Direct imaging of magma oceans in nearby young stellar associations Irene Bonati a,b, Tim Lichtenberg *,b, Dan J. Bower c, Sascha P. Quanz d, Miles L. Timpe e a Earth-Life Science Institute, Tokyo Institute of Technology, Japan b Institute of Geophysics, ETH Zürich, Switzerland c Center for Space and Habitability, University of Bern, Switzerland d Institute for Particle Physics and Astrophysics, ETH Zürich, Switzerland e Institute for Computational Science, University of Zürich, Switzerland * Presenter, now at: University of Oxford, United Kingdom irene.bonati@elsi.jp Ø Terrestrial planets are thought to undergo multiple magma ocean (MO) stages as a result of heat released during accretion (giant impacts), decay of short- lived radioisotopes and core formation. Ø Processes taking place during MO solidification set initial conditions for the planetary chemical structure, atmospheric composition, tectonic behavior, and habitability. Ø Next-generation direct imaging techniques could lead to the detection of such bodies, thus providing observational constraints for theoretical models and insights into the origin and diversification of planets in our Solar System and beyond. Ø We present a quantitative assessment of the observability of MO planets in nearby young stellar associations (SA) via future direct imaging facilities. II. 1D MO interior model2 I. N-body simulations1 à Occurrence rate of giant impacts (GI) during planet formation around A, G and M- stars à Surface temperature evolution after GIs à MO cooling through atmosphe- res of different emissivities (0 ≤ε ≤1) + steam atmosphere III. Telescope parameters: IWA + sensitivity • ELT ground telescope3 • Darwin-like space telescope4 à Explore optimal target selec- tion strategy à Constrain potential detectabi- lity of MO bodies IV. Probability of detecting at least one magma ocean planet in nearby stellar association5 References I. Timing and energy of giant impacts Ø Q > Qcrit à giant impact (GI) Ø Most GIs occur within the first 20 Myr of planet formation. Ø Post-impact bodies have radii 0.4 RE ≤R ≤1.1 RE. Ø Large planetary radius + low atmospheric emissivity à long MO lifetime Ø Evolution of steam atmosphere results in longer sustained MO Ø MO planets at angular separations θ ≥IWA à detectable II. Magma ocean (MO) cooling timescales III a. Detectability assessment: Inner Working Angle (IWA) III b. Detectability assessment: sensitivity IV. Probability of detecting MO planets IWA = 2λ D θ = tan−1 a d " #$ % &' [1] Grimm & Stadel, ApJ, 796, 23 (2014) [2] Bower et al., Phys. Earth Planet. Inter., 274,49-62 (2018) [3] Brandl et al., SPIE (2016) [4] Kammerer & Quanz, A&A, 204 (2018) [5] Mamajek, Proc. IAU Symp. (2015) + ref. therein Methodology Results References Conclusions Motivation Ø Target selection favoring young and close stellar associations containing a large amount of stars significantly increases the likelihood of detecting a MO event. Ø β Pictoris is the association best suited for potential future observations of collision-induced magma oceans, both with Darwin and ELT configurations. Ø Planetary flux evolution during lifetime of a MO Ø MO bodies having fluxes higher than telescope sensitivity thresholds à detectable Ø Observing mode: 30 h integration time for each star in a given stellar association θ = IWA Not detectable Detectable (inner working angle) 103 104 105 106 Time after GI (years) ! " ! " No. stars Association d (pc) Age (Myr) A G M β Pictoris 15 23 4 18 21 AB Doradus 20.1 150 0 23 8 β Tucanae 43 45 4 0 1 Tucana Horologium 48 45 2 27 5 Columba 50 42 2 37 1 TW Hydrae 53 10 2 0 33 Carina 65 45 0 22 0 32 Orionis 92 22 2 7 2 ⌘Chamaeleontis 94 11 1 0 11 χ1 For 99 50 2 0 0 PMO(λcen, d, ⌧⇤, ✏) = 1 − i=n⇤ Y i=1 1 −¯nGI,i · ∆tobs ¯R,i ∆tbin,i ! GI