Rotation velocities measured for 330 B-type stars in eight stellar clusters of the Carina complex, thanks to the Gaia-ESO Survey. Stars rotate on their axes. Some, such as young stars, spin very rapidly, with rotation periods as short as one or two days. In other cases, like red giant stars, rotation is much slower, with periods lasting several months.
Stars do not form in isolation. During gravitational collapse, molecular clouds fragment, forming a large number of stars. For this reason, young stars are typically observed as members of star clusters or associations. In the past decade, the study of stellar clusters in the Milky Way has undergone a revolution, thanks to observations from the Gaia satellite of the
The study of chemical abundances in the interstellar medium and stars in our Galaxy is of utmost importance, as it provides insights into the chemical enrichment of the galactic interstellar medium by massive stars and the evolution of different components of the Milky Way. Lithium is frequently the subject of spectroscopic surveys and studies aimed at determining its abundance in
In astrophysics, there are elements that provide important diagnostics used in various fields, such as Lithium. For instance, measurements of Lithium abundances are important in cosmology where there is a well-known problem of matching the measured abundances in population II stars with those predicted by cosmological models of Big Bang synthesis. Measurements of Lithium abundances are also essential for understanding
Spectroscopic observations of massive stars (i.e., those more massive than 8 solar masses) allow astronomers to study their rapid evolution, which occurs on much shorter timescales compared to solar mass stars, and the impact of parameters such as stellar rotation on their evolution. To achieve this, observations of stellar clusters are greatly valuable, as they are groups of stars formed
Star clusters are a product of the star formation process. During their gravitational collapse, in fact, molecular clouds fragment forming hundreds or even thousands of stars. During the first few tens of million of years of their evolution, the young stars formed in a cloud are bound by the intense mutual gravitational attraction, forming a stellar cluster. Star clusters are important
The chemical history of Lithium abundance in the Universe is very complex. This chemical element has been first produced during the Big Bang, even if in very small quantities compared with hydrogen and helium. Since then, lithium is continuously created and destroyed by several processes occurring in stellar interior. This means that the lithium abundances we observe in stars today
Measuring stellar ages is a difficult task but nevertheless very important. For instance, the study of stellar evolution requires accurate estimate of stellar ages. On the other hand, we can count on very few diagnostics that can allow astronomers to obtain reliable estimate of stellar ages, and typically these methods can be applied only to specific type of stars or
Despite its importance for our comprehension of stellar and galactic evolution, stellar age is one of the most elusive stellar properties. In fact, we are able to determine stellar age with a good precision only in a few cases. Typical methods to determine this quantity are: the study of the chemical abundance of Lithium, stellar kinematics, stellar pulsations analyzed by
Despite a significant fraction of stars form in stellar clusters counting hundreds to thousands of members, almost all the stars we observe today in the Milky Way is not associated to any stellar cluster. This occurs because newborn stellar clusters are typically dispersed in a few million of years by several intervening processes, such as the gravitational interaction among cluster
