Re: Why is Sirius B hotter than Sirius A?


"J. Scott Miller" <jsfmiller@xxxxxxxxxxxx> wrote in message
news:d3namf$1p6n$1@xxxxxxxxxxxxxxxxxxxxxx
> me wrote:
>> Hi
>>
>> Sirius B, a white dwarf, has a surface temperature of around 25,000
>> degrees C. Sirius A, a blue/white main sequence star has a surface
>> temperature of around 12,000 degrees C. Usually the bluer a star is, the
>> hotter it is. Just wondered why it's not the case here.
>
> Essentially, you have answered your own question, assuming you know what a
> white dwarf is supposed to be. A white dwarf is supposed to be the core
> of a now dead star, a low mass type like our Sun. As the core of a star,
> they simply retain the heat from those nuclear fusion processes that were
> proceeding prior to the end of the star's life. Now, heat stored within
> them, they simply radiate that heat, lowering their temperature eventually
> to absolute zero over 10s and possibly 100s of billions of years.
>
> And, since they are not generating their own energy but simply radiating
> stored energy, comparisons of their color to that of stars is comparing
> apples to oranges.

So what, they don't emit standard black-body radiation?



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