The Type Ib SN 1999dn: One Year of Photometric and Spectroscopic Monitoring

TL;DR

This paper presents a comprehensive one-year photometric and spectroscopic study of supernova SN 1999dn, revealing detailed explosion properties, progenitor characteristics, and spectral evolution, making it one of the best observed Type Ib supernovae.

Contribution

It provides extensive observational data and analysis of SN 1999dn, including estimates of nickel mass, ejecta mass, energy, and progenitor type, enhancing understanding of Type Ib supernovae.

Findings

Ejected about 0.11 solar masses of 56Ni.

Total ejecta mass estimated at 4-6 solar masses.

Explosion energy at least 5x10^{51} erg.

Abstract

Extensive optical and near-infrared (NIR) observations of the type Ib supernova 1999dn are presented, covering the first year after explosion. These new data turn this object, already considered a prototypical SNIb, into one of the best observed objects of its class. The light curve of SN 1999dn is mostly similar in shape to that of other SNeIb but with a moderately faint peak M_V=-17.2 mag). From the bolometric light curve and ejecta expansion velocities, we estimate that about 0.11 Msun of 56Ni were produced during the explosion and that the total ejecta mass was 4-6 Msun with a kinetic energy of at least 5x10^{51} erg. The spectra of SN 1999dn at various epochs are similar to those of other Stripped Envelope (SE) SNe showing clear presence of H at early epochs. The high explosion energy and ejected mass, along with the small flux ratio [CaII]/[OI] measured in the nebular spectrum, together with the lack of signatures of dust formation and the relatively high-metallicity environment point toward a single massive progenitor (M_ZAMS>=23-25 Msun) for SN 1999dn.