Alfirk — Double Star in Cepheus
HIP 106032; Beta Cephei; 8 Cephei
About Alfirk
Description
Alfirk is a blue giant of spectral type B1IV at magnitude 3.23 in Cepheus. Located about 690 light-years from Earth, it is the prototype of the Beta Cephei class of pulsating variable stars — massive hot stars that oscillate in brightness with periods of 3-7 hours. Alfirk's period is about 4.6 hours.
Observing Tips
Alfirk lies near the base of the house-shaped Cepheus, not far from Alderamin. It is a blue-white star circumpolar from mid-northern latitudes. Best observed August through December.
History
The name Alfirk comes from the Arabic 'al-firq,' meaning 'the flock.' As the prototype Beta Cephei variable, this star defines an important class of pulsating stars used to study the interiors of massive blue stars through asteroseismology.
Fun Facts
Beta Cephei variables are driven by an iron opacity mechanism — iron atoms deep in the stellar interior act as a valve, trapping heat and then releasing it, driving rhythmic pulsations. This mechanism was not understood until the 1990s.
Observe
1Physical Properties
2Position & Identifiers
3How easy to split?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Medium+ | Medium+ | Medium+ |
| 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.
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: 3.2 · B: 8.6 · Sep: 13.5″ · PA: 248° · N up, E right
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″
Explore
8
Size Comparison
9
Compare Stars
10
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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