Classical novae may have been erroneously typecast as simple, new study reveals

Scientists studying classical novae have found evidence that challenges the traditional understanding of these objects as simple explosions. The findings were presented during the 242nd proceedings of the American Astronomical Society.

The study, conducted by Montana Williams, a graduate student at New Mexico Tech, utilized the National Radio Astronomy Observatory's Very Long Baseline Array (VLBA) to observe V1674 Herculis, a classical nova hosted in a binary star system that is made up of a white dwarf and dwarf companion star.

Classical novae have historically been considered simple explosions producing only thermal emissions. However, Williams' investigation revealed unexpected non-thermal emission from V1674Her, shedding new light on the nature of these systems.

Detecting classical novae with dwarf companions using very long baseline interferometry (VLBI) is rare. In fact, prior to this study, only one other instance of resolved radio synchrotron components in this type of detection had been reported. The rarity of such findings is partly due to the presumed nature of classical novae, according to a post on NRAO's website.

"VLBI detections of novae are only recently becoming possible because of improvements to VLBI techniques, most notably the sensitivity of the instruments and the increasing bandwidth or the amount of frequencies we can record at a given time. Additionally, because of the previous theory of classical novae they weren't thought to be ideal targets for VLBI studies. We now know this isn't true because of multi-wavelength observations which indicate a more complex scenario," Williams explained.

The findings represent a significant leap in unravelling the intricacies of classical novae and the processes leading to their explosive behaviour.

"By studying images from the VLBA and comparing them to other observations from the Very Large Array (VLA), Fermi-LAT, NuSTAR, and NASA-Swift, we can determine what might be the cause of the emission and also make adjustments to the previous simple model," said Williams.

The selection of V1674Her for this study was based on previous indications from Fermi-LAT and NuSTAR observations that non-thermal emission might be present. Furthermore, the classical nova's hyper-fast evolution and its host system's ability to withstand the explosion without destruction added to its appeal.