HD 68988

HD 68988 is a star in the northern constellation of Ursa Major. It has been given the proper name Násti, which means star in the Northern Sami language. The name was selected in the NameExoWorlds campaign by Norway, during the 100th anniversary of the IAU.[8][9] HD 68988 is too faint to be seen with the naked eye, having an apparent visual magnitude of 8.20.[2] The star is located at a distance of 199 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −69 km/s and is predicted to come as close as 78 light-years in 617,000 years.[2]

HD 68988
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 08h 18m 22.1727s[1]
Declination +61° 27′ 38.5973″[1]
Apparent magnitude (V) 8.20[2]
Characteristics
Spectral type G0V[3] or G2V[4] or G2IV[2]
B−V color index 0.652±0.015[2]
Astrometry
Radial velocity (Rv)−69.45±0.11[2] km/s
Proper motion (μ) RA: 128.329±0.073[1] mas/yr
Dec.: 30.270±0.059[1] mas/yr
Parallax (π)16.4066 ± 0.0513[1] mas
Distance198.8 ± 0.6 ly
(61.0 ± 0.2 pc)
Absolute magnitude (MV)4.52[2]
Details[5]
Mass1.16±0.01 M☉
Radius1.08±0.01 R☉
Luminosity1.297±0.002 L☉
Surface gravity (log g)4.42±0.01 cgs
Temperature5919±11 K
Metallicity [Fe/H]0.29±0.01[2] dex
Rotational velocity (v sin i)6.4[6] km/s
Age1.0±0.4 Gyr
Other designations
BD+61°1038, HD 68988, HIP 40687, SAO 14494[7]
Database references
SIMBADdata

The stellar classification of HD 68988 has been given as G0V,[3] G2V,[4] and G2IV.[2] The age of this star was estimated as six billion years in 2002,[4] but was later revised down to one billion years in 2015.[5] It is rotating slowly and is chromospherically inactive.[10] The star has 16% more mass than the Sun and an 8% greater radius with a high metallicity; what astronomers term the abundance of heavier elements. It is radiating 1.3 times the luminosity of the Sun from its photosphere at an effective temperature of 5,919 K.[5]

Planetary system

There are two exoplanet: HD 68988 b was discovered in 2002[4] and HD 68988 c was discovered in 2006.[11] The orbit of the inner exoplanet is surprisingly eccentric for such a close in orbit, and over time it may become circularized.[10]

The HD 68988 planetary system[11][10]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >1.86 ± 0.16 MJ 0.0704 ± 0.0041 6.27711 ± 0.00021 0.1249 ± 0.0087 — —
c >5–20 MJ 5–7 4000–22000 ? — —

See also
  • List of extrasolar planets

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. 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. van Belle, Gerard T.; von Braun, Kaspar (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars". The Astrophysical Journal. 694 (2): 1085–1098. arXiv:0901.1206. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085.
  4. 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.
  5. 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.
  6. Luck, R. Earle (January 2017). "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants". The Astronomical Journal. 153 (1): 19. arXiv:1611.02897. Bibcode:2017AJ....153...21L. doi:10.3847/1538-3881/153/1/21. S2CID 119511744. 21.
  7. "HD 68988". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-13.
  8. "Approved names". NameExoworlds. Retrieved 2020-01-02.
  9. "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
  10. Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701.
  11. Wright, J. T.; et al. (2007). "Four New Exoplanets and Hints of Additional Substellar Companions to Exoplanet Host Stars". The Astrophysical Journal. 657 (1): 533–545. arXiv:astro-ph/0611658. Bibcode:2007ApJ...657..533W. doi:10.1086/510553.

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