8-12 juin, 2014

Résumé

Determining Fundamental parameters of T Tauri Stars

Hoori Ghashooni Rokhami (Western University)

John Landstreet

In this work, we present a method to determine temperature and gravity of a category of stars named T Tauri stars. These objects are classified as pre main sequence stars and are usually associated with nebulosities. They display interesting and unique spectra which contain several emission lines and strong IR and UV excesses. These interesting features can be explained by the existence of a flattened disk around them, through which they are accreting material from their gas clouds. To determine the temperature and gravity of a T Tauri star, a Fortran program named Zabun4, written by Dr Landstreet, is used. This program produces computed spectrum of a star by synthesizing its spectral line profiles. Two scripts, one in Bash Shell Script language and the other one in Python, has been written in this work. The first one automates Zabun4 for a grid of temperatures and gravities. Using Zabun4, the Bash script delivers a number of computed spectra and also a number of chi-squared values corresponding to each of them. These chi-squared values report how well the observed spectrum is fitted with the computed spectra. The Python program makes three dimensional surfaces of chi-squared values as a function of temperatures and gravities. The minimum points of these surfaces show which model spectra best fit an observed one, and how far the other model spectra are from achieving good fits.

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