So i asked a question about if the sun was hotter on the inside or the outside, and you said normal stars are are hotter as you go toward the center, so that made me wonder, Are there are abnormal stars that aren't hotter as you go down?

Perhaps I should have said that all stars increase in temperature as you go inward. However, for normal stars, the temperature increase is fairly rapid in most regions, as described in the previous reply. For 'dead' stars (white dwarfs and neutron stars), there is also a rapid increase in temperature in the outer layers, but once you reach the 'degenerate' interior, the temperature increase, though still present, is much smaller and to a first approximation their deep interior has constant temperature. Even for those stars, however, there is some temperature increase as you go downwards, because if the temperature did not increase, heat would flow inward until the temperature did increase as you go inward.

The only exception is black holes. Since the entire star has collapsed to a zero-size 'point' mass called a singularity, insofar as temperature has any meaning for such an object, it is the same temperature everywhere in that single point.

There is also a small caveat in that what really must increase as you go downward is brightness, not temperature. Inside the star, no matter what kind of star ('live' or 'dead'), the only way to increase the brightness is to increase the temperature. But above the surface, in the 'atmosphere' of the star, brightness is increased by increasing the density, not the temperature. So the atmosphere can be (and often is) hotter than the surface. However, being very low in density, its total heat is very small, no matter how high its temperature. And in the case of a question like yours, it would generally be assumed that you start at the 'surface' and go down, and ignore what is going on in the atmosphere, so in my initial reply I ignored that. (If you would like to see how this works in more detail, refer to The Brightness of the Sun at )

I have to head to the airport in just a few minutes, so though I've done a quick check of the above, there may be some spelling or grammatical errors (or worse). If so, please accept my apology, particularly if any of this is unclear; and continue to feel free to ask followup questions.


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Courtney Seligman


I can answer almost any question about astronomy and related sciences, such as physics and geology. I will not answer questions about astrology and similar pseudo-scientific rubbish.


I have been a professor of astronomy for over 40 years, and am working on an online text/encyclopedia of astronomy, and an online catalog of NGC/IC objects.

Astronomical Journal, Publications of the Astronomical Society of the Pacific (too long ago to be really relevant, but you could search for Courtney Seligman on Google Scholar)

I received a BA in astronomy and physics and a MA in astronomy, both from UCLA. I was working on my doctoral dissertation when I started teaching, and discovered that I preferred teaching to research.

Awards and Honors
(too long ago to be relevant, but Phi Beta Kappa and Sigma Xi still keep trying to get me to become a paying member)

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