Astronomy & Astrophysics Seminar

Zoom: https://us02web.zoom.us/j/84211520648?pwd=dllEbUhBU1VRUDZPL2lWRnhjWEdzZz09

Using a Global Network of Telescopes to Perform Asteroseismology of Massive Stars

Noi Shitrit, TAU

Massive stars are the progenitors of many interesting astrophysical systems, yet their evolution is still poorly understood. Asteroseismology has great potential for constraining some of the unknown interior parameters of massive stars. The observational challenge lies in sampling both short-duration pulsations and long-term beat frequencies produced by such stars. We aim to develop a ground-based observational method to address this challenge using the Las Cumbres Observatory global network of telescopes. We perform a feasibility study with continuous 48-hour observations from three different sites. I will present the conclusions from analyzing these data, the remaining challenges, and the prospects for performing asteroseismology of a population of massive stars using this facility.

A Cosmological Simulation Study of Multiphase Gas in the Circumgalactic Medium (CGM) of Galaxies

Yossi Cohen, TAU

We use the Illustris-TNG100 cosmological hydrodynamic simulation to study cold/warm/hot multiphase gas around galaxies in the local Universe. We calculate in post-processing the heavy element ionization structures and absorption signatures of the predicted CGM gas contents, for a wide range of virial masses and associated star-formation rates, along the z=0 galaxy main-sequence. The ionization states are controlled by the combined action of electron impact collisional ionization and photoionization by the metagalactic background UV/Xray radiation field. We compare the simulation results to a simple toy-model for the expected mean column densities of CIV, OVI, OVII, and OVIII absorbers. Our study is useful for interpreting recent UV/Xray observations of L* galaxies, and for predictions.

Seminar Organizer: Dr. Iair Arcavi