The Type IIP SN 2007od in UGC 12846: from a bright maximum to dust formation in the nebular phase

TL;DR

This study presents comprehensive UV, optical, NIR, and MIR observations of peculiar Type IIP supernova 2007od, revealing ejecta-CSM interaction, dust formation, and a likely super-AGB progenitor, expanding understanding of supernova diversity.

Contribution

It provides detailed multi-wavelength observations and modeling of SN 2007od, highlighting its unique features and proposing a super-AGB progenitor, which is a novel insight for Type IIP supernovae.

Findings

Ejecta mass estimated at 5-7.5 M⊙ with kinetic energy ≥0.5×10^51 erg.

Evidence of ejecta-CSM interaction and dust formation inside ejecta.

Super-AGB progenitor with initial mass 9.7-11 M⊙.

Abstract

Ultraviolet (UV), optical and near infrared (NIR) observations of the type IIP supernova (SN) 2007od are presented, covering from the maximum light to the late phase, allowing to investigate in detail different physical phenomena in the expanding ejecta. These data turn this object into one of the most peculiar IIP ever studied. The early light curve of SN 2007od is similar to that of a bright IIPs with a short plateau, a bright peak (MV = -18 mag), but a very faint optical light curve at late time. However, with the inclusion of mid infrared (MIR) observations during the radioactive decay we have estimate a M(56Ni) ~ 2\times10^-2 M\odot. Modeling the bolometric light curve, ejecta expansion velocities and black-body temperature, we estimate a total ejected mass was 5 - 7.5 M\odot with a kinetic energy of at least 0.5 \times 10^51 erg. The early spectra reveal a boxy H{\alpha} profile and high velocities features of the Balmer series that suggest interaction between the ejecta and a close circum-stellar matter (CSM). SN 2007od may be, therefore, an intermediate case between a Type IIn SN and a typical Type IIP SN. Also late spectra show a clear evidence of CSM and the presence of dust formed inside the ejecta. The episodes of mass loss short before explosion, the bright plateau, along with the relatively small amount of 56Ni and the faint [O I] observed in the nebular spectra are consistent with a super-asympthotic giant branch (super-AGB) progenitor (M~9.7 - 11 M\odot).