Finding Young stars from their Chromospheric activity with the FunnelWeb survey

Stellar age is one of the crucial parameters required to understand and characterise the evolution of young stars and their orbiting planets. A large portion of young solar-like and later-type dwarf stars show signs of magnetic activity, especially before they reach Solar age. Age-activity relation is based on decline of stellar magnetic activity over time. An order of magnitude age estimate is easily attainable in the range from a few tens of millions of years up to a few billions of years. Activity results in chromospheric emission seen in strong spectral lines and is thus easily detectable in the youngest stars. At the same time, machine learning and classification techniques enable systematic search for such stars in large stellar surveys. This project will use data from the FunnelWeb survey, aiming to robotically take spectra of the 2 million brightest stars in the southern hemisphere. These spectra will cover all optical signs of activity, including calcium lines Ca II HK and Ca II infrared triplet. In contrast with Ca II HK (at ~390nm) that have been extensively studied in the literature, Gaia spectrograph covers Ca II infrared triples lines. A correlation between these two activity measures will help to exploit relations discovered in the HK lines in the large Gaia sample of millions of stars and will thus play an important role in search for young stars, characterization of exoplanetary hosts and their environments.