In Class Research

May 29, 2019 at 4:28 pm

Grant Merz ǀ Simulating nuclear explosions on neutron stars

By Grant Merz
(B.S. Astrophysics, Honors Tutorial College, Class of 2020)

Editor’s Note: Grant worked with Dr. Zachary Meisel and performed simulations of type I X-ray bursts, thermonuclear explosions that occur on the surface of neutron stars, which are dense remnants of stellar explosions.  Grant’s work will identify the impact of uncertainties in nuclear reaction rates on the element formation occurring in X-ray bursts. This work will contribute to our understanding of the properties of ultradense matter.

My internship is about using software to model x-ray bursts, which are a kind of explosion that  happens in x-ray binary star systems.  A “donor” star gives material to an “accretor” neutron star and this eventually causes a thermonuclear explosion on the neutron star’s surface.  I am studying the nuclear reactions that happen during these bursts.

I learned a lot about coding and using different software to produce and graph data.  I also gained general knowledge about x-ray bursts (like how long they last, how often they recur and how bright they get) and nuclear reactions that fuel the bursts (like reaction cycles and strengths).

The next steps are to identify key nuclear reactions that affect different element abundances.  A certain set of elements can be important in affecting different properties of the burst.  We want to see when and where in the burst these are created, and through what nuclear reaction paths.

A significant challenge that still gives me trouble sometimes is working with ROOT, the software I use to graph data.  I had never used it before, so a lot is new to me.  I resolved several issues by  searching through the ROOT documentation or forums online, and just trying stuff until it works.

The astrophysical parts greatly intrigue me.  It is hard to fully understand what happens in these bursts, but a flame wave engulfs the star in a few seconds, and then brightens to tens of thousands of time the luminosity of the sun in an equally short amount of time.  I guess I really like explosions.

Tips for students who are seeking an internship– I would just say to get into a schedule.  Dr. Meisel let me do mostly self-guided work, which is nice but can be daunting without things set in stone.  It helped to get into a self-imposed routine.  I would also say that things sometimes turn out differently than how you expect them to, but that’s part of the research process.

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