Close-in exoplanets: nature’s own Parker Solar Probe/Solar Orbiter

Stellar outflows, in the form of winds and transient (bursty) mass ejections, drive the “exo-space weather” around exoplanets. The exo-space weather can be substantially dif-ferent from that of solar system planets. In particular, close-in exoplanets experience much harsher stellar wind conditions than any planet in the solar system. These exoplanets are con-veniently located in the region where the stellar wind is still accelerating, and they are thus nature’s own “Parker Solar Probe” or “Solar Orbiter”. Here, we present our recent efforts towards characterising the stellar wind properties of GJ 436. UV spectroscopic transits and optical spectropolarimetric observations of the host star, together with 3D MHD wind models, have allowed us to probe the wind of the planet hosting star GJ 436. This has implications for constraining exo-space weather and also for understanding the wind driving of cool dwarf stars.