Neutral hydrogen compact absorption features in Cassiopeia A

Very Large Array (VLA) observations of the λ21 cm H I line towards Cassiopeia A (Cas A) have been performed. The velocity interval observed was from -38 to -362 (LSR) km s -1, with a resolution of 2.6 km s -1 and a beam size of 14.2″ × 11.4×. Opacity images show the presence of a number of small abs...

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Detalles Bibliográficos
Publicado: 1997
Materias:
ISM: individual: Cas A
ISM: supernova remnants
Stars: mass loss
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v317_n1_p203_Reynoso
http://hdl.handle.net/20.500.12110/paper_00046361_v317_n1_p203_Reynoso
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_00046361_v317_n1_p203_Reynoso
record_format dspace
spelling paper:paper_00046361_v317_n1_p203_Reynoso2023-06-08T14:27:19Z Neutral hydrogen compact absorption features in Cassiopeia A ISM: individual: Cas A ISM: supernova remnants Stars: mass loss Very Large Array (VLA) observations of the λ21 cm H I line towards Cassiopeia A (Cas A) have been performed. The velocity interval observed was from -38 to -362 (LSR) km s -1, with a resolution of 2.6 km s -1 and a beam size of 14.2″ × 11.4×. Opacity images show the presence of a number of small absorption H I features in the velocity interval -62 to -69 km s -1 (LSR) which, on the basis of several arguments, are postulated to be physically associated with Cas A. These cold H I knots have sizes of < 0.1 pc and show spatial substructure. Their velocities lie well outside the range of the intervening H I in the Perseus spiral arm, i.e. 0 to -55 km s -1. We demonstrate that the H I knots cannot be described as shocked interstellar cloudlets engulfed by the blast wave of the supernova remnant (SNR). Instead, we propose that these low velocity H I features are recombined wind driven clumps moving ahead of the supernova (SN) shock front. This hypothesis is supported by the ages derived for the knots, varying from 8 × 10 3 to 5 × 10 4 years, which implies that these features were originally accelerated during the Wolf-Rayet (WR) phase of the precursor star. 1997 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v317_n1_p203_Reynoso http://hdl.handle.net/20.500.12110/paper_00046361_v317_n1_p203_Reynoso
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic ISM: individual: Cas A
ISM: supernova remnants
Stars: mass loss
spellingShingle ISM: individual: Cas A
ISM: supernova remnants
Stars: mass loss
Neutral hydrogen compact absorption features in Cassiopeia A
topic_facet ISM: individual: Cas A
ISM: supernova remnants
Stars: mass loss
description Very Large Array (VLA) observations of the λ21 cm H I line towards Cassiopeia A (Cas A) have been performed. The velocity interval observed was from -38 to -362 (LSR) km s -1, with a resolution of 2.6 km s -1 and a beam size of 14.2″ × 11.4×. Opacity images show the presence of a number of small absorption H I features in the velocity interval -62 to -69 km s -1 (LSR) which, on the basis of several arguments, are postulated to be physically associated with Cas A. These cold H I knots have sizes of < 0.1 pc and show spatial substructure. Their velocities lie well outside the range of the intervening H I in the Perseus spiral arm, i.e. 0 to -55 km s -1. We demonstrate that the H I knots cannot be described as shocked interstellar cloudlets engulfed by the blast wave of the supernova remnant (SNR). Instead, we propose that these low velocity H I features are recombined wind driven clumps moving ahead of the supernova (SN) shock front. This hypothesis is supported by the ages derived for the knots, varying from 8 × 10 3 to 5 × 10 4 years, which implies that these features were originally accelerated during the Wolf-Rayet (WR) phase of the precursor star.
title Neutral hydrogen compact absorption features in Cassiopeia A
title_short Neutral hydrogen compact absorption features in Cassiopeia A
title_full Neutral hydrogen compact absorption features in Cassiopeia A
title_fullStr Neutral hydrogen compact absorption features in Cassiopeia A
title_full_unstemmed Neutral hydrogen compact absorption features in Cassiopeia A
title_sort neutral hydrogen compact absorption features in cassiopeia a
publishDate 1997
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v317_n1_p203_Reynoso
http://hdl.handle.net/20.500.12110/paper_00046361_v317_n1_p203_Reynoso
_version_ 1768543780443521024

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