Field Notes: Star formation, magnetic fields, and the mysteries of a cloud

Field Notes: Star formation, magnetic fields, and the mysteries of a cloud

January 23, 2019

Astronomy graduate student Sarah Betti just published her first paper in a peer-reviewed journal. She's been studying star formation and galaxy evolution, investigating the mysteries of one particular gas cloud exhibiting strange behaviors — the Smith Cloud — as it boomerangs back toward the Milky Way.

 

Sarah Betti at Kitt Peak Observatory in Arizona. Photo by Dr. Kimberly Ward-Duong

What’s it like studying at UMass? 

The most important guidance I’ve received at UMass is that the best way to learn, understand, and be successful in your desired field is to read as much of the literature and attend as many talks as possible. By absorbing and understanding the state of the field, you can determine the direction you need to take your own research and what questions still need to be answered. Diving head first into research is the best way to learn and develop your own skills, which is what I did when I started the research for this paper at my undergraduate institution (Haverford College).   

I am currently working on my second-year research project with Dr. Rob Gutermuth in the astronomy department. I am studying how gas collapses in giant molecular hydrogen clouds in order to form stars, using both simulations and the Large Millimeter Telescope, a sub millimeter telescope that is a bi-national project between Mexico and UMass.        

What can you tell us about the research you did for this publication? 

My recent paper is researching the Smith Cloud, a gas cloud in the outskirts of our galaxy. Approximately 70 million years ago, the cloud passed through the Milky Way, and it is now traveling back to the galaxy. If a cloud travels more than 32,000 light years, we know that the surrounding environment would strip the cloud apart. However, the Smith Cloud has managed to travel more than 32,000 light years and remain intact.   

We want to know how the Smith Cloud has remained together throughout its journey. A magnetic field that surrounds and encloses the cloud could stop the gas from being stripped away. So my paper studies whether we can measure a magnetic field there, if it is strong enough to keep the cloud together, and what it looks like.   

Sarah at the Very Large Array

 

In order to measure the magnetic field, we use the Very Large Array (VLA), a radio telescope in Socorro, New Mexico, to look at distant galaxies with strong radio signals behind the Smith Cloud and measure what is called Faraday rotation measures. We use these rotation measures to calculate the magnetic field. By looking at thousands of quasars, we can build up a picture of the magnetic field. We find an average magnetic field of 5 microGauss that appears to drape over the gas cloud. (For comparison, a refrigerator magnet has a magnetic field of 50 Gauss. The magnetic field of the Smith Cloud is 10 million times smaller than that of a refrigerator magnet.) This field is strong enough to prevent the gas from being stripped away, and it helps explain how the cloud has remained intact.      

What else have you been up to?  

I also play field hockey, do calligraphy, and play piano. I hope to start taking flying lessons soon in order to become a pilot and fly planes! That’s a goal of mine as well. 

Read on:  
Astrophysical Journal paper 
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The views and opinions expressed in this article are those of the author(s) and do not necessarily reflect the official policy or position of UMass Amherst or the College of Natural Sciences. 

Top image: Smith Cloud. Saxton/Lockman/NRAO/AUI/NSF/Mellinger for NASA

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