Physics and Astronomy Departmental Colloquium (Prof. Gerard Williger)

Event Details

Speaker: Prof.  Gerard Williger (University of Louisville)

Date: Friday October 2, 2026, 3-4 p.m.

Place: Natural Sciences Building, Room 112 

Title: Spectroscopy and Photometry of Young Solar-mass Stars in the Chamaeleonis 1 Star-Forming Region

Abstract: 

The mechanisms producing variability in young solar-mass ("T Tau")
stars are complex, and are influenced by accretion changes, dust
in the surrounding disk, starspots etc.  The innermost parts of their
disks cannot be resolved by current high-resolution imagery, but can
be probed by high resolution spectroscopy and high time resolution
photometry.  The Konkoly Observatory star formation group has a project to
investigate a sample of 6 T Tau stars in the Chamaeleonis 1 (Cha 1)
complex, one of the closest star formation regions.  The group
received time on ESO and SMARTS telescopes for spectroscopy and
photometry of the sample, contemporaneous with a TESS campaign in
2019, and combined the data with ground-based photometry from
long-term photometric monitors such as ASAS-SN.

     The first three Cha 1 targets were analysed and published by G.
Zsidi and E.  Fiorellino, and yielded clues to rotation rates, the
circumstellar dust content, accretion rate variability and wind
component features.  Here, I give a status report on the remaining 3
stars in the project: CT Cha, VZ Cha and WW Cha.  I will present 25
years of data including light curves, Lomb-Scargle periodograms and
colour-magnitude diagrams, describe emission line profile variability,
and give a preview of work to be done to determine accretion rates.