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New Observations of HU Aqr with Eclipse Timings: P-dot Continues to Surprise

Published onJun 01, 2020
New Observations of HU Aqr with Eclipse Timings: P-dot Continues to Surprise

As part of an educational program for undergraduate students (“Our Solar Siblings”), we used the Las Cumbres Observatory worldwide network of robotic telescopes to obtain images the eclipsing polar HU Aqr, a cataclysmic variable in which the white dwarf is so highly magnetized that accretion from the red dwarf companion is channeled toward the white dwarf's magnetic poles in directed streams. The orbital period of the system is 125 minutes. Within uncertainties, our July–October 2019 observations are consistent with a change in the trend of observed minus calculated times of eclipse egress discovered by Schwope and Thinius that held from 2016–2018. A significant decay in the orbital period has transpired, such that the eclipses now occur more than 4 minutes early relative to an ephemeris based on data obtained between 2001 and 2011. Such a dramatic decrease in the orbital period cannot easily be explained. We hope to observe HU Aqr once more in May 2020, and we will include any new results with our poster.

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