Astronomy:HD 99706

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Short description: Star in the constellation Ursa Major
HD 99706
Observation data
Equinox J2000.0]] (ICRS)
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[1] mas
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. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 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, doi:10.3847/1538-3881/aaf5d0, Bibcode2019AJ....157..149L. 
  3. 3.0 3.1 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), Bibcode1993yCat.3135....0C. 
  4. 4.0 4.1 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, doi:10.1088/0067-0049/197/2/26, Bibcode2011ApJS..197...26J. 
  5. 5.0 5.1 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode2012AstL...38..331A. 
  6. 6.0 6.1 6.2 Bonfanti, A. et al. (2015), "Revising the ages of planet-hosting stars", Astronomy & Astrophysics 575: A18, doi:10.1051/0004-6361/201424951, Bibcode2015A&A...575A..18B. 
  7. 7.0 7.1 7.2 7.3 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, doi:10.3847/1538-4357/aac37c, Bibcode2018ApJ...860..109G. 
  8. "HD 99706". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+99706. 
  9. "The astronomical magnitude scale", International Comet Quarterly, http://www.icq.eps.harvard.edu/MagScale.html, 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, doi:10.1093/mnras/stw049, Bibcode2016MNRAS.457.2173G. 
  11. 11.0 11.1 Bryan, Marta L. et al. (2016), "Statistics of Long Period Gas Giant Planets in Known Planetary Systems", The Astrophysical Journal 821 (2): 89, doi:10.3847/0004-637X/821/2/89, Bibcode2016ApJ...821...89B. 

Coordinates: Sky map 11h 28m 30.2137s, +43° 57′ 59.6854″