| Autor: |
D. Farias, C. Gall, G. Narayan, S. Rest, V. A. Villar, C. R. Angus, K. Auchettl, K. W. Davis, R. J. Foley, A. Gagliano, J. Hjorth, L. Izzo, C. D. Kilpatrick, H. M. L. Perkins, E. Ramirez-Ruiz, C. L. Ransome, A. Sarangi, R. Yarza, D. A. Coulter, D. O. Jones, N. Khetan, A. Rest, M. R. Siebert, J. J. Swift, K. Taggart, S. Tinyanont, P. Wrubel, T. J. L. de Boer, K. E. Clever, A. Dhara, H. Gao, C.-C. Lin |
| Jazyk: |
angličtina |
| Rok vydání: |
2024 |
| Předmět: |
|
| Zdroj: |
The Astrophysical Journal, Vol 977, Iss 2, p 152 (2024) |
| Druh dokumentu: |
article |
| ISSN: |
1538-4357 |
| DOI: |
10.3847/1538-4357/ad8cd3 |
| Popis: |
We present a comprehensive analysis of the photometric and spectroscopic evolution of SN 2021foa, unique among the class of transitional supernovae for repeatedly changing its spectroscopic appearance from hydrogen-to-helium-to-hydrogen dominated (IIn-to-Ibn-to-IIn) within 50 days past peak brightness. The spectra exhibit multiple narrow (≈300–600 km s ^−1 ) absorption lines of hydrogen, helium, calcium, and iron together with broad helium emission lines with a full width at half-maximum (FWHM) of ∼6000 km s ^−1 . For a steady, wind mass-loss regime, light-curve modeling results in an ejecta mass of ∼8 M _⊙ and circumstellar material (CSM) mass below 1 M _⊙ , and an ejecta velocity consistent with the FWHM of the broad helium lines. We obtain a mass-loss rate of ≈2 M _⊙ yr ^−1 . This mass-loss rate is 3 orders of magnitude larger than derived for normal Type II supernovae. We estimate that the bulk of the CSM of SN 2021foa must have been expelled within half a year, about 12 yr ago. Our analysis suggests that SN 2021foa had a helium-rich ejecta that swept up a dense shell of hydrogen-rich CSM shortly after explosion. At about 60 days past peak brightness, the photosphere recedes through the dense ejecta-CSM region, occulting much of the redshifted emission of the hydrogen and helium lines, which results in an observed blueshift (∼−3000 km s ^−1 ). Strong mass-loss activity prior to explosion, such as those seen in SN 2009ip-like objects and SN 2021foa as precursor emission, are the likely origin of a complex, multiple-shell CSM close to the progenitor star. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
|
