| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | 18h58m 43.37714s[2] |
| Declination | −37° 06′ 26.4865″[2] |
| Apparent magnitude (V) | +4.75[3] |
| Characteristics | |
| Spectral type | F4V Fe-0.8[4] |
| U−B color index | +0.01[3] |
| B−V color index | +0.39[3] |
| Variable type | W UMa[5] |
| Astrometry | |
| Radial velocity (Rv) | 57.90 ± 1.2[6] km/s |
| Proper motion (μ) | RA: −132.40[2] mas/yr Dec.: −110.62[2] mas/yr |
| Parallax (π) | 33.13 ± 0.33 mas[2] |
| Distance | 98.4 ± 1.0 ly (30.2 ± 0.3 pc) |
| Absolute magnitude (MV) | 2.21[7] |
| Orbit[8] | |
| Period (P) | 0.59143357 ± 0.00000016 d |
| Semi-major axis (a) | 3.795 ± 0.052 R☉ |
| Eccentricity (e) | 0 |
| Inclination (i) | 73.05 ± 0.16° |
| Longitude of the node (Ω) | 2.0113 ± 0.0033° |
| Periastron epoch (T) | JD 2442296.95907 ± 0.0070 |
| Details | |
| ε CrA A | |
| Mass | 1.9[8] M☉ |
| Radius | 2.167[8][note 1] R☉ |
| Temperature | 6481 ± 20[8] K |
| Rotational velocity (v sin i) | 148.5[9] km/s |
| ε CrA B | |
| Mass | 0.24[8] M☉ |
| Radius | 0.869[8][note 1] R☉ |
| Temperature | 5939 ± 19[8] K |
| Other designations | |
ε CrA, CD−37°13001, CPD−37°8433, HD 175813, HIP 93174, HR 7152, SAO 210781[5] | |
| Database references | |
| SIMBAD | data |
Epsilon Coronae Australis (ε CrA), is a star system located in the constellation Corona Australis. Varying in brightness between apparent magnitudes of 4.74 to 5 over 14 hours, it is one of the brightest W Ursae Majoris variable (low mass contact binary) in the night sky.
Nicolas Louis de Lacaille gave Epsilon Coronae Australis its Bayer designation. It is also known as HR 7152, and HD 175813.
Epsilon Coronae Australis is an F4V dwarf star with an effective temperature of 6000 Kelvin. It ranges between apparent magnitudes of 4.74 to 5 over 14 hours,[10] an absolute magnitude of +2.45, and a mass of 1.1 solar masses. Epsilon Coronae Australis is a W Ursae Majoris variable, indicating that it has a contact companion within the Roche limit of the primary. The star is located at a distance of 30 pc (97 light years) from the Sun.[7] Yildiz and colleagues estimated the age of the system at 2.83 ± 0.28 billion years based on study of the properties of the system and estimated rate of mass transfer. They found the current masses of the primary and secondary to be 1.72 ± 0.04 and 0.22 ± 0.02 solar masses respectively, from their original masses of 1.06 ± 0.03 and 2.18 ± 0.06 solar masses.[11]
|
| |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||
| Stars |
| ||||||||||
| |||||||||||
| |||||||||||
| |||||||||||
