The Dwarf Nova V893 Sco Does Not Have a Giant Planet

Abstract

Abstract V893 Sco is an ordinary dwarf nova, with a narrow eclipse that allows for exact timings of minima. These eclipse times have been used to seek variations (compared to a linear ephemeris) by placement onto a traditional O − C diagram. Bruch collected 114 eclipse times from 1999 to 2013, and noted that the residuals in his O − C diagram had an apparent sinusoidal variation with a period of 10.2 yr. After rejecting a variety of possibilities, Bruch settled on the explanation that the binary was orbited by a planet with the mass of 9.5 Jupiters. We have tested this planet proposal by extending the O − C curve to 2014 and 2020–2021. For this, we measured 987 eclipse times in 2014 with the K2 mission, plus we measured 305 eclipse times in 2020 and 2021 with a remotely controlled observatory in the Atacama. We find that the O − C curve suffers a sharp break (from Bruch’s sinewave) to a shorter period after 2013. Thus, the planet-hypothesis has failed.