Open AccessThe origin of the high‐velocity circumstellar gas around SN 1998S
Author(s) -
Chugai N.N.,
Blinnikov S.I.,
Fassia A.,
Lundqvist P.,
Meikle W.P.S.,
Sorokina E.I.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05086.x
Subject(s) - physics , photosphere , ejecta , astrophysics , supernova , balmer series , shock wave , shock (circulatory) , line (geometry) , particle acceleration , spectral line , astronomy , acceleration , emission spectrum , mechanics , classical mechanics , medicine , geometry , mathematics
Modelling of high‐resolution Balmer line profiles in the early‐time spectra of SN 1998S shows that the inferred fast (≈400 km s −1 ) circumstellar (CS) gas on days 23 and 42 post‐explosion is confined to a narrow, negative velocity gradient shell just above the photosphere. This gas may be identified with a slow (v<40 km s −1 ) progenitor wind accelerated at the ejecta–wind interface. In this scenario, the photosphere coincides with a cool dense shell formed in the reverse shock. Acceleration by radiation from the supernova or by a shock‐accelerated relativistic particle precursor are both possible explanations for the observed fast CS gas. An alternative, equally plausible scenario is that the fast CS gas is accelerated within shocked clouds engulfed by the outer shock, as it propagates through the intercloud wind.