The James Webb Space Telescope has identified substantial pockets of hot dust arising from two Type II supernovae that erupted in spiral galaxy NGC 6946. A report by N+1 references a study published in the Monthly Notices of the Royal Astronomical Society (MNRAS).
In many distant galaxies, the origins of cosmic dust remain poorly understood. Scientists suspect that IIP-type supernovae, which occur when the cores of massive stars collapse, contribute significant dust to the interstellar medium. Yet direct evidence of the large reservoirs of both hot and cold dust formed during such explosions in faraway galaxies has been scarce. Observations to date have mainly confirmed dust production in a handful of nearby Type II supernovae.
A research team led by Melissa Shahbandeh of Johns Hopkins University has reported the discovery of massive dust clouds associated with the spiral galaxy NGC 6946, located roughly 22 million light-years away. These clouds appear to originate from the explosions of IIP-type supernovae SN 2004et and SN 2017eaw. Data were gathered in the mid-infrared range with the Mid-Infrared Instrument (MIRI) aboard the James Webb Space Telescope, capturing the echoes of dust formation 18 and 5 years after the respective outbursts became visible. The findings contribute a new chapter to our understanding of how dust is produced and distributed in galaxies beyond the local universe. (Attribution: Johns Hopkins University and collaborators, based on MIRI observations and analysis published in MNRAS.)
The detected hot dust in SN 2004et and SN 2017eaw has estimated masses exceeding 0.014×10−4 and 4×10−4 solar masses, respectively. For SN 2004et, this dust signature represents one of the most substantial infrared-observed dust deposits among extragalactic supernovae. The dust grains are heated by radiation generated by the shock waves produced as the stellar debris expands and interacts with the surrounding medium. (Attribution: Shahbandeh et al., MNRAS, 202x.)
Researchers note that if some portion of the dust resides in colder or optically thick environments, the total dust mass could be even larger. In fact, analyzing the aftermath up to roughly 10,000 days after the explosion suggests that several solar masses of dust might be detectable in extragalactic Type II supernovae. Such a finding could have profound implications for theories about the origin and abundance of cosmic dust in the early universe. (Attribution: observational team, MNRAS, 202x.)
Earlier Webb imagery has also highlighted spiral galaxies at substantial distances, underscoring the telescope’s capability to probe dust formation in distant stellar deaths and their role in galactic evolution. (Attribution: Webb observations and subsequent analyses.)