Parker's Solar Wind Model for a Polytropic Gas.

Area of Science:

• * Solar physics and plasma astrophysics.
• * Magnetohydrodynamics and fluid dynamics.

Background:

• * The Parker solar wind model provides a foundational understanding of the solar wind.
• * Previous models often assumed isothermal conditions, which are less realistic for the solar corona.

Purpose of the Study:

• * To extend Parker's hydrodynamic isothermal solar wind model to a more realistic polytropic gas flow.
• * To investigate the effects of variable coronal heating on solar wind dynamics.

Main Methods:

• * Developed a compatible theoretical formulation for polytropic gas flow.
• * Employed detailed numerical simulations and systematic asymptotic theoretical analyses.
• * Incorporated variable extended heating of the solar corona.

Main Results:

• * Polytropic conditions significantly enhance the conversion of thermal energy into kinetic energy in the solar wind.
• * The enhanced energy conversion leads to increased solar wind acceleration.
• * Demonstrated a quicker loss of the Sun's angular momentum.

Conclusions:

• * The polytropic solar wind model provides a more accurate representation of the solar wind's behavior.
• * Coronal heating plays a crucial role in solar wind acceleration and angular momentum loss.
• * This model has implications for understanding stellar evolution and space weather.