Delta Cephei
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Delta Cephei is a quadruple star system located approximately 887 light-years away in the northern constellation of Cepheus, the King. At this distance, the visual magnitude of the star is diminished by 0.23 as a result of extinction caused by gas and dust along the line of sight. It is the prototype of the Cepheid variable stars that undergo periodic changes in luminosity.
Image of Delta Cephei, in the center
Hermes Radial Velocity Curve of Delta Cephei A. The offset between points of identical color is due to the spectroscopic companion, Delta Cephei B.
Bow shock around Delta Cephei
Light curve
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In astronomy, a light curve is a graph of the light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y-axis and with time on the x-axis. The light is usually in a particular frequency interval or band.
Light curve of δ Cephei showing magnitude versus pulsation phase