Identifying extra-solar planets

Factual Questions
1

I read this article about a high school intern that discovered a planet. The story says that the planet is the size of Jupiter and orbits its star in 2 days!

Do we actually have a model that suggests this is possible?

The planet would have to be so close to its star that I would think the tidal forces would pull it apart. At any distance from the star its velocity would be enormous (I think Ludicrous Speed would be an appropriate description). For comparison Mercury’s orbital period is 88 days.

Does anyone have a good link to how the science of these measurements works? I’m curious about the amount of error that is in these measurements.

2

Exoplanet orbits

Because it is far easier to detect abnormalities from large planets near suns, a disproportional number of exoplanets fit this model.

3

For a body being torn apart by tidal forces, try this article:

4

Thanks for the links. I guess it is counter intuitive (to me at least) but looking at the equations, the larger the mass of the planet the closer it could be to its primary. Its greater mass keeps it from breaking up.

I find astronomy amazing. The size of objects and distances involved make me feel like my head is stretching just to understand it.

5

Assume a solar mass, solar radius star. Assume a rigid Jupiter-mass planet.

The rigid-body Roche limit for a Jupiter-mass planet orbiting a Sun-like star is 894,000 km.

An orbital radius with a two-day revolution periodis .032 au, or 4,787,131 km.

The planet is safe. It is travelling crazy fast, and it’s probably hotter than hell, but it’s not in imminent danger of breaking up.

More to your original point, the measurements cited are credible from a tidal force perspective.

6

Actually, it’s not the mass of the planet that’s relevant, but its density (and also its shape, but realistic planets are all going to be about the same shape). At any given density, if you increase the mass, you’ll increase the force holding the planet together (its own gravity), but you’ll also increase the force that’s trying to pull it apart (tidal forces depend on the size of the object).