Search for Life:- Extrasolar Planets

[SsDd]

The lecture video is embedded below.

Additionally, slides used in the lecture are embedded below, or can also be downloaded directly from here.

Questions after the lecture? Please feel free to post them in the same thread.

Click to play embedded YouTube video.

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[dougettinger]

How can extrasolar planets as large or larger than Jupiter possibly orbit inside an orbit comparable to Mercury's orbit around their parent star ? Would not the gases and ices have boiled away in a very short period of time ?

Doug Ettinger, Pittsburgh, PA 02/09/2011

[neufer]

How can extrasolar planets as large or larger than Jupiter possibly orbit inside an orbit comparable to Mercury's orbit around their parent star ? Would not the gases and ices have boiled away in a very short period of time ?

Planets don't really lose their atmospheres because they are hot;
Venus is much hotter than the Earth but it has plenty of atmosphere.

Planets lose their atmospheres because they are small like Mars.

The escape velocity of Jupiter is 5.3 times that of earth which
means that a Jupiter sized planet can be 5.3² times hotter (~ 7000 K)
than an Earth sized planet and still maintain its atmosphere as well.

[dougettinger]

Your explanation makes sense, but I believe the rocky terrestrial type planets are explained as occurring due to the escape velocity not being high enough to prevent super hot H and He from escaping their upper atmospheres.

The outer gas giants were too cold for volatiles to boil off. These gas giants not only kept their lighter elements but kept collecting them throughout most of the proto-star disk history. There seems to be a dichotomy in this and the previous explanations ??

Doug Ettinger, Pittsburgh, PA 02/10/2011