Kaler, James B. Department of Astronomy, College of Liberal Arts and Sciences, University of Illinois, Urbana-Champaign, Illinois.
- Related Primary Literature
- Additional Reading
A member of a class of evolved stars that occupy the top of the Hertzsprung-Russell diagram to the right of the main sequence. The absolute visual magnitudes (MV) of supergiants range approximately between −4 and −10, and they are the largest and brightest stars. They are recognized by their spectroscopic characteristics. For example, those in class A have narrow hydrogen lines. They were first identified as distinct by Ejnar Hertzsprung when he found that Williamina Fleming's narrow-line “c” class had low proper motions, showing the stars to be far away and luminous. The “c” designation is still used to denote supergiants, though the use of luminosity class I is much more common. Supergiants are subdivided into classes Ib (MV about −5) and Ia (MV about −7). A “hypergiant class zero” was later added near MV = −10; the use of transition class Ia–0 at absolute visual magnitudes near −9 is now common. Red supergiants are the largest of all stars, and at maximum can reach diameters approaching that of the orbit of Saturn. The apparently brightest supergiants are Betelgeuse and Antares; among the largest known, VV Cephei and Mu Cephei.
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