Indiana University faculty and graduate students presented their work at the 22nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun in San Diego in June. “Cool Stars,” held every two years, has become the premier conference series for cool star research.
Laurin Gray and Katherine Rhode presented their work on the rotational evolution and radii of young sun-like stars in the young star cluster NGC 2264. They determined projected rotational velocities of 220 T Tauri stars in the open cluster NGC 2264, measured using high-dispersion spectra from the WIYN 3.5m telescope's Hydra instrument. They found evidence that weak-lined T Tauri stars may rotate faster than their classical T Tauri counterparts with accreting disks and that stars in binary systems may rotate faster than single stars. Their study of NGC 2264 serves as a pilot study for analysis methods that will be applied to four other clusters ranging in age from 1 to 15 Myr, the timescale over which the protoplanetary disk dissipates, and planetary systems begin to form.
Zachary Maas and collaborators presented their chemical characterizations of massive, alpha-element enriched stars (MAES) that result from stellar mergers. They looked specifically at the carbon, nitrogen, and oxygen abundances and carbon isotope ratio of multiple thin disk and thick disk stars and MAES. They found that most MAES in their sample have carbon isotope ratios similar to thick disk stars while a few stars have high carbon isotope ratios, providing evidence that multiple formation channels may play a role in creating MAES.
Kristin Brady and collaborators Caty Pilachowski and Zachary Maas presented their analysis of fluorine abundances in 10 carbon stars, including two N-type, six R-type, and two J-type) with C/O ratios greater than 1.1. No significant fluorine enhancements were found in their sample of carbon-rich stars. Possible moderate enhancements were observed depending on the type of model atmosphere used. The R stars may reflect the trends of the galactic evolution of fluorine better than the [F/Fe] ratios anticipated from TDU events. The observed J-type stars have low F abundances for their C/O ratios compared to N-type carbon stars. Additionally, they have lower F abundances than their potential precursors, the R-type stars.
Cool Stars Conference 2024 Group Photo
The College of Arts