Origin of Broad He II 4686 Å Emission in Early Spectra of SNe IIP

We propose a model for the origin of the broad He II 4686 Å emission in early spectrum of SN 2020jfo (type IIP). The 4686 Å line is emitted presumably by dense fragments embedded into a hot gas of the forward shock wave. The fragments are produced as a result of a heavy braking of the dense low mass...

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Bibliographic Details
Published in:Astronomy letters 2023-11, Vol.49 (11), p.639-645
Main Authors: Chugai, N. N., Utrobin, V. P.
Format: Article
Language:English
Subjects:
Astronomy
Astrophysics and Astroparticles
Ejecta
Emission spectra
Emissions
Fragments
Helium
Helium isotopes
Hot electrons
Ionization
Luminosity
Observations and Techniques
Optical analysis
Optical thickness
Physics
Physics and Astronomy
Shock waves
Taylor instability
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Summary:We propose a model for the origin of the broad He II 4686 Å emission in early spectrum of SN 2020jfo (type IIP). The 4686 Å line is emitted presumably by dense fragments embedded into a hot gas of the forward shock wave. The fragments are produced as a result of a heavy braking of the dense low mass shell, at the ejecta boundary and a simultaneous Rayleigh–Taylor instability. The temperature of line-emitting fragments is K. Calculations of ionization and excitation of helium and hydrogen accounts for the He II 4686 Å luminosity, large flux ratio of He II 4686 Å/H and a significant optical depth of 4686 Å line. We demonstrate that fragments heating by hot electrons of the forward shock compensates cooling via He II 304 Å emission.
ISSN:1063-7737
1562-6873
DOI:10.1134/S1063773723350013