63 Andromedae

63 Andromedae (abbreviated 63 And) is an Alpha2 Canum Venaticorum (α2 CVn) variable star in the constellation Andromeda. Its variable star designation is PZ Andromedae. With an apparent magnitude of about 5.6, it is bright enough to be seen by naked eye. Based upon an annual parallax shift of 7.8991 mas, it is located 413 light years away.

63 Andromedae
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 02h 20m 58.21s[1]
Declination +50° 09′ 05.3″[1]
Apparent magnitude (V) 5.59[2]
Characteristics
Spectral type B9VpSi[3]
B−V color index –0.089[1]
Variable type α² CVn[2]
Astrometry
Radial velocity (Rv)–0.30[4] km/s
Proper motion (μ) RA: 39.389±0.243[5] mas/yr
Dec.: −31.197±0.210[5] mas/yr
Parallax (π)7.8991 ± 0.1090[5] mas
Distance413 ± 6 ly
(127 ± 2 pc)
Absolute magnitude (MV)+0.26[6]
Details[6]
Mass3.07 ± 0.14 M☉
Radius2.4 ± 0.3 R☉
Luminosity110 L☉
Surface gravity (log g)4.29 ± 0.11 cgs
Temperature11,967 K
Rotation4.189 days
Other designations
PZ And, BD+49 640, HD 14392, HIP 10944, HR 682, NSV 790, SAO 37960.
Database references
SIMBADdata

The spectral type of this star is B9VpSi, indicating that it is a chemically peculiar main sequence star with abnormally strong silicon lines. Although it has a B-type spectral class, this type of star is known as an Ap star, a class of stars with very strong spectral lines of certain heavy elements and strong magnetic fields. The chemical peculiarities are caused by stratification in the atmosphere due to slow rotation.[7]

The star has 3 times the mass of the Sun and 2.4 times the Sun's radius. It is radiating 110 times the Sun's luminosity from its photosphere at an effective temperature of 11,967 K.[6]

63 Andromedae varies in brightness by about 0.05 magnitudes with a period of 4.189 days. This is believed to occur as it rotates. This type of variable star is known as an α2 Canum Venaticorum variable after the first example to be studied.[2]

To the naked eye the star figures as a faint, dense asterism with 64 and 65 Andromedae (southwest and west), which together justify a rectangular projection (extreme) of the constellation (official boundaries).[8] North, west and east are an arm/hand, fictitiously and geometrically, of Perseus, whose character is related in traditional mythology as Andromeda's saviour, saving her from the sea monster, who forever retreats to beyond Pisces, Cetus. The closest star in the asterisms commonly drawn up to repesent the princess herself is 51 Andromedae, to the east. At an apparent to us (magnitude of) 3.57, this shines (0.02 of a magnitude more than) 6.31 times brighter, which a gap of 2 in magnitudes represents.[8]

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.Vizier catalog entry
  2. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  3. Abt, H. A.; Morrell, N. I. (July 1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182.
  4. 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.
  5. 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.
  6. North, P. (June 1998), "Do SI stars undergo any rotational braking?", Astronomy and Astrophysics, 334: 181–187, arXiv:astro-ph/9802286, Bibcode:1998A&A...334..181N
  7. Renson, P.; Manfroid, J. (2009). "Catalogue of Ap, HgMn and Am stars". Astronomy and Astrophysics. 498 (3): 961. Bibcode:2009A&A...498..961R. doi:10.1051/0004-6361/200810788.
  8. https://www.iau.org/static/public/constellations/gif/AND.gif
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