The James Webb Space Telescope measured the dust from 11 nearby supernovae, between about one and seven years after their stars exploded.
These explosions mark the end of some massive stars. After the event, the ejected matter cools and can form tiny solid grains. This cosmic dust then contributes to the material available to form new stars, planets and other objects. But the amount produced just after a supernova remains poorly understood.
Two dusty supernovae observed by the James Webb Telescope’s MIRI instrument.
Source: ESA/Webb
The astronomers used MIRI, the James Webb instrument sensitive to mid-infrared light. These wavelengths make it possible to detect the heat emitted by dust that is difficult to observe in visible light. The team studied 11 Type IIP supernovae, a family of explosions originating from massive stars whose brightness remains relatively stable for several weeks after reaching its peak.
The observations trace an evolution with age. Around 400 days after the explosion, the researchers detected warm emission corresponding to about 1,227 °C. Between roughly 600 and 2,500 days, other signatures became more pronounced. The colder dust measured at that stage ranged from about -153 °C to -23 °C.
The inferred quantities range from about 0.0001 to 0.01 times the mass of the Sun. Even the higher value remains modest in the face of an obvious question: how could young galaxies observed very far away in the Universe have accumulated so much dust so quickly? Supernovae have long been considered a possible source.
Yet in this sample, the amounts present between one and seven years after the explosion are not enough to directly explain the dust in typical galaxies observed very early in cosmic history. This does not mean that supernovae play a negligible role. They could provide small grains that later grow by gathering matter in interstellar space.
The study found no statistically clear relationship between dust mass and several properties of the explosion, including its peak luminosity or energy. However, some supernovae that showed early signs of dense matter around the star were among the most dust-rich objects in the sample.
The team therefore plans to rely on observations spanning more years to track the growth of these grains over a longer period. The current sample ends at about seven years after the explosion. The amount of dust could continue to change well beyond that point, something that future infrared measurements will make it possible to test.