The Atomic Physics Underlying the Spectroscopic Analysis of Massive Stars and Supernovae

Abstract

We have developed a radiative transfer code, CMFGEN, which allows us to model the spectra of massive stars and supernovae. Using CMFGEN we can derive fundamental parameters such as effective temperatures and surface gravities, derive abundances, and place constraints on stellar wind properties. The last of these is important since all massive stars are losing mass via a stellar wind that is driven from the star by radiation pressure, and this mass loss can substantially influence the spectral appearance and evolution of the star. Recently we have extended CMFGEN to allow us to undertake time-dependent radiative transfer calculations of supernovae. Such calculations will be used to place constraints on the supernova progenitor, to place constraints on the supernova explosion and nucleosynthesis, and to derive distances using a physical approach called the "Expanding Photosphere Method". We describe the assumptions underlying the code and the atomic processes involved. A crucial ingredient in the code is the atomic data. For the modeling we require accurate transition wavelengths, oscillator strengths, photoionization cross-sections, collision strengths, autoionization rates, and charge exchange rates for virtually all species up to, and including, cobalt. Presently, the available atomic data varies substantially in both quantity and quality.

8 pages, 2 figures, Accepted for publication in Astrophysics & Space Science

References in corpus (7)

• Mass loss from hot massive stars
• Type II Supernovae: Model Light Curves and Standard Candle Relationships
• Time Dependent Monte Carlo Radiative Transfer Calculations For 3-Dimensional Supernova Spectra, Lightcurves, and Polarization
• Supernova radiative-transfer modeling: A new approach using non-LTE and full time dependence
• Time-dependent Effects in Photospheric-Phase Type II Supernova Spectra
• On the sensitivity of HeI singlet lines to the FeIV model atom in O stars
• Including All the Lines

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• Photoionization of Co${}^{+}$ and electron-impact excitation of Co${}^{2+}$ using the Dirac R-matrix method
• On the treatment of $\ell$-changing proton-hydrogen Rydberg atom collisions
• The Emission and Suppression of Line Features in Luminous Transients
• Investigation of [KSF2015] 1381-19L, a WC9-type star in the high extinction Galactic region