Madore, Barry F. Observatories of the Carnegie Institution for Science, Pasadena, California.
Freedman, Wendy L. Observatories of the Carnegie Institution for Science, Pasadena, California.
- Distance indicators
- Light curves
- Period-luminosity relation
- Distance measurements
- Links to Primary Literature
- Additional Readings
A class of high-luminosity yellow (supergiant) stars. Individual Cepheids vary periodically in brightness. Those Cepheids with the longest periods on average have the highest luminosities. Approximately one out of a thousand of the intrinsically brightest stars in any galaxy, like the Milky Way Galaxy, is a classical Cepheid variable. Among the 6000 apparently brightest stars visible to the unaided human eye in the night sky, more than a dozen are Cepheids (including their naked-eye prototype, Delta Cephei; Beta Doradus in the south; and Polaris, the northern Pole Star). Cepheids have the same yellow color as the Sun (because they both have similar surface temperatures), but Cepheids have significantly larger radii than the Sun, and therefore they are intrinsically 1000 to over 100,000 times more luminous. Cepheids are very well understood observationally and theoretically; moreover, they have repeatedly proved to be immensely important to many aspects of modern astronomy. Not only are Cepheids intrinsically bright (supergiant) stars (so that they can be seen over large distances) but also they are at a particular stage in their structure and evolution such that they are unstable to periodic oscillations. Motions of a Cepheid's surface and the induced changes in their surface temperature and surface brightness manifest themselves as regular changes in the apparent luminosity with time and so they can be easily identified. See also: Polaris; Supergiant star
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 9000 highly qualified scientists and 43 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information