Prototypes: Delta Cephei (original) (raw)

The eponym of an own class of extremely regular pulsating variables, the Delta Cepheids. The yellow-white giant has a smaller blue companion far away.

From the period length of the Delta-Cepheids can be reasoned well-defined to their mass and their luminosity. Therefore they are often used to measure the distances of other galaxies.

Constellation: Cepheus
Age: 100 million years
Distance: 890 light-years
Radial velocity: 17 km/sec
Space between Delta Cephei A and B: 12 000 AU
Orbit period of Delta Cephei A and B: 500 000 years

| Delta Cephei A Spectral class: F5 - G2 Visual magnitude: 3.61 - 4.64 Luminosity: 1500 - 3000 * Sun Mass: 9 * Sun Diameter: circa 40 * Sun Pulsation period: 5.36643 days | | Delta Cephei B Spectral class: B7 Visual magnitude: 7.5 Luminosity: 500 * Sun Mass: 4 * Sun | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | ------------------------------------------------------------------------------------------------------------- |

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Photo T. Credner & S. Kohle, AlltheSky.com