Kappa Delphini is a triple star system in the constellation Delphinus, the dolphin. It’s best viewed in the summertime.
Backyard astronomers will appreciate studying the components of Kappa Del. At first glance, one will see several stars surrounding the warm, yellow primary, Kappa A. See my observations below. What’s interesting is that the closer, fainter Kappa B appears to be a binary companion, but it’s not.
Meanwhile, the more distant and brighter Kappa C is a companion. We know this from 160 years of observations of Kappa A and C. In addition, astronomers have detected a wobble in Kappa A, which has led to a theory that a white or red dwarf is orbiting close to the primary star. This would make Kappa Delphini a triple star (Kappa A, C, and the dwarf that we cannot see, which is near Kappa A). Please read Jim Kaler’s fine and comprehensive summary to learn more.
My Observations
| Date | September 20, 2022 |
| Time | 9:30 p.m. |
| Location | Seattle, WA |
| Magnification | 254x |
| Scope | Meade 8″ SCT |
| Eyepiece | 8mm |
| Seeing | Good |
| Transparency | Good |
The primary, Kappa A, is a golden-rich color, while the surrounding stars appear white. Kappa B is very faint and nearby A, while the true companion, Kappa C, is farther away and brighter.
I see several other stars nearby and sketched here, but I believe they are simply background stars.
Key Stats
| Constellation | Delphinus |
| Best Viewing | Summer |
| Visual Magnitude | +5.2, +8.6 (C) |
| Separation | 212″ | 6400 AU A-C |
| Spectral Class | A=G1, C=K2 |
| Absolute Visual Magnitude | +2.68 |
| Distance from Earth | 98 ly |
| Milky Way Location | Orion Spur |
| My Viewing Grade | B+ |
| Desingations | 7 Del, SAO 126059, HR 196755, HIP 101916 |
Sources and Notes
Sketch by Wayne McGraw
The Garden Astronomer 