Partecipanti: Fiorenzo Vincenzo (Università di Trieste)
Abstract
The patterns of chemical abundances, as derived in the atmosphere of the stars
or in the interstellar medium of galaxies, keep the imprint of the various
physical processes which take place and influence the interstellar medium of
galaxies during their evolution. In the first part of the talk, I will present
how we model the chemical evolution of some classical and ultra-faint dwarf
spheroidal galaxies of the Milky Way, starting from the chemical abundances of
alpha and n-capture elements which are observed in their member stars at the
present time. Thanks to the very efficient spectrographs currently working in
connection with large and medium-sized telescopes, which have provided us large
amounts of accurate data, the stellar populations of these galaxies have been
studied in always greater detail in the last years. In the second part of the
talk, I will focus on the (N/O) vs. (O/H) abundance pattern, as inferred in a
sample of SDSS galaxies (Data Release 7, Abazajian et al. 2009). This dataset -
integrated with the N and O abundances derived in metal-poor, star forming
dwarf galaxies - spans a wide metallicity range, enabling us to recover the
trend of the (N/O) vs. (O/H) relation with a definition never reached before.
This collection of data clearly demonstrates the existence of a plateau in the
(N/O) ratios at very low metallicity, followed by an increase which steepens as
the metallicity increases. This trend has been interpreted in the past as the
signature of two complementary producers of nitrogen acting in galaxies (pure
primary N from massive stars + primary and secondary N from low- and
intermediate-mass stars). I will present a set of novel chemical evolution
models to reproduce such trend.
See you on Thursday in the seminars’ room, floor -1, via Ranzani 1, on time at 14h.
Next seminars:
- Thursday September 17th, at 14:00 Leslie Hunt (INAF, Osservatorio Astrofisico di Arcetri)
- Thursday September 24th, at 14:00 TBD
The complete list of seminars is available at: http://davide2.bo.astro.it/?page_id=4531
The organizers of seminars: