Parker Winds Revisited: An Extension to Disk Winds

TL;DR

This paper extends the classical Parker wind model to include disk winds with two different geometries, highlighting that the self-similar geometry yields transonic solutions with distinct properties, relevant for modeling astrophysical disk winds.

Contribution

It introduces a new one-dimensional dynamical model for thermally driven disk winds with two geometries, emphasizing the importance of geometry choice for wind solution properties.

Findings

Geometry (ii) produces transonic solutions with different characteristics.

Self-similar geometry aligns more closely with numerical simulations.

Different geometries significantly affect wind dynamics.

Abstract

A simple, one-dimensional dynamical model of thermally driven disk winds, one in the spirit of the original Parker (1958) model, is presented. We consider two different axi-symmetric streamline geometries: geometry (i) is commonly used in kinematic models to compute synthetic spectra, while geometry (ii), which exhibits self-similarity and more closely resembles the geometry found by many numerical simulations of disk winds, is likely unused for this purpose - although it easily can be with existing kinematic models. We make the case that it should be, i.e. that geometry (ii) leads to transonic wind solutions with substantially different properties.