Observations of type IA supernova 2014j with flitecam on Sofia

Abstract

We present medium-resolution near-infrared (NIR) spectra, covering 1.1-3.4 μm, of the normal Type Ia supernova (SN Ia) SN 2014J in M82 obtained with the FLITECAM instrument on board Stratospheric Observatory for Infrared Astronomy (SOFIA) between 17 and 26 days after maximum B light. Our 2.8-3.4 μm spectra may be the first ∼3 μm spectra of an SN Ia ever published. The spectra spanning the 1.5-2.7 μm range are characterized by a strong emission feature at ∼1.77 μm with a FWHM of ∼11,000-13,000 km s-1. We compare the observed FLITECAM spectra to the recent non-LTE delayed detonation models of Dessart et al. and find that the models agree with the spectra remarkably well in the 1.5-2.7 μm wavelength range. Based on this comparison we identify the ∼1.77 μm emission peak as a blend of permitted lines of Co ii. Other features seen in the 2.0-2.5 μm spectra are also identified as emission from permitted transitions of Co ii. However, the models are not as successful at reproducing the spectra in the 1.1-1.4 μm range or between 2.8 and 3.4 μm. These observations demonstrate the promise of SOFIA, which allows access to wavelength regions inaccessible from the ground, and serve to draw attention to the usefulness of the regions between the standard ground-based NIR passbands for constraining SN models.