Lambda Arae

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Lambda Arae
Diagram showing star positions and boundaries of the Ara constellation and its surroundings
Cercle rouge 100%.svg
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]
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]
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]
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

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]


  1. ^ a b c d e f 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. ^ a b c d 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. ^ a b 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. ^ a b c 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. ^ a b c d Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics, 352: 495–507, Bibcode:1999A&A...352..495M
  7. ^ a b 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

External links[edit]