HD 170773
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| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | 18h 33m 00.91673s[2] |
| Declination | −39° 53′ 31.2751″[2] |
| Apparent magnitude (V) | 6.22±0.01[3] |
| Characteristics | |
| Spectral type | F5 V[4][5] |
| B−V color index | +0.42[6] |
| Astrometry | |
| Radial velocity (Rv) | −25.2±1.0[7] km/s |
| Proper motion (μ) | RA: +86.353 mas/yr[2] Dec.: −79.927 mas/yr[2] |
| Parallax (π) | 27.0749±0.03 mas[2] |
| Distance | 120.5 ± 0.1 ly (36.93 ± 0.04 pc) |
| Absolute magnitude (MV) | +3.38[8] |
| Details | |
| Mass | 1.30[9] M☉ |
| Radius | 1.43±0.07[10] R☉ |
| Luminosity | 3.62±0.01[2] L☉ |
| Surface gravity (log g) | 4.21±0.04[11] cgs |
| Temperature | 6,694±126[12] K |
| Metallicity [Fe/H] | −0.02±0.04[13] dex |
| Rotational velocity (v sin i) | 67.2±6.2[14] km/s |
| Age | 1.50+1.2 −0.7[11] Gyr |
| Other designations | |
| 14 G. Coronae Australis[15], CD−39°12704, CPD−39°8118, FK5 3470, GC 25304, HD 170773, HIP 90936, HR 6948, SAO 210286, TIC 313723578 | |
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| Database references | |
| SIMBAD | data |
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HD 170773 (HR 6948; 14 G. Coronae Australis) is a solitary star located in the southern constellation Corona Australis. It has an apparent magnitude of 6.22,[3] placing it near the limit for naked eye visibility, even under ideal conditions. The object is located relatively close at a distance of 120 light-years based on Gaia DR3 parallax measurements[2] and it is drifting closer with a heliocentric radial velocity of −25.2 km/s.[7] At its current distance, HD 170773's brightness is diminished by an interstellar extinction of 0.19 magnitudes[16] and it has an absolute magnitude of +3.38.[8]
HD 170773 has a stellar classification of F5 V,[4][5] indicating that it is an ordinary F-type main-sequence star that is generating energy via hydrogen fusion at its core. It has also been given a classification of F5 IV, indicating that it is a slightly evolved subgiant that is ceasing hydrogen fusion at its core. It has 1.30 times the mass of the Sun[9] and 1.43 times the radius of the Sun.[10] It radiates 3.62 times the luminosity of the Sun[2] from its photosphere at an effective temperature of 6,694 K,[12] giving it the typical yellowish-white hue of a F-type star. HD 170773 has a near solar metallicity of [Fe/H] = −0.02[13] and it is estimated to be 1.5 billion years old.[11] It spins fairly quickly with a projected rotational velocity of 67.2 km/s.[14]
The star has a debris disk located 78 AU away and it has a temperature of 43 K.[17] It was first observed in 1986 by astronomers K. Sakadane and M. Nishida in their survey of Vega-like stars due to the star displaying an infrared excess that could suggest the presence of a circumstellar disk.[18] However, the actual disk was not discovered until 2004 using the Spitzer Space Telescope.[19] There might be a second cooler disk surrounding the star, but subsequent observations have not confirmed this.[17]
