Insights Blog
-- Browse All Articles --
Physics Articles
Physics Tutorials
Physics Guides
Physics FAQ
Math Articles
Math Tutorials
Math Guides
Math FAQ
Education Articles
Education Guides
Bio/Chem Articles
Technology Guides
Computer Science Tutorials
Forums
Classical Physics
Quantum Physics
Quantum Interpretations
Special and General Relativity
Atomic and Condensed Matter
Nuclear and Particle Physics
Beyond the Standard Model
Cosmology
Astronomy and Astrophysics
Other Physics Topics
Trending
Featured Threads
Log in
Register
What's new
Search
Search
Search titles only
By:
Classical Physics
Quantum Physics
Quantum Interpretations
Special and General Relativity
Atomic and Condensed Matter
Nuclear and Particle Physics
Beyond the Standard Model
Cosmology
Astronomy and Astrophysics
Other Physics Topics
Menu
Log in
Register
Navigation
More options
Contact us
Close Menu
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
Astronomy and Cosmology
Astronomy and Astrophysics
Relationship between star radius and luminosity
Reply to thread
Message
[QUOTE="Ken G, post: 5975764, member: 116697"] Yes, that's what happens in the late stages of the pre-main-sequence phase of a star like the Sun. The way the solar core went from 5 million K to 7 milllion K is by gravitational contraction. So you had a higher temperature but a smaller volume. By the virial theorem, the T was proportional to M/R, and the light energy is proportional to T^4 R^3, so that's M^4 / R. M stays the same, so that's a small increase in the total light energy in the Sun. The luminosity takes that light energy and multiplies it by the rate of escape via radiative diffusion. If the opacity per gram stays fixed (a rough approximation), the escape rate scales like R/M (the light has less distance to go, but the density is higher, and diffusion cares more about the latter than the former), so the R cancels and you end up with constant luminosity as the Sun contracts and heats in the late stages of the pre-main-sequence phase. This behavior is called the "Henyey track." (Earlier stages involve complete convection, rather than radiative diffusion, and are called the "Hayashi track"). [/QUOTE]
Insert quotes…
Post reply
Forums
Astronomy and Cosmology
Astronomy and Astrophysics
Relationship between star radius and luminosity
Back
Top