The XXVI National Meeting of Astronomy and Astrophysics will take place at the University of Aveiro, on the 8th and 9th September 2016. This meeting is organized by the Department of Physics of the University of Aveiro and the Center for Research and Development in Mathematics and Applications (CIDMA), in partnership with the Portuguese Astronomy Society (SPA).
Gr@v researchers have found that there are only two equilibrium possibilities for the spin of black hole binaries, and that they are similar to the equilibria observed for the spin of the Moon, which was identified by Giovanni Domenico Cassini in 1693. The results were published this week in MNRAS Letters.
Abstract: The study of configurations where the orbital motions are in synchrony (resonances) is important to understand the formation and evolution of the solar-system and other planetary systems. In particular, dissipative forces acting on small bodies (e.g. gas drag in early stages of the planetary system) cause slow orbital decay until capture in a resonance with a planet occurs. Previous studies of capture in resonance have been restricted to coplanar or nearly coplanar configurations. However, small bodies can have orbits which are significantly inclined with respect to the planet's orbital plane. I will present results of simulations of resonance capture in a three-dimensional model which includes prograde and retrograde orbits (respectively, inclined by less or more than 90 degrees with respect to the planet's orbit). I will show that the probability of capture in resonance has a strong dependence on inclination. In particular, retrograde orbits are more likely to be captured in resonance than prograde orbits. This study has been published in Namouni & Morais, MNRAS, 446, 1998–2009, 2015.
To celebrate the centenial of General Relativity and simulataneously celebrate five years of the Gravitation Group at the University of Aveiro (Gr@v), established in the Fall 2010, Gr@v will organize a two days event, on 25-26 November 2015. This event will also mark the closing of the "Numerical Relativity and High Energy Physics" Marie Curie IRSES action, an international partnership which was coordinated by our group that ran over the period 2012-2015. Finally, the event will also be integrated in the IDPASC doctoral programme.
The chaotic rotation of Pluto's small moons has been explained by Gr@v researchers as a natural consequence of the gravitational dynamics in Pluto's system (A&A Letter).
C. Herdeiro was the guest interviewee of Porto Canal's "Mentes que Brilham". Watch and listen to the conversation with interviewer Cláudia Fonseca about black holes and some of the research work made at Gr@v in this area.
Abstract: Transiting exoplanets, that cross their stellar disk, are of special interest because their allow the determination of their bulk density by measuring both their radius and mass. Characterising transiting exoplanets is very important since it provides unique constraints to the theories of planet formation, migration and evolution. However, the planets that have been detected by the CoRoT and Kepler space missions transits relatively faint stars. The characterisation of the mass of those exoplanets is therefore challenging, especially in the low-mass regime. Those planets have a measured radius, but very poor constraints on their mass. In this seminar, I will present the objective of the search for transiting exoplanets and the methods to characterise them. Then, I will discuss the limitation of those techniques and finally, I will present the perspectives for the future exploration of the planet density's diversity.
Abstract: Coorbital bodies are observed around the Sun sharing their orbits with the planets, but also in some pairs of satellites around Saturn. The existence of coorbital planets around other stars has also been proposed. For close-in planets and satellites, the rotation slowly evolves until some kind of equilibrium is reached. When the orbits are nearly circular, the rotation period is believed to always end synchronous with the orbital period (as it happens for the Moon). Here we demonstrate that for coorbital bodies in quasi-circular orbits, stable non-synchronous rotation is possible for a wide range of mass ratios and body shapes. We further show that the rotation becomes chaotic when the natural rotational libration frequency has the same magnitude as the orbital libration frequency.
Our group coordinated the "Numerical Relativity and High Energy Physics" IRSES network (2012-2015). Here is a list of the global network meetings organized:
