New source of dust in the universe: Type Ia supernovae

He cosmic dust It is very similar to that on Earth: collections of molecules that have condensed and are held together in a grain. An international team of astronomers has discovered a previously unknown source of dust in the universe: a Type Ia supernova that interacts with the gas in its environment SN 2018evt.

The results are relevant because the exact nature of how this material formed in the universe has long been a mystery. The study, published in Natural astronomyhe runs it Lingzhi Wangassociate researcher at the South American Center for Astronomy of the Chinese Academy of Sciences (CASSACA), in collaboration with astronomers from China, the United States of America, Chile, the United Kingdom and Spain.

Among them scientists Lluis Galbany And Tomas Müller Bravo from the Institute of Space Sciences (ICE-CSIC) and the Institute of Space Studies of Catalonia (IEEC), which contributed data to the study in addition to participating in the analysis.

Two types of supernovae and galaxies

Supernovae are known to play an important role in dust formation, and so far dust formation has only been observed in Core collapse supernovae (or type II supernovae)., which are explosions of massive stars. Because these supernovae do not occur in elliptical galaxies, the nature of dust formation in them remains difficult to determine. These galaxies are not organized into a Spiral pattern like the Milky Way, but are huge swarms of stars.

But this study shows that the Type Ia thermonuclear supernovaeconsisting of the explosion of a white dwarf star in a binary star system with another star, could explain a significant amount of dust in this type of star Elliptical galaxies.

History of discovery

“At first this supernova did not attract our attention and we temporarily lost interest shortly after the start of our observation campaign when it temporarily disappeared behind the Sun. But to our surprise, when resurfaced a few months later, not only was it still visible, but it was also significantly brighter than expected. At that moment we realized that something truly extraordinary was happening,” says Galabany.

The authors tracked the supernova SN 2018evt for more than three years using space facilities such as Spitzer Space Telescope of NASA and its mission NEOWISEas well as terrestrial facilities such as global network of telescopes at Las Cumbres Observatory and other facilities in China, South America and Australia.

Researchers from ICE-CSIC and IEEC collaborated by monitoring data from the New Technology Telescope (NTT) in La Silla, Chile, as part of the ePESSTO+ collaboration. They also monitored the supernova using the A Novel Dual Imaging CAMera (ANDICAM) camera mounted on the 1.3-meter SMARTS telescope on Cerro Tololo, Chile.

Observations in the infrared

The team discovered that the supernova encountered material previously ejected from one or both stars of the binary system before the white dwarf exploded. The supernova sent one Shockwave to this already existing gas.

As the team observed the supernova for more than 1,000 days, they were able to see that its light dimmed sharply at the optical wavelengths visible to our eyes and then began to fade. shine brighter in the infrared range. This is a telltale sign that dust formed in the circumstellar gas as it cooled after the supernova shock wave passed through it.

“Since gas and dust emit infrared light, observations at these wavelengths are essential for this type of study,” he emphasizes. Müller“However, despite infrared monitoring of other thermonuclear supernovae, detecting dust formation in these phenomena remained difficult.” That is why we were surprised by this discovery.”

“The origin of cosmic dust has long been a mystery. “This research marks the first evidence of a rapid and significant dust formation process in the thermonuclear supernova that interacts with the circumstellar gas,” emphasizes Lingzhi Wang.

The origin of cosmic dust has been a mystery, but this study marks the first evidence of a rapid dust formation process in a thermonuclear supernova interacting with circumstellar gas

Lingzhi Wang (CASSACA)

The study estimated that this supernova event must have produced a large amount of dust. more than 1% of the sun’s mass. As the supernova cools, the amount of dust may increase tenfold.

Although these dust factories are not as numerous or efficient as core collapse supernovae, there may be enough thermonuclear supernovae interacting with their surroundings to be a significant or even dominant source of dust in elliptical galaxies.