(ORDO NEWS) — An international team of astronomers has studied the spectroscopic properties of a nearby superluminous Type I supernova known as SN 2018bsz.
This observational campaign sheds new light on the properties of this supernova, revealing an asymmetric cloud of circumstellar material in its vicinity.
Supernovae are powerful and bright stellar explosions. They are of great importance to astronomers because they provide a deeper understanding of the evolution of stars and galaxies.
In general, supernovae are divided into two groups based on their atomic spectra: Type I and Type II. The spectra of type I supernovae lack hydrogen, while the spectra of type II supernovae show hydrogen lines.
Superluminous supernovae are characterized by very high brightness and often very long light curves. The interaction of material erupted from a supernova explosion with surrounding circumstellar material is an efficient mechanism for converting the kinetic energy of the ejected material into radiation, and scientists believe that this process is responsible for the formation of superluminous supernovae.
Superluminous supernova SN 2018bsz was first detected on May 17, 2018 by the All Sky Automated Survey for SuperNovae (ASAS-SN).
At first, this event was classified as a type II supernova. However, further tracking of the source showed that it is a superluminous type I supernova. The superluminous supernova’s parent galaxy, 2MASX J16093905-3203443, has a redshift of 0.0267, making it the closest type I superluminous supernova detected to date.
The researchers observed the spectral evolution of the source SN 2018bsz and found multi-component alpha-hydrogen radiation that appeared 30 days after the maximum brightness of the supernova, which is unusual for a superluminous type I supernova.
This means that hydrogen has a spatial arrangement external to the supernova and lies in cloud of circumstellar material.
Astronomers believe that the existence of an asymmetric, disk-like structure of circumstellar material with multiple emitting regions could explain the observed spectral evolution of SN 2018bsz. They propose a scenario in which, after the explosion, the spectrum is dominated by lines of material erupted from the explosion, resulting in a predominantly blue component.
Subsequently, when the photosphere formed as a result of the explosion begins to disappear, we again begin to see circumstellar material, and red is added to the blue component. Ultimately, intense multicomponent alpha-hydrogen radiation begins to be observed in the spectrum, the authors explained their scenario.
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