Astronomy:Lambda Arae

Short description: Star in the constellation Ara
Observation dataEquinox J2000.0]] (ICRS) Constellation Location of λ Arae (circled) Ara 17h 40m 23.82481s[1] –49° 24′ 56.1015″[1] 4.77[2] F4 V[3] –0.04[2] +0.40[2] 0.22 3.10[4] Radial velocity (Rv) +3.6[4] km/s Proper motion (μ) RA: +103.22[1] mas/yr Dec.: –176.51[1] mas/yr Parallax (π) 46.62 ± 0.33[1] mas Distance 70.0 ± 0.5 ly (21.5 ± 0.2 pc) Absolute magnitude (MV) +3.06[5] Luminosity 4.6[6] L☉ Surface gravity (log g) 4.15[6] cgs Temperature 6,725[6] K Metallicity [Fe/H] –0.24[4] dex Rotational velocity (v sin i) 15.5[7] km/s CD –49° 11616, GJ 9597, HD 160032, HIP 86486, HR 6569, NSV 23218, NLTT 45187, SAO 228257.[8] SIMBAD data

Lambda Arae (λ Ara, λ Arae) is the Bayer designation for a star in the southern constellation of Ara. It is at a distance of 70.0 light-years (21.5 parsecs) from Earth.[1] The apparent visual magnitude of this star is 4.77,[2] making it bright enough to be seen with the naked eye.

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 shines with 4.6 times the luminosity of the Sun. The outer atmosphere is radiating this energy at an effective temperature of 6,725 K,[6] 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]

References

1. van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode2007A&A...474..653V
2. Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99), Bibcode1966CoLPL...4...99J.
3. Gray, R. O. et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal 132 (1): 161–170, doi:10.1086/504637, Bibcode2006AJ....132..161G.
4. Holmberg, J.; Nordstrom, B.; Andersen, J. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics 501 (3): 941–947, doi:10.1051/0004-6361/200811191, Bibcode2009A&A...501..941H.
5. Ammler-von Eiff, M.; Reiners, A. (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics 542: A116, doi:10.1051/0004-6361/201118724, Bibcode2012A&A...542A.116A.
6. Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics 352: 495–507, Bibcode1999A&A...352..495M
7. Fuhrmann, K. et al. (August 2011), "Evidence for the nearby F4V star λ Ara as a binary system", Monthly Notices of the Royal Astronomical Society 415 (2): 1240–1243, doi:10.1111/j.1365-2966.2011.18764.x, Bibcode2011MNRAS.415.1240F.
8. Lawler, S. M. et al. (November 2009), "Explorations Beyond the Snow Line: Spitzer/IRS Spectra of Debris Disks Around Solar-type Stars", The Astrophysical Journal 705 (1): 89–111, doi:10.1088/0004-637X/705/1/89, Bibcode2009ApJ...705...89L