Giada Casali

Biography

I am currently a postdoc at the ANU (Australian National University), associated with INAF-OAS Bologna. I got my Ph.D. degree at the University of Florence on 9th March 2021 with the supervision of Dr. Laura Magrini and Dr. Lorenzo Spina. I received my Master and Bachelor degrees at the University of Pisa respectively in 2017 and 2014.
I am strongly interested in the branch of astronomy called ‘Galactic Archaeology’, which is aimed at exploring the formation, evolution and structure of the Milky Way. My main interest is in analysing stellar spectra and using Gaia and large spectroscopic surveys to investigate the history of our Galaxy. My expertise focuses on high-precision stellar spectroscopy and stellar dating using chemical clocks.

Galactic archaeology

Like traditional archaeology, which studies the human history by investigating the remnants of past civilizations, Galactic archaeology traces the history of our Galaxy observing its stellar population. In fact, the chemical composition of the stellar atmospheres preserve the information of the gas from which stars formed. Our Galaxy is the best place where Galactic archaeology can be applied, since its stellar populations can be resolved. Moreover, stars of different ages can be studied in detail, obtaining for them, photometric, astrometric and spectroscopic data.

chemical clocks

An important ingredient of the Galactic Archaeology is the determination of stellar age. However, it is one of most difficult tasks of this field, because stellar ages cannot be directly measured. There are several methods to infer stellar age: isochrone fitting, stellar activity, lithium depletion boundary, gyrochronology, asteroseismology, etc. An additional method is based on the use of chemical abundances ratios which show a clear dependence on stellar ages, the so-called chemical clocks, e.g. [C/N] and [Y/Mg]. These abundance ratios, calibrated on stars with well-known ages (star clusters or solar-twins stars), allow us to derive ages of large sample of stars through empirical relationships.