Skip to main content Accessibility help
×
  1. Home
  2. Browse subjects
  3. Physics and Astronomy
  4. Astronomy Books

Refine listing

Refine listing

Access:
Content type:
Publication date:
Apply   From and To filters
Subject: Show more
Journals Show more
Publishers: Show more
Societies Show more
Series: Show more
Collections: Show more

Actions for selected content:

Select all | Deselect all
  • View selected items
  • Export citations
  • Download PDF (zip)
  • Save to Kindle
  • Save to Dropbox
  • Save to Google Drive

Save Search

You can save your searches here and later view and run them again in "My saved searches".

Please provide a title, maximum of 40 characters.
Cancel
×

17002 results

Page 160 of 851

  • 12 - The Interstellar Medium and Star Formation

  • from II - THE NATURE OF STARS
  • Bradley W. Carroll, Weber State University, Utah, Dale A. Ostlie, Weber State University, Utah
  • Book:
    An Introduction to Modern Astrophysics
    Published online:
    16 August 2019
    Print publication:
    07 September 2017, pp 398-445

  • Summary

    INTERSTELLAR DUST AND GAS

    When we look into the heavens, it appears as though the stars are unchanging, point-like sources of light that shine steadily. On casual inspection, even our own Sun appears constant. But, as we have seen in the last chapter, this is not the case; sunspots come and go, flares erupt, significant amounts of matter are launched into space via coronal mass ejections, the corona itself changes shape, and even the Sun's luminosity appears to be fluctuating over human timescales, as evidenced by the Maunder minimum. Of course, over the 4.57- Gyr lifetime of our Sun, the luminosity, effective temperature, and radius have all changed substantially (recall Fig. 11.1).

    In fact all stars change. Usually the changes are so gradual and over such long time intervals when measured in human terms that we do not notice them without very careful telescopic observation. Occasionally, however, the changes are extremely rapid and dramatic, as in the case of a supernova explosion. By invoking the understanding we developed thus far of the physics of stellar interiors and atmospheres, we can now begin to examine the processes governing how stars evolve during their lives.

    The Interstellar Medium

    In some sense the evolution of stars is a cyclic process. A star is born out of gas and dust that exists between the stars, known as the interstellar medium (ISM). During its lifetime, depending on the star's total mass, much of that material may be returned to the ISM through stellar winds and explosive events. Subsequent generations of stars can then form from this processed material. As a result, to understand the evolution of a star, it is important to study the nature of the ISM.

    Understanding the interstellar medium is critical for more than its role in stellar evolution, however. The ISM is of profound importance in describing the structure, dynamics, and evolution of our MilkyWay Galaxy, as well as galaxies throughout the universe. In addition, it impacts our observations of everything from relatively nearby stars to the most remote galaxies and quasars.

Page 160 of 851