Astronomy:Lambda Arae

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Short description: Star in the constellation Ara
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
Equinox J2000.0]] (ICRS)
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

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. 1.0 1.1 1.2 1.3 1.4 1.5 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. 2.0 2.1 2.2 2.3 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. 3.0 3.1 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. 4.0 4.1 4.2 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. 6.0 6.1 6.2 6.3 Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics 352: 495–507, Bibcode1999A&A...352..495M 
  7. 7.0 7.1 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. "lam Ara". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=lam+Ara. 
  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, doi:10.1088/0004-637X/705/1/89, Bibcode2009ApJ...705...89L 

External links