Kappa Delphini
Astrometric binary star system in the constellation Delphinus
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κ Delphini (Latinised as Kappa Delphini, abbreviated to κ Del or kappa Del) is a binary star system in the constellation Delphinus. It is faintly visible to the naked eye, with an apparent magnitude of 5.05.[2] It is located about 98.8 light-years away, based on its parallax.[1]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Delphinus |
| Right ascension | 20h 39m 07.78430s[1] |
| Declination | +10° 05′ 10.3383″[1] |
| Apparent magnitude (V) | 5.05[2] |
| Characteristics | |
| Spectral type | G1IV + ? + K2IV[3] |
| U−B color index | 0.235[4] |
| B−V color index | 0.69[4] |
| Astrometry | |
| Radial velocity (Rv) | -53.51[2] km/s |
| Proper motion (μ) | RA: 323.83[1] mas/yr Dec.: 21.80[1] mas/yr |
| Parallax (π) | 33.0268±0.1631 mas[5] |
| Distance | 98.8 ± 0.5 ly (30.3 ± 0.1 pc) |
| Absolute magnitude (MV) | 2.7[6] |
| Orbit[6] | |
| Period (P) | 45 ± 5 yr |
| Semi-major axis (a) | 0.520 ± 0.030″ |
| Eccentricity (e) | 0.8 ± 0.4 |
| Inclination (i) | 107 ± 18° |
| Longitude of the node (Ω) | 326 ± 17° |
| Periastron epoch (T) | B 1971.2 ± 1.8 |
| Argument of periastron (ω) (secondary) | 8 ± 34° |
| Details[7] | |
| κ Del Aa | |
| Mass | 1.43 M☉ |
| Luminosity | 8.3 L☉ |
| Surface gravity (log g) | 3.69 cgs |
| Temperature | 5,643 K |
| Metallicity [Fe/H] | +0.01 dex |
| Rotational velocity (v sin i) | 1.77 km/s |
| Age | 3.1 Gyr |
| κ Del Ab | |
| Mass | 0.4±0.2[6] M☉ |
| Other designations | |
| κ Del, 7 Delphini, BD+09°4600, HD 196755, HIP 101916, HR 7896, SAO 126059, CCDM J20392+1005A, WDS J20391+1005A[2] | |
| Database references | |
| SIMBAD | data |
Kappa Delphini is an astrometric binary. The primary star is an early G-type subgiant star. It has a mass 1.61 times that of the Sun, and is 6.8 times more luminous. The companion star regularly perturbs the G-type primary star primary, causing it to wobble around the barycenter. From this, an orbital period of 45 years has been calculated.[6] The secondary star is a low-mass star, at only 0.4 M☉.[6]
A third star is 12th magnitude ADS 14101 B, 10″ away in 2001, but it is a background object. HD 196794 is an 8th magnitude K2 subgiant, 214″ away in the sky, being at the same distance as κ Delphini and sharing a common proper motion.[6]