Beta Delphini
 Location of β Delphini (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Delphinus |
| Right ascension | 20h 37m 32.94130s[1] |
| Declination | +14° 35′ 42.3195″[1] |
| Apparent magnitude (V) | 3.617±0.016[2] (4.11 + 5.01)[3] |
| Characteristics | |
| Spectral type | F5 III + F5 IV[4] |
| B−V color index | A: 0.43±0.14 B: 0.56±0.25[1] |
| Astrometry | |
| Beta Delphini A | |
| Proper motion (μ) | RA: +118.09[1] mas/yr Dec.: -48.06[1] mas/yr |
| Parallax (π) | 32.33 ± 0.47[1] mas |
| Distance | 101 ± 1 ly (30.9 ± 0.4 pc) |
| Absolute magnitude (MV) | 1.58±0.12[2] |
| Beta Delphini B | |
| Absolute magnitude (MV) | 2.79±0.14[2] |
| Orbit[3] | |
| Period (P) | 26.660 yr |
| Semi-major axis (a) | 0.440" |
| Eccentricity (e) | 0.36 |
| Inclination (i) | 61° |
| Longitude of the node (Ω) | 177° |
| Periastron epoch (T) | 1989.50 yr |
| Argument of periastron (ω) (secondary) |
349° |
| Semi-amplitude (K1) (primary) |
7.6[5] km/s |
| Details | |
| Beta Delphini A | |
| Mass | 1.75±0.002[2] M☉ |
| Luminosity | 24[6] L☉ |
| Surface gravity (log g) | 3.50[6] cgs |
| Temperature | 6587[6] K |
| Metallicity [Fe/H] | –0.05[2] dex |
| Rotational velocity (v sin i) | 49.8[6] km/s |
| Age | 1.79+0.17 −0.72[2] Gyr |
| Beta Delphini B | |
| Mass | 1.47±0.04[2] M☉ |
| Luminosity | 8[7] L☉ |
| Other designations | |
Beta Delphini (Beta Del, β Delphini, β Del) is a binary star in the constellation of Delphinus. As a practical joke, the astronomer Niccolò Cacciatore gave it the name Rotanev, which is a reversal of his Latinized family name, Venator.[10] The name first appeared in Giuseppe Piazzi's Palermo Catalogue, published in 1814. Beta Delphini was found to be a binary star system in 1873 by the American astronomer S. W. Burnham.[11]
In Chinese, 瓠瓜 (Hù Guā), meaning Good Gourd, refers to an asterism consisting of β Delphini, α Delphini, γ2 Delphini, δ Delphini, and ζ Delphini.[12] Consequently, β Delphini itself is known as 瓠瓜二 (Hù Guā-er, English: the Second Star of Good Gourd.).[13]
This system consists of a pair of F-type stars stars that orbit each other with a period of 26.66 years and an eccentricity of 0.36. The plane of the orbit is inclined by an angle of 61° to the line of sight from the Earth. The two stars have an angular separation of about 0.44 arcseconds, making them a challenge to resolve with a telescope. The larger member of the pair is a giant star with 1.75 times the mass[2] and 24 times the luminosity of the Sun,[6] while the secondary component is a subgiant star that has 1.47 times the Sun's mass[2] and around 8 times the Sun's luminosity.[7] The system is around 1.8 billion years old.[2]
See also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 6.0 6.1 6.2 6.3 6.4 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 7.0 7.1 Rotanev, Stars, Jim Kaler. Accessed on line October 1, 2008.
- ↑ HD 196524 -- Spectroscopic binary, database entry, SIMBAD. Accessed on line October 1, 2008.
- ↑ Entry 20375+1436, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line October 1, 2008.
- ↑ 10.0 10.1 HR 7882, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line October 1, 2008.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ↑ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
External links
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