The Near Infrared Camera (NIRCam) of the James Webb Space Telescope has captured an interesting sight at a distance of 3.6 billion light-years from Earth – a supernova that appears three times, at three different times during its explosion, in one image. Importantly, this image can help scientists better understand how fast the Universe is expanding.
The team of researchers decided to observe the galaxy cluster PLCK G165.7+67.0, also known as G165. Scientists were interested in the high rate of star formation, which also leads to a greater number of supernovae. The image above captures what looks like a streak of light with three distinct dots that appear brighter than the rest. As explained by Dr. Brenda Fry of the University of Arizona, these dots correspond to an exploding white dwarf star. The image also has a gravitational lens — that is, there is a cluster of galaxies between us and the star that served as a lens, bending the light from the supernova into multiple images. Fry compared it to a triple mirror that shows a different image of a person sitting in front of it. It should be noted that this is the most distant Type Ia supernova, which is a supernova that occurs in a binary system, that has been observed to date.
Because of this cluster of galaxies in front of the supernova, the light from the explosion traveled through three different paths, each of which had a different length. This means that the Webb Telescope was able to capture different periods of the explosion in a single image: at the beginning of the event, in the middle, and at the end. Triple images of a supernova are special, Fry said, because «time delays, the distance to the supernova, and the properties of the gravitational lens give a value of the Hubble constant or H0 (pronounced H-zero)».
NASA describes the Hubble constant as a number that characterizes the current rate of expansion of the Universe, which in turn can 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 rate of expansion of the Universe», Fry said.
In 2001, Wendy Friedman of the University of Chicago led a team that found a Hubble constant of 72. Other teams have found Hubble’s constant to be between 69.8 and 74 km/s per megaparsec. Meanwhile, Fry’s 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 is consistent with other measurements in the local Universe and somewhat contradictory to values obtained when the Universe was young,» Fry said.
However, the supernova and the value of the Hubble constant derived from it need to be investigated further, and the team expects that future observations of «will improve the uncertainties of» for more accurate calculations.
Source: Engadget