S Coronae Australis
Variable star in the constellation Corona Australis
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S Coronae Australis (S CrA), is a young binary star system estimated to be around 2 million years old located in the constellation Corona Australis. It is composed of a G-type main sequence star that is about as luminous as and just over twice as massive as the Sun, and a smaller K-type main sequence star that has around 50-60% of the Sun's luminosity and 1.3 times its mass. Both stars are T Tauri stars and both show evidence of having circumstellar disks. The system is around 140 parsecs distant.[4]
A visual band light curve for S Coronae Australis, adapted from Mundt (1979).[1] The error bar shown on the left-most point applies to all points. | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | 19h 01m 08.59709s[2] |
| Declination | −36° 57′ 19.8950″[2] |
| Apparent magnitude (V) | 10.49 - 13.20[3] |
| Characteristics | |
| Spectral type | G0Ve + K0Ve[4] |
| Variable type | T Tau[3] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | 0.0[5] km/s |
| Proper motion (μ) | RA: +7.054[6] mas/yr Dec.: −26.511[6] mas/yr |
| Parallax (π) | 6.2291±0.0683 mas[6] |
| Distance | 524 ± 6 ly (161 ± 2 pc) |
| B | |
| Radial velocity (Rv) | +6.0[7] km/s |
| Proper motion (μ) | RA: +2.477[8] mas/yr Dec.: −28.079[8] mas/yr |
| Parallax (π) | 6.7857±0.0745 mas[8] |
| Distance | 481 ± 5 ly (147 ± 2 pc) |
| Details | |
| A | |
| Mass | 0.8[9] M☉ |
| Radius | 2.3[9] R☉ |
| Luminosity | 1.7[9] L☉ |
| Surface gravity (log g) | 3.6[10] cgs |
| Temperature | 4,300[11] K |
| Rotation | 7.3[9] days |
| Rotational velocity (v sin i) | 10[10] km/s |
| B | |
| Mass | 0.6[11] M☉ |
| Luminosity | 0.76[11] L☉ |
| Temperature | 3,800[11] K |
| Other designations | |
| S CrA, S Coronae Australis, HH 82 | |
| Database references | |
| SIMBAD | data |
Johann Friedrich Julius Schmidt discovered that the star is a variable star, in 1866. It appeared with its variable star designation in Annie Jump Cannon's 1907 work Second Catalogue of Variable Stars.[12]