The James Webb Space Telescope's Near Infrared Camera (NIRCam) captured a curious sight in a region 3.6 billion light years from Earth: a supernova that appears three timesin three different periods during its explosion, in one image. More importantly, this image could help scientists better understand how quickly the universe is expanding.
A team of researchers chose to observe the galaxy cluster PLCK G165.7+67.0, also known as G165, for its high rate of star formation that also leads to higher rates of supernovae. One image, which you can see above, captures what appears to be a beam of light with three distinct spots that appear brighter than the rest. As Dr. Brenda Frye of the University of Arizona explained, those points correspond to an exploding white dwarf star. It also has a gravitational lens, meaning there is a galaxy cluster between us and the star that served as a lens, bending the light from the supernova into multiple images. Frye compared it to a three-way mirror that shows a different image of the person sitting in front of it. It should be noted that it is the most distant Type Ia supernova, which is a supernova that occurs in a binary system, observed to date.
Due to that cluster of galaxies in front of the supernova, the light from the explosion traveled three different paths, each with a different length. That means the Webb telescope was able to capture different periods of its explosion in one image: at the beginning of the event, in the middle, and near the end. The triple supernova images are special, Frye said, because “the time delays, the distance of the supernova and the properties of gravitational lensing produce a value for the Hubble constant or H0 (pronounced H-nothing).”
POT describe the Hubble constant as the number that characterizes the current expansion rate of the universe, which, in turn, could tell us more about the age and history of the universe. Scientists have not yet agreed on its exact value and the team hopes that this supernova image can provide some clarity. “The supernova was named SN H0pe because it gives astronomers hope to better understand the changing expansion rate of the universe,” Frye said.
Wendy Freedman of the university of chicago He led a team in 2001 that found a value of 72. Other teams placed the Hubble constant between 69.8 and 74 kilometers per second per megaparsec. Meanwhile, this team reported a value of 75.4, plus 8.1 or minus 5.5. “Our team's results are striking: the value of the Hubble constant matches other measurements in the local universe and is in some tension with values obtained when the universe was young,” Frye said. However, the supernova and the Hubble constant value derived from it need to be further explored, and the team hopes that future observations will “improve uncertainties” for a more precise calculation.
