Wasat — Double Star in Gemini
HIP 35550; Delta Geminorum; 55 Geminorum
About Wasat
Description
Wasat, Delta Geminorum, is an F-type subgiant of spectral class F2 V Fe-0.5 about 60 light-years away, notable for being a subgiant at a close, bright distance. It shines at magnitude 3.53 and is a known radial-velocity variable, with a very long-period companion suggested by decades of monitoring. Wasat is approaching the end of its main-sequence life.
Observing Tips
Wasat is in the middle of Gemini's body, between Castor and Pollux to the north and Alhena to the south. In binoculars it appears crisp and pale yellow-white. Wasat famously lies very near the ecliptic — the Sun, Moon, and planets pass close by frequently, producing occultations. Best observed December through April.
History
The name Wasat is Arabic for "the middle," referring to its position in the body of the celestial Gemini twins.
Fun Facts
Pluto was discovered only 0.3 degrees from Wasat by Clyde Tombaugh in 1930 — the star served as a key reference point in the photographic plates that led to the discovery. Wasat has been used as a target in occultation-timing campaigns to measure the angular diameters of asteroids.
Observe
1Physical Properties
2Position & Identifiers
3How easy to split?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Hard | Hard | Hard |
| 150 mm Newton 150mm Newt. | Medium+ | Medium+ | Medium+ |
| 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 Triple
Separation over time
Slow change over generations — observable in lifetime comparisons.
Measured from the WDS observational archive. No orbital solution has been derived — most likely the period is too long to fit an orbit to the available measurement arc.
Eyepiece View
A: 3.5 · B: 8.2 · Sep: 5.5″ · PA: 229° · N up, E right
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″
Explore
7
Size Comparison
8
Compare Stars
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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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