Gamma Coronae Australis (γ CrA), is a binary star located in the constellation Corona Australis. The system has a combined apparent visual magnitude of 4.20,[2] making it faintly visible to the naked eye. It is located 56.4 light-years (17.3 parsecs) from the Sun, based on its parallax.[1] Gamma Coronae Australis is a member of the Milky Way's thin disk.[6]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | 19h 06m 25.11014s[1] |
| Declination | −37° 03′ 48.3901″[1] |
| Apparent magnitude (V) | 4.20[2] |
| Characteristics | |
| Spectral type | F8V + F8V[3] |
| U−B color index | +0.51[4] |
| B−V color index | +0.01[4] |
| Astrometry | |
| Radial velocity (Rv) | −51.60 ± 0.3[5] km/s |
| Proper motion (μ) | RA: 96.74 ± 1.05[1] mas/yr Dec.: −281.71 ± 0.58[1] mas/yr |
| Parallax (π) | 57.79 ± 0.75 mas[1] |
| Distance | 56.4 ± 0.7 ly (17.3 ± 0.2 pc) |
| Absolute magnitude (MV) | 3.73 / 3.80[6] |
| Orbit[7] | |
| Period (P) | 121.76 yr |
| Semi-major axis (a) | 1.896″ |
| Eccentricity (e) | 0.320 |
| Inclination (i) | 149.6° |
| Longitude of the node (Ω) | 50.3° |
| Periastron epoch (T) | 2000.64 |
| Argument of periastron (ω) (secondary) | 349.0° |
| Details[6] | |
| γ CrA A | |
| Mass | 1.15 M☉ |
| Radius | 1.47 R☉ |
| Surface gravity (log g) | 4.17 cgs |
| Temperature | 6,090 K |
| Metallicity [Fe/H] | −0.07 dex |
| Age | 5 Gyr |
| γ CrA B | |
| Mass | 1.14 M☉ |
| Radius | 1.42 R☉ |
| Surface gravity (log g) | 4.19 cgs |
| Temperature | 6,100 K |
| Metallicity [Fe/H] | −0.07 dex |
| Age | 5 Gyr |
| Other designations | |
| γ CrA A: HD 177474, HR 7226[8] | |
| γ CrA B: HD 177475, HR 7227[9] | |
| Database references | |
| SIMBAD | γ CrA |
| γ CrA A | |
| γ CrA B | |
The system is a visual binary, where the orbit is calculated from observations of one star orbiting the other. The primary, Gamma Coronae Australis A, is a late F-type main-sequence star with an effective temperature of 6,090 K.[6] It has an absolute an absolute magnitude of +3.73, and a mass of 1.15 solar masses.[6] The secondary, Gamma Coronae Australis B, is also F-type. With an effective temperature of 6,100 K, an absolute magnitude of +3.80, and a mass of 1.14 solar masses, the companion is almost identical to the primary.[6] Gamma Coronae Australis has been known to be a binary for a long time, and its two components have been given Henry Draper Catalogue designations of HD 177474[8] and HD 177475,[9] respectively. The two stars are separated by 1.896″ and orbit each other every 121.76 years.[7]
Constellation of Corona Australis | |||||||||||
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