<p>I found one "hot Jupiter" in the Kepler data (Kepler 45b). The star is a M dwarf with an effective temperature of 3820K. The planet has an estimated mass of 160.5 M(Earth) and radius of 10.76 R(Earth). This gives a density of about 0.8 g/cm2 which is consistent. The planet is located at approximately 0.03 AU from the star with an orbital eccentricity of 0.11. Also, it may be interesting that the star has a very high metallicity of Fe/H = 0.28. (This data is from <a href="http://kepler.nasa.gov/Mission/discoveries/" rel="noreferrer">http://kepler.nasa.gov/Mission/discoveries/</a> ).</p>

<p>It must be said, however, that M dwarfs only made up about 4.3% of the initial Kepler study which found 82 "Jupiter size" planets (as of my tally in April of 2015). Thus, there is an indication that there are less "hot Jupiters" around M dwarfs, but sample size is way too small. There does seem to be a correlation between stars hosting "hot Jupiters" and their metallicity (more common around higher Fe/H stars).</p>

<p>My gut feeling is that "hot Jupiters" in general are uncommon. They are just the easiest thing to find.</p>

CC BY-SA 3.0
2016-03-16T15:30:12.793Z
I need to make the comment that the numbers in the answer above are not from the entire Kepler study, but just the listing of confirmed exoplanets from the Kepler 1 mission as of April 1, 2015. Also, I just looked at James Kilfiger's link and it's the same star/ "hot Jupiter" that I mentioned.
Jack R. Woods
CC BY-SA 3.0
2016-03-16T17:31:15.653Z
I wouldn't call them "uncommon", because during planetary formation, large planets migrating inwards seems fairly common.   Jupiter is thought to have done this, but fortunately, it stopped somewhere outside of Mars and then migrated back outwards.  (I think) hot jupiters are fairly common, but I agree with you on being the easiest to discover.
userLTK
CC BY-SA 3.0
2016-03-17T03:02:10.413Z
@userLTK Too bad we're not famous like Hawking and Thorne or I'd bet you a Penthouse subscription. Hopefully, we will have a good idea within the next decade or so.
Jack R. Woods
CC BY-SA 3.0
2016-03-17T10:28:17.753Z
@userLTK Hot Jupiter's are uncommon (found around only ~1% of stars). Hot Jupiter's around M dwarfs are even less common. No gut feelings required. This has been answered on Astro SE before I'm sure.
ProfRob
CC BY-SA 3.0
2016-03-17T10:30:37.087Z
Indeed. http://astronomy.stackexchange.com/questions/107/what-proportion-of-planetary-systems-have-been-found-with-hot-jupiters However, Jack's answer, presenting a single example, fully answers the question as asked...
ProfRob
CC BY-SA 3.0
2016-03-17T15:25:55.503Z
Looks like I lost the bet.   Thank-you for the correction.
userLTK
CC BY-SA 3.0
2016-03-16T15:17:01.117Z
2016-03-16T15:17:01.117Z
Jack R. Woods
<p>Do we know of any hot jupiters that could be orbiting a red dwarf (or, more probably, orbiting a barycenter between the two)? Is this scenario even physically possible?</p>

CC BY-SA 3.0
2016-03-10T22:16:24.343Z
Rare but not unknown http://arxiv.org/abs/1112.0017
James K
CC BY-SA 3.0
2016-03-11T01:52:16.177Z
"or, more probably, orbiting a barycenter between the two" I'd say 100% probable since that is how it always works.
zephyr
CC BY-SA 3.0
2016-03-11T07:52:06.250Z
Yes, they are known.
ProfRob
CC BY-SA 3.0
2016-03-11T14:33:29.497Z
@zephyr I mean a barycenter external to the star.
Breaking Bioinformatics
CC BY-SA 3.0
2016-03-11T21:52:11.230Z
@BreakingBioinformatics  The barycenter point is interesting.  The larger red dwarfs have a luminosity of only about 4% of the sun.  A "hot" Jupiter would need to be some 1/5 of an AU away from such a star to approach being hot.  (receive earth level solar energy).   I would think all hot jupiters around red dwarfs would have a barycenter inside the dwarf, unless it was a very massive Jupiter.    My calculations were done rather quickly though, but I think in most cases, the barycenter would be in the red dwarf.
userLTK
CC BY-SA 3.0
2016-03-17T10:30:57.510Z
Related http://astronomy.stackexchange.com/questions/107/what-proportion-of-planetary-systems-have-been-found-with-hot-jupiters
ProfRob
<orbit><exoplanet><star-formation><red-dwarf><hot-jupiter>
Are there any hot jupiters orbiting red dwarfs?
Breaking Bioinformatics
# Are there any hot jupiters orbiting red dwarfs?

(Asked by: username_0 on 2016-03-10)

Do we know of any hot jupiters that could be orbiting a red dwarf (or, more probably, orbiting a barycenter between the two)? Is this scenario even physically possible?

**Tags:** orbit, exoplanet, star-formation, red-dwarf, hot-jupiter

> **Comments:**
> **username_1**: Rare but not unknown http://arxiv.org/abs/1112.0017  
> **username_2**: "or, more probably, orbiting a barycenter between the two" I'd say 100% probable since that is how it always works.  
> **username_3**: Yes, they are known.  
> **username_0**: @username_2 I mean a barycenter external to the star.  
> **username_4**: @username_0  The barycenter point is interesting.  The larger red dwarfs have a luminosity of only about 4% of the sun.  A "hot" Jupiter would need to be some 1/5 of an AU away from such a star to approach being hot.  (receive earth level solar energy).   I would think all hot jupiters around red dwarfs would have a barycenter inside the dwarf, unless it was a very massive Jupiter.    My calculations were done rather quickly though, but I think in most cases, the barycenter would be in the red dwarf.  
> **username_3**: Related http://astronomy.stackexchange.com/questions/107/what-proportion-of-planetary-systems-have-been-found-with-hot-jupiters  

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## 1 answers

### Answer by username_5 on 2016-03-16. Score: 4 | Accepted answer

I found one "hot Jupiter" in the Kepler data (Kepler 45b). The star is a M dwarf with an effective temperature of 3820K. The planet has an estimated mass of 160.5 M(Earth) and radius of 10.76 R(Earth). This gives a density of about 0.8 g/cm2 which is consistent. The planet is located at approximately 0.03 AU from the star with an orbital eccentricity of 0.11. Also, it may be interesting that the star has a very high metallicity of Fe/H = 0.28. (This data is from <http://kepler.nasa.gov/Mission/discoveries/> ).

It must be said, however, that M dwarfs only made up about 4.3% of the initial Kepler study which found 82 "Jupiter size" planets (as of my tally in April of 2015). Thus, there is an indication that there are less "hot Jupiters" around M dwarfs, but sample size is way too small. There does seem to be a correlation between stars hosting "hot Jupiters" and their metallicity (more common around higher Fe/H stars).

My gut feeling is that "hot Jupiters" in general are uncommon. They are just the easiest thing to find.

> **Comments:**
> **username_5**: I need to make the comment that the numbers in the answer above are not from the entire Kepler study, but just the listing of confirmed exoplanets from the Kepler 1 mission as of April 1, 2015. Also, I just looked at username_1 Kilfiger's link and it's the same star/ "hot Jupiter" that I mentioned.  
> **username_4**: I wouldn't call them "uncommon", because during planetary formation, large planets migrating inwards seems fairly common.   Jupiter is thought to have done this, but fortunately, it stopped somewhere outside of Mars and then migrated back outwards.  (I think) hot jupiters are fairly common, but I agree with you on being the easiest to discover.  
> **username_5**: @username_4 Too bad we're not famous like Hawking and Thorne or I'd bet you a Penthouse subscription. Hopefully, we will have a good idea within the next decade or so.  
> **username_3**: @username_4 Hot Jupiter's are uncommon (found around only ~1% of stars). Hot Jupiter's around M dwarfs are even less common. No gut feelings required. This has been answered on Astro SE before I'm sure.  
> **username_3**: Indeed. http://astronomy.stackexchange.com/questions/107/what-proportion-of-planetary-systems-have-been-found-with-hot-jupiters However, username_5's answer, presenting a single example, fully answers the question as asked...  
> **username_4**: Looks like I lost the bet.   Thank-you for the correction.  

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