[mesa-users] A common stellar-structure myth

[Tomasz Plewa]

The original problem did not involve time, but two stellar profiles.

Tomek
--


> On Aug 30, 2016, at 10:27 PM, RICHARD H D TOWNSEND <townsend at astro.wisc.edu> wrote:
> 
> But the virial theorem is insufficient, since it only gives the instantaneous relationship between thermal and gravitational energies. It does not indicate how these quantities vary with time — i.e., the star’s luminosity.
> 
> cheers,
> 
> Rich
> 
>> On Aug 30, 2016, at 9:14 PM, Tomasz Plewa <tomekplewa at gmail.com> wrote:
>> 
>> The problem does not involve time. Then we may not need anything more than the virial theorem to solve it.
>> 
>> Tomek
>> --
>> 
>> 
>>> On Aug 30, 2016, at 6:17 PM, RICHARD H D TOWNSEND <townsend at astro.wisc.edu> wrote:
>>> 
>>> That’s as maybe, but the gravity is not stronger.
>>> 
>>> In any case, what really drives the large energy generation rate in massive stars is the energy loss rate through the stellar surface, which scale as L ~ M^3 (independent of nuclear reactions). The pre-MS star continues to contract until the core energy generation rate matches this loss rate.
>>> 
>>> cheers,
>>> 
>>> Rich
>>> 
>>>> On Aug 30, 2016, at 5:05 PM, Tomasz Plewa <tomekplewa at gmail.com> wrote:
>>>> 
>>>> It's a deeper potential well.
>>>> 
>>>> Tomek
>>>> --
>>>> 
>>>> 
>>>>> On Aug 30, 2016, at 5:52 PM, RICHARD H D TOWNSEND <townsend at astro.wisc.edu> wrote:
>>>>> 
>>>>> Hi folks —
>>>>> 
>>>>> While reading the textbook I’m going to be teaching from this semester (“Pathways to Astronomy”, by Schneider & Arny), I came across this common myth about stellar structure:
>>>>> 
>>>>> “The stronger gravity of a more massive star drives up the rate of nuclear fusion dramatically, while smaller stars consume their fuel at a more leisurely pace”.
>>>>> 
>>>>> The attached figure, courtesy of MESA, shows the internal gravity for 1Msun and 10Msun stars at the ZAMS — and nicely busts the myth.
>>>>> 
>>>>> cheers,
>>>>> 
>>>>> Rich
>>>>> 
>>>>> <gravity.pdf>
>>>>> ------------------------------------------------------------------------------
>>>>> _______________________________________________
>>>>> mesa-users mailing list
>>>>> mesa-users at lists.sourceforge.net
>>>>> https://lists.sourceforge.net/lists/listinfo/mesa-users
>