A Search for Variable Hot Subdwarf Stars and Their Significance to Astrophysics

Speaker: Dr. Brad Barlow (Physics, High Point University)

Title: A Search for Variable Hot Subdwarf Stars and Their Significance to Astrophysics

Abstract: The enigmatic hot subdwarf stars represent one of the least-understood stages of stellar evolution. Theory shows they likely formed from red giants that lost their outer hydrogen envelopes due to Roche lobe overflow and common envelope interactions with a nearby companion. Observations seem to support this idea as the large majority of hot subdwarfs are, in fact, in binaries. Many hot subdwarfs show photometric variations, and detailed studies of their light curves help constrain stellar parameters through asteroseismological analyses or binary light curve modeling. We have utilized a novel method for identifying new variable hot subdwarf stars using data from the Gaia spacecraft and have been collecting follow-up photometry of these candidate variables using NASA's TESS spacecraft for several years. This work has led to discoveries of systems that might shed further light on how substellar objects affect stellar evolution, whether planets can survive the red giant stage of their host stars, and how many Type 1a supernovae progenitor binaries exist in our Galaxy. In this talk, I will present a general overview of hot subdwarf stars, review their broader significance to astronomy, present the details of our novel variable selection method, and discuss the results of our ongoing photometric survey.

About the speaker: Dr. Brad Barlow is an Associate Professor of Astrophysics and Director of the Culp Planetarium at High Point University. Before moving to the NC Triad, he completed his Ph.D. in the Department of Physics & Astronomy at UNC-Chapel Hill in 2011 and spent two years as a Postdoctoral Research Scholar at Penn State University. His research primarily focuses on pulsating stars, late stellar evolution, and binary star systems. He has also collaborated on research projects involving X-ray binaries, white dwarfs, and exoplanets. While at UNC Chapel Hill he helped develop software for the Goodman spectrograph on the 4.1-m SOAR telescope on Cerro Pachon in Chile. Originally from Biloxi, Mississippi, Brad did his undergraduate studies at Mississippi State University. His other interests include playing the piano, writing music, cycling, and public outreach.

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This is Face-to-Face colloquium. Wearing face mask is highly recommended.

Location: Science 234
Time: 3:30pm - 4:30pm

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