We present three new spectra of the nearby Type Ia supernova (SN Ia) 2011fe covering ≈480–850 days after maximum light and show that the ejecta undergoes a rapid ionization shift at ∼500 days after explosion. The prominent Fe iii emission lines at ≈4600 Å are replaced with Fe i +Fe ii blends at ∼4400 Å and ∼5400 Å. The ≈7300 Å feature, which is produced by [Fe ii ]+[Ni ii ] at ≲400 days after explosion, is replaced by broad (≈±15,000 km s −1 ) symmetric [Ca ii ] emission. Models predict this ionization transition occurring ∼100 days later than what is observed, which we attribute to clumping in the ejecta. Finally, we use the nebular-phase spectra to test several proposed progenitor scenarios for SN 2011fe. Nondetections of H and He exclude nearby nondegenerate companions, [O i ] nondetections disfavor the violent merger of two white dwarfs, and the symmetric emission-line profiles favor a symmetric explosion.
Tucker, M. A., et al. "A Rapid Ionization Change in the Nebular-phase Spectra of the Type Ia SN 2011fe." The Astrophysical Journal. Letters, vol. 926, no. 2, Feb. 2022. https://doi.org/10.3847/2041-8213/ac4fbd
Tucker, M. A., Ashall, C., Shappee, B. J., Kochanek, C. S., Stanek, K. Z., & Garnavich, P. (2022). A Rapid Ionization Change in the Nebular-phase Spectra of the Type Ia SN 2011fe. The Astrophysical Journal. Letters, 926(2). https://doi.org/10.3847/2041-8213/ac4fbd
Tucker, M. A., Ashall, C., Shappee, B. J., et al., "A Rapid Ionization Change in the Nebular-phase Spectra of the Type Ia SN 2011fe," The Astrophysical Journal. Letters 926, no. 2 (2022), https://doi.org/10.3847/2041-8213/ac4fbd
@article{osti_1845928,
author = {Tucker, M. A. and Ashall, C. and Shappee, B. J. and Kochanek, C. S. and Stanek, K. Z. and Garnavich, P.},
title = {A Rapid Ionization Change in the Nebular-phase Spectra of the Type Ia SN 2011fe},
annote = {Abstract We present three new spectra of the nearby Type Ia supernova (SN Ia) 2011fe covering ≈480–850 days after maximum light and show that the ejecta undergoes a rapid ionization shift at ∼500 days after explosion. The prominent Fe iii emission lines at ≈4600 Å are replaced with Fe i +Fe ii blends at ∼4400 Å and ∼5400 Å. The ≈7300 Å feature, which is produced by [Fe ii ]+[Ni ii ] at ≲400 days after explosion, is replaced by broad (≈±15,000 km s −1 ) symmetric [Ca ii ] emission. Models predict this ionization transition occurring ∼100 days later than what is observed, which we attribute to clumping in the ejecta. Finally, we use the nebular-phase spectra to test several proposed progenitor scenarios for SN 2011fe. Nondetections of H and He exclude nearby nondegenerate companions, [O i ] nondetections disfavor the violent merger of two white dwarfs, and the symmetric emission-line profiles favor a symmetric explosion. },
doi = {10.3847/2041-8213/ac4fbd},
url = {https://www.osti.gov/biblio/1845928},
journal = {The Astrophysical Journal. Letters},
issn = {ISSN 2041-8205},
number = {2},
volume = {926},
place = {United States},
publisher = {American Astronomical Society},
year = {2022},
month = {02}}