Facts about Delta Cephei
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Cepheid variables like Delta Cephei have been used to establish the cosmic distance ladder, with astronomers relying on their predictable brightness patterns to measure distances up to 30 million light-years away.
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About 46 times the Sun's mass, Delta Cephei's pulsations are driven by the helium ionization zone within its interior, which acts as a natural heat engine.
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Observations from the Hipparcos satellite in 1997 refined Delta Cephei's distance to 891 light-years, significantly closer than the previously accepted 2,000 light-year estimate.
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Yellow supergiant Delta Cephei is expanding and contracting with each pulsation cycle, causing its radius to change by approximately 6 percent.
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Spectroscopic observations reveal that Delta Cephei is actually a binary star system, with a faint companion orbiting the primary supergiant every 44.3 years.
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Roughly 46 times more massive than our Sun, Delta Cephei will eventually explode as a supernova and leave behind a neutron star or black hole.
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In 1786, Delta Cephei was catalogued by the astronomer William Herschel as having a spectral type of F7Ib-G1Ib, making it a supergiant star roughly 2,000 times more luminous than our Sun.
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Delta Cephei's surface temperature fluctuates between approximately 5,200 and 6,100 Kelvin as it pulsates, causing its brightness variations throughout its cycle.
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At approximately 2,000 light-years away, Delta Cephei serves as a crucial standard candle for measuring distances to farther galaxies through the period-luminosity relationship.
- 01
The first known variable star, Delta Cephei, has a period of 5.366 days and was discovered to vary in brightness by John Goodricke in 1784.