Delta Arae
Star in the constellation Ara
From Wikipedia, the free encyclopedia
Delta Arae is a binary star[7] in the southern constellation Ara. Its name is a Bayer designation that is Latinized from δ Arae, and abbreviated Delta Ara or δ Ara. This system has an apparent visual magnitude of 3.62[2] and is visible to the naked eye as a point of light. Based upon an annual parallax of 16.48 mas, it is about 198 light-years (61 parsecs) distant from the Earth.[1]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ara |
| Right ascension | 17h 31m 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[1] Dec.: −99.25 mas/yr[1] |
| Parallax (π) | 16.48±0.34 mas[1] |
| Distance | 198 ± 4 ly (61 ± 1 pc) |
| Absolute magnitude (MV) | −0.31[6] |
| Orbit[7] | |
| Primary | A |
| Name | B |
| Period (P) | 2.46697±0.00500 yr |
| Semi-major axis (a) | 52.0±0.2 mas |
| Eccentricity (e) | 0.7380±0.0264 |
| Inclination (i) | 90.32±0.97° |
| Longitude of the node (Ω) | 127.13±0.91° |
| Argument of periastron (ω) (secondary) | 347.80±1.05° |
| Details | |
| δ Ara A | |
| Mass | 3.44±0.01[7] M☉ |
| Radius | 3.12±0.15[8] R☉ |
| Luminosity | 214[6] L☉ |
| Surface gravity (log g) | 3.81±0.06[8] cgs |
| Temperature | 12,549[7] K |
| Rotational velocity (v sin i) | 255[9] km/s |
| Age | 125[10] Myr |
| δ Ara B | |
| Mass | 2.03±0.01[7] M☉ |
| Temperature | 9,161[7] K |
| Other designations | |
| δ Ara, CPD−60°6842, FK5 648, GC 23681, HD 158094, HIP 85727, HR 6500, SAO 253945, PPM 362756, WDS J17311-6041A[11] | |
| Database references | |
| SIMBAD | data |
Characteristics
This is an astrometric binary system, identified using data from the Gaia spacecraft. The components have an orbital period of about 2.47 years and a high orbital eccentricity of 0.7380. The orbit is nearly edge-on relative to Earth.[7]
The brighter component is an intermediate-mass 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.[9] The star has 3.44 times the mass[7] and 3.1 times the radius of the Sun.[8] It is radiating 214 times the luminosity of the Sun from its photosphere[6] at an effective temperature of 12,549 K.[7]
The secondary is 1.27 times fainter than the primary at Gaia's G-band, it has 2.03 times the mass of the Sun and an effective temperature of 9,161 K.[7]
There is a magnitude 9.5 companion G-type main sequence star that may (17% chance) form a gravitationally bound system with Delta Arae.[4] A 12th magnitude optical companion is located 47.4 arcseconds away along a position angle of 313°.[10]