Measuring the Solar Wind Angular Momentum Flux and Examining its Astrophysical Implications

The rate at which the solar wind extracts angular momentum from the Sun has been predicted by theoretical models for many decades, and yet we lack a conclusive measurement from in-situ spacecraft. Complementary information can be gained by studying other Sun-like stars, as it is known that the rotation rates of Sun-like stars follow a tight relationship with age. This allows us to evaluate their angular momentum-loss rates, without any knowledge of stellar wind physics, and produce an independent prediction of the current solar angular momentum-loss rate to compare with numerical models and in-situ observations of the solar wind. I will discuss recent measurements of the solar wind angular momentum flux from Parker Solar Probe, in context with previous observations and model predictions. I aim to show that by better understanding the current solar angular momentum-loss rate we can further constrain rotation-evolution models of low-mass stars, which will subsequently influence how magnetic activity evolves during the late main sequence. It is thought that in future, a combination of observations from Parker Solar Probe and Solar Orbiter may lead to a better evaluation the solar wind angular momentum-loss rate.