The Cygnus Loop: Shock Precursors and Electron–Ion Equilibration

Autor: John C. Raymond, Ji Yeon Seok, Bon-Chul Koo, Igor V. Chilingarian, Kirill Grishin, Nelson Caldwell, Min Xie, Robert Fesen
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: The Astrophysical Journal, Vol 954, Iss 1, p 34 (2023)
Druh dokumentu: article
ISSN: 1538-4357
DOI: 10.3847/1538-4357/ace692
Popis: The outermost edges of some supernova remnants are marked by filaments of pure Balmer line emission produced by nonradiative shock fronts. The H α profiles of these filaments provide the shock speed and electron–proton temperature ratio in the shock. We have used the Hectochelle multiobject spectrograph on the MMT telescope to observe nine positions along the eastern nonradiative filaments of the Cygnus Loop, thereby extending the studies of Medina et al. to lower shock speeds. We complement the spectra with images from 1993 to 2020 to measure proper motions to further constrain the parameters. We also present observations of the photoionization precursor to show that the gas is strongly heated, and that the H α emission from the precursor is dominated by collisional excitation rather than recombination.
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