Webb is a true ‘Supernova Discovery Machine’

With infrared instruments, the Webb Space Telescope can look deep into space. Recent observations with Webb show that he has found ten times more supernovae in the early universe than previously. This makes Webb a true “supernova finder,” as Christa DeCoursey (Steward Observatory and University of Arizona, Tucson) puts it. This week he presented his team’s results at the 244th meeting American Astronomical Society (AAS) in Madison, Wisconsin. He and his team used the observations it made JWST Advanced Deep Extragalactic Survey (JADES) program. Before Webb, a handful of supernovae with a redshift greater than 2 were known, meaning they originated in the 3.3 billion year old universe, or 25% of its current age. The JADES observations go further back in time, less than two billion years old. Photographs of galaxies from that early universe show so-called “transients,” objects that fluctuate in brightness. Some of these are true supernovae, and analysis of JADES data has revealed up to 80 supernovae.

The redshift of the most distant supernova appears to be z ~ 3.6, meaning it exploded when the universe was only 1.8 billion years old. it is a type II supernova, a massive star whose core exploded and blew away its outer layers. Astronomers are particularly interested in Type Ia supernovae, which are white dwarf stars that explode when they become heavier than a certain limit due to their mass reserve. These supernovae always have the same absolute maximum luminosity and can therefore be used as a reliable distance meter. Webb found one Type Ia SN at redshift z ∼ 2.9, dating from when the universe was 2.3 billion years old, 11.5 billion years ago. The previous record holder Type Ia SN z was 1.95 when the universe was 3.4 billion years old. Astronomers can use these supernovae to learn more about the expansion rate of the universe. Source: NASA.