  Many gaseous exoplanets in short-period orbits are on the verge or are in the
process of Roche-lobe overflow (RLO). Moreover, orbital stability analysis
shows tides can drive many hot Jupiters to spiral inevitably toward their host
stars. Thus, the coupled processes of orbital evolution and RLO likely shape
the observed distribution of close-in exoplanets and may even be responsible
for producing some of the short-period rocky planets. However, the exact
outcome for an overflowing planet depends on its internal response to mass
loss, and the accompanying orbital evolution can act to enhance or inhibit RLO.
In this study, we apply the fully-featured and robust Modules for Experiments
in Stellar Astrophysics (MESA) suite to model RLO of short-period gaseous
planets. We show that, although the detailed evolution may depend on several
properties of the planetary system, it is largely determined by the core mass
of the overflowing gas giant. In particular, we find that the orbital expansion
that accompanies RLO often stops and reverses at a specific maximum period that
depends on the core mass. We suggest that RLO may often strand the remnant of a
gas giant near this orbital period, which provides an observational prediction
that can corroborate the hypothesis that short-period gas giants undergo RLO.
We conduct a preliminary comparison of this prediction to the observed
population of small, short-period planets and find some planets in orbits that
may be consistent with this picture. To the extent that we can establish some
short-period planets are indeed the remnants of gas giants, that population can
elucidate the properties of gas giant cores, the properties of which remain
largely unconstrained.
