56 Arietis

56 Arietis is a single,[8] variable star in the northern zodiac constellation of Aries. It has the variable star designation SX Arietis, while 56 Arietis is the Flamsteed designation. This object is visible to the naked eye as a faint, blue-white hued point of light with a baseline apparent visual magnitude of 5.79.[2] The estimated distance to this star is approximately 406 light-years (124 parsecs), based on parallax,[1] and it is drifting further away with a radial velocity of +18 km/s.[5]

56 Arietis
Observation data
Epoch J2000      Equinox J2000.0 (ICRS)
Constellation Aries
Right ascension  03h 12m 14.24595s[1]
Declination +27° 15′ 25.0931″[1]
Apparent magnitude (V) 5.79[2] (5.75 – 5.81)[3]
Characteristics
Spectral type B9pSi[4]
U−B color index –0.42[2]
B−V color index –0.12[2]
Variable type SX Ari[3]
Astrometry
Radial velocity (Rv)+18.0[5] km/s
Proper motion (μ) RA: +12.035[1] mas/yr
Dec.: –18.791[1] mas/yr
Parallax (π)8.0413 ± 0.1723[1] mas
Distance406 ± 9 ly
(124 ± 3 pc)
Absolute magnitude (MV)+0.25[6]
Details
Mass3.16±0.17[6] M☉
Radius2.3±0.3[6] R☉
Luminosity110[6] L☉
Surface gravity (log g)4.36±0.12[6] cgs
Temperature12,445[6] K
Rotation0.7278972 days[6]
Other designations
56 Ari, SX Ari, BD+26°523, HD 19832, HIP 14893, HR 954, SAO 75788[7]
Database references
SIMBADdata

This is a magnetic, chemically peculiar star of the silicon type with a stellar classification of B9pSi,[4] and it has a rapid rotation period of 17.5 hours.[9] This period is increasing by about two seconds every hundred years.[10] The star displays evidence of a five year period for procession of its axis.[11] 56 Arietis is the prototype of a class of variable stars known as SX Arietis variables, which are rotationally variable stars with strong magnetic fields. It ranges in brightness from 5.75 down to 5.81 with a cyclical period matching its rotation rate.[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. Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
  3. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S.
  4. Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819
  5. Bonsack, Walter K. (February 1958), "Wavelength Variations in the Spectrum of 56 ARIETIS", Publications of the Astronomical Society of the Pacific, 70 (412): 90, Bibcode:1958PASP...70...90B, doi:10.1086/127180
  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. "56 Ari". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-07-31.
  8. 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.
  9. Ziznovsky, J.; et al. (January 2000), "The Variable Light Curve of 56 Arietis", Information Bulletin on Variable Stars, 4835: 1, Bibcode:2000IBVS.4835....1Z.
  10. Sokolov, N. A. (December 2006), "Ultraviolet variability of the magnetic chemically peculiar star 56 Arietis", Monthly Notices of the Royal Astronomical Society, 373 (2): 666–676, Bibcode:2006MNRAS.373..666S, doi:10.1111/j.1365-2966.2006.11037.x.
  11. Adelman, Saul J.; Malanushenko, V.; Ryabchikova, T. A.; Savanov, I. (September 2001), "On the rotation of the chemically peculiar magnetic star 56 Arietis", Astronomy and Astrophysics, 375: 982–988, Bibcode:2001A&A...375..982A, doi:10.1051/0004-6361:20010895.
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