Insights into planetary systems through JWST imaging of debris disks Mark Wyatt Institute of Astronomy, Cambridge What is a debris disk? Infrared emission of nearby main sequence Imaging shows emission from stars above photosphere: e.g., Fomalhaut 130AU dust ring (Acke et al. 2012) 70K Flux density (Jy) Flux Wavelength (µm) DETAILED DISCOVERY and STATISTICS CHARACTERISATION Debris disks are components of planetary systems Planetesimal Kuiper belt belts are analogous to the Kuiper belt and Asteroid Asteroid belt belt Disk structure is indicative of the architecture of the planetary system Planets inevitably affect disk structure spiral 50 stirring Planet: 1Mjup 5AU e=0.1 0 I=5o Disk: 20-60AU AU offset -50 Time: warp 100Myr after formation -50 0 50 100 AU Matthews et al. PPVI JWST contribution to debris disk science (1) Scattered light coronagraphic imaging of structure in extrasolar Kuiper belts (2) Mid-IR (coronagraphic) imaging of structure in extrasolar Kuiper belts and mid-planetary system planetesimal belts (3) TBD… (1) Scattered light coronagraphic imaging of structure in extrasolar Kuiper belts HST images show detailed structure of Fomalhaut’s disk (Kalas et al. 2013): eccentricity, sharp inner edge, azimuthal gap Also a planet (Fom-b) orbiting not along the inner edge, but on highly elliptical orbit Debris disks are planet signposts, and provide constraints on planets Debris disk coherence sets tight Best explanation: ~MNeptune and constraints on the Fom-b: either it’s very a cloud of irregular satellites low mass, or was put on its belt-crossing around it (Kennedy & Wyatt 2011; Tamayo 2014; Kenyon & Bromley 2015) orbit very recently (Beust et al. 2013) Planet 0 Myr 5 Myr Planetaryradii Circumplanetary dust Planetary radii NIRCAM imaging of disk structure Will improve on what can currently be done from the ground and with HST Double ring in Brightness Spiral in HD141569 HD92945 asymmetry in HD15115 (Clampin et al. 2003) (Rodigas et al. 2013) (Golimowski et al. 2011) Warp in β Pic Fast moving features in AU Mic Boccaletti et al. (2015) (Golimowski et al. 2006) ● Deeper means fainter (less extreme, older) disks can be imaged? ● Multiwavelength information ● Simultaneous imaging of planets interacting with disks (2) Mid-IR imaging of structure in extrasolar Kuiper belts Golimowski et al. (2006); Scattered light warp at Lagrange et al. (2010) 80AU in β Pic explained by a misaligned ~9MJupiter planet at 8AU 2003 2010 (Augereau et al. 2001; Lagrange et al. 2010) Telesco et al. (2005) Mid-IR (8-18µm) images show a clump at 52AU in the SW But that clump is absent at 25µm Multi-wavelength imaging is key to interpretation Sub-mm Mid-IR (small Scattered light and CO (short-lived continuum but bound short mid-IR (small gas) (planetesimals) dust) unbound dust) 4 4 Observed 2 2 β Pic 0 0 Dec offset (") Dec offset (") -2 -2 -4 -4 4 2 0 -2 -4 4600 2 0 -2 -4 RA offset (") RA offset (") 200 200 200 400 100 100 100 Model 200 0 0 0 0 AU AU AU (face-on) AU -200 -100 -100 -100 -400 -200 -200 -200 -600 200 100 0 -100 -200 200 100 0 -100 -200 200 100 0 -100 -200 AU AU AU 600 400 200 0 -200 -400 -600 AU Clump (and different structure at different wavelengths) explained by a >MNeptune planet which migrated out to ~60AU trapping planetesimals into its mean motion resonances (Wyatt 2006) Ground-based mid-IR imaging is hard (sensitivity) Most of the A star debris disks that can be resolved in the mid-IR from the ground have been imaged (Smith & Wyatt 2010) Space-based imaging also hard (resolution) Spitzer imaged a few disks at And Fomalhaut 24µm like Vega (Su et al. 2005) (Stapelfeldt 2004) But relatively few disks were resolved Imaging with MIRI will be very productive Almost all of the known debris disks around A stars will be imageable with MIRI (Smith & Wyatt 2010) Example: imaging of giant impact debris Simulated MIRI images of debris from Ceres-sized break-up at 6au 0.01-0.1Myr post-impact (Kral et al. 2015) Debris is asymmetric, since all orbits Lyot mask obscures impact site, pass through collision point, easily but reveals asymmetry on detectable by MIRI at 11-15µm opposite side from small grains Mid-planetary system dust Debris disk holes not always empty (Su et al. 2013); e.g., η Corvi (right) is a 1Gyr F star with 150au Kuiper belt (Wyatt et al. 2005; Duchêne et al., in prep) and 1.5au dust (Smith, Wyatt & Haniff 2009) Origin of hot dust could be in mid-planetary N E ALMA 870µm system belts (like the 100 asteroid belt), but could Panic et au 0 be cometary, and al. in prep regardless is telling of -100 planetary system -200 -100 0 100 200 au Dust at intermediate distances, if present, is most readily imaged at 10-25µm 3.1 Evolution of circumstellar gas 103 Searches for CO HD100546 show usually not 102 detected in debris 101 η Tel (CII) disks suggesting HD21997 ) 49 Cet significant depletion -1 HD141569 100 in gas (as well as HR4796A HD32297 (NaI+CII) dust) after proto- (Jy km s 10-1 β Pic planetary disk HD172555 (CaII+OI) CO, 100 pc dispersal S 10-2 Dent+ 2005 (JCMT) Panic+ 2010 (APEX) But there are some Moor+ 2011 (APEX) debris disks with CO 10-3 Dent+ 2014 (ALMA) Hales+ 2014 (APEX+ASTE) Fomalhaut detections, others Matra+ in2015 prep. (ALMA) 10-4 with CII or OI 10-1 100 101 102 103 104 Age (Myr) Origin of DD gas: remnant of protoplanetary disk or secondary (break-up of icy planetesimals)? 3.1 JWST: Imaging gas in debris disks ALMA imaging of CO in β Pic shows gas is Mapping of gas within debris created by break-up of icy comets (Dent et al. 2014) disks is already possible: 40 CO (J=3-2) 20 VLT/FLAMES/GIRAFFE 0 IFU of metallic ions in β Pic -20 (Nilsson et al. 2012) Height (AU) -40 -150 -100 -50 0 50 100 150 Distance along midplaneVelocity (AU) information allows deprojection of gas distribution Searches for OH as photodissociation product of water, look for H2O lines, H2 to see remnant of protoplanetary disk? Fe, S, Si? 3.2 Exocomets KIC8462852 shows aperiodic dips as large as 20% loss in flux best explained by exocomet family (Boyajian et al. 2015) JWST can detect and characterise the thermal emission expected from such comets What will the field be like in 3 years? • Already have all far-IR info from Spitzer and Herschel • ALMA follow-up imaging of some targets will be complete • ALMA discoveries of gas will have grown • Lots of SPHERE/GPI disks imaged, increasing the number of scattered light images and extrasolar planets Conclusions Debris disks provide unique constraints on both the current architecture of extrasolar planetary systems and their formation and evolution JWST will: • image extrasolar Kuiper belts and perturbing planets in scattered light • image extrasolar Kuiper belts and mid-planetary system belts in mid-IR • search for gas/exocomets in debris disks? .