Beta Crateris
Binary star system in the constellation Crater
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Beta Crateris, Latinized from β Crateris, is a binary star[3] system in the southern constellation of Crater. It is visible to the naked eye with an apparent visual magnitude of 4.46.[2] Based upon an annual parallax shift of 9.59 mas as seen from Earth, it is around 340 light years from the Sun.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Crater |
| Right ascension | 11h 11m 39.48783s[1] |
| Declination | â22° 49â² 33.0593â³[1] |
| Apparent magnitude (V) | 4.46[2] (4.61 + 13.40)[3] |
| Characteristics | |
| Spectral type | A2 III[3] + DA1.4[3] |
| UâB color index | +0.05[2] |
| BâV color index | +0.02[2] |
| Astrometry | |
| Radial velocity (Rv) | +5.6±0.5[4] km/s |
| Proper motion (μ) | RA: + 5.220 ± 0.546[5] mas/yr Dec.: â103.457 ± 0.483[5] mas/yr |
| Parallax (Ï) | 11.0358±0.2918 mas[5] |
| Distance | 296 ± 8 ly (91 ± 2 pc) |
| Absolute magnitude (MV) | â0.62[6] + 8.19[3] |
| Details | |
| Luminosity | 147[7] Lâ |
| Surface gravity (log g) | 3.5[8] cgs |
| Temperature | 8,830[7] K |
| Rotational velocity (v sin i) | 49[9] km/s |
| β Crt B | |
| Mass | 0.43[10] Mâ |
| Radius | 0.027[11] Râ |
| Surface gravity (log g) | 7.40[11] cgs |
| Temperature | 36,885[11] K |
| Other designations | |
| β Crt, 11 Crateris, BDâ22° 3095, FK5 421, HD 97277, HIP 54682, HR 4343, SAO 179624, WD 1109-225.[12] | |
| Database references | |
| SIMBAD | data |
This is an astrometric binary[13] star system with an orbital period of 6.0 years and a projected separation of 8.3 AU. The orbit has an estimated semimajor axis of 9.3 AU.[3] The primary component A is listed as an A-type giant star with a stellar classification of A2 III.[3][13][10] However, Houk and Smith-Moore (1988) give a main sequence classification of A1 V,[14] while Abt and Morrell (1995) list it as a subgiant star with a class of A2 IV.[15] The spectrum shows enhanced barium, possibly as a result of a previous mass transfer event.[8]
The companion, component B, is a white dwarf[10] of class DA with an effective temperature of 36,885 K that has been cooling down for around four million years.[11] It has an unusually low mass, 43% that of the Sun, suggesting that the white dwarf progenitor may have transferred matter to its companion. Alternative scenarios require either the evolution of a triple star system or a binary system with a highly eccentric orbit, resulting in grazing interactions.[3] The dwarf is a source of X-ray emission.[16]
Name
This star was one of the sets assigned by the 16th-century astronomer Al Tizini[17] to Al SharÄsÄ«f (Ø£ÙشراسÙÙ), the Ribs (of Hydra), which included the stars from β Crateris westward through κ Hydrae.[18][19]
According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al SharÄsÄ«f were the titles for two stars: β Crateris as Al SharasÄ«f II and κ Hydrae as Al SharasÄ«f I.[20]
In Chinese, 翼宿 (Yì Sù), meaning Wings (asterism), refers to an asterism consisting of β Crateris, α Crateris, γ Crateris, ζ Crateris, λ Crateris, ν Hydrae, η Crateris, δ Crateris, ι Crateris, κ Crateris, ε Crateris, HD 95808, HD 93833, θ Crateris, HD 102574, HD 100219, HD 99922, HD 100307, HD 96819, Ï1 Hydrae, HD 102620 and HD 103462.[21] Consequently, β Crateris itself is known as 翼宿åå (Yì Sù shÃliù, English: the Sixteenth Star of Wings.)[22][23]