Abstract We present near-infrared (NIR) and optical observations of the highly reddened and moderately energetic Type Ib supernova (SN) 2023dbc, covering a period from 2 to 136 days after the explosion. By comparing its color evolution, specifically in r-JHKₒ and i-JHKₒ, with those of broad-lined Type Ic (Ic-BL) and Type IIb SNe, we estimate a significant extinction of Aₕ=4. 1 0. 1 mag toward the SN. The extinction-corrected peak absolute magnitudes are M₉ = -16. 8 0. 2 mag, M₇ = -16. 8 0. 2 mag, and M₊_ₒ = -17. 0 0. 2 mag. The SN exhibited an r-band rise time of 14. 9 days. The spectra display broad features indicative of high expansion velocities; the He i line velocity was measured at 16000\, km\, s^-1 at t=-4 d. Its spectral profile is broader than those of typical moderately energetic Type Ib SNe, yet narrower than those of Type Ic-BL SNe, placing it in an intermediate category. Based on the light-curve timescale and velocity, we estimate a kinetic energy of Eₖ = (4. 1 0. 7) 10^51 erg, an ejecta mass of M₄₉ = 2. 3 0. 7\, M, and a radioactive ^56Ni mass of (3. 8 0. 1) 10^-2\, M. An analysis using a two-component model suggests a steep density profile in the outer layer contrasted with a dense inner core, which implies ejecta asphericity. The low ^56Ni mass is consistent with a partial fallback scenario. We conclude that SN 2023dbc originated from an aspherical explosion with partial core fallback, arising from a progenitor (M₈₍₈ 15\, M) that had retained its helium envelope within a binary system.
Yamanaka et al. (Thu,) studied this question.