Identifying the SN 2022acko progenitor with JWST

We report on analysis using the JWST to identify a candidate progenitor star of the Type II-plateau (II-P) supernova SN 2022acko in the nearby, barred spiral galaxy NGC 1300. To our knowledge, our discovery represents the first time JWST has been used to localize a progenitor system in pre-explosion archival Hubble Space Telescope (HST) images. We astrometrically registered a JWST NIRCam image from 2023 January, in which the SN was serendipitously captured, to pre-SN HST F160W and F814W images from 2017 and 2004, respectively. An object corresponding precisely to the SN position has been isolated with reasonable confidence. That object has a spectral energy distribution (SED) and overall luminosity consistent with a single-star model having an initial mass possibly somewhat less than the canonical 8 M-& ODOT; theoretical threshold for core collapse (although masses as high as 9 M-& ODOT; for the star are also possible); however, the star's SED and luminosity are inconsistent with that of a super-asymptotic giant branch star that might be a forerunner of an electron-capture SN. The properties of the progenitor alone imply that SN 2022acko is a relatively normal SN II-P, albeit most likely a low-luminosity one. The progenitor candidate should be confirmed with follow-up HST imaging at late times, when the SN has sufficiently faded. This potential use of JWST opens a new era of identifying SN progenitor candidates at high spatial resolution.

Automated summary

The study reports on the use of JWST to identify a potential progenitor star for the Type II-plateau supernova SN 2022acko. This is the first time JWST has been used to locate a progenitor system in pre-explosion HST images. By accurately aligning the JWST image with the pre-SN HST images, a candidate object corresponding to the SN position has been identified. The significance of this study lies in the new era of using JWST to identify supernova progenitor candidates at high spatial resolution.