Related papers: Planets around extreme horizontal branch stars
At least 10-15% of nearby sun-like stars have known Jupiter-mass planets. In contrast, very few planets are found in mature open and globular clusters such as the Hyades and 47 Tuc. We explore here the possibility that this dichotomy is due…
Eccentricity is an important orbital parameter. Understanding its effect on planetary climate and habitability is critical for us to search for a habitable world beyond our solar system. The orbital configurations of M-dwarf planets are…
Planets with several Earth masses and a few day orbital periods have been discovered through radial velocity and transit surveys. Regardless of their formation mechanism, a key evolution issue is the efficiency of their retention near their…
In the high-eccentricity migration (HEM) scenario, close-in planets reach the vicinity of the central star on high-eccentricity orbits that become circularized---with a concomitant decrease in the semimajor axis---through a tidal…
The orbital eccentricity-radius relation for small planets is indicative of the predominant dynamical sculpting processes during late-stage orbital evolution. Previous studies have shown that planets orbiting Sun-like stars exhibit an…
Planets and brown dwarfs in close orbits will interact with their host stars, as soon as the stars evolve to become red giants. However, the outcome of those interactions is still unclear. Recently, several brown dwarfs have been discovered…
We investigate the interaction between an eccentric planet and a less massive external debris disc. This scenario could occur after planet-planet scattering or merging events. We characterise the evolution over a wide range of initial…
We investigate the evolution of interacting binaries where the donor star is a low-mass giant more massive than its companion. It is usual to assume that such systems undergo common-envelope (CE) evolution, where the orbital energy is used…
Strong tidal interaction with the central star can circularize the orbits of close-in planets. With the standard tidal quality factor Q of our solar system, estimated circularization times for close-in extrasolar planets are typically…
Substellar objects such as brown dwarfs and planets are generally expected to remain detached from their main-sequence host stars unless orbital decay or stellar expansion brings them into contact, leading to rapid engulfment and…
Many exoplanets in close-in orbits are observed to have relatively high eccentricities and large stellar obliquities. We explore the possibility that these result from planet-planet scattering by studying the dynamical outcomes from a large…
It has been shown that there is a possible mass-period correlation for extrasolar planets from the current observational data and this correlation is, in fact, related to the absence of massive close-in planets, which are strongly…
Subdwarf B (sdB) stars are thought to be core helium burning stars with low mass hydrogen envelopes. In recent years it has become clear that many sdB stars lose their hydrogen through interaction with a binary companion and continue to…
Recent observations have shown that at least some close-in exoplanets maintain eccentric orbits despite tidal circularization timescales that are typically shorter than stellar ages. We explore gravitational interactions with a distant…
Observations of the population of cold Jupiter planets ($r>$1 AU) show that nearly all of these planets orbit their host star on eccentric orbits. For planets up to a few Jupiter masses, eccentric orbits are thought to be the outcome of…
To date, two planetary systems have been discovered with close-in, terrestrial-mass planets (< 5-10 Earth masses). Many more such discoveries are anticipated in the coming years with radial velocity and transit searches. Here we investigate…
Based on the large number of elliptical planetary nebulae I argue that about 55 per cent of all progenitors of planetary nebulae have planets around them. The planets spin up the stars when the later evolve along the red giant branch or…
We quantify an evolutionary channel for single sdB stars based on mergers of binaries containing a red giant star and a lower mass main sequence or brown dwarf companion in our Galaxy. Population synthesis calculations that follow mergers…
Observational evidence of white dwarf planetary systems is dominated by the remains of exo-asteroids through accreted metals, debris discs, and orbiting planetesimals. However, exo-planets in these systems play crucial roles as perturbing…
The evolution of many close binary and multiple star systems is defined by phases of mass exchange and interaction. As these systems evolve into contact, tidal dissipation is not always sufficient to bring them into circular, synchronous…