Researchers found a classic nova anything but simple

June 07, 2023

(Nanowerk News) While studying classic novas using the National Radio Astronomy Observatory’s Very Long Baseline Array (VLBA), a graduate researcher found evidence that the object may have been a simple typo. The new observations, which detect non-thermal emission from a classic nova with a dwarf companion, were presented today at a press conference during the American Astronomical Society’s 242nd process in Albuquerque, New Mexico.

V1674 Herculis is a classic nova delivered by a white dwarf and its companion dwarf and is currently the fastest classic nova on record. While studying V1674Her with the VLBA, Montana Williams, a graduate student at New Mexico Tech who led an investigation into the VLBA properties of this nova, confirmed something unexpected: non-thermal emissions coming from it. This data is important because it tells Williams and his collaborators a lot about what’s going on in the system. What the team found was far from the simple explosion of heat that scientists had previously expected from a classic nova. This artist’s conception depicts V1674 Herculis, a classic nova hosted in a double star system consisting of a white dwarf and a dwarf companion star. Scientists studying this nova have detected non-thermal emissions, deviating from historical beliefs that the system produces only thermal emissions. (Image: B. Saxton NRAO/AUI/NSF)

“Classical novas have historically been thought of as simple explosions, emitting mostly heat energy,” said Williams. “However, based on recent observations with the Fermi Large Area Telescope, this simple model is not entirely correct. On the other hand, it seems they are a bit more complicated. Using the VLBA, we can get a very detailed picture of one of the main complications, namely non-thermal emissions.”

Very long baseline interferometry (VLBI) detection of classic novae with dwarf companions such as V1674Her is rare. They are so rare, in fact, that this same type of detection, with a completed radio sync component, has been reported once again to date. That’s partly due to assumed classical nova properties.

“The recent detection of VLBI nova was made possible due to improvements in VLBI techniques, especially instrument sensitivity and increased bandwidth or the number of frequencies we can record at any given time,” said Williams. “In addition, because of previous classical nova theory, they are not considered ideal targets for VLBI studies. We now know this is not true because the multi-wavelength observations suggest a more complex scenario.”

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

“By studying images from the VLBA and comparing them with other observations from the Very Large Array (VLA), Fermi-LAT, NuSTAR, and NASA-Swift, we can determine the cause of the emissions and also make adjustments to earlier simple models,” said Williams. “Currently, we are trying to determine whether the non-thermal energy comes from a gas plume flowing into another gas plume producing a shock, or something else.”

Because Fermi-LAT and NuSTAR observations have indicated that there may be non-thermal emissions coming from V1674Her, that makes the classic nova an ideal candidate for study as Williams and his collaborators are on a mission to confirm or disprove these types of findings. . It’s also all the more interesting, or hilarious, as Williams puts it, because of how fast it evolves, and because, unlike a supernova, the host system doesn’t disintegrate during that evolution, but instead remains almost completely intact and unchanged thereafter. explosion.

“Many astronomical sources don’t change much over a year or even 100 years. But this nova gets 10,000 times brighter in one day, then fades back to its normal state in only about 100 days,” he said. “Because the host system of classic novas remains intact, they are repeatable, which means we might see this one erupt, or hilariously explode, again and again, giving us more opportunities to understand why and how it happened.”

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