As summer skies pass overhead, steer your attention to the southern sky, where the constellation Capricornus makes its home. Here, several rich objects appear, including the pretty optical double star Algedi Prima and this nearby binary named Dabih, derived from the Arabic word for “butcher.” Dabih has several intriguing factors, including that it sails along the ecliptic, so it can be occulted by the Moon. Also, the stars are far apart at more than 21,000 light-years! With this distance, it takes 700,000 years for the stars to orbit each other.
Do you like precious metals like platinum and gold? The secondary, dimmer star in Dabih, called β2 Cap, is full of them—100,000 times the levels believed to be in our sun. If only we could go mining.1
My Observations
| Date | September 8, 2021 |
| Time | 9:50 p.m. |
| Location | Seattle, WA |
| Magnification | 92x |
| Scope | Meade 8″ SCT |
| Eyepiece | 22mm |
| Seeing | Average |
| Transparency | Average |
In just a matter of ten minutes since observing Algedi Prima nearby, clouds have started to move in. This double star doesn’t stand out as strongly as Algedi, but I do appreciate the contrast in colors it brings. The larger, brighter-appearing star is yellow, while the fainter companion appears white with perhaps a tinge of blue. I’ll have to revisit this when the skies are clearer.
Key Stats
| Constellation | Capricornus |
| Best Viewing | Early Autumn |
| Visual Magnitude | +3.1 | +6.1 |
| Absolute Visual Magnitude | -1.92 |
| Separation | 205″ | 21,000 AU |
| Position Angle | 266° |
| Distance from Earth | 330 ly |
| Orbital Period | Unknown |
| Milky Way Location | Orion Spur |
| My Viewing Grade | B |
| Designations | SAO 163481, Beta Capricorni, β Cap, Beta Cap, STFA 52 |
Sources and Notes
Banner is pulled from the Sloan Digital Sky Survey.
1Information pulled from Jim Kaller’s site.
Sketch by Wayne McGraw
The Garden Astronomer 