HD 166724
HD 166724 is a star in the southern constellation of Corona Australis. It is invisible to the naked eye with an apparent visual magnitude of +9.33.[2] The star is located at a distance of 147 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −18 km/s.[1] It is predicted to come as close as 97.0 light-years in around 1.2 million years from now.[2] The star has an absolute magnitude of 6.20.[2]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | 18h 13m 59.67583s[1] |
| Declination | –42° 34′ 31.3562″[1] |
| Apparent magnitude (V) | +9.33[2] |
| Characteristics | |
| Spectral type | K0IV/V[3] |
| B−V color index | 0.861±0.032[2] |
| Astrometry | |
| Radial velocity (Rv) | −17.84±0.65[1] km/s |
| Proper motion (μ) | RA: +36.110[1] mas/yr Dec.: –80.147[1] mas/yr |
| Parallax (π) | 22.1273 ± 0.0439 mas[4] |
| Distance | 147.4 ± 0.3 ly (45.19 ± 0.09 pc) |
| Absolute magnitude (MV) | 6.20[2] |
| Details[5] | |
| Mass | 0.81±0.02 M☉ |
| Radius | 0.80+0.01 −0.02[1] R☉ |
| Luminosity | 0.388±0.001[1] L☉ |
| Surface gravity (log g) | 4.43±0.08 cgs |
| Temperature | 5,101+50 −41[1] K |
| Metallicity [Fe/H] | −0.09±0.03 dex |
| Age | 4.0±3.8 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| Extrasolar Planets Encyclopaedia | data |
The stellar classification of HD 166724 is K0IV/V,[3] showing blended features of a K-type main-sequence star with a more evolved subgiant star. It is slightly active with chromospheric activity being demonstrated by an emission peak in the Ca II K absorption line.[5] The age of the star is poorly constrained, but it is spinning slowly with a period of around 30 days.[5] It has 81% of the mass of the Sun and 80%[5] of the Sun's girth. The star is radiating 39%[1] of the luminosity of the Sun from its photosphere at an effective temperature of 5,101 K.[5]
Planetary system
From 1998 to 2012, the star was under observance from "the CORALIE echelle spectrograph at La Silla Observatory". In 2012, a long-period, wide-orbiting exoplanet was deduced by radial velocity variations. This was published in November. The discoverers noted that HD 166724 b is among "the three most eccentric planets with a period larger than 5 years" alongside HD 98649 b and HD 219077 b; but unlike them, too dim as a candidate for direct imaging with current technology. The reason for this high orbital eccentricity is unknown.[5]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | >3.53 ± 0.11 MJ | 5.42 ± 0.43 | 5144+705 −467 |
0.734 ± 0.020 | — | — |
References
- 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.
- 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.
- Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H
- van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.Vizier catalog entry
- Marmier, M.; et al. (2013). "The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets". Astronomy and Astrophysics. 551. A90. arXiv:1211.6444. Bibcode:2013A&A...551A..90M. doi:10.1051/0004-6361/201219639. S2CID 59467665.
- "HD 166724". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-03-21.
- "hd_166724_b".
