On the Role of Chapman's Hydrostatic Solar Wind Mechanism in Parker's Hydrodynamic Solar Wind Model

TL;DR

This paper demonstrates that Chapman's hydrostatic mechanism plays a fundamental and global role in Parker's hydrodynamic solar wind model, with solar gravity effects effectively incorporated by Chapman's density profile across various models.

Contribution

It reveals that Chapman's hydrostatic mechanism is globally operative in Parker's model, unifying local and global perspectives of solar wind acceleration.

Findings

Chapman's hydrostatic density profile acts as a multiplicative factor in the model.

Solar gravity effects are encapsulated by Chapman's mechanism in Parker’s model.

The results hold for isothermal, polytropic, and multi-dimensional models.

Abstract

The global role of Chapman's hydrostatic solar wind mechanism in Parker's hydrodynamic solar wind model is investigated by using the de Laval nozzle analogy for the generation of flow acceleration in the latter model. The action of solar gravity in Parker's hydrodynamic solar wind model is shown to be geometrically equivalent to a renormalization of the actual wind channel area via a multiplicative factor, which is precisely Chapman's hydrostatic density profile. So, Chapman's hydrostatic solar wind mechanism appears to continue to be operative, on a global level (not just locally near the coronal base), in Parker's hydrodynamic solar wind model, the effects of solar gravity in Parker's hydrodynamic model being essentially encapsulated by Chapman's hydrostatic model. This result is shown to be robust by considering both isothermal gas and polytropic gas models as well as an n-dimensional (n= 1, 2, 3) underlying space for the solar wind.