15 Lacertae

15 Lacertae is a binary star[7] system in the northern constellation of Lacerta, near the southeast constellation border with Andromeda. It is faintly visible to the naked eye with an apparent visual magnitude of 4.95.[2] The distance to this system is approximately 337 light years based on parallax.[1] It is drifting closer to the Sun with a radial velocity of −19 km/s.[2] The absolute magnitude of 15 Lacertae is −0.04.[2]

15 Lacertae
Observation data
Epoch J2000      Equinox J2000
Constellation Lacerta
Right ascension 22h 52m 02.03323s[1]
Declination +43° 18′ 44.7028″[1]
Apparent magnitude (V) 4.95[2] + 11.9[3]
Characteristics
Spectral type M0 III[4]
B−V color index 1.559±0.010[2]
Astrometry
Radial velocity (Rv)−19.21±0.20[2] km/s
Proper motion (μ) RA: +109.890±0.214[1] mas/yr
Dec.: +23.581±0.215[1] mas/yr
Parallax (π)9.6841 ± 0.1425 mas[1]
Distance337 ± 5 ly
(103 ± 2 pc)
Absolute magnitude (MV)−0.04[2]
Details
Radius37.30+0.61
−1.02[1] R☉
Luminosity294.5±5.1[1] L☉
Surface gravity (log g)1.352[5] cgs
Temperature3,915+55
−32[1] K
Other designations
15 Lac, BD+42° 4521, GC 31896, HD 216397, HIP 112917, HR 8699, SAO 52436, WDS J22520+4319[6]
Database references
SIMBADdata

The primary component is an aging red giant with a stellar classification of M0 III.[4] With the supply of hydrogen at its core exhausted, the star has cooled and expanded to 37 times the Sun's radius. It is radiating 295 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,915 K,[1] giving it a reddish hue.

The secondary companion was discovered by American astronomer S. W. Burnham in 1888. It has a visual magnitude of 11.9 and is located at an angular separation of 23.6″ from the primary along a position angle of 159°, as of 2014.[3]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  3. 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.
  4. Abt, H. A. (September 1985), "Visual multiples. VIII - 1000 MK types", Astrophysical Journal Supplement Series, 59: 95–112, Bibcode:1985ApJS...59...95A, doi:10.1086/191064
  5. Ghosh, Supriyo; et al. (April 2019). "Spectral calibration of K-M giants from medium-resolution near-infrared HK-band spectra". Monthly Notices of the Royal Astronomical Society. 484 (4): 4619–4634. arXiv:1901.09170. Bibcode:2019MNRAS.484.4619G. doi:10.1093/mnras/stz299. S2CID 119462500.
  6. "15 Lac". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-08-10.
  7. 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.
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