15 Andromedae

15 Andromedae, abbreviated 15 And, is a single,[9] variable star[6] in the northern constellation of Andromeda. 15 Andromedae is the Flamsteed designation, while its variable star designation is V340 And.[8] Its apparent visual magnitude is 5.55,[2] which indicates it is faintly visible to the naked eye. Its estimated distance from the Earth is 252 light years, and it is moving further away with a heliocentric radial velocity of 13 km/s.[2]

15 Andromedae
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Andromeda
Right ascension 23h 34m 37.53652s[1]
Declination +40° 14′ 11.1795″[1]
Apparent magnitude (V) 5.55[2]
Characteristics
Spectral type A1 III,[3] A1 Va,[4] or kA1hA3mA0.5 Va+.[5]
U−B color index 0.08
B−V color index 0.096±0.005[2]
Variable type δ Sct[6]
Astrometry
Radial velocity (Rv)13.1±0.6[2] km/s
Proper motion (μ) RA: -18.165 mas/yr
Dec.: −46.183[1] mas/yr
Parallax (π)12.9406 ± 0.0973[1] mas
Distance252 ± 2 ly
(77.3 ± 0.6 pc)
Absolute magnitude (MV)+1.16±0.16[7]
Details[3]
Mass2.7 M☉
Luminosity27 L☉
Surface gravity (log g)3.90±0.03[7] cgs
Temperature9,225 K
Rotational velocity (v sin i)105[7] km/s
Age130 Myr
Other designations
15 And, V340 And, BD+39° 5114, FK5 1616, HD 221756, HIP 116354, HR 8947, SAO 73346[8]
Database references
SIMBADdata

Depending on the source, this star has been classified as a giant star with a stellar classification of A1 III,[3] an A-type main-sequence star with a class of A1 Va,[4] or a Lambda Boötis star with a class of kA1hA3mA0.5 Va+.[5] It is a Delta Scuti variable that changes in brightness by 0.03 magnitude.[6] Two variability cycles, with periods 0.0403 and 0.0449 days, have been observed, a common feature for Lambda Boötis stars.[10] The star is around 130[3] million years old and has a high rotation rate, showing a projected rotational velocity of 105 km/s.[7] It has 2.7 times the mass of the Sun and is radiating 27 times the Sun's luminosity from its photosphere at an effective temperature of 9,225 K.[3]

This system has an excess emission of infrared radiation that suggests the presence of an orbiting disk of dust at a distance of around 50 AU from the host star.[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.
  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. Wyatt, M. C.; et al. (July 2007), "Steady State Evolution of Debris Disks around A Stars", The Astrophysical Journal, 663 (1): 365–382, arXiv:astro-ph/0703608, Bibcode:2007ApJ...663..365W, doi:10.1086/518404, S2CID 18883195
  4. Paunzen, E.; et al. (July 2001), "A spectroscopic survey for λ Bootis stars. II. The observational data", Astronomy and Astrophysics, 373 (2): 625–632, Bibcode:2001A&A...373..625P, doi:10.1051/0004-6361:20010630.
  5. Murphy, Simon J.; et al. (2015), "An Evaluation of the Membership Probability of 212 λ Boo Stars. I. A Catalogue", Publications of the Astronomical Society of Australia, 32: e036, arXiv:1508.03633, Bibcode:2015PASA...32...36M, doi:10.1017/pasa.2015.34, ISSN 1323-3580, S2CID 59405545.
  6. Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  7. Paunzen, E.; et al. (November 2002), "The status of Galactic field λ Bootis stars in the post-Hipparcos era", Monthly Notices of the Royal Astronomical Society, 336 (3): 1030–1042, arXiv:astro-ph/0207488, Bibcode:2002MNRAS.336.1030P, doi:10.1046/j.1365-8711.2002.05865.x, S2CID 2389489.
  8. "15 And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 20, 2018.
  9. 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.
  10. Dorokhova, T. N.; et al. (March 2008), "The pulsating λ Bootis star 15 Andromedae: results from a three-site photometry campaign.", Astronomy and Astrophysics, 480 (1): 187–191, Bibcode:2008A&A...480..187D, doi:10.1051/0004-6361:20078750.

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