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.[12][9]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cassiopeia[2] |
| AB | |
| Right ascension | 23h 30m 01.93946s[3] |
| Declination | +58° 32′ 56.1120″[3] |
| Apparent magnitude (V) | 4.883 (4.912 / 8.814)[4] |
| CD | |
| Right ascension | 23h 29m 52.2802s[5] |
| Declination | +58° 32′ 54.458″[5] |
| Apparent magnitude (V) | 7.09[6] |
| Characteristics | |
| AB | |
| Spectral type | B4 V + A6 V[4] |
| U−B color index | −0.62[7] |
| B−V color index | −0.12[7] |
| Variable type | Algol[8] |
| CD | |
| Spectral type | B9 V[6] |
| U−B color index | −0.14[7] |
| B−V color index | +0.01[7] |
| FG | |
| Spectral type | F7 IV + F9 V[9] |
| Astrometry | |
| Radial velocity (Rv) | −15.9±0.9[10] km/s |
| Proper motion (μ) | RA: 17.90[3] mas/yr Dec.: 4.15[3] mas/yr |
| Parallax (π) | 5.25 ± 0.52 mas[3] |
| Distance | 620 ± 60 ly (190 ± 20 pc) |
| Aa | |
| Absolute magnitude (MV) | −1.87±0.13[4] |
| Absolute bolometric magnitude (Mbol) | −3.56±0.13[4] |
| Ab | |
| Absolute magnitude (MV) | 2.20±0.11[4] |
| Absolute bolometric magnitude (Mbol) | 2.18±0.11[4] |
| Orbit[4] | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 6.0663170 d |
| Eccentricity (e) | 0.240 |
| Inclination (i) | 85.34±0.50° |
| Periastron epoch (T) | JD 2436847.9404±0.0055 |
| Argument of periastron (ω) (secondary) | 41.82±0.47° |
| Details[4] | |
| Aa | |
| Mass | 5.90±0.20 M☉ |
| Radius | 5.05±0.06 R☉ |
| Surface gravity (log g) | 3.80±0.02 cgs |
| Temperature | 17,200±500 K |
| Ab | |
| Mass | 1.86±0.06 M☉ |
| Radius | 1.60±0.03 R☉ |
| Surface gravity (log g) | 4.30±0.02 cgs |
| Temperature | 8,150±200 K |
| Other designations | |
| AR Cassiopeiae (AB): 1H. Cas[11], AR Cas, BD+57°2748, HD 221253, HIP 115990, HR 8926, SAO 35478[8] | |
| HD 221237 (CD): BD+57°2747, HD 221237, SAO 35476 | |
| FG: UCAC4 743-089692 | |
| Database references | |
| SIMBAD | AR Cas (AB) |
| CD | |
| D | |
| F | |
| G | |
Nomenclature
editThe 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.[8]
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.[11] It was the first star in Cassiopeia that Flamsteed's edition of Hevelius catalogued,[13] thus "1 Hev. Cas" or "1 H. Cas" (similar to Gould designations), which becomes IH Cas through corruption.[11]
Properties
editThe primary star system, AR Cassiopeiae, is a triple. AR Cassiopeiae B is located 0.800″ away from AR Cassiopeiae A.[9] AR Cassiopeiae A itself is an Algol-type eclipsing binary with an orbital period of about 6.07 days.[4] 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.[4]
Farther out are two other stars, designated components C and D. They are 76.1″, or about 1.27′, away from the central system.[9] Their combined spectrum matches that of another B-type main-sequence star.[6] This pair is also designated HD 221237.[6] 67.2″ (1.12′) away from AR Cassiopeiae is another pair of stars, F and G, both F-type stars.[9]
All these stars are known to be common proper motion companions.[9] However, the star listed as component E in most multiple star catalogues is an unrelated background star.
References
edit- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- ^ WikiSky, "HD 221253" (accessed 2010-10-27)
- ^ a b c d e van Leeuwen, F.; et al. (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.
- ^ a b c d e f g h i j Holmgren, D. E.; Hadrava, P.; Harmanec, P.; Eenens, P.; Corral, L. J.; Yang, S.; Ak, H.; Bozić, H. (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. 345: 855. Bibcode:1999A&A...345..855H.
- ^ a b Gaia Collaboration (2016). "Gaia Data Release 1". Astronomy & Astrophysics. 595: A2. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512. S2CID 1828208.
- ^ a b c d "HD 221237". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 23 August 2017.
- ^ a b c d Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- ^ a b c "V* AR Cas". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 23 August 2017.
- ^ a b c d e f Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series. 124: 75–84. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181.
- ^ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
- ^ a b c Somerville, W. B. (1986). "1H. Cas = AR Cas". The Observatory. 106: 40–42. Bibcode:1986Obs...106...40S.
- ^ 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. S2CID 14878976.
- ^ John Flamsteed (1725). Historia coelestis Britannica, Volume 2. OCLC 311875456.