Habitability conditions and radio emission under calm and extreme space weather conditions around Proxima b Luis Pe˜na-Mo˜nino1, Miguel P´erez-Torres1, Jacobo Varela2 & Philippe Zarka3 1CSIC, Instituto de Astrof´ısica de Andaluc´ıa, Granada, Spain 2 Institute for Fusion Studies, University of Texas, Austin, TX 78712, United States, 3 LESIA, Observatoire de Paris, CNRS, PSL, SU/UPD, Meudon, France We acknowledge support through the Severo Ochoa grant CEX2021-001131-S and the Spanish National grant PID2020-117404GB-C21, funded by MCIU/AEI/ 10.13039/501100011033. LPM also acknowledges funding through grant PRE2020-095421, funded by MCIU/AEI/10.13039/501100011033 and by FSE Investing in your future. We also acknowledge the Spanish Prototype of an SRC (SPSRC) service and support financed by the Spanish Ministry of Science, Innovation and Universities, by the Regional Government of Andalusia, by the European Regional Development Funds and by the European Union NextGenerationEU/PRTR. MOTIVATION and GOALS MOTIVATION: • Habitability of exoplanets hosted by M dwarfs drastically depends on space weather. • Main players: ram and magnetic pressure of stellar wind + magnetic field of exoplanet. • Most likely drive radio emission arising close to the planet. GOALS: ▶Characterize habitability of the Earth-like planet Proxima b using 3D MHD simulations. ▷Calm and extreme space weather conditions. ▷Study role of stellar wind and planetary magnetic field, and their mutual orientation. ▶Determine radio emission arising from interaction between the stellar wind of Proxima and the magnetosphere of its planet Proxima b. MHD simulations - We used PLUTO: open 3D magneto-hydrodynamic code Main parameters of the PLUTO simulations Parameter Calm space weather Extreme space weather Sub-Alfv´enic Super-Alfv´enic CME scenario scenario scenario nsw [cm−3] 50 50 250 |vsw| [× 107 cm s−1] 5 10 25 BIMF [mG] 3.2 1.6 16 BProxima [G] 1200 600 600 BProxima b [G] 0.16−1.28 0.16−1.28 0.16−0.64 i [degrees] [0 - 90] [0 - 90] [0 - 45] ▶Sub-Alfv´enic scenario: ρsw v 2 sw < B2 sw/(8 π) ▶Super-Alfv´enic scenario: ρsw v 2 sw > B2 sw/(8 π) (Bow shock is formed) ▶Coronal mass ejection: Super-Alfv´enic scenario, with both ρsw v 2 sw and B2 sw/(8 π) increased enormously for short time period. HABITABILITY - Magnetopause standoff distance as a proxy for planetary shielding - Life not that harsh in Proxima b! 0 20 40 60 80 Tilt(deg) 1 2 3 4 5 Rmp/RProxima b Sub-Alfvénic Standoff distance 0 20 40 60 80 Tilt(deg) 1 2 3 4 5 6 7 Rmp/RProxima b Super-Alfvénic Standoff distance 0 10 20 30 40 Tilt(deg) 1.5 2.0 2.5 3.0 3.5 Rmp/RProxima b CME Standoff distance 0.64G 0.32G 0.16G 0.2 0.4 0.6 0.8 1.0 1.2 BProxima b(G) 4 5 6 7 8 9 Rmp/RProxima b Sub-Alfvénic Standoff distance 23 deg 0 deg 0.2 0.4 0.6 0.8 1.0 1.2 BProxima b(G) 6 7 8 9 10 11 12 Rmp/RProxima b Super-Alfvénic Standoff distance 23 deg 0 deg 0.2 0.3 0.4 0.5 0.6 BProxima b(G) 1.5 2.0 2.5 3.0 3.5 Rmp/RProxima b CME Standoff distance 45 deg 23 deg 0 deg • Shielding decreases as tilt increases (top). • Shielding increases as intrinsic planetary magnetic field increases (bottom panels). ▶Calm space weather: If magnetic field of Proxima b similar to that of the Earth (Bp = B⊕≈0.32 G) or larger, magnetopause standoff distance is large enough to shield the surface from the stellar wind for essentially any planetary tilt. ▶Coronal mass ejection (CME): Proxima b well shielded if magnetosphere Earth-like (Bp≈B⊕), or tilt smaller than that of Earth (i ≈i⊕≈23.5 deg). RADIO EMISSION - Detection prospects - Radio emission very high under Super-Alfv´en and CME-like conditions. Caveat: Low frequency 0 20 40 60 80 Tilt(deg) 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 P(1019erg/s) Sub-Alfvénic Magnetopause 0 20 40 60 80 Tilt(deg) 0.2 0.4 0.6 0.8 1.0 P(1019erg/s) Super-Alfvénic Magnetopause 0 20 40 60 80 Tilt(deg) 2.4 2.5 2.6 2.7 2.8 P(1019erg/s) Super-Alfvénic Bow Shock 0 10 20 30 40 Tilt(deg) 2 4 6 8 10 12 P(1021erg/s) CME Total Emission 0.64G 0.32G 0.16G 0.2 0.