Spectral modelling of Type IIb Supernovae
arXiv:2206.11014 · doi:10.1051/0004-6361/202243448
Abstract
We use the new NLTE lightcurve and spectral synthesis code JEKYLL to evolve a macroscopically mixed ejecta model of a type IIb Supernova (SN) originating from a star with an initial mass of 12 solar masses through the photospheric and nebular phase. We compare to SN 2011dh, and find that both the spectra and the lightcurves are well reproduced. Our work further strengthens the evidence that this SN originated from a star with an initial mass of about 12 solar masses that had lost all but tiny (<0.1 solar masses) fraction of its hydrogen envelope. We also investigate the effects of the macroscopic mixing by comparing macroscopically and microscopically mixed models, and by varying the clumping geometry. In the photospheric phase, we find strong effects on the effective opacity in the macroscopically mixed regions, which affects the model lightcurves. The diffusion peak is considerably narrower in the macroscopically mixed case, and differs strongly if the radioactive material in the helium envelope is allowed to expand more than in our standard model. The effect is mainly geometrical, and is driven by the expansion of the clumps containing radioactive material. These findings has implications for lightcurve modelling of stripped-envelope SNe in general, and the effect would increase the estimated ejecta masses. In the nebular phase, we find strong effects on the collisional cooling rates in the macroscopically mixed regions, which affects lines driven by collisional cooling, in particular the [Ca II] 7291, 7323 and [O I] 6300, 6364 lines. As these lines are often used for mass determinations, it highlights the importance of how the calcium- and oxygen-rich material is mixed. As shown in this and earlier work, both NLTE and macroscopic mixing are essential ingredients to accurately model the lightcurves and spectra of Type IIb SNe throughout their evolution.
Accepted for publication by Astronomy and Astrophysics
References in corpus (9)
- Nucleosynthesis and Remnants in Massive Stars of Solar Metallicity
- Early-time light curves of Type Ib/c supernovae from the SDSS-II Supernova Survey
- Late-time spectral line formation in Type IIb supernovae, with application to SN 1993J, SN 2008ax, and SN 2011dh
- Uncovering the Putative B-Star Binary Companion of the SN 1993J Progenitor
- The Bubble-like Interior of the Core-Collapse Supernova Remnant Cassiopeia A
- Spitzer IRAC Images and Sample Spectra of Cassiopeia A's Explosion
- Nebular phase properties of supernova Ibc from He-star explosions
- Radiative-transfer modeling of nebular-phase type II supernovae. Dependencies on progenitor and explosion properties
- Carbon monoxide formation and cooling in supernovae