| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ara |
| Right ascension | 16h 39m 44.726s[2] |
| Declination | −56° 59′ 39.92″[2] |
| Apparent magnitude (V) | 6.17 (- 6.20) - 7.32[3] |
| Characteristics | |
| Spectral type | B9Vp[4](B5V + F1IV[5]) |
| B−Vcolor index | 0.10[5] |
| Variable type | Algol[4] |
| Astrometry | |
| Radial velocity (Rv) | +5.5[5] km/s |
| Proper motion (μ) | RA: −4.991[6]mas/yr Dec.: −17.810[6]mas/yr |
| Parallax (π) | 3.3603±0.0647 mas[6] |
| Distance | 970 ± 20 ly (298 ± 6 pc) |
| Absolute magnitude (MV) | −0.48 +0.00[5] |
| Orbit[5] | |
| Period (P) | 4.425 d |
| Eccentricity (e) | 0 |
| Inclination (i) | 78.0° |
| Semi-amplitude (K1) (primary) | 55.3 km/s |
| Semi-amplitude (K2) (secondary) | 181.6 km/s |
| Details[5] | |
| A | |
| Mass | 5.0 M☉ |
| Radius | 3.41 R☉ |
| Luminosity | 257 L☉ |
| Surface gravity (log g) | 4.07 cgs |
| Temperature | 12,500 K |
| Rotational velocity (v sin i) | 202[5] km/s |
| B | |
| Mass | 1.5 M☉ |
| Radius | 5.97 R☉ |
| Luminosity | 78 L☉ |
| Surface gravity (log g) | 3.07 cgs |
| Temperature | 7,000 K |
| Rotational velocity (v sin i) | 73 km/s |
| Other designations | |
| AAVSO 1631-56,CD−56°6482,HD 149730,HIP 81589,SAO 244037 | |
| Database references | |
| SIMBAD | data |
R Arae is anAlgol-type eclipsing binary in the constellationAra. Located approximately 298 parsecs (970 ly) distant, it normally shines atmagnitude 6.17, but during eclipses can fall as low as magnitude 7.32.[3] When an eclipse is not occurring, it will be faintly visible to thenaked eye under ideal observing conditions.
In 1892, R Ara was discovered to be an eclipsing binary byAlexander William Roberts at Lovedale observatory inSouth Africa. The discovery was published in 1894.[7] Roberts referred to the star as "(5949) Arae", its designation as an unconfirmed variable star inSeth Carlo Chandler's catalog of variable stars.[8] It was listed with its modernvariable star designation, R Arae, inAnnie Jump Cannon's 1907Second Catalogue of Variable Stars.[9]
It has been suggested by multiple studies thatmass transfer is occurring between the two stars of this system,[10][11] and the period of eclipses seems to be increasing over time.[11] The primary is a blue-white main sequence star of spectral type B5V that is 5 times as massive as the Sun, while the secondary is a yellow-white star of spectral type F1IV that is 1.5 times as massive as the Sun. Stellar material is being stripped off the secondary and accreting on the primary.[5]
R Arae has an 8th-magnitude companion3″ away.[5] The companion star is at a similar distance.[12]
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