HD 215497

HD 215497 is a single[4] star in the southern constellation of Tucana. It has an orange hue with an apparent visual magnitude of 8.96,[2] which is too dim to be viewed with the naked eye. A 2015 survey ruled out the existence of any stellar companions at projected distances from 26 to 300 astronomical units.[6] Based on parallax measurements,[1] it is located at a distance of 132 light years from the Sun. The star is drifting further away with a radial velocity of +49 km/s, having come as close as 45 light-years some 774,000 years ago.[3] The absolute magnitude of this star is 5.77.[3]

HD 215497
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Tucana
Right ascension 22h 46m 36.75396s[1]
Declination −56° 35′ 58.3285″[1]
Apparent magnitude (V) 8.96[2]
Characteristics
Spectral type K3V[2]
Apparent magnitude (B) 9.913[3]
Apparent magnitude (J) 7.339±0.024[3]
Apparent magnitude (H) 6.917±0.053[3]
Apparent magnitude (K) 6.784±0.024[3]
B−V color index 0.953±0.025[3]
Astrometry
Radial velocity (Rv)+49.31[3] km/s
Proper motion (μ) RA: −54.660±0.041[1] mas/yr
Dec.: −61.028±0.045[1] mas/yr
Parallax (π)24.6339 ± 0.0324 mas[1]
Distance132.4 ± 0.2 ly
(40.59 ± 0.05 pc)
Absolute magnitude (MV)5.77[3]
Details[4]
Mass0.86±0.02 M☉
Radius0.87±0.02 R☉
Luminosity0.47±0.02 L☉
Surface gravity (log g)4.49±0.03 cgs
Temperature5,128±12 K
Metallicity [Fe/H]0.23±0.07[2] dex
Rotational velocity (v sin i)1.67[2] km/s
Age9.9±2.8 Gyr
Other designations
CPD−57°10139, HD 215497, HIP 112441, SAO 247578, PPM 350516, TYC 8826-00247-1, 2MASS J22463675-5635584[5]
Database references
SIMBADdata
Exoplanet Archivedata

The stellar classification of HD 215497 is K3V,[2] indicating this is a K-type main-sequence star that is generating energy through core hydrogen fusion. The star is about ten[4] billion years old with a low magnetic activity level and is spinning with a projected rotational velocity of 1.67 km/s.[2] It is smaller than the Sun, with 86% of the Sun's mass and 87% of the radius.[4] This is a metal-rich star, which means the abundance of heavier elements in the atmosphere is significantly higher than in the Sun.[2] It is radiating 47% of the luminosity of the Sun from its photosphere at an effective temperature of 5,128 K.[4]

Planetary system

Announced in 2009, two extrasolar planets were discovered to be orbiting the star.[2] Both planets are less massive than Jupiter. The inner exoplanet HD 215497 b orbits very close to the star and is termed a "hot super-Earth". The outer exoplanet HD 215497 c is a giant planet that orbits a little bit further from the star than the Earth, at around 1.282 AU, with a high eccentricity. A check for transits of the inner planet did not reveal any passages.[7]

The HD 215497 planetary system[2]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥6.6 M🜨 0.047 3.93404 ± 0.00066 0.16 ± 0.09 — —
c ≥0.33 MJ 1.282 567.94 ± 2.70 0.49 ± 0.04 — —

References
  1. 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.
  2. Lo Curto, G.; et al. (2015). "The HARPS search for southern extra-solar planets. XXII. Multiple planet systems from the HARPS volume limited sample". Astronomy and Astrophysics. 512. A48. arXiv:1411.7048. Bibcode:2010A&A...512A..48L. doi:10.1051/0004-6361/200913523.
  3. 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.
  4. Bonfanti, A.; et al. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: 14. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692. A5.
  5. "HD 215497". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-11-08.
  6. Mugrauer, M.; Ginski, C. (12 May 2015). "High-contrast imaging search for stellar and substellar companions of exoplanet host stars". Monthly Notices of the Royal Astronomical Society. 450 (3): 3127–3136. Bibcode:2015MNRAS.450.3127M. doi:10.1093/mnras/stv771. Retrieved 19 June 2020.
  7. Gillon, M.; et al. (May 2017). "The Spitzer search for the transits of HARPS low-mass planets. II. Null results for 19 planets". Astronomy & Astrophysics. 601: 23. arXiv:1701.01303. Bibcode:2017A&A...601A.117G. doi:10.1051/0004-6361/201629270. S2CID 86862862. A117.
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