Super Earth Atmosphere Detected Options

[JRehling]

http://www.forbes.com/sites/bridaineparnel...s/#6b7276f41879

This is a potentially blockbuster result. If Super Earths tend to have atmospheres with a lot of hydrogen, that would have implications for how earthlike they might ever become. And for a hot Super Earth to have a lot of hydrogen and helium would seemingly make it more likely for warm and cool ones to hold those lighter gases, as well.

There has to be a transition between atmospheres dominated by H2 and He and those dominated by other gases, and it will be fascinating to see how that transition operates. This is the first data point in that exploration. Well, the first new data point since we measured Neptune's atmospheric composition.

[alan]

Some important details left out of the Forbes article: 55 Cancri e, 8.6 Earth masses, period 0.74 days.

[dvandorn]

Which makes this particular example sound more like a hot Jupiter that is in the final stages of losing its atmospheric mass, rather than a super-Earth that developed with a largely hydrogen/helium atmosphere in the first place.

So, I hate to say, I don't think this says anything about the atmospheric constituents on super-Earths that are not also hot Jupiters that have spiraled in to their suns so far that they are orbiting every 18 hours...

-the other Doug

[JRehling]

Excellent point, other Doug. It would be useful to analyze the capacity of this planet, given its escape velocity and temperature, to hold various gases. That sort of thing is only knowable within loose bounds, but it's a useful next step.

If this planet is losing its hydrogen and helium, that process would presumably accelerate over time, and perhaps terminate rather rapidly over geological time scales. If so, then it would be fairly unlikely to witness a case of partial loss. But that's something we'll have to verify as more cases are observed, and this is only number one.