Photo: Royal Astronomical Society Monthly Notices (2023). DOI: 10.1093/mnras/stad1681
Observations with the James Webb Space Telescope have gone a long way in confirming supernovae as a source of dust in early galaxies.
Observations of two Type II supernovae, Supernova 2004et (SN 2004et) and Supernova 2017eaw (SN 2017eaw), have revealed large amounts of dust within the ejecta of each of these objects. The mass found by the researchers supports the theory that supernovae played a key role in supplying the early universe with dust.
Dust is a building block for many things in our universe, in particular, the planets. As dust from dying stars spreads through space, it carries essential elements to help give birth to the next generation of stars and their planets. The origin of that dust has puzzled astronomers for decades. A major source of cosmic dust could be supernovae: after the dying star explodes, the leftover gas expands and cools to create dust.
“Until now, direct evidence for this phenomenon has been scant, and our capabilities only allow us to study the dust population in one relatively nearby supernova to date: supernova 1987A, 170,000 light-years from Earth,” said the author. principal, Melissa Shahbandeh. from Johns Hopkins University and the Space Telescope Science Institute in Baltimore, Maryland. “When the gas cools enough to form dust, that dust is only detectable at mid-infrared wavelengths, provided you have sufficient sensitivity.”
For supernovae more distant than SN 1987A like SN 2004et and SN 2017eaw, both in NGC 6946 about 22 million light-years away, that combination of wavelength coverage and exquisite sensitivity can only be obtained with MIRI (Mid-Infrared Instrument) by Webb.
Webb’s observations are the first advance in the study of supernova dust production since the detection of newly formed dust in SN 1987A with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope nearly a decade ago.
Another particularly intriguing result of their study is not just the detection of dust, but the amount of dust detected at this early stage in the supernova’s life. In SN 2004et, the researchers found more than 5,000 Earth masses of dust. “When you look at the calculation of the amount of dust we’re seeing in SN 2004et especially, it rivals the measurements in SN 1987A, and it’s only a fraction of the age,” program leader Ori Fox of the Institute of Sciences added in a statement. of the Space Telescope. “It is the highest dust mass detected in supernovae since SN 1987A.”
Observations have shown astronomers that young, distant galaxies are littered with dust, but these galaxies are not old enough for intermediate-mass stars, such as the Sun, to have supplied the dust as they age. The most massive and short-lived stars could have died early enough and in large enough numbers to create so much dust.
While astronomers have confirmed that supernovae produce dust, the question remains about how much of that dust can survive the internal shocks that reverberate after the explosion. Seeing this much dust at this stage in the life of SN 2004et and SN 2017eaw suggests that the dust can survive the shock wave, evidence that supernovae are really important dust factories after all.
The researchers also note that current estimates of the mass may be the tip of the iceberg. While Webb has allowed researchers to measure colder dust than ever before, there may be undetected colder dust that radiates further into the electromagnetic spectrum and remains hidden by the outermost layers of dust. The researchers stressed that the new findings are also just a hint at newly discovered research capabilities into supernovae and their dust production using Webb, and what that can tell us about the stars they come from. “There is growing enthusiasm to understand what this dust also implies about the core of the exploded star,” Fox said. “After looking at these particular findings, I think our fellow researchers will think of innovative ways to work with these dusty supernovae in the future”.