Antonio Armeni, Space-Based Astrophysics, IAAT — January 13, 2025

Newly formed stars accrete material from their parent cloud. Conservation of angular momentum causes the accreting material to collapse into a disk-like structure around the young star. After one million years from the beginning of star formation, the envelope is completely dissipated and the star-disk system becomes visible at optical wavelengths, making it possible to study the interaction between the star and the disk. 
Low-mass stars in this stage are called Classical T Tauri Stars and are known to have strong magnetic fields that can disrupt the accretion disk at a distance of a few stellar radii from the star. Accretion proceeds along the magnetic field lines, in a process called magnetospheric accretion, and ends at the stellar surface with a shock that heats the stellar photosphere, producing a hot spot. 

Magnetospheric accretion is a complex process in which matter, energy, and angular momentum are exchanged between the disk and the star. In this talk I will show how high-resolution spectroscopic and photometric data can help study the interaction between the young star and its disk. Permitted emission lines in the optical spectra of young stars can be used to study of the structure of the magnetosphere, while high-cadence light curves offer the possibility of testing magnetohydrodynamic simulations on magnetospheric accretion by studying the rotational modulation of the hot spot.