Study investigates a rare Type Icn supernova

A global workforce of astronomers has carried out optical and near-infrared observations of a uncommon Kind Icn supernova referred to as SN 2022ann. The outcomes of the examine, printed November 9 on the preprint server arXiv, shed extra gentle on the character of this supernova and its distinctive properties.

Supernovae (SNe) are highly effective and luminous stellar explosions. They’re vital for the scientific community as they provide important clues into the evolution of stars and galaxies. Generally, SNe are divided into two teams primarily based on their atomic spectra: Kind I and Kind II. Kind I SNe lack hydrogen of their spectra, whereas these of Kind II showcase spectral traces of hydrogen.

Kind Icn SNe are an excessive subtype of interacting stripped-envelope supernovae (SESN). They’ve robust, slender oxygen and carbon traces however weak or absent hydrogen and helium traces, presenting further problems to the stripping mechanism. They’ve slender emission options indicative of circumstellar interplay.

So far, solely 5 Kind Icn SNe have been found, and SN 2022ann is the newest addition to the brief record of this SN subtype. SN 2022ann was detected on January 27, 2022 within the faint host galaxy SDSS J101729.72–022535, at a distance of about 710 million light years.

Shortly after the explosion, a workforce of astronomers led by Kyle Davis of College of California, Santa Cruz, commenced photometric and spectroscopic monitoring of SN 2022ann utilizing numerous ground-based services.

“We’ve got offered optical photometry and optical/NIR spectroscopy of SN 2022ann, the fifth reported SN Icn, and its host galaxy, SDSS J101729.72–022535.6. (…) Our observations of SN 2022ann present distinctive perception into the origins of the rarest SN explosions, and undiscovered endpoints of stellar evolution,” the researchers wrote within the paper.

The observations present that early optical spectra of SN 2022ann are dominated by slender carbon and oxygen P-Cygni options with absorption velocities of round 800 km/s. That is slower than different SNe Icn and beneath the escape velocity for a compact huge star that’s essential to keep away from robust hydrogen emission. Subsequently, the astronomers recommend that the progenitor star of SN 2022ann might have been “overvalued” by an outburst and out of hydrostatic equilibrium earlier than explosion.

The examine discovered that SN 2022ann has a uniquely fixed brightness at early occasions after the explosion and a comparatively fast late-time decline in redder bands after this plateau. Furthermore, SN 2022ann at peak has a comparatively low luminosity in comparison with the opposite 4 identified Kind Icn SNe. Primarily based on the bolometric gentle curve of SN 2022ann, the researchers estimate that its ejecta mass is at a degree of 1.73 solar lots.

Based on the researchers, all the outcomes recommend {that a} binary star companion is required to adequately strip the progenitor earlier than explosion and produce a low-velocity outflow such because the one in SN 2022ann. They added that the rarity of SNe Icn might point out that they’re created throughout a short or unusual stage in binary evolution.

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