"Reading between the lines": unveiling the innermost structure of young stars via time-resolved spectroscopy

Accretion is one of the defining characteristics of young stars. For the late-type ones (and, surprisingly, some not-so-late ones), accretion is channelled by the stellar magnetic field. Magnetospheric accretion thus connects the protoplanetary disk to the young star and opens a gap in the innermost disk, which can affect planet migration. While direct mapping cannot access these regions, emission (and absorption) lines in young stars trace their winds, accretion-related structures, spots, and sometimes, the innermost disk.

Young stars are rich in emission (and absorption) lines, related to their winds, accretion, hot spots, and innermost gaseous disk. Optical, near-UV, and near-IR lines include a large number of species with various excitation potentials that can provide information on the temperature, density, and velocity of hot and tiny structures. Combining the velocity information with repeated, time-resolved data, we can reconstruct scales of a few stellar radii. With time-resolved spectroscopy covering several rotational and disk orbital periods, we can obtain a detailed view of the structure and variability of accretion columns and spots and information on the presence and launching points of stellar/disk winds in young stars. Data acquired over months-to-year can reveal the long-term stability of the accretion process and related structures.

This project involves analysis of time-domain and velocity-resolved archival data from multiple ground-based telescopes to gain information on the tiny scales of stellar radii and the innermost planet-forming regions of disks, which is not possible with direct imaging. You will use the STAR-MELT code developed at the University of Dundee to analyse a variety of targets, gaining skills in spectroscopy data analysis, Python programming, and statistics. 

Knowledge of stellar astrophysics and/or star formation as well as Python programming will be appreciated.

References:

Sicilia-Aguilar, A. et al. 2023, "Stable accretion in young stars: the cases of EX Lupi and TW Hya",  Monthly Notices of the Royal Astronomical Society 526, 4885-4907, doi:10.1093/mnras/stad3029

Campbell-White, J., Sicilia-Aguilar, A., et al., 2021, "The STAR-MELT PYTHON package for emission-line analysis of YSOs", Monthly Notices of the Royal Astronomical Society 507, 3331-3350. doi:10.1093/mnras/stab2300

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