HD 99706
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 11h 28m 30.2137s[1]
Declination +43° 57′ 59.6854″[1]
Apparent magnitude (V) 7.65[2]
Characteristics
Evolutionary stage Subgiant[2]
Spectral type K0[3]
B−V color index 1.0[4]
Astrometry
Radial velocity (Rv)−30.07[1] km/s
Proper motion (μ) RA: 45.406[1] mas/yr
Dec.: −87.500[1] mas/yr
Parallax (π)6.7929 ± 0.0518 mas[1]
Distance480 ± 4 ly
(147 ± 1 pc)
Absolute magnitude (MV)2.12[5]
Details[2]
Mass1.46 M☉
Radius5.52 R☉
Luminosity13.1±0.1[6] L☉
Surface gravity (log g)3.09 cgs
Temperature4,862 K
Metallicity [Fe/H]0.05[7] dex
Rotational velocity (v sin i)1.8±0.6[7] km/s
Age2.8±0.2[6] Gyr
Other designations
BD+44°2096, HD 99706, HIP 55994, TYC 3015-1137-1, 2MASS J11283020+4357597[8]
Database references
SIMBADdata

HD 99706 is an orange-hued star in the northern circumpolar constellation of Ursa Major. With an apparent visual magnitude of 7.65,[2] it is too dim to be visible to the naked eye but can be viewed with a pair of binoculars.[9] Parallax measurements provide a distance estimate of approximately 480 light years from the Sun, and the Doppler shift shows it is drifting closer with a radial velocity of −30 km/s.[1] It has an absolute magnitude of 2.12,[5] indicating it would be visible to the naked eye as a 2nd magnitude star if it were located 10 parsecs away.

This is an aging subgiant[2] star belonging to spectral class K0,[3] having exhausted the supply of hydrogen at its core and begun to evolve into a giant. Its age is younger than the Sun's at 2.8±0.2 billion years and it is spinning slowly with a projected rotational velocity of 2 km/s.[7] The star has 1.5 times the mass of the Sun and has expanded to 5.5 times the Sun's radius. It is slightly enriched in heavy elements, having 110% of solar abundance.[7] HD 99706 is radiating 13[6] times the luminosity of the Sun from its photosphere at an effective temperature of 4,862 K.[2]

An imaging survey at Calar Alto Observatory in 2016 failed to detect any stellar companions to HD 99706.[10]

Planetary system

In 2011 one superjovian exoplanet, HD 99706 b, on a mildly eccentric orbit around star HD 99706 was discovered utilizing the radial velocity method.[4] Another superjovian exoplanet on an outer orbit was detected in 2016.[11]

The HD 99706 planetary system[2][11]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
HD 99706 b >1.23 MJ 1.98 841 0.25 — 1.244 RJ
HD 99706 c >5.69+1.43
−0.96 MJ		 — 1278+151
−198		 0.411+0.231
−0.178		 — —

References

  1. 1 2 3 4 5 6 7 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. 1 2 3 4 5 6 7 Luhn, Jacob K.; et al. (2018), "Retired A Stars and Their Companions VIII: 15 New Planetary Signals Around Subgiants and Transit Parameters for California Planet Search Planets with Subgiant Hosts", The Astronomical Journal, 157 (4): 149, arXiv:1811.03043, Bibcode:2019AJ....157..149L, doi:10.3847/1538-3881/aaf5d0, S2CID 102486961.
  3. 1 2 Cannon, A. J.; Pickering, E. C. (October 1993), "Henry Draper Catalogue and Extension", VizieR On-line Data Catalog: III/135A. Originally published in: Harv. Ann. 91-100 (1918-1924), Bibcode:1993yCat.3135....0C.
  4. 1 2 Johnson, John Asher; et al. (2011), "Retired a Stars and Their Companions. Vii. 18 New Jovian Planets", The Astrophysical Journal Supplement Series, 197 (2): 26, arXiv:1108.4205, Bibcode:2011ApJS..197...26J, doi:10.1088/0067-0049/197/2/26, S2CID 15088371.
  5. 1 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.
  6. 1 2 3 Bonfanti, A.; et al. (2015), "Revising the ages of planet-hosting stars", Astronomy & Astrophysics, 575: A18, arXiv:1411.4302, Bibcode:2015A&A...575A..18B, doi:10.1051/0004-6361/201424951, S2CID 54555839.
  7. 1 2 3 4 Ghezzi, Luan; et al. (2018), "Retired a Stars Revisited: An Updated Giant Planet Occurrence Rate as a Function of Stellar Metallicity and Mass", The Astrophysical Journal, 860 (2): 109, arXiv:1804.09082, Bibcode:2018ApJ...860..109G, doi:10.3847/1538-4357/aac37c, S2CID 118969017.
  8. ↑ "HD 99706". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 23 October 2020.
  9. ↑ "The astronomical magnitude scale", International Comet Quarterly, retrieved 2021-02-18.
  10. ↑ Ginski, C.; et al. (2016), "A lucky imaging multiplicity study of exoplanet host stars II", Monthly Notices of the Royal Astronomical Society, 457 (2): 2173–2191, arXiv:1601.01524, Bibcode:2016MNRAS.457.2173G, doi:10.1093/mnras/stw049, S2CID 53626523.
  11. 1 2 Bryan, Marta L.; et al. (2016), "Statistics of Long Period Gas Giant Planets in Known Planetary Systems", The Astrophysical Journal, 821 (2): 89, arXiv:1601.07595, Bibcode:2016ApJ...821...89B, doi:10.3847/0004-637X/821/2/89, S2CID 19709252.
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