Stars and the interstellar medium
This branch of astrophysics principally concerns the study of objects belonging to our galaxy, the Milky Way. There are also various international projects studying the interstellar medium and stellar populations in external galaxies, particularly nearby spiral galaxies and young dwarf galaxies.
The galaxies, enormous collections of stars and gigantic clouds of gas and dust, can be though of as the "building blocks" of the Universe, of which the Universe contains many billions. Each galaxy might be considered a miniature Universe in itself: a self-gravitating system that generally evolves separately from the other galaxies, even though nearby galaxies often interact, getting deformed by their reciprocal gravitational attraction, or even colliding and giving rise to very violent phenomena.
Our galaxy contains about 100 billion stars and the Solar System belongs to one of its spiral arms, where the youngest stars are found, with ages from a few tens of millions of years to a few billion years. The spiral arms do not contain only stars but also gas and dust. The Sun is located in the outskirts of the Milky Way at about 28 thousand light years from the centre, about which it takes approximately 250 million years to complete an orbit. Together with the Large Magellanic Cloud, the Andromeda galaxy and more than 50 other smaller galaxies, the Milky Way makes up the so-called Local Group, a mini cluster of galaxies.
The study of stellar evolution, and how this interacts with the interstellar medium, allows us to understand how the Milky Way formed, and learn something of how other galaxies formed. In particular, this field is turning out to be decisive for the discovery and characterisation of planetary systems other than our own, able to host planets similar to Earth.
The study of the stars is fundamental to the understanding of the Universe in which we live, in which Italian researchers have distinguished themselves in recent years. In fact, an article in this field, by a team of Italian and INAF researchers, published in 2008 in the journal Astronomy and Astrophysics, was nominated as a "New Hot Paper" by the Thomson Reuters agency, that is, one of the most cited papers worldwide in the space science category. This acknowledgement is testimony to the scientific importance of the work, that resulted in the creation of a large archive of theoretical simulation data for stellar evolution studies, consultable on-line, and already used in the studies of tens of astrophysicists all over the world.
In this field various lines of research have been developed in which Italian groups have established a great deal of visibility and international leadership, accompanied by a significant success rate in obtaining time on the largest and most prestigious telescopes, both on the ground and in space.
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