16080025.
  4. 1 2 3 4 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.
  5. 1 2 3 Unger, N.; Ségransan, D.; et al. (December 2023). "Exploring the brown dwarf desert with precision radial velocities and Gaia DR3 astrometric orbits". Astronomy & Astrophysics . 680: A16. arXiv: 2310.02758 . Bibcode:2023A&A...680A..16U. doi:10.1051/0004-6361/202347578.
  6. 1 2 3 4 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. arXiv: astro-ph/0202458 . Bibcode:2002A&A...390..267U. doi:10.1051/0004-6361:20020685. S2CID   9389274.
  7. 1 2 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. arXiv: 1902.02127 . Bibcode:2019A&A...624A..78D. doi:10.1051/0004-6361/201834783. S2CID   90259810. A78.
  8. ↑ Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: A5, 14 pp. arXiv: 1511.01744 . Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID   53971692.
  9. 1 2 Gaia Collaboration; et al. (June 2023). "Gaia Data Release 3: Stellar multiplicity, a teaser for the hidden treasure". Astronomy & Astrophysics . 674: A34. arXiv: 2206.05595 . Bibcode:2023A&A...674A..34G. doi:10.1051/0004-6361/202243782.
  10. ↑ "HD 162020". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2018-04-02.
  11. ↑ Bailer-Jones, C.A.L.; et al. (2018). "New stellar encounters discovered in the second Gaia data release". Astronomy & Astrophysics. 616: A37. arXiv: 1805.07581 . Bibcode:2018A&A...616A..37B. doi:10.1051/0004-6361/201833456. S2CID   56269929.
  12. ↑ 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. arXiv: 1106.0189 . Bibcode:2011ApJ...735...59P. doi:10.1088/0004-637X/735/1/59. S2CID   11359940. 59.
  13. ↑ "Exoplanets Galore!" (Press release). Garching, Germany: European Southern Observatory. April 15, 2000. Retrieved December 30, 2012.
  14. ↑ 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. arXiv: 1706.05805 . Bibcode:2017MNRAS.471.4494A. doi: 10.1093/mnras/stx1449 . S2CID   119227856.
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