Christene Lynch

Congratulations to Dr. Christene Lynch!

Christene Lynch

Congratulations to Christene Lynch for successfully defending her PhD dissertation on "Radio Studies of Magnetic Fields of Cool Stars."

"This thesis reports on EVLA radio studies of two classes of stars with active magnetospheres. The first is the well-known pre-main sequence object DG Tauri. This star has a bright x-ray luminous core and an extended jet extending more than 140 AU from the central star. The radio observations confirmed previously published optical observations, viz that the jet has an onion-like density and velocity structure, with the densest, fast-moving plasma in the center of the jet. The time-lapse radio images support a model in which shocks fronts are moving radially outward at 200 km/s and expanding adiabatically. The second study consisted of very wideband multi-epoch observations of two ultra-cool dwarf stars, TVLM0513-46 and 2M0746+20. Both stars exhibit both pulsed and continuous radio emission. The pulsed dynamic spectra were well modeled by highly beamed cyclotron-maser emission from isolated magnetic loops attached to an oblique rotating magnetosphere. The continuum emission was modeled as gyrosynchrotron emission from mildly relativistic electrons in a global magnetosphere with a surface field strength approximately 100 Gauss. The overall magnetic configuration supports recent suggestions that radio-loud ultra-cool dwarfs have weak non-axisymmetric magnetic topologies, with isolated regions of very high field strength."
— Robert Mutel, PhD advisor