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 | |
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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]
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 | — | — |
Constellation of Corona Australis | |||||||||||
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Stars |
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