2 results
Search Results
Now showing 1 - 2 of 2
- ItemDifferential population studies using asteroseismology: Solar-like oscillating giants in CoRoT fields LRc01 and LRa01(Les Ulis : EDP Sciences, 2013) Miglio, A.; Chiappini, C.; Morel, T.; Barbieri, M.; Chaplin, W.J.; Girardi, L.; Montalbán, J.; Noels, A.; Valentini, M.; Mosser, B.; Baudin, F.; Casagrande, L.; Fossati, L.; Aguirre, V.S.; Baglin, A.Solar-like oscillating giants observed by the space-borne satellites CoRoT and Kepler can be used as key tracers of stellar populations in the Milky Way. When combined with additional photometric/spectroscopic constraints, the pulsation spectra of solar-like oscillating giant stars not only reveal their radii, and hence distances, but also provide well-constrained estimates of their masses, which can be used as proxies for the ages of these evolved stars. In this contribution we provide supplementary material to the comparison we presented in Miglio et al. (2013) between populations of giants observed by CoRoT in the fields designated LRc01 and LRa01.
- ItemConstraining the formation of the Milky Way: Ages(Les Ulis : EDP Sciences, 2013) Chiappini, C.; Minchev, I.; Martig, M.We present a new approach for studying the chemodynamical evolution of the Milky Way, which combines a thin disk chemical evolution model with the dynamics from N-body simulation of a galaxy with properties similar to those of our Galaxy. A cosmological re-simulation is used as a surrogate in order to extract ∼11 Gyrs of self-consistent dynamical evolution. We are then in a position to quantify the impact of radial migration at the Solar Vicinity. We find that the distribution of birth radii, r0, of stars ending up in a solar neighborhood-like location after ∼11 Gyr of evolution peaks around r0 = 6 kpc due to radial migration. A wide range of birth radii is seen for different age groups. The strongest effect from radial migration is found for the oldest stars and it is connected to an early merger phase typical from cosmological simulations. We find that while the low-end in our simulated solar vicinity metallicity distribution is composed by stars with a wide range of birth radii, the tail at larger metallicities (0.25 <[Fe/H]< 0.6) results almost exclusively from stars with 3 < r0< 5 kpc. This is the region just inside the bar's corotation (CR), which is where the strongest outward radial migration occurs. The fraction of stars in this tail can, therefore, be related to the bar's dynamical properties, such as its strength, pattern speed and time evolution/formation. We show that one of the main observational constraints of this kind of models is the time variation of the abundance gradients in the disk. The most important outcome of our chemodynamical model is that, although we used only a thin-disc chemical evolution model, the oldest stars that are now in the solar vicinity show several of the properties usually attributed to the Galactic thick disc. In other words, in our model the MW "thick disc" emerges naturally from stars migrating from the inner disc very early on due to strong merger activity in the first couple of Gyr of disc formation, followed by further radial migration driven by the bar and spirals at later times. These results will be extended to other radius bins and more chemical elements in order to provide testable predictions once more precise information on ages and distances would become available (with Gaia, asteroseismology and future surveys such as 4MOST).