Marfik — Double Star in Ophiuchus
Lambda Oph
About Marfik
Description
Marfik, Lambda Ophiuchi, is a binary star system about 173 light-years away in the constellation Ophiuchus. The primary is a B9/A0 III subgiant and the companion is an A-type dwarf at 1.5 arcseconds separation. Combined magnitude is 3.82. The orbital period is about 130 years, making Marfik a fine binary for long-term observation.
Observing Tips
Marfik sits in the eastern part of Ophiuchus, near the boundary with Serpens Cauda. The 1.5-arcsecond double challenges small scopes — needs a 4-inch or larger at 200x on steady seeing nights. The two components are similar in brightness, providing a pleasing matched pair. Best observed May through September.
History
The name Marfik comes from the Arabic "al-mirfaq," meaning "the elbow" — referring to Ophiuchus's elbow in the traditional figure. The IAU adopted the name in 2017.
Fun Facts
The Marfik binary has been observed since the 19th century, and its orbit is now well-determined through accumulated position measurements. Its 130-year period means that a single human lifetime can witness roughly two-thirds of a full revolution — a modest but real demonstration of gravitational orbital motion.
Observe
1Physical Properties
2Position & Identifiers
3How easy to split?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | V. hard+ | V. hard+ | V. hard+ |
| 150 mm Newton 150mm Newt. | Hard+ | Hard+ | Hard+ |
| Celestron C8 (203 mm SCT) C8 203mm | Medium | Medium | Medium |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
Set a location in User Settings to see visibility data.
5Multiple Star System Quadruple D: 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: 3.8 · B: 5.2 · Sep: 1.3″ · PA: 46° · N up, E right
Unresolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″
Explore
7
Size Comparison
8
Compare Stars
9
Spectral Classification
10
Hertzsprung-Russell Diagram
11
Stellar Lifecycle
12
Blackbody Spectrum
13
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
14
Stellar Fusion
Discover
15Stellar Notes
16
Light Travel Time Machine
17
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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