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.
| 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] |
| Distance | 480 ± 4 ly (147 ± 1 pc) |
| Absolute magnitude (MV) | 2.12[5] |
| Details[2] | |
| Mass | 1.46 M☉ |
| Radius | 5.52 R☉ |
| Luminosity | 13.1±0.1[6] L☉ |
| Surface gravity (log g) | 3.09 cgs |
| Temperature | 4,862 K |
| Metallicity [Fe/H] | 0.05[7] dex |
| Rotational velocity (v sin i) | 1.8±0.6[7] km/s |
| Age | 2.8±0.2[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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
editIn 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]
| 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
edit- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ "HD 99706". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 23 October 2020.
- ^ "The astronomical magnitude scale", International Comet Quarterly, retrieved 2021-02-18.
- ^ 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.
- ^ 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.