Hot Jupiters.

[Gareth56]

If hot jupiters (e.g. 51 Peg b) orbit so close to their parent star why doesn't the heat or radiation or solar wind blast the gas off the hot jupiter?

[Klaynos]

I'd guess it was because their gravity could overcome this force... But that is purely speculation.

[Reaper]

Most of these Jupiters that have been found are much, much larger than Jupiter; they are typically dubbed Super-Jupiters. I would not be surprised if such planets would have the gravity necessary to hold on to their material.

[insane_alien]

there would likely be some loss of material. a significant amount in human terms(multi-million tonnes per annum?) but this wouldn't really be all that big in terms of a super jupiter. kind of like shaving a millimeter per millenium off of the top of everest.

[gonelli]

kind of like shaving a millimeter per millenium off of the top of everest.

 

And even then you wouldn't notice its effects since Everest is becoming higher at a faster rate.

[Gareth56]

Thanks for the replies. So the consensus of opinion is that the gravitational attraction exerted by these planets (Super- Jupiters) on the gas molecules/atoms is sufficiently great to prevent them from being blown off by the parent star's radiation.

[D H]

This paper at arXiv, http://arxiv.org/abs/astro-ph/0508591v3 is quite relevant to the topic at hand.

[Ugouka]

I'm surprised that no one mentioned anything about magnetic fields. I'm not sure how effective they would be that close to the parent star, but a hot jupiter would have a powerful magnetic field that would repel the majority of antagonistic forces trying to strip it of its gas. I agree that gravity has something to do with it, but if you think about it, it needs to be more than that. I'm sure if it was powerful enough to retain it's gasses in that environment by gravity alone, it would not only be retaining gas, but stealing some from the parent star. I could be wrong, but I could be right. If this were true and it was relying on gravity alone, it could eventually turn into a binary system that could result in a collision because of the massive growth caused by the reactions inside the newly formed star. I will go off on this tangent more if you'd like me to, but if you don't want to hear it, then I won't waste our time.

[Reaper]

I'm surprised that no one mentioned anything about magnetic fields. I'm not sure how effective they would be that close to the parent star, but a hot jupiter would have a powerful magnetic field that would repel the majority of antagonistic forces trying to strip it of its gas. I agree that gravity has something to do with it, but if you think about it, it needs to be more than that. I'm sure if it was powerful enough to retain it's gasses in that environment by gravity alone, it would not only be retaining gas, but stealing some from the parent star. I could be wrong, but I could be right. If this were true and it was relying on gravity alone, it could eventually turn into a binary system that could result in a collision because of the massive growth caused by the reactions inside the newly formed star. I will go off on this tangent more if you'd like me to, but if you don't want to hear it, then I won't waste our time.

 

No it would not. Magnetism only works on other materials that are magnetized, and the gases of a hot Jupiter probably wouldn't have that much. Second, magnetism only occurs when there is an electric current, and even then it's strength is dependent entirely on it's magnetic current. For all intents and purposes it is weak compared to the 4 fundamental forces (even gravity).

 

To take an example for Jupiter, it's magnetic field is incredibly weak; it's field is only ten times stronger then that of Earth at the top of the clouds. We can make much stronger magnetic fields with a simple hammer and iron, or an electromagnet.

 

Gravity, on the other hand, acts on all matter and particles. Thus it would be the predominant force that would keep the super-Jupiters together.

[NowThatWeKnow]

No it would not. Magnetism only works on other materials that are magnetized, and ...

 

http://en.wikipedia.org/wiki/Earth's_magnetic_field

 

"The magnetosphere shields the surface of the Earth from the charged particles of the solar wind and is generated by electric currents located in many different parts of the Earth. It is compressed on the day (Sun) side due to the force of the arriving particles, and extended on the night side."

[Reaper]

http://en.wikipedia.org/wiki/Earth's_magnetic_field

 

"The magnetosphere shields the surface of the Earth from the charged particles of the solar wind and is generated by electric currents located in many different parts of the Earth. It is compressed on the day (Sun) side due to the force of the arriving particles, and extended on the night side."

 

Yes, notice how it says CHARGED PARTICLES, not ALL particles. Gamma rays and regular light can penetrate the magnetic field with ease. It supports my position completely.

[NowThatWeKnow]

Yes, notice how it says CHARGED PARTICLES, not ALL particles. Gamma rays and regular light can penetrate the magnetic field with ease. It supports my position completely.

So you are saying that charged particles from the solar wind would have no influance on the atmosphere of a planet if they got through the magnetic field? Just a question, I do not know the answer.