How Stars and Planets Interact: a Look Through the High-Energy Window Katja Poppenhaeger Queen's University Belfast → University Potsdam / Leibniz Institute for Astrophysics AIP Star-exoplanet systems Star-exoplanet systems Star-exoplanet systems Star-exoplanet systems Star-exoplanet systems tidal interaction Star-exoplanet systems tidal interaction star spinning faster → higher Lx Star-exoplanet systems magnetic interaction Star-exoplanet systems magnetic interaction stellar flares, hot spots Star-exoplanet systems planetary effects Star-exoplanet systems planetary effects atmospheric blow-off Star-exoplanet systems planetary effects aurorae Star-exoplanet systems planetary effects hot planet dynamos Star-exoplanet systems tidal interaction star spinning faster → higher Lx Tidal interaction Mathis & Remus (2013) see also Lanza & Mathis (2016) How stars age on the main sequence loss of angular momentum through stellar wind (“magnetic braking”) Bias-controlled sample: planet-hosting wide binaries image credit: Mugrauer et al. (2007); see also Raghavan (2006) upsilon And Ab B And upsilon HD 189733 Ab B HD 189733 HD 46375 Ab B Ab 46375 HD Planet-hosting widebinaries HD 178911 A Bb A 178911 HD tau Boo Ab B Boo tau CoRoT-2 Ab B CoRoT-2 55 Cnc Abcde B Abcde Cnc 55 HAT-P-20 Ab Ab B HAT-P-20 HD 109749 Ab B HD 109749 Poppenhaeger et al. (2014), Poppenhaeger et al. in prep. Planet-hosting wide binaries strong tidal interaction weak tidal interaction more active Planet-hosting widebinaries more active Planet-hosting widebinaries more active Planet-hosting widebinaries more active Planet-hosting widebinaries more active Planet-hosting widebinaries more active Several over-active systems Poppenhaeger et al. to be submitted to be et al. Poppenhaeger (2014), et al. Poppenhaeger Star-exoplanet systems magnetic interaction stellar flares, hot spots Planet-induced activity? HD 179949 upsilon And P = 4.6 d Porb = 3.1 d orb P = 9.5 d Prot = 11 d rot Shkolnik et al. (2005, 2008) Planet-induced activity? courtesy of O. Cohen; see also Pillitteri et al. 2014 Planet-induced activity? courtesy of O. Cohen; see also Pillitteri et al. 2014 Planet-induced activity? courtesy of O. Cohen; see also Pillitteri et al. 2014 Planet-induced activity? courtesy of O. Cohen; see also Pillitteri et al. 2014 Planet-induced activity? courtesy of O. Cohen; see also Pillitteri et al. 2014 Planet-induced activity? courtesy of O. Cohen; see also Pillitteri et al. 2014 Planets in eccentric orbits 2 stars: Flares from colliding magnetospheres: Getman et al. (2011); but: Getman et al. (2016) Planets in eccentric orbits star + planet: periastron Planets in eccentric orbits Maggio et al. (2015) Planets in eccentric orbits star + planet: periastron -> flare triggering This should depend on the planet's magnetosphere! Star-exoplanet systems planetary effects atmospheric blow-off Atmospheres and high-energy photons image credit: NASA Extended atmospheres in UV/X-ray Hot Neptune GJ 436 b: comet-like tail Kulow et al. (2014), Ehrenreich et al. (2015) X-ray transits: extended atmospheres HD 189733 b Poppenhaeger et al. (2013) X-ray transits: extended atmospheres HD 189733 b Poppenhaeger et al. (2013) X-ray transits: extended atmospheres HD 189733 b Poppenhaeger et al. (2013) Extended atmospheres in UV/X-ray Different windows to exoplanetary atmospheres: Hydrogen Ly-alpha (UV) Soft X-rays probe atomic hydrogen probe heavier elements (C, N, O, Ne, ...) Survival of exoplanet atmospheres Erosion by high-energy irradiation: time-limited because cool stars spin down. Strong spin-down/X-ray dimming at old ages: slope of -2.8 instead of canonical -1 for younger stars! Booth, Poppenhaeger et al. (2017) Star-exoplanet systems planetary effects hot planet dynamos The hottest known planet: KELT-9b A0 type host star, 206 pc young-ish system (300 Myr) hot Jupiter in 1.5 day orbit equilibrium temperature 4000K →hotter than most stars! Gaudi et al. (2017) Strong magnetic fields for very hot exoplanets Simulations: strongly irradiated Hot Jupiters can have strong magnetic fields powered through enhanced dynamo processes Rogers & McElwaine (2017) Yadav & Thorngren (2017) Strong magnetic fields for very hot exoplanets Jupiter: ~5 G ! Simulations: strongly irradiated Hot Jupiters can have strong magnetic fields powered through enhanced dynamo processes Rogers & McElwaine (2017) Yadav & Thorngren (2017) X-ray detection experiment for KELT-9b 50 ks XMM exposure (DDT) Poppenhaeger, Yadav, Guenther, Pillitteri, Schmitt, Wolk X-ray detection experiment for KELT-9b Star: X-ray dark (non-chemically peculiar A star) upper limit planet: 27 LX < 7 x 10 erg/s i.e. X-ray dimmer than cool stars at same age Can test for surface fluxes similar to cool stars with Athena! Poppenhaeger, Yadav, Guenther, Pillitteri, Schmitt, Wolk Star-exoplanet systems tidal interaction probably yes Star-exoplanet systems magnetic interaction probably yes stellar flares, hot spots Star-exoplanet systems planetary effects common in short-period systems atmospheric blow-off Star-exoplanet systems planetary effects testable with next-gen X-ray telescopes hot planet dynamos Extra slides Young M dwarf & Hot Jupiter (?) PTFO 8-8695, a young (3 Myr) M dwarf in the 25 Ori association Young M dwarf & Hot Jupiter (?) Transit light curve of varying depth & duration & hundreds of more transits by now, van Eyken et al. (2012) Light curve dips of young M dwarfs Barnes et al. (2013) Light curve dips of young M dwarfs Stauffer et al. 2017 The system in X-ray observations 2009 Poppenhaeger et al. in prep. The system in X-ray observations 2017 Poppenhaeger et al. in prep. Light curve dips of young M dwarfs Stauffer et al. 2017 Light curve dips of young M dwarfs Dips tied to stellar rotation period - planet at co-rotation radius, triggering flares? - ejected coronal material (like slingshot prominences)? Stauffer et al. 2017.