During the past week, NuSTAR observed IGR J19713+0747, a variable high-energy X-ray source. Optical studies show that the source has a very short orbital period of 13 minutes and that it is likely a Cataclysmic Variable (CV) of an intermediate polar (IP) type. X-ray emission from these highly magnetized white dwarf stars is thought to be powered by accretion of matter from a companion star. However, this source also has another star close by with a measured consistent proper motion. This means that the nearby star could be another companion to the CV, making the source a rare triple system. The primary goal of this NuSTAR observation is to verify if the hard X-ray source is a bona fide intermediate polar CV and measure the mass of the white dwarf. The NuSTAR hard X-ray spectrum will also look for potential effects of the tertiary star on the CV system.

Authors: Sol Bin Yun (Graduate Student, Caltech)