HD_99706 Latitude and Longitude:
Sky map 11h 28m 30.2137s, +43° 57′ 59.6854″
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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
SIMBAD data

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. ^ a b c d e f g 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. ^ a b c d e f g 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. ^ a b 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. ^ a b 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. ^ a b 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. ^ a b c 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. ^ a b c d 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. ^ a b 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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