An international team of scientists, including Dr Mariusz Gromadzki from the UW’s Astronomical Observatory, has identified a previously unknown source of cosmic dust. The observed phenomenon is a result of the interaction of the matter ejected during a type Ia supernova explosion with the surrounding circumstellar gas. The discovery is described in Nature Astronomy.

Dust in space is of great importance to the evolution of the Universe and the life within it. Astronomers have so far identified two main mechanisms for its formation: in the atmospheres of cool stars and during Type II supernovae, which are formed by the collapse of very massive stars.

Type II supernovae develop in Milky Way-like galaxies. They appear as stars in the spiral arms of galaxies composed of dust and gas, and within a few million years explode as Type II supernovae.

An international team of scientists, which included Dr Mariusz Gromadzki from the UW’s Astronomical Observatory, published their findings in Nature Astronomy, suggesting that type Ia supernova explosions, related to the explosion of a white dwarf in a binary system, may be largely responsible for the production of dust in elliptical galaxies, in which source of dust was unexplained mystery. White dwarfs are formed by the rejection of a hydrogen envelope by low-mass stars.

Type Ia supernova

During a systematic and almost three-year-long monitoring of the supernova SN 2018evt, astronomers noticed that as the object’s brightness decreased rapidly in the visible range, it gradually became brighter in infrared light. This is a clear indication that after the shock generated during the supernova explosion passed through, the gas that had accumulated there before the explosion cooled rapidly and dust began to form. This is the first time the rapid formation of dust in the gas around a Type Ia supernova has been observed.

More than a dozen telescopes deployed around the globe and in space were used to monitor supernova SN 2018evt. One of the main instruments providing spectroscopic data was the 3.54-metre NTT telescope located at the European Southern Observatory (ESO) on La Silla Hill in Chile. The data were collected as part of the ePESSTO+ project, in which Dr Mariusz Gromadzki has been involved for several years.