Delta Cassiopeiae
Template:Location mark Location of δ Cassiopeiae (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cassiopeia[1] |
| Right ascension | Template:RA[2] |
| Declination | Template:DEC[2] |
| Apparent magnitude (V) | 2.68[3] |
| Characteristics | |
| Spectral type | A5 IV[4] |
| U−B Template:Engvar | +0.13[3] |
| B−V Template:Engvar | +0.13[3] |
| Variable type | Algol?[5] |
| Astrometry | |
| Radial velocity (Rv) | −6.7[6] km/s |
| Proper motion (μ) | RA: +296.57[2] mas/yr Dec.: −49.22[2] mas/yr |
| Parallax (π) | 32.81±0.14 mas[2] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | +0.28[7] |
| Details | |
| Mass | 2.49[8] Template:Solar mass |
| Radius | 3.90[9] Template:Solar radius |
| Luminosity | 72.88[8] Template:Solar luminosity |
| Temperature | 7,980[8] K |
| Rotational velocity (v sin i) | 123[8] km/s |
| Age | 600[9] Myr |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Ruchbah, Ksora,[10] Rucba, Rucbar,[11] 37 Cassiopeiae, BD+59°248, FK5 48, HD 8538, HIP 6686, HR 403, SAO 22268, WDS J01258+6014A[12] | |
| Database references | |
| SIMBAD | data |
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Delta Cassiopeiae (δ Cassiopeiae, abbreviated Delta Cas, δ Cas) is an eclipsing binary star system in the northern circumpolar constellation of Cassiopeia. Based on parallax measurements taken during the Hipparcos mission, it is approximately Script error: No such module "convert". from the Earth.[2]
Delta Cassiopeiae is the primary or 'A' component of a multiple star system designated WDS J01258+6014. Delta Cassiopeiae's two components are therefore designated WDS J01258+6014 Aa and Ab. Aa is officially named Ruchbah Template:IPAc-en, the traditional name for the system.[13][14]
Nomenclature
δ Cassiopeiae (Latinised to Delta Cassiopeiae) is the star's Bayer designation. WDS J01258+6014A is its designation in the Washington Double Star Catalog.
It also bore the traditional names Ruchbah and Ksora; the former deriving from the Arabic word ركبة rukbah meaning "knee",[10] and the latter appeared in a 1951 publication, Atlas Coeli (Skalnate Pleso Atlas of the Heavens) by Czech astronomer Antonín Bečvář. Professor Paul Kunitzch has been unable to find any clues as to the origin of the name.[15] The star Alpha Sagittarii also bore the traditional name Ruchbah (as well as Rukbat). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[16] to catalogue and standardize proper names for stars. The WGSN approved the name Ruchbah for the component WDS J01258+6014 Aa on 21 August 2016 and it is now so included in the List of IAU-approved Star Names (Alpha Sagittarii's primary was given the name Rukbat).[14]
In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Flying Corridor, refers to an asterism consisting of Delta Cassiopeiae, Iota Cassiopeiae, Epsilon Cassiopeiae, Theta Cassiopeiae, Nu Cassiopeiae and Omicron Cassiopeiae.[17] Consequently, the Chinese name for Delta Cassiopeiae itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx).[18]
Properties
Delta Cassiopeiae is a possible eclipsing binary star system consisting of a pair of stars that orbit about each other over a period of 759 days.[19][20] The combined apparent visual magnitude of the two stars is 2.68, making it readily observable with the naked eye. Eclipses have been reported with a period of 759 days,[19] when the brightness drops by 0.07 magnitudes.[5] Modern studies have shown no brightness variations greater than 0.01 magnitudes.[21]
The primary member of the system (WDS J01258+6014 Aa) has a stellar classification of A5 IV, with the luminosity class of IV indicating that it has exhausted the hydrogen at its core and has begun to evolve through the subgiant phase into a giant star. It is calculated that it is 4% beyond the end of its main sequence lifetime,[8] with an age of about 600 million years.[9] It has expanded to about 3.9 times the Sun's radius.[9]
An excess infrared emission has been observed at a wavelength of 60 μm, which suggests the presence of a circumstellar debris disk. This emission can be characterized by heat radiated from dust at a temperature of 85 K, which corresponds to an orbital radius of 88 Astronomical Units, or 88 times the distance of the Earth from the Sun.[9] For comparison, the region of the remote Kuiper belt in the Solar System extends from 30–50 AU.
The Washington Double Star Catalog lists a 12th magnitude companion Script error: No such module "val". away. It is an unrelated background object.[22]
References
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- ↑ a b Script error: No such module "citation/CS1".
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- ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
- ↑ Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ↑ a b Script error: No such module "citation/CS1".
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