Lambda Arae
Star in the constellation Ara
From Wikipedia, the free encyclopedia
Lambda Arae is a star in the southern constellation of Ara. Its name is a Bayer designation that is Latinized from λ Arae, and abbreviated Lambda Ara or λ Ara. The apparent visual magnitude of this star is 4.77,[2] making it bright enough to be seen with the naked eye. Based on parallax measurements, it is located at a distance of 68 light-years (21 parsecs) from Earth. This star is drifting further away from the Sun with a radial velocity of +3 km/s.[5]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Ara |
| Right ascension | 17h 40m 23.826s[1] |
| Declination | −49° 24′ 56.10″[1] |
| Apparent magnitude (V) | 4.77[2] |
| Characteristics | |
| Spectral type | F4 V[3] |
| U−B color index | −0.04[2] |
| B−V color index | +0.40[2] |
| R−I color index | +0.22 |
| Variable type | 3.10[4] |
| Astrometry | |
| Radial velocity (Rv) | +3.3±0.3[5] km/s |
| Proper motion (μ) | RA: +104.233 mas/yr[1] Dec.: −175.956 mas/yr[1] |
| Parallax (π) | 47.7045±0.1368 mas[1] |
| Distance | 68.4 ± 0.2 ly (20.96 ± 0.06 pc) |
| Absolute magnitude (MV) | +3.06[6] |
| Details | |
| Mass | 1.37±0.04[1] M☉ |
| Radius | 1.711±0.035[1] R☉ |
| Luminosity | 4.69+0.03 −0.05[1] L☉ |
| Surface gravity (log g) | 4.064+0.005 −0.003[1] cgs |
| Temperature | 6,495+3 −7[1] K |
| Metallicity [Fe/H] | −0.24[4] dex |
| Rotational velocity (v sin i) | 15.5[7] km/s |
| Age | 2.44±0.39[1] Gyr |
| Other designations | |
| λ Ara, λ Arae, NSV 23218, CD−49°11616, GC 23918, GJ 686.2, GJ 9597, HD 160032, HIP 86486, HR 6569, SAO 228257, PPM 323240, NLTT 45187[8] | |
| Database references | |
| SIMBAD | data |
The spectrum of this star matches a stellar classification of F4 V,[3] which places it among the category of F-type main sequence stars. It is an estimated 2.4 billion years old,[1] and is spinning with a projected rotational velocity of 15.5 km/s.[7] This star has 40% more mass than the Sun and a 70% greater radius. It shines with 4.7 times the luminosity of the Sun. The outer atmosphere is radiating this energy at an effective temperature of 6,495 K,[1] giving it the yellow-white hue of an F-type star. There is some evidence that this may be a binary star system consisting of two stars with identical masses.[7]
Examination of Lambda Arae with the Spitzer Space Telescope shows an excess of infrared emission at a wavelength of 70 μm. This suggests it may be orbited by a disk of dust at a radius of more than 15 astronomical units.[9]