Delta Cephei is a binary star system located in the constellation Cepheus. It is classified as a Cepheid variable, meaning its brightness changes periodically. The primary star is a yellow supergiant, while the companion star is a smaller, less luminous star. The variability of Delta Cephei makes it an important object for astronomers. Its distance from Earth is approximately 887 light-years, and its brightness fluctuates over a period of about 5.5 days. This characteristic allows scientists to use it as a standard candle for measuring cosmic distances.