Epsilon Persei — Double Star in Perseus
About Epsilon Per
Description
Epsilon Persei is a hot blue binary star of spectral type B0.5V at magnitude 2.89 in Perseus. Located about 540 light-years from Earth, it consists of a massive B-type primary and a fainter A-type companion. Combined luminosity is about 26,000 times solar.
Observing Tips
Epsilon Per lies in the body of Perseus, south of the Alpha Persei Cluster. It is a blue-white star in a rich Milky Way field. Best observed October through February when Perseus is well-placed in the evening sky.
History
Epsilon Persei has no widely used traditional name. It is a member of the Perseus OB1 association, a group of young massive stars in the Perseus arm of the Milky Way.
Fun Facts
Epsilon Per is one of the hottest bright stars in Perseus, with a surface temperature of about 28,000 K. Despite appearing as a single point of light, it is actually a close binary whose orbit has been studied through speckle interferometry.
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 | Medium+ | Medium+ | Medium+ |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
Set a location in User Settings to see visibility data.
5Light Curve
6Multiple Star System Triple
Separation over time
Essentially fixed on human timescales — the same view your grandchildren will see.
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: 2.9 · B: 8.9 · Sep: 8.8″ · PA: 12° · N up, E right
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″
Explore
8
Size Comparison
9
Compare Stars
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Spectral Classification
11
Hertzsprung-Russell Diagram
12
Stellar Lifecycle
13
Blackbody Spectrum
14
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
15
Stellar Fusion
Discover
16Stellar Notes
17
Light Travel Time Machine
18
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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