Poster Abstracts

Name/Affiliation:  Alexis Lavail (Uppsala University)

Title:  A study of magnetic fields in Intermediate Mass T-Tauri Stars

Intermediate Mass T-Tauri Stars (IMTTS) are the precursors of the pre-main sequence Herbig Ae/Be stars, themselves the likely precursors of the main sequence A/B stars. About 10% of A/B stars and also Herbig Ae/Be stars host strong and organised fossil magnetic fields which origin is uncertain. It is believed that they could either be the result of the galactic magnetic field being captured during stellar formation, or generated by dynamo processes during stellar formation. By studying magnetic fields in IMTTS, we intend to improve our understanding on the origin of these fossil magnetic fields. IMTTS possess convective envelopes and are at the transition between fully-convective and fully/partially radiative regimes. It is expected that IMTTS magnetic properties evolve with their age, and that they can present either dynamo fields (complex, rapidly evolving) or strong and stable organised fields. We use high-resolution infrared spectra in the H and K bands, acquired at the VLT with the CRIRES spectrograph to study a sample of 10 stars with effective temperatures ranging from roughly 4000 K to 6000 K. We aim to detect magnetic fields and determine their strengths using Zeeman broadening of magnetically sensitive spectral lines.