Supernovae dust led to the birth of new stars in early galaxies, finds JWST

Observations of Fireworks Galaxy

To find possible clues, the JWST targeted NGC 6946, or "Fireworks Galaxy" — located 22 million light-years away from Earth. This galaxy is known to host several supernovae, making it an attractive target for studying the role of supernova dust in star formation. 

Astronomers observed Supernova 2004et and Supernova 2017eaw using Webb’s advanced MIRI instrument (Mid-Infrared Instrument). 

Remarkably, the Webb data revealed vast dust emitted by stars in their death throes. 

Obtaining direct evidence of how supernova dust contributes to the birth of new stars has previously been difficult for astronomers, but Webb made it feasible. 

Webb's imaging wavelengths allow it to peer into stellar dust clouds, revealing intimate cosmic phenomena such as star formation.

“Direct evidence of this phenomenon has been slim up to this point, with our capabilities only allowing us to study the dust population in one relatively nearby supernova to date – Supernova 1987A, 170,000 light-years away from Earth,” said lead author Melissa Shahbandeh of Johns Hopkins University and the Space Telescope Science Institute in Baltimore, Maryland, in an official release.

Amount of dust

Additionally, Webb calculated the quantity of dust in supernovae at this early stage of the universe. 

Over 5,000 Earth masses of dust were estimated to be in SN 2004et. As a result, it has the "highest dust mass" ever detected in a supernova.

The computed mass supports the notion that supernovae were likely dust suppliers to the infant galaxies, as per the statement.

“When you look at the calculation of how much dust we’re seeing in SN 2004et especially, it rivals the measurements in SN 1987A [supernova], and it’s only a fraction of the age. It’s the highest dust mass detected in supernovae since SN 1987A,” said Ori Fox of the Space Telescope Science Institute. 

Over a decade ago, the Atacama Large Millimeter/submillimeter Array (ALMA) telescope detected newly produced dust in SN 1987A. And it has been an ideal target for studying supernovae dust processes since its discovery.

The two supernovae observed by the Webb are part of a science program called GO 2666, "Are Supernovae Dust Factories?" 

The findings have been published in the journal Monthly Notices of the Royal Astronomical Society.

Study abstract:

Supernova (SN) explosions have been sought for decades as a possible source of dust in the Universe, providing the seeds of galaxies, stars, and planetary systems. SN 1987A offers one of the most promising examples of significant SN dust formation, but until the James Webb Space Telescope (JWST), instruments have traditionally lacked the sensitivity at both late times (>1 yr post-explosion) and longer wavelengths (i.e. >10 μm) to detect analogous dust reservoirs. Here we present JWST/MIRI observations of two historic Type IIP SNe, 2004et and SN 2017eaw, at nearly 18 and 5 yr post-explosion, respectively. We fit the spectral energy distributions as functions of dust mass and temperature, from which we are able to constrain the dust geometry, origin, and heating mechanism. We place a 90 per cent confidence lower limit on the dust masses for SNe 2004et and 2017eaw of >0.014 and >4 × 10−4 M⊙, respectively. More dust may exist at even colder temperatures or may be obscured by high optical depths. Dust formation in the ejecta is the most plausible and consistent scenario.