Non-Thermal Emissions from Classical Nova V1674 Heralcis Challenges Understanding of Celestial Objects

Tuesday - July 4 2023, 05:53 UTC - 1 year ago

A researcher discovered non-thermal emissions from the classical nova V1674 Herculis, which challenges the current views of classical novae as simple heat-induced explosions. The data from the Very Long Baseline Array (VLBA) reveals more complexity in the behavior of classical novae. Montana Williams is leading an investigation into the VLBA properties of this nova and is hoping to determine if the steep spectrum in the radio synchrotron is the signature of a neutron star or a pulsar powering the emission.

A researcher has discovered non-thermal emissions from the classical nova V1674 Herculis, challenging the conventional understanding of these celestial objects as simple heat-induced explosions. This rare finding, using the Very Long Baseline Array (VLBA), reveals more complexity in the behavior of classical novae and could provide new insights into their explosive tendencies.

While studying classical novae using the National Radio Astronomy Observatory’s Very Long Baseline Array (VLBA), a graduate researcher uncovered evidence the objects may have been erroneously typecast as simple. The new observations, which detected non-thermal emission from a classical nova with a dwarf companion, were presented in June at a press conference during the 242nd proceedings of the American Astronomical Society in Albuquerque, New Mexico.

V1674 Herculis is a classical nova hosted by a white dwarf and dwarf companion and is currently the fastest classical nova on record. While studying V1674Her with the VLBA, Montana Williams, a graduate student at New Mexico Tech who is leading the investigation into the VLBA properties of this nova, confirmed the unexpected: non-thermal emission coming from it. This data is important because it tells Williams and her collaborators a lot about what’s happening in the system. What the team has found is anything but the simple heat-induced explosions scientists previously expected from classical novae.

"Classical novae have historically been considered simple explosions, emitting mostly thermal energy," said Williams. "However, based on recent observations with the Fermi Large Area Telescope, this simple model is not entirely correct. Instead, it seems they’re a bit more complicated. Using the VLBA, we were able to get a very detailed picture of one of the main complications, the non-thermal emission." .

Very long baseline interferometry (VLBI) detections of classical novae with dwarf companions like V1674Her are rare. They’re so rare, in fact, that this same type of detection, with resolved radio synchrotron components, has been reported just one other time to date. That’s partly because of the assumed nature of classical novae.

"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," said Williams. "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." .

That rarity makes the team’s new observations an important step in understanding the hidden lives of classical novae and what ultimately leads to their explosive behavior.

"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. "Right now, we’re trying to determine if the steep spectrum in the radio synchrotron is a signature of a neutron star or a pulsar powering the emission." .

The team is exploring both possibilities as they look for signatures of these systems that can provide insight into classical novae and, specifically, V1674Her. With their current models, they can better understand where the emission is coming from and how it is related to the remarkable explosions that follow the events of V1674Her, offering an unprecedented view into the physics of stellar explosions that create classical novae.

TLDR: A researcher discovered non-thermal emissions from the classical nova V1674 Herculis, which challenges the current views of classical novae as simple heat-induced explosions. The data from the Very Long Baseline Array (VLBA) reveals more complexity in the behavior of classical novae. Montana Williams is leading an investigation into the VLBA properties of this nova and is hoping to determine if the steep spectrum in the radio synchrotron is the signature of a neutron star or a pulsar powering the emission.