An optimal hydrodynamic model for the normal type IIP supernova 1999em

Abstract

Context. There is still no consensus about progenitor masses of type IIP supernovae. Aims. We study a normal type IIP SN 1999em in detail and compare it to a peculiar type IIP SN 1987A. Methods. We computed the hydrodynamic and time-dependent atmosphere models interpreting simultaneously both the photometric and spectroscopic observations. Results. The bolometric light curve of SN 1999em and the spectral evolution of its Hα line are consistent with a presupernova radius of 500 ± 200 R , an ejecta mass of 19.0 ± 1.2 M , an explosion energy of (1.3 ± 0.1) × 10 51 erg, and a radioactive 56 Ni mass of 0.036 ± 0.009 M . A mutual mixing of hydrogen-rich and helium-rich matter in the inner layers of the ejecta guarantees a good fit of the calculated light curve to that observed. Based on the hydrodynamic models in the vicinity of the optimal model, we derive the approximate relationships between the basic physical and observed parameters. The hydrodynamic and atmosphere models of SN 1999em are inconsistent with the short distance of 7.85 Mpc to the host galaxy. Conclusions. We find that the hydrogen recombination in the atmosphere of a normal type IIP SN 1999em, as well as most likely other type IIP supernovae at the photospheric epoch, is essentially a time-dependent phenomenon. It is also shown that in normal type IIP supernovae the homologous expansion of the ejecta in its atmosphere takes place starting from nearly the third day after the supernova explosion. A comparison of SN 1999em with SN 1987A reveals two very important results for supernova theory. First, the comparability of the helium core masses and the explosion energies implies a unique explosion mechanism for these core collapse supernovae. Second, the optimal model for SN 1999em is characterized by a weaker 56 Ni mixing up to ≈660 km s −1 compared to a moderate 56 Ni mixing up to ∼3000 km s −1 in SN 1987A, hydrogen being mixed deeply downward to ∼650 km s −1 .

Dust formation in the ejecta of the type II-P supernova 2004dj

“…These steep density distributions in the SN ejecta are also predicted by numerical simulations (e.g. Chugai et al 2007;Utrobin 2007). We computed symmetric grids for the density distribution with 10 grid points on each axis, but for comparison we also produced models with higher resolution grids using 15, 30 and 49 grid points.…”

High mass of the type IIP supernova 2004et inferred from hydrodynamic modeling

“…Utrobin (2007) found that both this one-group approach and the multi-group approach of Baklanov et al (2005) measured similar ejecta mass and explosion energy for SN 1999em. The basic equations and details of the input physics, including calculations of mean opacities, are described in Utrobin (2004).…”

“…At present, we can only state firmly that the multi-group treatment of radiation transfer cannot notably change the inferred SN parameters. This conclusion is based on the comparison between the multigroup (Baklanov et al 2005) and one-group (Utrobin 2007) approaches to the SN 1999em modeling. A major drawback of our model may be its one-dimensional approximation.…”

A comparative study of Type II-P and II-L supernova rise times as exemplified by the case of LSQ13cuw

“…Radiation hydrodynamic calculations of the explosion and evolution of Type II SNe have been presented by Grassberg et al (1971), Falk & Arnett (1977), Falk (1978), Klein & Chevalier (1978), Hillebrandt & Müller (1981), and Litvinova & Nadezhin (1983, 1985, as well as more specifically for SNe II-P by Young (2004), Utrobin (2007), Utrobin & Chugai (2009), Bersten et al (2011), and Dessart & Hillier (2011), for SNe II-L by Swartz et al (1991) and Blinnikov & Bartunov (1993) and for the peculiar Type II-P SN 1987A by Blinnikov et al (2000), Dessart & Hillier (2010) and Pumo & Zampieri (2011). Here we give a summary view of the physical processes at play and the various evolutionary stages seen in these simulations.…”