Tokyo Institute of Technology · Physics and Astronomy
Professor Ramon Brasser's research lab specializes in solar system dynamics, focusing on the origin and evolution of small bodies such as trans-Neptunian objects, Centaurs, and long-period comets. The lab investigates planetary migration, particularly the giant planet instability and 'jumping Jupiter' scenarios, to explain the dynamical architecture of the outer solar system. Using high-precision numerical simulations, the group explores the origin of the Oort cloud, the role of galactic tides, and the stability of exo-Earth systems. Their work bridges planetary formation, orbital dynamics, and the observational constraints from discovered trans-Neptunian objects and exoplanets.
Figures are computed from collected data and may differ slightly.
We investigate the dynamical evolution of the terrestrial planets during the planetesimal-driven migration of the giant planets. A basic assumption of this work is that giant planet migration occurred after the completion of terrestrial planet formation, such as in the models that link the former to the origin of the late heavy bombardment. The divergent migration of Jupiter and Saturn causes the g 5 eigenfrequency to cross resonances of the form g 5 = g k with k ranging from 1 to 4. Consequentl
We analyse the origin of three Centaurs with perihelia in the range 15 AU to 30 AU, inclinations above 70 deg and semi-major axes shorter than 100 AU. Based on long-term numerical simulations we conclude that these objects most likely originate from the Oort cloud rather than the Kuiper Belt or Scattered Disc. We estimate that there are currently between 1 and 200 of these high-inclination, high-perihelion Centaurs with absolute magnitude H<8.
Evidence in the Solar system suggests that the giant planets underwent an epoch of radial migration that was very rapid, with an e-folding time-scale shorter than 1 Myr. It is probable that the cause of this migration was that the giant planets experienced an orbital instability that caused them to encounter each other, resulting in radial migration. A promising and heavily studied way to accomplish such a fast migration is for Jupiter to have scattered one of the ice giants outwards; this event
The detached object Sedna is likely at the inner edge of the Oort cloud, more precisely the inner Oort cloud (IOC). Until recently it was the sole member of this population. The recent discovery of the detached object 2012 VP113 has confirmed that there should be more objects in this region. Three additional IOC candidates with orbits much closer to Neptune have been proposed in the past decade since Sedna's discovery: 2000 CR105, 2004 VN112 and 2010 GB174. Sedna and 2012 VP113 have perhelia nea
In this study we present the results from numerical simulations of the formation of the Oort comet cloud where we positioned the Sun in various parts of the disc of the Galaxy, starting at 2 kpc up to 20 kpc from the Galactic centre. All simulations were run for 4 Gyr. We report that the final trapping efficiency of comets in the Oort cloud is approximately 4% and is almost independent of the solar distance from the Galactic centre. This efficiency is not enough to explain the flux of long-perio
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