AR Andromedae

AR Andromedae (AR And) is a dwarf nova of the SS Cygni type in the constellation Andromeda. Its typical apparent visual magnitude is 17.6, but increases up to 11.0 magnitude during outbursts. The outbursts occur approximately every 23 days.[2]

AR Andromedae
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension  01h 45m 03.27259s[1]
Declination +37° 58′ 33.24084″[1]
Apparent magnitude (V) 11.0 – 17.6 variable [2]
Characteristics
Spectral type pec(UG)[2]
Apparent magnitude (B) 12.8[3]
Apparent magnitude (V) 11.00[4]
Apparent magnitude (G) 16.3185[1]
Apparent magnitude (J) 14.589[5]
Apparent magnitude (H) 13.996[5]
Apparent magnitude (K) 13.730[5]
Variable type UGSS
Astrometry
Radial velocity (Rv)91[3] km/s
Proper motion (μ) RA: 4.665±0.657 [1] mas/yr
Dec.: −7.443±0.191[1] mas/yr
Parallax (π)2.2785 ± 0.1701[1] mas
Distance1,400 ± 100 ly
(440 ± 30 pc)
Orbit[6]
Period (P)0.16302±0.00032 days
Periastron epoch (T)HJD 2450005.6924±0.0021
Semi-amplitude (K1)
(primary)		91±7 km/s
Other designations
2MASS J01450327+3756334
Database references
SIMBADdata

System

Dwarf novae systems are made up by a classical star with a white dwarf companion. By measuring the Doppler shift of spectral lines, it was found to have an orbital period of 3.91 hours.[6]

Variability

The light emitted by dwarf novae like AR Andromedae comes entirely from the accretion disc and the white dwarf; the luminosity increase during outbursts is typically induced by a variation in the accretion rate of the white dwarf.

Spectrum

The spectral type of AR Andromedae is classified as peculiar of the U Geminorum type[2], since the spectrum is not a typical stellar blackbody. It also shows strong emission lines of the first two Balmer series lines as well as HeI ones. In addition, an unusually strong FeII line with other possible weak lines of the same origin were also reported.[6]

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. AR And, database entry, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250 Accessed on line 2018-10-24.
  3. "AR And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 24, 2018.
  4. Database entry, Catalogue of Stellar Photometry in Johnson's 11-color system (2002 Ed.), J. R. Ducati, CDS ID Accessed on line 2018-10-24.
  5. Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; et al. (June 2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues (2246): II/246. Bibcode:2003yCat.2246....0C.
  6. Taylor, C. J.; Thorstensen, J. R. (October 1996). "Orbital Periods of the Dwarf Novae AR And, AM Cas, and PY Per". Publications of the Astronomical Society of the Pacific. 108. Bibcode:1996PASP..108..894T.
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