Shore, Steven N. Department of Physics “Enrico Fermi,” University of Pisa, Italy.
- Development of concept
- Populations in galaxies
- Characteristics of populations
- Delineation of populations
- Links to Primary Literature
- Additional Readings
One of the categories into which stars may be classified, based on their place in the evolution of the galaxy that they occupy. The stellar component of the Milky Way Galaxy consists of three populations: the thin disk, the thick disk, and the halo. The thin disk, originally referred to as population I, is the youngest, located amid most of the molecular and cold atomic gas, and confined to a height of order 1 kiloparsec (3.3 × 103 light-years or 3.1 × 1016 km or 1.9 × 1016 mi) from the plane. The bulge and halo, roughly corresponding to the original population II, is a much older, far more extended structure, having an approximately spherical distribution with a scale length of order 3.5 kpc.
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 8500 articles and Research Reviews 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