AR Cassiopeiae
Star system in the constellation Cassiopeia
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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.[19][14]
 | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Cassiopeia[1] |
| AB | |
| Right ascension | 23h 30m 01.93946s[2] |
| Declination | +58° 32′ 56.1120″[2] |
| Apparent magnitude (V) | 4.883 (4.912 / 8.814)[3] |
| C | |
| Right ascension | 23h 29m 52.27982s[4] |
| Declination | +58° 32′ 54.4530″[4] |
| Apparent magnitude (V) | 7.23±0.01[5] |
| D | |
| Right ascension | 23h 29m 52.18197s[6] |
| Declination | +58° 32′ 53.3423″[6] |
| Apparent magnitude (V) | 9.00 - 9.05[7] |
| F | |
| Right ascension | 23h 29m 58.79260s[8] |
| Declination | +58° 33′ 58.3908″[8] |
| Apparent magnitude (V) | 11.01[9] |
| G | |
| Right ascension | 23h 30m 00.11097s[10] |
| Declination | +58° 34′ 01.5021″[10] |
| Apparent magnitude (V) | 11.11[9] |
| Characteristics | |
| AB | |
| Spectral type | B4 V + A6 V[3] |
| U−B color index | −0.62[11] |
| B−V color index | −0.12[11] |
| Variable type | Algol[12] |
| CD | |
| Spectral type | B9 V[13] |
| U−B color index | −0.14[11] |
| B−V color index | +0.01[11] |
| FG | |
| Evolutionary stage | main sequence[8][10] |
| Spectral type | F7 IV + F9 V[14] |
| Astrometry | |
| Radial velocity (Rv) | −15.9±0.9[15] km/s |
| Proper motion (μ) | RA: 17.90[2] mas/yr Dec.: 4.15[2] mas/yr |
| Parallax (π) | 5.25±0.52 mas[2] |
| Distance | 662.5 ± 13.8 ly (203.13±4.24 pc)[16] |
| Aa | |
| Absolute magnitude (MV) | −1.87±0.13[3] |
| Absolute bolometric magnitude (Mbol) | −3.56±0.13[3] |
| Ab | |
| Absolute magnitude (MV) | 2.20±0.11[3] |
| Absolute bolometric magnitude (Mbol) | 2.18±0.11[3] |
| C | |
| Proper motion (μ) | RA: 18.797±0.024[4] mas/yr Dec.: 1.953±0.024[4] mas/yr |
| Parallax (π) | 4.7329±0.0236 mas[4] |
| Distance | 685.7 ± 1.2 ly (210.25±0.36 pc)[16] |
| D | |
| Proper motion (μ) | RA: 20.435±0.059[6] mas/yr Dec.: 1.802±0.051[6] mas/yr |
| Parallax (π) | 4.6548±0.0362 mas[6] |
| Distance | 698.1 ± 1.0 ly (214.03±0.32 pc) |
| F | |
| Radial velocity (Rv) | −12.86±1.18[8] km/s |
| Proper motion (μ) | RA: 20.240±0.011[8] mas/yr Dec.: 1.884±0.011[8] mas/yr |
| Parallax (π) | 4.7301±0.0109 mas[8] |
| Distance | 685.939 ± 0.033 ly (210.31±0.01 pc)[16] |
| G | |
| Radial velocity (Rv) | −13.20±1.65[10] km/s |
| Proper motion (μ) | RA: 20.452±0.016[10] mas/yr Dec.: 2.050±0.014[10] mas/yr |
| Parallax (π) | 4.7539±0.0138 mas[10] |
| Distance | 682.45 ± 0.78 ly (209.24±0.24 pc) |
| Orbit[3] | |
| Primary | Aa |
| Name | 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° |
| Semi-amplitude (K1) (primary) | 55.5 km/s |
| Details[3] | |
| 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 |
| Rotational velocity (v sin i) | 129.3[3] km/s |
| 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 |
| B | |
| Mass | 1.43[14] M☉ |
| C | |
| Mass | 3.125±0.046[4] M☉ |
| Radius | 2.415+0.053 −0.054[4] R☉ |
| Luminosity | 112.2±2.2[4] L☉ |
| Surface gravity (log g) | 4.01[4] cgs |
| Temperature | 12083±8[4] K |
| Metallicity [Fe/H] | -1.49[4] dex |
| D | |
| Mass | 1.28[14] M☉ |
| Temperature | 5,095[17] K |
| F | |
| Mass | 1.139±0.040[8] M☉ |
| Radius | 1.139±0.023[8] R☉ |
| Luminosity | 1.666+0.011 −0.010[8] L☉ |
| Surface gravity (log g) | 4.30[8] cgs |
| Temperature | 6098+27 −26[8] K |
| Metallicity [Fe/H] | -0.35[8] dex |
| Age | 2.04[8] Gyr |
| G | |
| Mass | 1.044+0.040 −0.041[10] M☉ |
| Radius | 1.144±0.012[10] R☉ |
| Luminosity | 1.493+0.014 −0.015[10] L☉ |
| Surface gravity (log g) | 4.32[10] cgs |
| Temperature | 5934±67[10] K |
| Metallicity [Fe/H] | -0.32[10] dex |
| Age | 5.82[10] Gyr |
| Other designations | |
| ADS 16795, CCDM J23300+5833, WDS J23300+5833 | |
| AR Cassiopeiae (AB): 1H. Cas[18], AR Cas, AG+58 1562, BD+57°2748, HD 221253, HIP 115990, HR 8926, SAO 35478, GSC 04011-01296, 2MASS J23300196+5832561, Gaia DR3 2011150635728091648[12] | |
| HD 221237 (CD): BD+57°2747, HD 221237, SAO 35476, 2MASS J23295227+5832542 | |
| FG: UCAC4 743-089692 | |
| Database references | |
| SIMBAD | AR Cas (AB) |
| CD | |
| C | |
| D | |
| F | |
| G | |
Nomenclature
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.[12]
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.[18] It was the first star in Cassiopeia that Flamsteed's edition of Hevelius catalogued,[21] thus "1 Hev. Cas" or "1 H. Cas" (similar to Gould designations), which becomes IH Cas through corruption.[18]
Properties
The primary star system, AR Cassiopeiae, is a triple. AR Cassiopeiae B is located 0.800″ away from AR Cassiopeiae A.[14]
In 1921, Joel Stebbins announced that observations from 1917 through 1921 had shown that the star is an eclipsing binary.[22] AR Cassiopeiae A is an Algol-type eclipsing binary with an orbital period of about 6.07 days.[3] 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.[3]
Farther out are two other stars, designated components C and D. They are 76.1″, or about 1.27′, away from the central system.[14] Their combined spectrum matches that of another B-type main-sequence star.[13] This pair is also designated HD 221237.[13] 67.2″ (1.12′) away from AR Cassiopeiae is another pair of stars, F and G, both F-type stars.[14]
All these stars are known to be common proper motion companions.[14] However, the star listed as component E and H in most multiple star catalogues is an unrelated background star.[23][24]
Visual companions
There are three visual companions to AR Cassiopeiae; none of the three are thought to be physically associated with AR Cassiopeiae.
| Component | Primary | Right ascension (α) Equinox J2000.0 | Declination (δ) Equinox J2000.0 | Epoch of observed separation | Angular distance from primary | Position angle (relative to primary) | Apparent magnitude (V) | Database reference |
|---|---|---|---|---|---|---|---|---|
| E | A | 23h 29m 58.793s[23] | +58° 33′ 58.39″[23] | 2012 | 39.9″ | 117° | 11.28 | SIMBAD |
| H | C | 23h 29m 50.924s[24] | +58° 33′ 19.20″[24] | 2015 | 26.9″ | 337° | 13.0 | SIMBAD |
| I | A | 23h 29m 48.436s[25] | +58° 29′ 30.86″[25] | 2016 | 234″ | 208° | 9.87 | SIMBAD |