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Near-Infrared and Optical Observations of Type Ic SN2021krf

Presentation #232.09 in the session Supernovae II.

Published onJun 29, 2022
Near-Infrared and Optical Observations of Type Ic SN2021krf

We present near-IR (NIR) and optical observations of the Type Ic supernova (SN Ic) SN 2021krf in the galaxy 2MASX J12511712+0031138, using Gemini, NASA Infrared Telescope Facility (IRTF), Las Cumbres Observatory (LCO), Southern Astrophysical Research Telescope (SOAR), and other ground-based telescopes. The explosion date is approximately on 2021 April 26. Three NIR spectra are taken at days 13, 43, and 68 since the explosion. The NIR spectrum from Gemini at day 68 exhibits a rising K-band continuum flux density longward of ~2.0 μm, which is likely from freshly formed dust. We estimate a dust mass of ~10-5 M and a dust temperature of ~1200 K associated with this rising continuum. Optical spectra of SN2021krf utilizing the SYN++ model show strong absorption lines of O I (7774 Å) and Ca II (8566 Å). Measured photospheric velocities by day 12 are ~10000 km s-1 which slows down to ~6000 km s-1 by day 70. Optical spectra show significant temporal changes in continuity, with combined contributions from Ca II and O I lines, between 8000-9000 Å.

LCO optical light curves of SN2021krf show a relatively slow rising time. Interestingly, the light curves did not decline as we expect from the 56Co decay at late times (between 70 d–300 d). This case is similar to the light curves of iPTF15dtg. It suggests the existence of an extra power source such as magnetar or CSM interaction. Optical spectrum from Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II 10-meter telescope during this stage (at day ~259) show strong C and O lines from the SN. Additionally, H and He lines may be present. We will present the progenitor parameters of SN2021krf by applying STELLA models and discuss possible powering sources of the light curves at late-time.

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