The Precataclysmic Binary HS 1136+6646 May Have a Companion

Abstract

ABSTRACTBecause of the similarity of the primary star of HS 1136+6646 to the planetary nebula central star BE Ursae Majoris, we performed wide‐field imaging of the former with an Hα filter. No nebulosity was detected. On the other hand, the point‐spread function of the star appears extended. A partially resolved red component is detected in an image from the five‐band Sloan Digital Sky Survey. Most importantly, a companion is easily resolved in a Hubble Space Telescope acquisition image from the published Space Telescope Imaging Spectrograph observations. A companion to the precataclysmic binary is present at a separation of 1.″349 at a position angle of 54.°4. Evidence indicates that it is likely of spectral type K. We cannot demonstrate conclusively that this component has common proper motion with the close binary. However, the similar apparent z magnitudes and spectral types of HS 1136+6646B and the resolved component make it likely that we have, in reality, a hierarchical triple system. In any case, the presence of this component needs to be taken into account in future ground‐based studies.