20
Lines of
constant R in the H-R diagram
•Main sequence not quite constant R
•B stars: R
~10 RSun
•M stars: R
~0.1 RSun
•Betelgeuse: R~
1,000 RSun
•Larger than 1 AU
•White dwarfs: R~
0.01 RSun
•A few Earth radii
•What causes the “main sequence”?
•Why “similar” size, with precise R related to T?
•Why range of T?
•Why are a few stars (giants, white dwarfs) not on main sequence?
From our text: Horizons, by Seeds