  According to the computations results obtained by Bisikalo et al. (2013b) for
the gas-dynamical effect of stellar winds on exoplanet atmospheres, three types
of gaseous envelopes can form around hot Jupiters: closed, quasi-closed, and
open. The type of envelope that forms depends on the position of the frontal
collision point (where the dynamical pressure of the wind is equal to the
pressure of the surrounding atmosphere) relative to the Roche-lobe boundaries.
Closed envelopes are formed around planets whose atmospheres lie completely
within their Roche lobes. If the frontal collision point is located outside the
Roche lobe, the atmospheric material begins to flow out through the Lagrangian
points $\mathrm{L_1}$ and $\mathrm{L_2}$, which can result in the formation of
quasi-closed (if the dynamical pressure of the stellar wind stops the outflow
through $\mathrm{L_1}$) or open gaseous envelopes. The example of the typical
hot Jupiter HD 209458 b is considered for four sets of atmospheric parameters,
to determine the mass-loss rates for the different types of envelopes arising
with these parameters. The mass-loss rates based on the modeling results were
estimated to be $\dot{M} \leq 10^{9}$ g/s for a closed atmosphere, $\dot{M}
\simeq 3 \times 10^{9}$ g/s for a quasi-closed atmosphere, and $\dot{M} \simeq
3 \times 10^{10}$ g/s for an open atmosphere. The matter in the closed and
quasi-closed atmospheres flows out mainly through $\mathrm{L_2}$, and the
matter in open envelopes primarily through $\mathrm{L_1}$.
