The evolution of the solar wind

Abstract

How has the solar wind evolved to reach what it is today? In this review, I discuss the long-term evolution of the solar wind, including the evolution of observed properties that are intimately linked to the solar wind: rotation, magnetism and activity. Given that we cannot access data from the solar wind 4 billion years ago, this review relies on stellar data, in an effort to better place the Sun and the solar wind in a stellar context. I overview some clever detection methods of winds of solar-like stars, and derive from these an observed evolutionary sequence of solar wind mass-loss rates. I then link these observational properties (including, rotation, magnetism and activity) with stellar wind models. I conclude this review then by discussing implications of the evolution of the solar wind on the evolving Earth and other solar system planets. I argue that studying exoplanetary systems could open up new avenues for progress to be made in our understanding of the evolution of the solar wind.

Atmospheric mass-loss and stellar wind effects in young and old systems – I. Comparative 3D study of TOI-942 and TOI-421 systems

“…To date, there is a number of studies dedicated to the 3D interaction between planetary outflows and stellar winds (Bisikalo et al 2013;Schneiter et al 2016;Carroll-Nellenback et al 2017;Villarreal D'Angelo et al 2018, 2021McCann et al 2019;Khodachenko et al 2019;Esquivel et al 2019;Debrecht et al 2020;Carolan et al 2021a,b). These models can be grouped into local planetcentered models where the stellar wind is set as an external boundary condition (as ours) and global models that include both the star and the planet in the computation domain (see Carroll-Nellenback et al 2017;Villarreal D'Angelo et al 2018, 2021Esquivel et al 2019). The benefit of the latter approach is that it can account for effects non-accessible in the planet-centered frameworks, such as the formation of a disk around the star (Debrecht et al 2018).…”

“…For evolved mainsequence stars, such as the Sun, the speed of the stellar wind reaches a velocity of a few hundred km s −1 at the distance of 1 AU (see, e.g., Gosling et al 1976;Zieger & Mursula 1998;Abbo et al 2016). Young stars are characterized by higher coronal activity and higher mass loss rates (Vidotto 2021), and their winds, therefore, are expected to be denser, hotter, and faster compare to the Gyr-old stars.…”

“…Furthermore, Carolan et al (2021a) have demonstrated that due to the confinement of the atmosphere by strong stellar wind these signatures can be reduced, or even fully "erased", for planets in sub-Neptune/hot-Jupiter mass ranges. In more moderate cases, the absorption profiles become asymmetric with dominant blue-wing absorption (towards the observer) due to the atmosphere being pressed by the stellar wind in the direction trailing the orbit (see, e.g., Villarreal D'Angelo et al 2018, 2021.…”

The winds of young Solar-type stars in Coma Berenices and Hercules-Lyra

“…reproduces Solar wind conditions. A corrective scaling pΠ {𝐵q " pΠ {𝐵q d p𝑅{𝑅 d q 0.3 as suggested by Sokolov et al (2013) has previously been employed by Garraffo et al (2016); Dong et al (2018) in M-dwarf wind modelling, see also Vidotto (2021). That corrective scaling is not applied as it would change the value of pΠ {𝐵q by less than 10 % for the stellar radii in this study; we find that the two smallest 𝑅 stars 5 AV 523 and A DX Leo give wind mass loss values of "80 % of their unscaled values and similar or lower variation for the other parameters of interest.…”

“…The total wind mass loss 9 𝑀 and total wind angular momentum loss 9 𝐽 are two of the most studied quantities that may be derived from stellar and Solar wind maps. Mass loss values are difficult to constrain observationally, see the reviews of Wood (2004) and (Vidotto 2018(Vidotto , 2021.…”