2024MNRAS.529..236H

A nova super-remnant (NSR) is an immense structure associated with a nova that forms when frequent and recurrent nova (RN) eruptions sweep up surrounding interstellar medium (ISM) into a high-density and distant shell. The prototypical NSR, measuring over 100 pc across, was discovered in 2014 around the annually erupting nova M 31N 2008-12a. Hydrodynamical simulations demonstrated that the creation of a dynamic NSR by repeated eruptions transporting large quantities of ISM is not only feasible but that these structures should exist around all novae, whether the white dwarf (WD) is increasing or decreasing in mass. But it is only the RN with the highest WD masses and accretion rates that should host observable NSRs. KT Eridani is, potentially, the eleventh RNe recorded in the Galaxy and is also surrounded by a recently unveiled H α shell tens of parsecs across, consistent with an NSR. Through modelling the nova ejecta from KT Eri, we demonstrate that such an observable NSR could form in approximately 50 000 yr, which fits with the proper motion history of the nova. We compute the expected H α emission from the KT Eri NSR and predict that the structure might be accessible to wide-field X-ray facilities.