Ultraviolet light gives astronomers new clues on mysterious stellar eruptions
This is where the story gets hot
In December 2019, astronomers at the Zwicky Transient Facility (ZTF) in California spotted a supernova they dubbed SN2019yvq. Analysis of the data revealed this was a type Ia [one A] supernova, a fairly-common type of explosion forwhite dwarf stars. Taking place roughly 140 million light years from Earth, this event was seen near the tail of the constellation Draco.
“These are some of the most common explosions in the universe. But what’s special is this UV flash. Astronomers have searched for this for years and never found it. To our knowledge, this is actually only the second time a UV flash has been seen with a type Ia supernova,” Miller said.
The production of ultraviolet light usually suggests processes happening at temperatures several times hotter than the surface of the Sun. This display lasted for several days, suggesting anenergetic processcaused this unusual flash.
However, white dwarfs usually become cooler over time, confounding researchers. Currently, astrophysicists have several theories on why these white dwarf stars occasionally produce flashes of ultraviolet light before exploding.
Some stars in binary systems might consume material from its partner star until it builds up to a critical mass and explodes. Expelled material from the eruption could race outwards,colliding with the companion star, generating the ultraviolet flash.
Another possibility is that radioactive material in the core of the white dwarf might mix with the outer layers of thestar, raising the surface temperature to a range where it radiates in ultraviolet light.
A third idea holds that helium ignites thermonuclear reactions in carbon within the star, resulting in a double explosion producing the ultraviolet flash.
Another possibility is that the ultraviolet radiation comes from material ejected by the collision of a pair ofwhite dwarfs.
As dark as a knight
Most of the iron in the Universe was produced in type Ia supernovae. Some of that iron goes on to produce planets, including the core of the Earth. By learning more about these explosions, astronomers hope they might learn about the formation of our own planet.
Type Ia supernovae are all believed to explode with a certain brightness. By measuring the apparent brightness of these events as seen from Earth, astronomers are able to measure distances to distant galaxies. By measuring the Doppler shift of these galaxies (the change in frequency of light seen in moving objects), astronomers are able to determine the velocity at which theUniverse is expanding. With a more complete explanation of the mechanisms behind these explosions, astronomers could get a more complete understanding of dark energy driving theexpansion of the Universe.
Billion of years from now, our own Sun will become a white dwarf in its final days, although it will not explode like the pair of events recently seen by astronomers.
Analysis of the study was detailed inThe Astrophysical Journal.
Once the region around this star clears, the remnants left behind will provide researchers with an unprecedented look at howwhite dwarfsexplode as supernovae, giving us a better understanding of the Cosmos.
This article was originally published onThe Cosmic CompanionbyJames Maynard, founder and publisher of The Cosmic Companion. He is a New England native turned desert rat in Tucson, where he lives with his lovely wife, Nicole, and Max the Cat. You can read this original piecehere.
Astronomy News with The Cosmic Companionis also available as a weekly podcast, carried on all major podcast providers. Tune in every Tuesday for updates on the latest astronomy news, and interviews with astronomers and other researchers working to uncover the nature of the Universe.
Story byThe Cosmic Companion
Exploring the wonders of the Cosmos, one mystery at a time.Exploring the wonders of the Cosmos, one mystery at a time.
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