Delta Arae
 δ Arae (lower center) in the Ara Constellation |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Ara |
| Right ascension | 17h 31m 05.91272s |
| Declination | –60° 41′ 01.8522″ |
| Apparent magnitude (V) | 3.62 |
| Characteristics | |
| Spectral type | B8 Vn + G8 V |
| U−B color index | –0.31 |
| B−V color index | –0.10 |
| Astrometry | |
| Radial velocity (Rv) | +10 km/s |
| Proper motion (μ) |
RA: –54.01 mas/yr Dec.: –99.25 mas/yr |
| Parallax (π) | 16.48 ± 0.34mas |
| Distance | 198 ± 4 ly (61 ± 1 pc) |
| Details | |
| Mass | 3.56 M☉ |
| Radius | 3.12 ± 0.15 R☉ |
| Surface gravity (log g) | 3.81 ± 0.06 cgs |
| Temperature | 11,962 ± 86 K |
| Rotational velocity (v sin i) | 255 km/s |
| Age | 125 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Delta Arae (δ Arae, δ Ara) is the Bayer designation for a double star in the southern constellation Ara. It has an apparent visual magnitude of 3.62 and is visible to the naked eye. Based upon an annual parallax of 16.48 mas, it is about 198 light-years (61 parsecs) distant from the Earth.
Delta Arae is massive B-type main sequence star with a stellar classification of B8 Vn. The 'n' suffix indicates the absorption lines are spread out broadly because the star is spinning rapidly. It has a projected rotational velocity of 255 km/s, resulting in an equatorial bulge with a radius 13% larger than the polar radius. It has a magnitude 9.5 companion G-type main sequence star that may form a binary star system with Delta Arae.
There is a 12th magnitude optical companion located 47.4 arcseconds away along a position angle of 313°.
Delta Arae was known as 龜三 (meaning: "the 3rd (star) of Guī") in traditional Chinese astronomy.
Allen erroneously called it with ζ Arae as Tseen Yin (天陰). He probably confused constellation "Ara" with "Ari". Tseen Yin was lain in Aries.
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