<p>In our current universe white dwarfs are the first ones that should cool, because they are already "cold" (not producing anything anymore, just radiating heat)  remnants of a former star. The time for this to happen is disputed (10^15 or 10^37 years), but is far bigger than the age of universe, so nobody expects to find one "cooled star" yet. See <a href="http://en.wikipedia.org/wiki/Black_dwarf" rel="nofollow">this article</a> for details on "black dwarfs" as they are called.</p>

<p>In your sudden stop hypothetical universe probably the first one to cool would be the smallest and coolest stars, a M9V red dwarf (with 7.5% solar mass, 8% solar radius, 2,300K temperature). Note that brown dwarfs are categorized as substellar objects, so they shouldn't be considered. I don't think the poorly understood "Mpemba effect" can be yet applied to stars.</p>

CC BY-SA 3.0
2014-05-04T14:26:55.140Z
As pointed out, this is incorrect as white dwarfs are the hottest (they wouldn't be white if they weren't). Are you thinking of brown dwarfs?
Beta Decay
CC BY-SA 3.0
2014-05-04T14:27:41.683Z
But with white dwarfs being the hottest, surely the Mpemba effect would come in to effect
Beta Decay
CC BY-SA 3.0
2014-05-04T14:32:59.883Z
The consideration of brown dwarfs as a star is disputed, but generally they are considered substellar objects, and thus wouldn't fit the terms of your question. Presumably, the answerer refers to white dwarfs as _cold_ to indicate that they have ceased core reactions and compression, and have begun the long process of cooling. These would likely cool first, even if all other stars suddenly stopped producing heat (as per your question), as they have a head start.
Mitch Goshorn
CC BY-SA 3.0
2014-05-04T14:37:14.607Z
@Mitch Goshorn My question asks what would happen `If all stars suddenly stopped producing heat (or heating up)`. Note that I specify that in the hypothetical universe, all stars have stopped heating up as well: all decreases in temperature would start at the same time.
Beta Decay
CC BY-SA 3.0
2014-05-04T14:38:48.367Z
@Mitch Goshorn The main thing I was looking for was whether the Mpemba effect applied (hotter object cool faster than colder ones)
Beta Decay
CC BY-SA 3.0
2014-05-04T14:47:46.490Z
The Mpemba effect is not well defined and the parameters to observe it are not generally clear. Regardless this affect is generally discussed regarding water with (relative to astronomical bodies) very small temperature differences in far more complex environments. Given that, it would be hard to extrapolate the Mpemba effect to this level. Personally, I doubt it.
Mitch Goshorn
CC BY-SA 3.0
2014-05-04T18:49:54.403Z
This answer appears to be intended as a comment to an other answer.
Gerald
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2014-05-05T06:43:58.467Z
If you have a new question, please ask it by clicking the [Ask Question](http://astronomy.stackexchange.com/questions/ask) button. Include a link to this question if it helps provide context.
Envite
CC BY-SA 3.0
2014-05-03T23:12:13.093Z
2014-05-04T19:26:53.533Z
2014-05-04T19:26:53.533Z
symbiotech
<p>If all stars suddenly stopped producing heat (or heating up) which stars would cool to absolute zero first and how long would it take?</p>

CC BY-SA 3.0
2014-05-13T20:37:06.663Z
some details about the effect you were interested in [this article](http://www.wired.com/2014/05/whats-up-with-that-mpemba-effect/)
symbiotech
<star><the-sun>
Cooling of stars
Beta Decay
# Cooling of stars

(Asked by: username_0 on 2014-05-03)

If all stars suddenly stopped producing heat (or heating up) which stars would cool to absolute zero first and how long would it take?

**Tags:** star, the-sun

> **Comments:**
> **username_1**: some details about the effect you were interested in [this article](http://www.wired.com/2014/05/whats-up-with-that-mpemba-effect/)  

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## 1 answers

### Answer by username_1 on 2014-05-03. Score: 4 | Accepted answer

In our current universe white dwarfs are the first ones that should cool, because they are already "cold" (not producing anything anymore, just radiating heat) remnants of a former star. The time for this to happen is disputed (10^15 or 10^37 years), but is far bigger than the age of universe, so nobody expects to find one "cooled star" yet. See [this article](http://en.wikipedia.org/wiki/Black_dwarf) for details on "black dwarfs" as they are called.

In your sudden stop hypothetical universe probably the first one to cool would be the smallest and coolest stars, a M9V red dwarf (with 7.5% solar mass, 8% solar radius, 2,300K temperature). Note that brown dwarfs are categorized as substellar objects, so they shouldn't be considered. I don't think the poorly understood "Mpemba effect" can be yet applied to stars.

> **Comments:**
> **username_0**: As pointed out, this is incorrect as white dwarfs are the hottest (they wouldn't be white if they weren't). Are you thinking of brown dwarfs?  
> **username_0**: But with white dwarfs being the hottest, surely the Mpemba effect would come in to effect  
> **username_2**: The consideration of brown dwarfs as a star is disputed, but generally they are considered substellar objects, and thus wouldn't fit the terms of your question. Presumably, the answerer refers to white dwarfs as _cold_ to indicate that they have ceased core reactions and compression, and have begun the long process of cooling. These would likely cool first, even if all other stars suddenly stopped producing heat (as per your question), as they have a head start.  
> **username_0**: @username_2 My question asks what would happen `If all stars suddenly stopped producing heat (or heating up)`. Note that I specify that in the hypothetical universe, all stars have stopped heating up as well: all decreases in temperature would start at the same time.  
> **username_0**: @username_2 The main thing I was looking for was whether the Mpemba effect applied (hotter object cool faster than colder ones)  
> **username_2**: The Mpemba effect is not well defined and the parameters to observe it are not generally clear. Regardless this affect is generally discussed regarding water with (relative to astronomical bodies) very small temperature differences in far more complex environments. Given that, it would be hard to extrapolate the Mpemba effect to this level. Personally, I doubt it.  
> **username_3**: This answer appears to be intended as a comment to an other answer.  
> **username_4**: If you have a new question, please ask it by clicking the [Ask Question](http://astronomy.stackexchange.com/questions/ask) button. Include a link to this question if it helps provide context.  

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