Photometry and spectroscopy of the Type IIP SN 1999em from outburst to dust formation

• DOI: 10.1046/j.1365-8711.2003.06150.x
• Publication Date: 2003-03-12T14:30:14Z
• Authors: A. Elmhamdi; I. J. Danziger; N. Chugai; A. Pastorello; M. Turatto; E. Cappellaro; G. Altavilla; S. Benetti; F. Patat; M. Salvo
• Keywords: Photosphere

We present photometry and spectra of the Type IIP supernova 1999em in NGC 1637 from several days after outburst till day 642. The radioactive tail recovered bolometric light curve SN indicates that amount ejected 56Ni is . Hα He i 10 830-Å lines at nebular epoch show distribution bulk can be represented approximately by a sphere with velocity 1500 km s−1, which shifted towards far hemisphere about 400 s−1. fine structure photospheric reminiscent 'Bochum event' 1987A analysed terms two plausible models: bipolar jets non-monotonic behaviour optical depth combined one-sided ejection. late-time dramatic transformation [O i] 6300-Å line profile between 465 510, we interpret as an effect dust condensation during this period. Late-time supports formation scenario 465. suggests occupies ≈800 s−1 ≫10. latter exceeds dusty zone more than times. Use made Expanding Photosphere Method to estimate distance explosion time, D≈ 7.83 Mpc t0≃ 1999 October 24.5 ut, accord observational constraints on time other results detailed studies method. plateau brightness duration expansion suggest pre-supernova radius 120–150 R⊙, ejecta mass 10–11 M⊙ energy (0.5–1) × 1051 erg. neutron star conservative assumption loss implies main sequence progenitor Mms≈ 12–14 M⊙. derived range agreement upper limit found using field images Smartt et al. From 6300, 6364 Å doublet luminosity infer oxygen factor four lower consistent estimated according nucleosynthesis stellar evolution theory. note 'second-plateau' beginning tail. This feature seems common SNe low mass.