| |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ara |
| Right ascension | 17h31m 05.91272s[1] |
| Declination | –60° 41′ 01.8522″[1] |
| Apparent magnitude (V) | 3.62[2] |
| Characteristics | |
| Spectral type | B8 Vn[3] + G8 V[4] |
| U−B color index | –0.31[2] |
| B−V color index | –0.10[2] |
| Astrometry | |
| Radial velocity (Rv) | +10[5] km/s |
| Proper motion (μ) | RA: –54.01[1] mas/yr Dec.: –99.25[1] mas/yr |
| Parallax (π) | 16.48 ± 0.34 mas[1] |
| Distance | 198 ± 4 ly (61 ± 1 pc) |
| Absolute magnitude (MV) | −0.31[6] |
| Details | |
| Mass | 3.56[7] M☉ |
| Radius | 3.12 ± 0.15[8] R☉ |
| Luminosity | 214[6] L☉ |
| Surface gravity (log g) | 3.81 ± 0.06[8] cgs |
| Temperature | 11,962 ± 86[8] K |
| Rotational velocity (v sin i) | 255[4] km/s |
| Age | 125[9] Myr |
| Other designations | |
δ Ara, CPD –60° 6842, FK5 648, HD 158094, HIP 85727, HR 6500, SAO 253945.[10] | |
| Database references | |
| SIMBAD | data |
Delta Arae, Latinized from δ Arae, is the Bayer designation for a double star in the southern constellation Ara. It has an apparent visual magnitude of 3.62[2] and is visible to the naked eye. Based upon an annual parallax of 16.48 mas, it is about 198 light-years (61parsecs) distant from the Earth.[1]
Delta Arae is massive B-type main sequence star with a stellar classification of B8 Vn.[3] 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.[4] It has a magnitude 9.5 companion G-type main sequence star that may form a binary star system with Delta Arae.[7]
There is a 12th magnitude optical companion located 47.4 arcseconds away along a position angle of 313°.[9]
Delta Arae was known as 龜三 (meaning: "the 3rd (star) of Guī") in traditional Chinese astronomy.[11][12]
Allen erroneously called both Delta and Zeta Arae "Tseen Yin" (天陰).[13] He probably confused the constellation "Ara" with "Ari", as 天陰 is actually in Aries.[11][12]
{{cite web}}: CS1 maint: postscript (link)
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