Lambda Arae

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.

Lambda Arae
Location of λ Arae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ara
Right ascension  17h 40m 23.82481s[1]
Declination –49° 24′ 56.1015″[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)+3.6[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
Distance70.0 ± 0.5 ly
(21.5 ± 0.2 pc)
Absolute magnitude (MV)+3.06[5]
Details
Luminosity4.6[6] L☉
Surface gravity (log g)4.15[6] cgs
Temperature6,725[6] K
Metallicity [Fe/H]–0.24[4] dex
Rotational velocity (v sin i)15.5[7] km/s
Other designations
CD –49° 11616, GJ 9597, HD 160032, HIP 86486, HR 6569, NSV 23218, NLTT 45187, SAO 228257.[8]
Database references
SIMBADdata

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, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
  2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...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, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
  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, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191.
  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, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724.
  6. Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics, 352: 495–507, Bibcode:1999A&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, Bibcode:2011MNRAS.415.1240F, doi:10.1111/j.1365-2966.2011.18764.x.
  8. "lam Ara". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-07-30.
  9. 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, arXiv:0909.0058, Bibcode:2009ApJ...705...89L, doi:10.1088/0004-637X/705/1/89
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