In the popular 1980s book ‘Cosmos’, Carl Sagan wrote of what makes us: ‘All the elements of the Earth, except hydrogen and some helium, were cooked into stars billions of years ago by some sort of stellar alchemy, some of which are unremarkable today. . white dwarfs on the other side of the Milky Way galaxy. The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies are made in the interior of collapsing stars. We are made of ‘stardust.'”
Chris Ashall, an assistant professor of astrophysics in the Virginia Tech College of Science’s Department of Physics, wants to learn more about where and how this “starstuff” is made.
This week, Ashall began using NASA’s James Webb Space Telescope to collect data on the presence of heavy elements in exploding, dying stars or supernovae. As James Webb’s mission center in Baltimore passes orders to the distant telescope to collect observations on supernovae targeted by Ashall, his team at Virginia Tech will study the collected data along with more than 30 other scientists from around the world as part of the Mid – Infrared Supernova Collaboration leading Ashall.
Ashall is one of the few scientists selected to use the telescope for two projects during the mission’s first cycle. The projects will study two types of supernovae: type Ia supernovae, which describe exploding carbon-oxygen white dwarf stars, and collapse supernovae.
“Virtually everything around us comes from dying stars,” Ashall said. “We’re made of stardust. To be able to study that fact—what we’re made of—in detail and understand where the elements around us come from is really amazing.”
Stars produce heavy elements through the process of stellar nucleosynthesis. As stars burn, die and explode, thermonuclear reactions take place within them.
Supernovas are one of the places with the highest temperature and density in the universe, Ashall said. The material in stars burns and burns to form progressively heavier elements, from hydrogen to helium, helium to carbon, carbon to oxygen, and so on, all the way through the periodic table to iron.
When the stars finally explode, they throw all this material back into the universe at speeds up to 30 percent of the speed of light to create the next generation of stars and planets. “So the planet and everything around us can have all these heavy elements,” Ashall said. “They were made into dying stars.”
It’s generally accepted that most of the heavy elements in the universe are made through stellar nucleosynthesis, but Ashall wants to know more — to trace certain elements to the varieties of supernovas out there and measure the levels at which those elements are made. by the stars.
In his first project, Ashall will look for elements commonly found on Earth, such as manganese, chromium, cobalt and nickel, by focusing the James Webb telescope on one Ia supernova in particular: a third-generation white dwarf. SN2021aefx, which exploded a year ago in the spiral galaxy NGC1566, also known as the Spanish Dancer.
“A year after it exploded, you can see right through the center of the supernova,” Ashall said. “That’s where all this high-density combustion happens. The nucleosynthesis happens in just a few seconds, but we see the high-density central region a year after the explosion.”
Ashall will use the telescope to collect imaging and spectroscopy data on elements within SN2021aefx. Spectroscopy involves looking at spectra produced by material when it interacts with or emits light by refracting the light into its constituent colors, according to NASA. “Spectroscopy tells us about several elementary lines,” Ashall said. “If there’s a line, we know the element is there.”
NASA’s new telescope is the first capable of collecting the kind of data Ashall needs. James Webb can observe in wavelength regimes that Hubble just couldn’t, Ashall said.
“Hubble could observe mainly in the ultraviolet, optical and a little bit in the near-infrared, but James Webb was made to observe in the near-infrared and the mid-infrared,” he said. “It opens up a whole new wavelength window to do astrophysics.”
Ashall’s second project will focus on detecting carbon monoxide and silicon monoxide, also building blocks for life in the universe, in collapsing supernovae. Nuclear collapse supernovae are massive dying stars with a mass more than eight times the mass of our sun. The supernova’s name comes from the type of explosion that takes place, Ashall said: When the massive star dies, it collapses, creating an explosion more than 100 billion times brighter than the sun.
Using the observations from the James Webb Space Telescope, Ashall will not only look for heavy elements, but also investigate when they were ejected by the exploding supernova. His team will study how supernovae explode by linking the data to computer simulations of explosions.
“If we measure these lines, we can figure out the speeds of the explosion,” Ashall said. “So then we’ll understand how quickly these elements are thrown into the universe.”
Starting with the single type Ia supernova, Ashall hopes to build a sample of different types of supernovas to produce meaningful statistics about their role as element makers. He is open to anything they will find.
“If we don’t find those elements that come from supernovae, we’ll have to reassess what we know about how stars die and how these elements are released into the universe,” Ashall said. “It’s interesting anyway.”
Massive stars may not explode as supernovas, but simply implode silently into black holes
Quote: Using James Webb Space Telescope to Study Supernovae as Source of Heavy Elements in the Universe (2022, October 20) retrieved October 20, 2022 from https://phys.org/news/2022-10-james-webb-space- telescope- supernovae.html
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