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An international team of astronomers has conducted detailed multicolor photometric and spectroscopic observations of SN 2022xlp—a type Iax supernova. Results of the observational campaign, September 9 on the arXiv pre-print server, could shed more light on the nature of this rare subclass of supernovae.

Type Ia supernovae (SN Ia) are generally found in binary systems in which one of the stars is a white dwarf (WD). Stellar explosions of this type are important for astronomers, as they can offer essential clues into the evolution of stars and galaxies.

Type Iax SNe represent a very rare subtype of SN Ia, which leaves behind a remnant star, rather than completely dispersing the WD. In general, they are similar to type Ia SNe, but have a lower ejection velocity and lower luminosity.

SN 2022xlp is a supernova discovered in 2022, which exploded in the galaxy NGC 3938, located some 72.2 million light years away. Based on the first spectrum obtained of SN 2022xlp, the supernova was classified as a type Iax SN.

SN 2022xlp reached a peak absolute brightness of -16.04 mag, which makes it the second determined intermediate-luminosity Iax supernova.

Given that it represents a rare luminosity range for SNe Iax, a group of astronomers led by Dominik Bánhidi of the University of Szeged in Hungary, decided to perform photometry and spectroscopy of this supernova, using various ground-based and space telescopes, in order to get more insights into its properties.

"We present our multicolor photometric and spectroscopic observations of SN 2022xlp, which is the second intermediate-luminosity type Iax SN with detailed follow-up, as its V-band LC [light curve] peaks at M_max(V) = −16.04 ± 0.25 mag," the scientists wrote in the paper.

The observational campaign started six days after the explosion and covered a period of 73 days. The collected images, together with archival data, show a relatively rapid color evolution due to the decreasing photospheric temperature in the early phase. The change in color-indexes was found to be about 1.5 mag between eight days prior to explosion and 20 days after.

By analyzing the light curve properties, color evolution, and spectral features of SN 2022xlp, the astronomers found that it is very similar to SN 2019muj—the first known intermediate-luminous Iax supernova. Moreover, by comparing the color evolution of various luminous SNe Iax, they found that the amplitude of the color change is greater in the case of brighter Iax supernovae.

The study also found that the estimated bolometric flux of SN 2022xlp peaks at 887 duodecillion erg/s and indicates the production of about 0.02 solar masses of radioactive nickel. The explosion energy of the supernovae was calculated to be around 20 quindecillion ergs and the ejecta mass was estimated to be 0.14 solar masses.