SN 2019odp – A massive oxygen-rich Type Ib supernova

¹ Department of Astronomy, The Oskar Klein Centre, Stockholm University, AlbaNova, 10691 Stockholm, Sweden
² Technische Universität München, TUM School of Natural Sciences, Physik-Department, James-Franck-Straße 1, 85748 Garching, Germany
³ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Straße 1, 85748 Garching, Germany
⁴ Department of Physics, The Oskar Klein Center, Stockholm University, AlbaNova, 10691 Stockholm, Sweden
⁵ School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
⁶ Department of Astronomy, University of Maryland, College Park, MD 20742, USA
⁷ Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA
⁸ Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, D-85748 Garching, Germany
⁹ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 234 Herzl St, 76100 Rehovot, Israel
¹⁰ IPAC, California Institute of Technology, 1200 E. California Blvd, Pasadena CA 91125, USA
¹¹ Caltech Optical Observatories, California Institute of Technology, Pasadena, CA 91125, USA
¹² Université Clermont Auvergne, CNRS/IN2P3, LPC, F-63000 Clermont-Ferrand, France

^⋆ Corresponding author; tassilo.schweyer@astro.su.se

Received: 3 March 2023
Accepted: 3 October 2024

Abstract

Aims. Stripped envelope (SE) supernovae are explosions of stars that have somehow lost most of their outer envelopes. We present the discovery and analyse the observations of the Type Ib supernova 2019odp (a.k.a. ZTF19abqwtfu) covering epochs within days of the explosion to late nebular phases at 360 d post-explosion.

Methods. Our observations include an extensive set of photometric observations and low- to medium-resolution spectroscopic observations, both covering the complete observable time range. We analysed the data using analytic models for the recombination cooling emission of the early excess emission and the diffusion of the peak light curve. We expanded on existing methods to derive oxygen mass estimates from nebular phase spectroscopy, and briefly discuss progenitor models based on this analysis.

Results. Our spectroscopic observations confirm the presence of He in the supernova ejecta and we thus (re)classify SN 2019odp as a Type Ib supernova. From the pseudo-bolometric light curve, we estimate a high ejecta mass of M_ej ∼ 4 − 7 M_⊙. The high ejecta mass, large nebular [O I]/[Ca II] line flux ratio (1.2 − 1.9), and an oxygen mass above ⪆0.5 M_⊙ point towards a progenitor with a pre-explosion mass higher than 18 M_⊙. Whereas a majority of analysed SE supernovae in the literature seem to have low ejecta masses, indicating stripping in a binary star system, SN 2019odp instead has parameters that are consistent with an origin in a single massive star. The compact nature of the progenitor (≲10 R_⊙) suggests that a Wolf-Rayet star is the progenitor.