2016 SUMMER STUDENT RESEARCH SERIES — Alan Vasquez Soto

HPU’s Summer Undergraduate Research Program in the Sciences (SuRPS) included two astrophysics-related projects this year, one led by Ryan Hegedus (already featured) and the other led by rising junior Alan Vasquez. Seven years ago, a pulsating UV-bright star named CS 1246 was discovered to have some of the largest-amplitude brightness variations known in its class. Every six minutes the star would expand and contract in radius by over 1000 miles, giving rise to a variable 3% change in its brightness. During the 2015 SuRPS program, Alan monitored the star using the robotic SKYNET telescopes and observed that the pulsation amplitude had decreased *dramatically* since 2009. Over the past few months, Alan has been working with Dr. Barlow to obtain new data and analyze archived data in order to better characterize and understand the decay in pulsation strength. This work has required him to write a series of Python codes to (i) extract light curves from raw telescope images, (ii) perform Fourier signal analyses of 100s of light curves, and (iii) extract stellar surface motion velocities from shifts in the star’s emitted wavelengths on the order of 10 picometers! His results show that the pulsation amplitude (in both brightness and velocity space) has been decreasing exponentially. This is the first time such an exponential decay has been observed in a pulsating star of this type. The physical cause of the decay is currently not clear, but Alan and Dr. Barlow have started working with theorists in Canada and the UK to get to the bottom of this enigmatic object.