We present an analysis of the bulk composition of the MEarth transiting super Earth exoplanet GJÂ 1214b using planet interior structure models .
We consider three possible origins for the gas layer on GJÂ 1214b : direct accretion of gas from the protoplanetary nebula , sublimation of ices , and outgassing from rocky material .
Armed only with measurements of the planet mass ( M _ { p } = 6.55 \pm 0.98 ~ { } M _ { \oplus } ) , radius ( R _ { p } = 2.678 \pm 0.13 ~ { } R _ { \oplus } ) , and stellar irradiation level , our main conclusion is that we can not infer a unique composition .
A diverse range of planet interiors fits the measured planet properties .
Nonetheless , GJÂ 1214b ’ s relatively low average density ( \rho _ { p } = 1870 \pm 400 ~ { } { kg m ^ { -3 } } ) means that it almost certainly has a significant gas component .
Our second major conclusion is that under most conditions we consider GJÂ 1214b would not have liquid water .
Even if the outer envelope is predominantly sublimated water ice , the envelope will likely consist of a super-fluid layer sandwiched between vapor above and plasma ( electrically conductive fluid ) below at greater depths .
In our models , a low intrinsic planet luminosity \left ( \lesssim 2 ~ { } TW \right ) is needed for a water envelope on GJÂ 1214b to pass through the liquid phase .