Star in the constellation Corona Australis
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] light-years (45 parsecs ) from the Sun based on parallax , but is drifting closer with a radial velocity of −18 km/s.[ 1] [ 2] absolute magnitude of 6.20.[ 2]
The stellar classification of HD 166724 is K0IV/V,[ 3] 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 .[ 4] period of around 30 days.[ 4] [ 4] [ 5] photosphere at an effective temperature of 5,101 K.[ 4]
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.[ 4] true mass of HD 166724 b were determined via astrometry .[ 7]
References
^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties" . Astronomy and Astrophysics . 674 : A1. arXiv :2208.00211 Bibcode :2023A&A...674A...1G . doi :10.1051/0004-6361/202243940 S2CID 244398875 . Gaia DR3 record for this source at VizieR .^ a b c d e f 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 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 ^ a b c d e f 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 . ^ a b c d 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 .^ "HD 166724" . SIMBAD Centre de données astronomiques de Strasbourg . Retrieved 2021-03-21 .^ a b Xiao, Guang-Yao; Liu, Yu-Juan; et al. (May 2023). "The Masses of a Sample of Radial-Velocity Exoplanets with Astrometric Measurements". Research in Astronomy and Astrophysics 23 (5): 055022. arXiv :2303.12409 Bibcode :2023RAA....23e5022X . doi :10.1088/1674-4527/accb7e .
