Graduate Profile

Jennifer Stone, MPhys 2005, Astronomy Research, USA

Jennifer Stone

After four very enjoyable years on the M.Phys. Astrophysics course at St Andrews, in August 2005 I moved to the University of Wisconsin-Madison to pursue a Ph.D. in Astronomy. It was certainly a big change going from such a small town to one of the largest universities in the United States! My decision to study so far from home was based on a desire to have greater control over the direction of my thesis work, to take yet more classes, to gain teaching experience, and also to learn how science is done in another country.

My transition to the US academic system was very smooth, which I owe to my St Andrews education! It provided me with a solid grounding in the fundamentals of the major areas of physics and astronomy, and I found there to be a good overlap between my undergraduate knowledge and that to be gained in my new classes. With this armory I was able to broaden my knowledge by taking additional classes in the mathematics and engineering departments. Of course, the reputation of St. Andrews also helped – people are always impressed when I tell them of my alma mater!

My research is concerned with physical processes in the interstellar medium (ISM), particularly the role of magnetic fields. This was a subject I developed a strong interest in while preparing my essay and presentation for the Transferable Skills module during my second year at St Andrews.
The ISM is a multi-phase magnetised system consisting of gas phases of different densities, temperatures, and ionization fractions. It is of crucial importance in fueling star formation and hence the evolution of our Galaxy, and magnetic fields in turn affect the dynamics and energy balance of the ISM.

While the existence of the multi-phase ISM is understood in general terms, the specific properties of the system are not well known, including the interactions between the various phases of gas and their magnetic connectivity. The actual transitions between phases have received only scant attention in the literature, and are not resolved by current numerical simulations.

For my Ph.D. thesis, I conducted the first study of the magnetohydrodynamic properties of the phase transition layers separating the cold and warm phases of the diffuse ISM. Through detailed analytic and numerical calculations of their structure and stability, I demonstrated that phase transition layers have important ramifications for transport processes and structure formation in the diffuse ISM. For example, I showed that their thin extent enables the efficient diffusion of magnetic field from one phase to another. This is in agreement with the observation that magnetic field strength is approximately constant in the diffuse ISM and is not correlated with gas density. I believe my work will prove useful in the interpretation of large neutral hydrogen surveys of our Galaxy, with the challenge being to incorporate phase transitions into numerical simulations for a complete picture of the ISM.

The methods and techniques I developed for my thesis research were designed to be generic such that, by incorporating the relevant physics, they may be applied to be any multi-phase astrophysical system. I will continue this work in astrophysical fluid dynamics as a postdoctoral fellow in the Laboratory for Theoretical Astronomy and Astrophysics at Nagoya University, Japan, starting in September 2011.

I feel extremely fortunate that I have been able to travel the world for my research career so far. I owe many of the opportunities I have been afforded to the wonderful start I had at St Andrews!

Astronomy at University of Wisconsin-Madison

NASA's Spitzer Space Telescope

Laboratory for Theoretical Astronomy and Astrophysics, Nagoya University

First posted BDS 8.06

Updated 11.9.11