Young Stellar Objects

In star formation, the stage between the appearance of an overdensity in a giant interstellar gas cloud and the emergence of a fully formed star with its planetary system is known as the young stellar object (YSO) phase. During this stage, YSOs accrete mass from their surroundings through circumstellar discs, stars break through their cocoons of gas and dust to emerge as optically visible sources, and clusters of YSOs assemble and later disperse. The identification of YSOs began in the 1940s, when the 'Objects of Joy' (the T Tauri stars) were recognised as the beginning of a star’s life cycle. More recently, large surveys have classified hundreds of thousands of these objects.  With them, we can now map young stars across the Solar neighbourhood and into the nearby spiral arms of the Galaxy, revealing where stars are born and which conditions are most important in sparking star formation. This talk…