| Binary
Star System
aka HR 707, HD 15089, HIP 11569, BD +66 00213, ADS 1860, CCDM 2292+6725, TYC 04058-1504 1, GSC 04058-1504 RA: 02h29m04.0s Dec: +67°24'09" (Cassiopeia) Integrated Visual Magnitude: 4.5 Distance: 140 +/- 5 ly Minimum requirements to detect: 3-inch telescope |
Burnham's
describes iota Cas as "One of the finest triple stars in the sky, resolvable
in a good 3-inch telescope when the seeing conditions permit." Most
observers find the primary star to be yellow; the two companions to be
tinted slightly blue.
The primary star is of spectral type A5. It is a variable of the Alpha CVn type which varies by about 0.02 magnitudes over a period of 1.7 days. The close visible companion is 8.5 magnitude and orbits with a period of around 900 years. It is currently separated from the primary by 2.6" at P.A. 231o. The third visible component is 9th magnitude and lies 7" distant. Once presumed to be gravitationally bound to the first pair, it turns out to lie about half-way between us and that system. The primary star is also an unseen binary with a 7th magnitude companion in a 50-year orbit, currently separated by just 0.11".
I recently observed this trio in my 18-inch f/4.5 Dob. All three were easily split at 260x, but the best view came at 430x. To my eye, the primary star appeared to be a white-blue color. The close companion appeared golden and the further companion appeared a blue-violet.
| Millennium
Star Atlas Vol I Chart 33
Sky Atlas 2000 Chart 1 Uranometria 2000 Vol I Chart 17 Herald-Bobroff Astroatlas B-01 C-04 |
