Conveners
Day 2
- Laura Magrini (Istituto Nazionale di Astrofisica (INAF))
Recently, we have studied barium lines in high-quality spectra of two metal-poor giants in the
Galactic halo. The hyperfine splitting effects on the barium lines seem to confirm the theoretical expectation that both r-process events and also s-process contribution by rotating massive stars have polluted the ancient halo of our Galaxy.
Nowadays, this kind of result can be achieved only for...
The abundances of CNO isotopes provide powerful diagnostics of different physical processes acting in stars and galaxies. In particular, carefully chosen isotopic ratios allow us to set useful constraints to galactic chemical evolution (GCE) models, with special regard to the shape of the integrated galaxy-wide stellar initial mass function. After a brief recap of the significance of the CNO...
In the last few years, the synergy between spectroscopy and asteroseismology was key to the improving the precision and accuracy of the inferred stellar properties (surface gravity, effective temperature, chemical composition, radius, mass, age).
For instance, given the difficulties associated with measuring log g via spectroscopic analyses, large-scale spectroscopic surveys have now...
New spectrographs like HRMOS hold great promise to provide high-precision abundance measurements through high-resolution spectra of dozens of stars at a time. However, the chemical composition of stars cannot be directly measured from their spectra, but must be estimated through comparisons to theoretical radiative transfer calculations. At present, shortcomings in this theory are holding back...
High resolution spectroscopy has fundamentally shaped my scientific career and has consequently become my stock in trade. I will present several benchmark examples of my work with high resolution spectroscopy of stellar spectra (a definitely biased point of view but which became relatively extensive overtime), illustrating the needs and requirements for future high resolution spectrographs...
In their youth, low-mass (0.1-1.5 Msun) stars are rapidly rotating, magnetically active and may be accreting gas from a circumstellar disk. As they age, planets form and possibly migrate, disks disperse and stars spin down, becoming less magnetically active. The magnetic field, generated by a rotation-driven dynamo process, plays a key role in all of these events; the stressing and twisting...
Young stellar objects are characterised by highly dynamical processes related to the interaction of the still accreting star and its proto-planetary disk. These include accretion of matter, funnelled through magnetic field lines from the disk to the stellar surface, as well as mass ejection in the form of collimated jets and disk winds, responsible for the disk dissipation and removal of...
One method to estimate stellar ages is based on the so-called chromospheric activity (CA), according to which we can infer that chromospherically active isolated objects must be young. At the same time, stellar orbits in the Galaxy give rise to a statistical relationship according to which anomalous velocities are probably associated with old stars. This work was built in function of objects...
HRMOS will enable radial velocity searches for planets in clusters and towards the Galactic bulge at a scale previously unobtainable with single-object spectrographs. At present, the most comparable cluster planet searches have been for transiting planets with wide-field cameras. We have led a transiting planet search using data from the Kepler telescope towards NGC 6791, an old, metal-rich...
I will present a new probe of possible variations in the fine-structure constant on Galactic size-scales: solar twins and analogues. This method has been demonstrated on local solar twin spectra from ESO HARPS. We have also recently discovered much more distant solar twins, 4kpc closer to our Galaxy's centre, where the dark matter density is 3 times higher than the local environment. ESPRESSO...
