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I’m suspicious about one statement you’ve made here. Either you haven’t made it precisely, or it may not logically follow. We’ve observed many super earths beca

by sulam 9y ago

I’m suspicious about one statement you’ve made here. Either you haven’t made it precisely, or it may not logically follow. We’ve observed many super earths because that is what we can observe. The sensitivity of our instruments make it hard to observe Earth-like planets unless they are at Mercury-type orbital distance or even closer. There are some recent counter-examples, but to say that these are the most common because that’s what we’ve been able to observe is a selection bias of the first order. Now, perhaps planetary formation models predict many closely orbiting Neptune class planets, and independently observations are demonstrating that this is true. That would be a stronger statement, although still perhaps somewhat driven by observational data, since any model which doesn’t predict this might be kicked to the curb by now.

dr_zoidberg 9y ago
Yes, I see your point. Basically I mentioned the Kepler mission results, without providing the relevant link[0]. Right there you can see that super-earths are quite high in frequency. However, I remember a talk held sometime last year (or maybe this year) where the mission team talked about the Kepler results and they specifically said that super-earths were now the most common planet type found. But I can't find it, and can't back that up with a strong source. What's more, looking at the published results[1], gas giants are far more frequent (and that would line up with the selection bias you noted). The only thing I can think that would back the claim about super-earths, would be considering them on radius alone, in which case yes, the 2 < R ≤ 6 R_Earth class is the most common class[1]. Edit: I was looking mainly at the mass results (in which case a SE is any planet between 2-10x Earths mass), not the radius results. But then, the definition is still a bit shaky, with different criteria[2]. [0] https://en.wikipedia.org/wiki/Kepler_(spacecraft)#2011 https://en.wikipedia.org/wiki/Kepler_(spacecraft)#2011 [1] https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail.html https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail... [2] https://en.wikipedia.org/wiki/Super-Earth#Definition https://en.wikipedia.org/wiki/Super-Earth#Definition

by sulam 9y ago

dr_zoidberg 9y ago

Yes, I see your point. Basically I mentioned the Kepler mission results, without providing the relevant link[0]. Right there you can see that super-earths are quite high in frequency. However, I remember a talk held sometime last year (or maybe this year) where the mission team talked about the Kepler results and they specifically said that super-earths were now the most common planet type found. But I can't find it, and can't back that up with a strong source. What's more, looking at the published results[1], gas giants are far more frequent (and that would line up with the selection bias you noted). The only thing I can think that would back the claim about super-earths, would be considering them on radius alone, in which case yes, the 2 < R ≤ 6 R_Earth class is the most common class[1]. Edit: I was looking mainly at the mass results (in which case a SE is any planet between 2-10x Earths mass), not the radius results. But then, the definition is still a bit shaky, with different criteria[2]. [0] https://en.wikipedia.org/wiki/Kepler_(spacecraft)#2011 https://en.wikipedia.org/wiki/Kepler_(spacecraft)#2011 [1] https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail.html https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail... [2] https://en.wikipedia.org/wiki/Super-Earth#Definition https://en.wikipedia.org/wiki/Super-Earth#Definition