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
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]
| 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
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