Mu Librae

μ Librae (Latinised as Mu Librae) is the Bayer designation for a probable triple star[3] system in the zodiac constellation of Libra. They have a combined apparent visual magnitude of 5.32,[2] which is bright enough to be faintly visible to the naked eye. With an annual parallax shift of 13.71 mas,[1] the system is located at an estimated distance of around 240 light years.

Mu Librae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Libra
Right ascension 14h 49m 19.05130s[1]
Declination −14° 08′ 56.4766″[1]
Apparent magnitude (V) 5.32[2] (5.69 + 6.72[3] + 14.70[4])
Characteristics
Spectral type A1pSrCrEu + A6m[3]
B−V color index +0.07[2]
Astrometry
Radial velocity (Rv)−3.2±1.4[5] km/s
Proper motion (μ) RA: −65.95[1] mas/yr
Dec.: −14.54[1] mas/yr
Parallax (π)13.71 ± 0.69 mas[1]
Distance240 ± 10 ly
(73 ± 4 pc)
Absolute magnitude (MV)1.32±0.20[6]
Details
μ Lib A
Mass2.31±0.12[7] M☉
Radius2.59[8] R☉
Luminosity41.7[7] L☉
Temperature9,592±260[7] K
Rotational velocity (v sin i)29.0±1.7[7] km/s
Age417[6] Myr
μ Lib B
Radius2.59[8] R☉
Rotational velocity (v sin i)32.0±6[8] km/s
Other designations
μ Lib, BD−13° 3986, HD 130559, HIP 72489, HR 5523, SAO 158821.[9]
Database references
SIMBADdata

The inner pair consists of two A-type stars that, as of 2006, had an angular separation of 1.79 arc seconds along a position angle of 5.5°.[10] They have an estimated physical separation of 139 AU.[8] The primary, component A, is a visual magnitude 5.69[3] magnetic Ap star showing overabundances of the elements aluminum, strontium, chromium, and europium.[7] Hence, it has a stellar classification of A1pSrEuCr.[3] It is a photometric variable with periods of 25.3992±0.1970 d and 1.8871±0.0008 d. The surface magnetic field strength is 1,375 Gauss.[7]

The secondary, component B, is an Am star with a stellar classification of A6m.[3] It has a visual magnitude of 6.72.[3] The tertiary member, component C, is a magnitude 14.70 star at an angular separation of 12.90 arc seconds along a position angle of 294°, as of 2000.[4]

References
  1. van Leeuwen, F. (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, S2CID 18759600.
  2. Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C.
  3. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  4. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  6. Kochukhov, O.; Bagnulo, S. (2006), "Evolutionary state of magnetic chemically peculiar stars", Astronomy and Astrophysics, 450 (2): 763, arXiv:astro-ph/0601461, Bibcode:2006A&A...450..763K, doi:10.1051/0004-6361:20054596, S2CID 18596834.
  7. Wraight, K. T.; et al. (February 2012), "A photometric study of chemically peculiar stars with the STEREO satellites - I. Magnetic chemically peculiar stars", Monthly Notices of the Royal Astronomical Society, 420 (1): 757–772, arXiv:1110.6283, Bibcode:2012MNRAS.420..757W, doi:10.1111/j.1365-2966.2011.20090.x, S2CID 14811051.
  8. Howe, K. S.; Clarke, C. J. (January 2009), "An analysis of v sin (i) correlations in early-type binaries", Monthly Notices of the Royal Astronomical Society, 392 (1): 448–454, Bibcode:2009MNRAS.392..448H, doi:10.1111/j.1365-2966.2008.14073.x.
  9. "mu. Lib". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-01-24.{{cite web}}: CS1 maint: postscript (link)
  10. Mason, Brian D.; et al. (October 2007), "Speckle Interferometry at the US Naval Observatory. XIII.", The Astronomical Journal, 134 (4): 1671–1678, Bibcode:2007AJ....134.1671M, doi:10.1086/521555, S2CID 250820656, archived from the original on June 17, 2017.
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