Guniibuu — Double Star in Ophiuchus
HIP 84405; 36 Ophiuchi
About Guniibuu
Description
36 Ophiuchi is a triple K-dwarf system about 19.5 light-years away. The two main components A and B are K1 V and K1 V stars almost identical in mass and luminosity (magnitudes 5.07 and 5.10), separated by 5–7″ in a 471-year orbit. A faint third component C lies 12 arc-minutes away and is a K5 V dwarf physically bound to the inner pair.
Observing Tips
Very pretty pair in any small telescope — two equal-magnitude orange K-stars, an unusual sight. Use 80×–150× to comfortably split AB. Component C is a wide field-of-view target, easy to identify because it shares the system's high proper motion (1.13″/yr).
History
Discovered as a binary by Sir John Herschel in 1837 during his Cape of Good Hope southern survey. Long studied as a benchmark for K-dwarf physics because the near-twin components allow direct comparison without the complications of unequal masses.
Fun Facts
All three components are slow rotators with active chromospheres — they appear chemically depleted in lithium, a hallmark of mature K-dwarfs that have churned their outer layers down to fusion temperatures over billions of years.
Observe
1Physical Properties
2Position & Identifiers
3How easy to split?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Easy | Easy | Easy |
| 150 mm Newton 150mm Newt. | Easy | Easy | Easy |
| Celestron C8 (203 mm SCT) C8 203mm | Easy | Easy | Easy |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
Set a location in User Settings to see visibility data.
5Multiple Star System Quintuple D,E: optical
Separation over time
Apparent separation over time, computed from ORB6 orbital elements. Steep curves indicate fast-changing pairs — catch them while they're splittable.
Eyepiece View
A: 5.1 · B: 5.1 · Sep: 5.2″ · PA: 138° · N up, E right
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″
Explore
6
Size Comparison
7
Compare Stars
8
Spectral Classification
9
Hertzsprung-Russell Diagram
10
Stellar Lifecycle
11
Blackbody Spectrum
12
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
13
Stellar Fusion
Discover
14Stellar Notes
15
Light Travel Time Machine
16
Relativistic Travel
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
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