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) Planet-hosting wide binaries
HD 189733 Ab B CoRoT-2 Ab B 55 Cnc Abcde B
. , ) p 4 e r 1 p 0
2 n i (
. . l l a a upsilon And Ab B tau Boo Ab B HAT-P-20 Ab B t t e e
r r e e g g e e a a h h n n e e p p p p o o P P HD 109749 Ab B HD 46375 Ab B HD 178911 A Bb Planet-hosting wide binaries strong tidal interaction
weak tidal interaction
Planet-hosting wide binaries
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Planet-hosting wide binaries
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Planet-hosting wide binaries
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Planet-hosting wide binaries
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Planet-hosting wide binaries
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Several over-active systems
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Poppenhaeger et al. (2014), Poppenhaeger et al. to be submitted 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