Prototypes: Beta Cephei (Alfirk) (original) (raw)

Beta Cephei A or Alfirk A is the prototype of a class of subgiants, which pulsate relatively quick, but weak. Alfirk A changes every 4.57 hours its luminosity for 0.07 magnitudes. Such a change isn't visible to the naked eye.
The blue star has two smaller, white stars as companions.

Constellation: Cepheus
Distance: 595 light-years
Space between Beta Cephei A and B: 45 AU
Orbit period of Beta Cephei A and B: 90 years
Space between Beta Cephei A and C: 2400 AU
Orbit period of Beta Cephei A and C: 30 000 years

| Alfirk A Spectral class: B2 Visual magnitude: 3.23 Luminosity: 14 600 * Sun Mass: 12 * Sun | | Alfirk B Spectral class: A | | Alfirk C Spectral class: A | | ------------------------------------------------------------------------------------------------------------ | | ------------------------------ | | ------------------------------ |

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01/03/2007

Photo: ESO Online Digitized Sky Survey (negative)