Date of Award

2003

Document Type

Restricted Thesis

Terms of Use

© 2003 Stephanie Tonnesen. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Physics & Astronomy Department

First Advisor

David H. Cohen

Abstract

O stars make important contributions to the energy and composition of the interstellar medium through their stellar winds and tendency to become super-novae. The Chandra satellite has recently observed X-ray emission lines from these stellar winds, producing spectra of unprecedented resolution. One of these observed stars is the young star θ¹ Orionis C. The X-ray lines from this star are narrow and symmetric, in direct contrast to the line profiles observed from ζ Puppis, which has a standard X-ray emitting wind. In addition, observations of Zeeman splitting and optical polarization have detected a magnetic field around this star (Donati et al., 2002). θ¹ Orionis C is unusual in that its rotational axis is misaligned from both the magnetic field axis and the observer's axis. This allows us to view this star from all possible angles with respect to the magnetic axis. In order to examine the wind structure producing the narrow, symmetric X-ray emission line profiles from θ¹ Orionis C, we calculate analytic and numerical models based on an adaptation of the Magnetically Confined Wind Shock (MCWS) model. From these models we are able to create line profiles that can be compared to observed line profiles from θ¹ Orionis C. Here we describe the process by which our program creates line profiles from analytic and numerical wind models. We find that our most sophisticated model, a numerical magnetohydrodynamic (MHD) simulation of a non-isothermal wind that emits X-rays from material with a temperature over 10⁶ K, matches the data well. The characteristics of the line profiles from the model and the data are consistent in three important ways: the lines are narrow; the centroids of the line profiles do not shift far from the rest wavelength; and the flux decreases with increasing viewing angle. We conclude that our adaptation of the MCWS model is a good description of the wind structure around θ¹ Orionis C, and around other hot stars with magnetic fields.

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