Their topics include fundamentals of stellar variability observations, stellar structure and evolution theory, stellar pulsation theory, Cepheid and related variable stars, pulsating stars close to the lower main sequence in the H-R diagram
, hot subdwarf pulsators, and pulsating degenerate stars.
In its usual form established by Russell, the H-R diagram
is a graph showing the relation of stellar luminosities on the vertical axis and temperatures on the horizontal axis, with the brighter stars near the top and the hotter stars on the left.
A PhD-level science educator/co-editor of a series that provides systematic overviews of the latest ideas on the nature and evolution of major celestial objects covers the properties and types of stars in the context of the H-R Diagram
(for inferring information about a star's life stage by measuring its temperature and luminosity), and the large systems of stars known as galaxies.
Simply written in expository prose, "The Lives of Stars" has chapters that define how a star is born, the H-R diagram
(a way of measuring the intensity of stars that reveals the star's projected life story), descriptions of many different types of stars, star clusters, the origin of the elements, and what to considre about the possibility of life in space, to name just a few.
Giving Hertz-sprung credit for priority, it is usually called the Hertzsprung-Russell diagram, or the H-R diagram
The most difficult part in constructing an H-R diagram
is measuring each star's luminosity.
As a humanist, I was fascinated that the H-R diagram
could serve as a metaphor for human lives as well.
In Extreme Stars: At the Edge of Creation, University of Illinois astronomy professor James Kaler tells some enthralling tales of star life as he takes the reader for a walk on the wild side of the H-R diagram
Bodies migrate in characteristic ways across the H-R diagram
. Normally, significant motion occurs only on time scales of millions or billions of years--thus it's impossible to watch a star travel across the diagram in a human lifetime.
When these are plotted against each other on a graph, the result is called a Hertzsprung-Russell or H-R diagram
. This has been a fundamental astrophysical tool ever since it was invented around 1911.
Star Probe is accompanied by a 19-page manual containing brief instructions, four cookbook-type worksheets that use the program (including "Plot an H-R Diagram
" and "Chart Evolutionary Pathways"), and three suggested supplementary activities -- such as observing the Sun -- which require additional equipment.
The backbone of the H-R diagram
is the main sequence (see the illustration at left).