English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

In the present paper, we model the wind of solar analogues at different agesto investigate the evolution of the solar wind. Recently, it has been suggestedthat winds of solar type stars might undergo a change in properties at oldages, whereby stars older than the Sun would be less efficient in carrying awayangular momentum than what was traditionally believed. Adding to this, recentobservations suggest that old solar-type stars show a break in coronalproperties, with a steeper decay in X-ray luminosities and temperatures atolder ages. We use these X-ray observations to constrain the thermalacceleration of winds of solar analogues. Our sample is based on the stars fromthe `Sun in time' project with ages between 120-7000 Myr. The break in X-rayproperties leads to a break in wind mass-loss rates ($\dot{M}$) at roughly 2Gyr, with $\dot{M}$ (t < 2 Gyr) $\propto t^{-0.74}$ and $\dot{M}$ (t > 2 Gyr)$\propto$ $t^{-3.9}$. This steep decay in $\dot{M}$ at older ages could be thereason why older stars are less efficient at carrying away angular momentum,which would explain the anomalously rapid rotation observed in older stars. Wealso show that none of the stars in our sample would have winds dense enough toproduce thermal emission above 1-2 GHz, explaining why their radio emissionshave not yet been detected. Combining our models with dynamo evolution modelsfor the magnetic field of the Earth we find that, at early ages ($\approx$100Myr) our Earth had a magnetosphere that was 3 or more times smaller than itscurrent size.

The solar wind in time: a change in the behaviour of older winds?