The general applicability of self-similar solutions for thermal disc winds
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Authors
Sellek, Andrew D
Clarke, Cathie J
Booth, Richard A
Publication Date
2021Journal Title
Monthly Notices of the Royal Astronomical Society
ISSN
0035-8711
Publisher
Royal Astronomical Society
Volume
506
Issue
1
Pages
1-20
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Sellek, A. D., Clarke, C. J., & Booth, R. A. (2021). The general applicability of self-similar solutions for thermal disc winds. Monthly Notices of the Royal Astronomical Society, 506 (1), 1-20. https://doi.org/10.1093/mnras/stab1693
Abstract
Thermal disc winds occur in many contexts and may be particularly important to the secular evolution and dispersal of protoplanetary discs heated by high energy radiation from their central star. In this paper, we generalize previous models of self-similar thermal winds – which have self-consistent morphology and variation of flow variables – to the case of launch from an elevated base and to non-isothermal conditions. These solutions are well-reproduced by hydrodynamic simulations, in which, as in the case of isothermal winds launched from the midplane, we find winds launch at the maximum Mach number for which the streamline solutions extend to infinity without encountering a singularity. We explain this behaviour based on the fact that lower Mach number solutions do not fill the spatial domain. We also show that hydrodynamic simulations reflect the corresponding self-similar models across a range of conditions appropriate to photoevaporating protoplanetary discs, even when gravity, centrifugal forces, or changes in the density gradient mean the problem is not inherently scale free. Of all the parameters varied, the elevation of the wind base affected the launch velocity and flow morphology most strongly, with temperature gradients causing only minor differences. We explore how launching from an elevated base affects Ne II line profiles from winds, finding it increases (reduces) the full width at half maximum (FWHM) of the line at low (high) inclination to the line of sight compared with models launched from the disc midplane and thus weakens the dependence of the FWHM on inclination.
Keywords
accretion, accretion discs, hydrodynamics, protoplanetary discs, circumstellar matter
Sponsorship
Science and Technology Facilities Council (ST/S000623/1)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (823823)
Science and Technology Facilities Council (2277492)
Identifiers
External DOI: https://doi.org/10.1093/mnras/stab1693
This record's URL: https://www.repository.cam.ac.uk/handle/1810/329596
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