Which stellar types occupy the upper right region of the H-R diagram, despite sometimes having modest surface temperatures?
Answer
Giants and supergiants
Stars that have evolved off the Main Sequence into the Giant or Supergiant phase are characterized by immense physical radii, even if their surface temperatures are relatively cool, sometimes cooler than the Sun. Because the Stefan-Boltzmann Law dictates that luminosity scales with the square of the radius ($R^2$), this enormous surface area allows these stars to emit a massive total amount of energy, placing them high on the vertical axis of the Hertzsprung-Russell diagram, regardless of their cooler spectral classification.
Related Questions
If two stars have identical size, how much more luminous is one whose surface temperature is twice as high as the other?What intrinsic property of a star describes its total energy output irrespective of the observer's distance?Which stellar types occupy the upper right region of the H-R diagram, despite sometimes having modest surface temperatures?How is the surface temperature of a star directly observable or determined through analysis?What fundamental physical relationship precisely quantifies the link between a star's luminosity and its temperature?What defines the primary energy generation process for stars situated along the Main Sequence on the H-R diagram?What causes White Dwarfs to exhibit very low luminosity despite possessing extremely high surface temperatures?Which spectral class corresponds to the coolest stars on the Main Sequence, typically displaying an orange to deep red color?What insight does the H-R diagram provide regarding the physical factors separating stars far from the Main Sequence diagonal?What specific characteristic determines the color associated with hotter stars versus cooler stars?