AR Cassiopeiae

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title: "AR Cassiopeiae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["cassiopeia-(constellation)", "algol-variables", "multiple-star-systems", "objects-with-variable-star-designations", "durchmusterung-objects", "henry-draper-catalogue-objects", "bright-star-catalogue-objects", "hipparcos-objects", "b-type-main-sequence-stars"] description: "Star system in the constellation Cassiopeia" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/AR_Cassiopeiae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Star system in the constellation Cassiopeia ::

| image = |image=Cassiopeia constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=AR Cassiopeiae |x=712|y=532 | caption = Location of AR Cassiopeiae (circled in red) | constell = Cassiopeia | epoch = J2000.0 | component1 = AB | ra1 = | dec1 = | appmag_v1 = 4.883 (4.912 / 8.814) | component2 = CD | ra2 = | dec2 = | appmag_v2 = 7.09 | component1 = AB | class = B4 V + A6 V | b-v = −0.12 | u-b = −0.62 | variable = Algol | component2 = CD | class2 = B9 V | b-v2 = +0.01 | u-b2 = −0.14 | component1 = FG | class = F7 IV + F9 V | radial_v = | prop_mo_ra = 17.90 | prop_mo_dec = 4.15 | parallax = 5.25 | p_error = 0.52 | parallax_footnote = | component1 = Aa | absmag_v = | absmag_bol = | component2 = Ab | absmag_v2 = | absmag_bol2 = | reference = | primary = Aa | name= Ab | period_unitless = 6.0663170 d | periastron = JD | periarg = | inclination = | eccentricity = 0.240 | source = | component1 = Aa | mass = | radius = | temperature = | gravity = | component2 = Ab | mass2 = | radius2 = | temperature2 = | gravity2 = | names = | component2 = AR Cassiopeiae (AB) | names2 = | component3 = HD 221237 (CD) | names3 = | component4 = FG | names4 = UCAC4 743-089692 | Simbad = AR+Cas | sn=AR Cas (AB) | Simbad2 = HD+221237 | sn2=CD | Simbad3 = ADS+16795+D | sn3=D | Simbad4 = CCDM+J23300%2B5833F | sn4=F | Simbad5 = CCDM+J23300%2B5833G | sn5=G

AR Cassiopeiae (AR Cas) is a variable star in the constellation of Cassiopeia. It is thought to be a member of a septuple star system, one of only two known star systems with a multiplicity of 7, the other being Nu Scorpii.

Nomenclature

::figure[src="https://upload.wikimedia.org/wikipedia/commons/f/f4/ARCasLightCurve.png" caption="''TESS'']] data"] ::

The multiple star system as a whole has the designations ADS 16795, CCDM J23300+5833, and WDS J23300+5833AB in the Aitken Double Star Catalogue, the Catalogue of Components of Double and Multiple Stars, and the Washington Double Star Catalog respectively.

AR Cassiopeiae has been referred to as IH Cas in some literature, looking similar to a variable star designation although not a valid one since the second letter of a variable star designation is always equal to the first or occurs later in the alphabet. The origin of the designation "IH Cassiopeiae" is from the 17th century catalogue and constellation map by Johannes Hevelius, which was kept in use due to the lack of a Flamsteed designation or Bayer designation for the star. It was the first star in Cassiopeia that Flamsteed's edition of Hevelius catalogued, thus "1 Hev. Cas" or "1 H. Cas" (similar to Gould designations), which becomes IH Cas through corruption.

Properties

The primary star system, AR Cassiopeiae, is a triple. AR Cassiopeiae B is located 0.800″ away from AR Cassiopeiae A.

In 1921, Joel Stebbins announced that observations from 1917 through 1921 had shown that the star is an eclipsing binary. AR Cassiopeiae A is an Algol-type eclipsing binary with an orbital period of about 6.07 days. Its primary is a B-type main-sequence star, and the secondary an A-type main-sequence star. The secondary star may be an Am star.

Farther out are two other stars, designated components C and D. They are 76.1″, or about 1.27′, away from the central system. Their combined spectrum matches that of another B-type main-sequence star. This pair is also designated HD 221237. 67.2″ (1.12′) away from AR Cassiopeiae is another pair of stars, F and G, both F-type stars.

All these stars are known to be common proper motion companions. However, the star listed as component E in most multiple star catalogues is an unrelated background star.

References

| last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | title=A catalogue of multiplicity among bright stellar systems | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869–879 | date=September 2008 | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E | arxiv=0806.2878 | s2cid=14878976

References

1. WikiSky, [http://server1.sky-map.org/starview?object_type=1&object_id=1657 "HD 221253"] (accessed 2010-10-27)
2. van Leeuwen, F.. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.
3. Gaia Collaboration. (2016). "Gaia Data Release 1". Astronomy & Astrophysics.
4. "HD 221237".
5. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data.
6. "V* AR Cas".
7. Wilson, Ralph Elmer. (1953). "General catalogue of stellar radial velocities". Washington.
8. (1999). "Search for forced oscillations in binaries. III. Improved elements and the detection of line-profile variability of the B4V + A6V: system AR Cassiopeiae". Astronomy and Astrophysics.
9. Somerville, W. B.. (1986). "1H. Cas = AR Cas". The Observatory.
10. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute.
11. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series.
12. (September 1921). "The eclipsing variable IH. Cassiopeiae, with evidence on the darkening at the limb of a stellar disk". Astrophysical Journal.
13. John Flamsteed. (1725). "Historia coelestis Britannica, Volume 2".

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