Rotanev
 Location of β Delphini (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Delphinus |
| Right ascension | 20h 37m 32.94130s |
| Declination | +14° 35′ 42.3195″ |
| Apparent magnitude (V) | 3.617±0.016(4.11 + 5.01) |
| Characteristics | |
| Spectral type | F5 III + F5 IV |
| B−V color index | A: 0.43±0.14 B: 0.56±0.25 |
| Astrometry | |
| Beta Delphini A | |
| Proper motion (μ) |
RA: +118.09 mas/yr Dec.: -48.06 mas/yr |
| Parallax (π) | 32.33 ± 0.47mas |
| Distance | 101 ± 1 ly (30.9 ± 0.4 pc) |
| Absolute magnitude (MV) | 1.58±0.12 |
| Beta Delphini B | |
| Absolute magnitude (MV) | 2.79±0.14 |
| Orbit | |
| 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 km/s |
| Details | |
| Beta Delphini A | |
| Mass | 1.75±0.002 M☉ |
| Luminosity | 24 L☉ |
| Surface gravity (log g) | 3.50 cgs |
| Temperature | 6587 K |
| Metallicity [Fe/H] | –0.05 dex |
| Rotational velocity (v sin i) | 49.8 km/s |
| Age |
1.79+0.17 −0.72 Gyr |
| Beta Delphini B | |
| Mass | 1.47±0.04 M☉ |
| Luminosity | 8 L☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
Beta Delphini (β Delphini, abbreviated Beta Del, β Del), also named Rotanev, is a binary star in the constellation of Delphinus.
β Delphini (Latinised to Beta Delphini) is the star's Bayer designation.
It bore an historical name, Rotanev, which arose as follows: Niccolò Cacciatore was the assistant to Giuseppe Piazzi, and later his successor as Director of the Palermo Observatory. The name first appeared in Piazzi's Palermo Star Catalogue. When the Catalogue was published in 1814, the unfamiliar names Sualocin and Rotanev were attached to Alpha and Beta Delphini, respectively. Eventually the Reverend Thomas Webb, a British astronomer, puzzled out the explanation. Cacciatore's name, Nicholas Hunter in English translation, would be Latinized to Nicolaus Venator. Reversing the letters of this construction produces the two star names. They have endured, the result of Cacciatore's little practical joke of naming the two stars after himself. How Webb arrived at this explanation 45 years after the publication of the catalogue is still a mystery.
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Rotanev for Beta Delphini on 12 September 2016 and it is now so entered in the IAU Catalog of Star Names.
In Chinese, 瓠瓜 (Hù Guā), meaning Good Gourd, refers to an asterism consisting of Beta Delphini, Alpha Delphini, Gamma2 Delphini, Delta Delphini, and Zeta Delphini.
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