# Summary of K2 Program GO8024

Title: Precession in Algol and Cataclysmic Variable (CV) Close Binary Systems

PI: Montgomery, Michele (University of Central Florida)
CoIs: Goel, Amit; Demasi, Michael; voloshina, irina; Richards, Mercedes T

In this proposal, we request of the K2, Cycle 3, Campaigns 8 & 10 to observe two CVs, a CV candidate, and three Algols, all of which have been confirmed to fall on silicon. The goal is to record via the LC mode the long term photometric variability in each of these systems. Long term variability in several CV system types is known to be due to precession -- tidal torques by the secondary star on the disk around the primary star. For the first time ever, Kepler found in previous campaigns a long term variability in Algol systems, with WX Dra from Kepler Quarters 2-4, 6-8, 10-12, and 14-16 being the poster system. This long term variability has never been observed and confirmed from the ground, necessitating the need for the K2 campaigns. In this work, we hypothesize the source to this long term variability in Algol systems as a precession. Through modeling of the CV and Algol light curves, we aim to determine the type of precession in the Algol systems (i.e., whether prograde or retrograde) and to identify the source to the modulated light (e.g., from a precession of a bright/hot spot hitting a disk around the primary in the Algol, from a precession of a bright/hot spot hitting the primary's photosphere, from a precession of the disk, etc. and not due to star spots or exoplanets). As CVs and Algols share the same dynamics of the mass transfer process in close binary systems and the largest difference between CVs and Algols is the orbital period (or, similarly, the separation distance), this K2 study naturally fits into the long term goals of further establishing the connections between these two types of close binary systems and the evolutions of these star systems. In addition to the K2 observations, we will also observe some of these K2 target candidates (and other like systems) from the ground to establish a photometric modulation baseline. To complete these tasks, we have put together a team of experts in CVs and Algols and we include two students.

# Targets requested by this program that have been observed (2)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
220615486, 19.0573502, 9.3711014, 19.058, GO8045_LC|GO8014_LC|GO8024_LC|GO8045_SC
229228561, , , , GO8024_LC