HD 170521
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  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | 18h 31m 56.22382s[1] |
| Declination | −43° 30′ 26.5714″[1] |
| Apparent magnitude (V) | 5.69±0.01[2] |
| Characteristics | |
| Spectral type | K2 III[3] |
| B−V color index | +1.34[4] |
| Astrometry | |
| Radial velocity (Rv) | 7.2±0.4[5] km/s |
| Proper motion (μ) | RA: −1.328 mas/yr[1] Dec.: −8.795 mas/yr[1] |
| Parallax (π) | 2.1538±0.1596 mas[1] |
| Distance | 1,500 ± 100 ly (460 ± 30 pc) |
| Absolute magnitude (MV) | −1.90[6] |
| Details | |
| Mass | 1.55[7] M☉ |
| Radius | 78.6±4.1[8] R☉ |
| Luminosity | 934[9] L☉ |
| Surface gravity (log g) | 0.96[10] cgs |
| Temperature | 4,474±122[11] K |
| Metallicity [Fe/H] | −0.49[7] dex |
| Rotational velocity (v sin i) | 6.5±1[12] km/s |
| Other designations | |
| 12 G. Coronae Australis[13], CD−43°12600, CPD−34°8647, GC 25272, HD 170521, HIP 90842, HR 6937, SAO 229094[14] | |
| Database references | |
| SIMBAD | data |
HD 170521, also known as HR 6937 or rarely 12 G. Coronae Australis, is a solitary star[15] located in the southern constellation Corona Australis. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.69.[2] The object is located relatively far at a distance of approximately 1,500 light years based on Gaia DR3 parallax measurements,[1] and it is receding with a heliocentric radial velocity of 7.2 km/s.[5] At its current distance, HD 170521's brightness is heavily diminished by 0.46 magnitudes due to extinction from interstellar dust[16] and it has an absolute magnitude of −1.90.[6]
HD 170521 has a stellar classification of K2 III,[3] indicating that it is an evolved red giant. It has 1.55 times the mass of the Sun[7] but it has expanded to 78.6 times the Sun's radius.[8] The object radiates 934 times the luminosity of the Sun[9] from its enlarged photosphere at an effective temperature of 4,474 K.[11] HD 170521 is metal deficient with an iron abundance only 32.4% that of the Sun (Fe/H) = −0.49[7] and it spins modestly with a projected rotational velocity of 6.5 km/s.[12]
