IW Andromedae

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IW Andromedae
IWAndLightCurve.png
A visual band light curve for IW Andromedae, plotted from AAVSO data [1]
Observation data
Epoch J2000       Equinox J2000
Constellation Andromeda
Right ascension 01h 01m 08.907s [2]
Declination 43° 23′ 25.79″ [2]
Apparent magnitude  (V)13.7 to 17.3 [3]
Characteristics
Spectral type sdOB [4]
Variable type Z Cam(?) [3]
Astrometry
Proper motion (μ)RA: +2.471  mas/yr [2]
Dec.: −5.904  mas/yr [2]
Parallax (π)1.1413 ± 0.0326  mas [2]
Distance 2,860 ± 80  ly
(880 ± 30  pc)
Details
White dwarf
Mass 0.75 [5]   M☉
Radius 0.015 [5]   R☉
Temperature 25,000 [5]   K
Donor star
Mass 0.27 [5]   M☉
Other designations
IW And, 2MASS J01010890+4323257, AAVSO 0055+42 [6]
Database references
SIMBAD data

IW Andromedae is a binary star system in the northern constellation of Andromeda, abbreviated IW And. It is the prototype of a class of variable stars known as IW And variables, which is an anomalous sub-class of the Z Camelopardalis (Z Cam) variables. [7] The brightness of this system ranges from an apparent visual magnitude of 13.7 down to 17.3, [3] which requires a telescope to view. The system is located at a distance of approximately 2,860  light years from the Sun based on parallax measurements. [2]

The irregular variability of this star was discovered by L. Meinunger in 1975. [8] [9] The spectra was found to resemble a blue–hued OB star with some peculiarities. It is a confirmed cataclysmic variable (CV) but its properties differ markedly from other sub-classes of that type. [10] The photometric behavior of the star is dissimilar to that of a dwarf or polar nova as it shows rapid brightening of up to three magnitudes in periods of around a day, [11] but stays in a low excitement state about 72% of the time. [10] Evidence for weak emission of the hydrogen–alpha line was discovered by W. Liu and associates in 1999. [9]

This is a close binary system with an orbital period of 223 minutes (3.7 hours). The primary component is a white dwarf star with 75% of the mass of the Sun. The secondary component has 27% of the Sun's mass and is overflowing its Roche lobe, resulting in mass transfer to an accretion disk orbiting the primary. The accretion rate for the primary is 3×10−9 M☉·yr−1. [5]

T. Kato and associates in 2003 found the light curve matched a Z Cam variable, with the previously observed inactive states being caused by a characteristic standstill. The duty cycle of its standstill is unusually long for a variable of this class. [10] Outbursts during these standstills may be explained by flares on the secondary, which result in brief surges in mass transfer. [12]

Other variables displaying IW And–type behavior have since been discovered, including HO Puppis, [13] BC Cassiopeiae, [14] IM Eridani, V507 Cygni, and FY Vulpecula. [7]

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<span class="mw-page-title-main">Pi Cassiopeiae</span> Variable star in the constellation Cassiopeia

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Z Andromedae is a binary star system consisting of a red giant and a white dwarf. It is the prototype of a type of cataclysmic variable star known as symbiotic variable stars or simply Z Andromedae variables. The brightness of those stars vary over time, showing a quiescent, more stable phase and then an active one with a more pronounced variability and stronger brightening and/or dimming.

<span class="mw-page-title-main">WZ Sagittae</span> Variable star in the constellation Sagitta

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Z Camelopardalis (Z Cam) is a cataclysmic variable star system in the northern constellation of Camelopardalis. It has an apparent visual magnitude which varies between 9.8 and 14.5. This system is the prototype star for the family of Z Camelopardalis variable stars: dwarf novae with standstills at a brightness intermediate between their maxima and minima. It may be the same bright nova that was recorded by Chinese astrologers in the autumn of 77 BCE.

<span class="mw-page-title-main">RX Andromedae</span> Cataclysmic variable star system in the constellation Andromeda

RX Andromedae is a variable star in the constellation of Andromeda. Although it is classified as a dwarf nova of the Z Camelopardalis (UGZ) type, it has shown low-luminosity periods typical of VY Sculptoris stars. However, for most of the time it varies from an apparent visual magnitude of 15.1 at minimum brightness to a magnitude of 10.2 at maximum brightness, with a period of approximately 13 days.

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<span class="mw-page-title-main">TZ Cassiopeiae</span> Star in the constellation Cassiopeia

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<span class="mw-page-title-main">V455 Andromedae</span> Dwarf nova star in the constellation Andromeda

V455 Andromedae is a dwarf nova in the constellation Andromeda. It has a typical apparent visual magnitude of 16.5, but reached a magnitude of 8.5 during the only observed outburst.

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<span class="mw-page-title-main">RZ Leonis Minoris</span> Variable star in the constellation Leo Minor

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<span class="mw-page-title-main">ER Ursae Majoris</span> Variable binary star system in the constellation Ursa Major

ER Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major, abbreviated ER UMa. It is a prototype system for a subclass of SU Ursae Majoris dwarf novae. The system ranges in brightness from a peak apparent visual magnitude of 12.4 down to 15.2, which is too faint to be visible to the naked eye. The distance to this system, based on parallax measurements, is approximately 1,163 light years.

<span class="mw-page-title-main">CR Boötis</span> Star system in the constellation Boötes

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<span class="mw-page-title-main">DO Draconis</span> Binary star in the constellation of Draco

YY Draconis and DO Draconis are separate identifiers for what is likely the same cataclysmic variable system in the northern constellation of Draco, abbreviated YY Dra and DO Dra, respectively. The DO Dra binary star system is classified as a U Geminorum variable that ranges in luminosity from an apparent visual magnitude of 10.0 down to 15.1. It is located at a distance of approximately 639 light years from the Sun.

References

  1. ↑ "Download Data", aavso.org, AAVSO, retrieved 9 April 2023.
  2. 1 2 3 4 5 6 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  3. 1 2 3 Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports , 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID   125853869.
  4. ↑ Meinunger, L. (May 1980), "Spectra of Four Blue Irregular Variables in Andromeda", Information Bulletin on Variable Stars, 1795: 1, Bibcode:1980IBVS.1795....1M.
  5. 1 2 3 4 5 Szkody, Paula; et al. (December 2013), "A Study of the Unusual Z Cam Systems IW Andromedae and V513 Cassiopeia", Publications of the Astronomical Society of the Pacific, 125 (934): 1421–1428, arXiv: 1311.1557 , Bibcode:2013PASP..125.1421S, doi:10.1086/674170, S2CID   118631716.
  6. ↑ "IW ANd". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2023-04-07.
  7. 1 2 Kato, Taichi (January 2019), "Three Z Camelopardalis-type dwarf novae exhibiting IW Andromedae-type phenomenon", Publications of the Astronomical Society of Japan, 71 (1): 20, arXiv: 1811.05038 , Bibcode:2019PASJ...71...20K, doi:10.1093/pasj/psy138, 20.
  8. ↑ Meinunger, L. (1975), "Veränderliche in einem Feld um ν Andromedae", Mitteilungen über Veränderliche Sterne, 7: 1–21, Bibcode:1975MitVS...7....1M.
  9. 1 2 Liu, Wu; et al. (May 1999), "Spectroscopic Confirmation of 55 Northern and Equatorial Cataclysmic Variables. I. 27 Confirmed Cataclysmic Variables", The Astrophysical Journal Supplement Series, 122 (1): 243–255, Bibcode:1999ApJS..122..243L, doi: 10.1086/313210 , S2CID   122899189.
  10. 1 2 3 Kato, Taichi; et al. (February 2003), "IW And is a Z Cam-Type Dwarf Nova", Information Bulletin on Variable Stars, 5376: 1, arXiv: astro-ph/0204353 , Bibcode:2003IBVS.5376....1K.
  11. ↑ Meinunger, L.; Andronov, I. L. (September 1987), "Photometric Study of the Blue Variables IW, IZ and IO Andromedae", Information Bulletin on Variable Stars, 3081: 1, Bibcode:1987IBVS.3081....1M.
  12. ↑ Hameury, J. -M.; Lasota, J. -P. (September 2014), "Anomalous Z Cam stars: a response to mass-transfer outbursts", Astronomy & Astrophysics, 569: A48, arXiv: 1407.3156 , Bibcode:2014A&A...569A..48H, doi:10.1051/0004-6361/201424535, S2CID   119238557, A48.
  13. ↑ Lee, Chien-De; et al. (April 2021), "HO Puppis: Not a Be Star, but a Newly Confirmed IW And-type Star", The Astrophysical Journal, 911 (1): 51, arXiv: 2102.09748 , Bibcode:2021ApJ...911...51L, doi: 10.3847/1538-4357/abe871 , S2CID   231979353, 51.
  14. ↑ Kato, Taichi; Kojiguchi, Naoto (December 2020), "BC Cassiopeiae: First detection of IW Andromedae-type phenomenon among post-eruption novae", Publications of the Astronomical Society of Japan, 72 (6): 98, arXiv: 2009.12993 , Bibcode:2020PASJ...72...98K, doi:10.1093/pasj/psaa096, 98.
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