33 research outputs found
On the Survival of Short-Period Terrestrial Planets
The currently feasible method of detection of Earth-mass planets is transit
photometry, with detection probability decreasing with a planet's distance from
the star. The existence or otherwise of short-period terrestrial planets will
tell us much about the planet formation process, and such planets are likely to
be detected first if they exist. Tidal forces are intense for short-period
planets, and result in decay of the orbit on a timescale which depends on
properties of the star as long as the orbit is circular. However, if an
eccentric companion planet exists, orbital eccentricity () is induced and
the decay timescale depends on properties of the short-period planet, reducing
by a factor of order if it is terrestrial. Here we examine the
influence companion planets have on the tidal and dynamical evolution of
short-period planets with terrestrial structure, and show that the relativistic
potential of the star is fundamental to their survival.Comment: 13 pages, 2 figures, accepted for publication in Ap
Dynamical Interactions Make Hot Jupiters in Open Star Clusters
Explaining the origin and evolution of exoplanetary "hot Jupiters" remains a
significant challenge. One possible mechanism for their production is
planet-planet interactions, which produces hot Jupiters from planets born far
from their host stars but near their dynamical stability limits. In the much
more likely case of planets born far from their dynamical stability limits, can
hot Jupiters can be formed in star clusters? Our N-body simulations of
planetary systems inside star clusters answer this question in the affirmative,
and show that hot Jupiter formation is not a rare event. We detail three case
studies of the dynamics-induced births of hot Jupiters on highly eccentric
orbits that can only occur inside star clusters. The hot Jupiters' orbits bear
remarkable similarities to those of some of the most extreme exoplanets known:
HAT-P-32 b, HAT-P-2 b, HD 80606 b and GJ 876 d. If stellar perturbations formed
these hot Jupiters then our simulations predict that these very hot, inner
planets are often accompanied by much more distant gas giants in highly
eccentric orbits.Comment: 18 pages, 4 figure
On the Possibility of Tidal Formation of Binary Planets Around Ordinary Stars
The planet formation process and subsequent planet migration may lead to
configurations resulting in strong dynamical interactions among the various
planets. Well-studied possible outcomes include collisions between planets,
scattering events that eject one or more of the planets, and a collision of one
or more of the planets with the parent star. In this work we consider one other
possibility that has seemingly been overlooked in the various scattering
calculations presented in the literature: the tidal capture of two planets
which leads to the formation of a binary planet (or binary brown dwarf) in
orbit about the parent star. We carry out extensive numerical simulations of
such dynamical and tidal interactions to explore the parameter space for the
formation of such binary planets. We show that tidal formation of binary
planets is possible for typical planet masses and distances from the host star.
The detection (or lack thereof) of planet-planet binaries can thus be used to
constrain the properties of planetary systems, including their mutual spacing
during formation, and the fraction of close planets in very eccentric orbits
which are believed to form by a closely related process.Comment: 11 pages, 10 Figures, submitted to Ap