Debris Disks with ALMA and JWST A Multi-Wavelength View of Planet - PowerPoint PPT Presentation

Debris Disks with ALMA and JWST – A Multi-Wavelength View of Planet Formation Meredith A. MacGregor NSF Postdoctoral Fellow, Carnegie DTM January 2020 à Assistant Professor, University of Colorado Boulder SF@JWST – Courmayeur, Italy August 26—30, 2019

MacGregor The Formation of Planetary Systems molecular cloud 0 Myr Star Formation main sequence star + planets (?) + debris disk (?) > 10 Myr pre-main sequence star + protoplanetary disk Planet Formation 1-10 Myr

MacGregor Protoplanetary Disks evolve into Debris Disks Pre-main sequence stars Main sequence stars Rich in primordial gas Gas from cometary collisions < 10 Myr < Giant planet formation? Terrestrial planet formation? Reservoirs for planet formation Fossil record of planet formation Credit: Andrews+ (2019), Kennedy+ (2018), MacGregor+ (2017, 2019), Marino+ (2016, 2018, 2019)

MacGregor Debris disks are observed at optical through radio wavelengths First debris disks detected as ‘excess’ infrared emission by IRAS (Aumann+ 1984) SPHERE/VLT 30 ALMA 70 µ m Herschel VLA 20 Offset / arcsec 10 0 -10 -20 -30 30 20 10 0 -10 -20 30 Offset / arcsec Credit: Boccaletti+ (2015), Matthews+ (2015), MacGregor+ (2013), MacGregor+ (2016a) optical through near-IR = scattered light mid-IR through radio = thermal emission from Herschel DUNES

MacGregor Millimeter interferometry has been especially important Millimeter Interferometry Few effects from stellar High resolution for resolving radiation and winds distant sources Reliably traces underlying Good at picking out detailed planetesimal belt structure structure (rings, clumps, etc.) from Herschel DUNES

MacGregor The Atacama Large Millimeter/submillimeter Array (ALMA) has revolutionized our understanding of circumstellar disk structure. → Baselines that span up to 16 km for a resolution of ~0.01’’

MacGregor Before ALMA, (sub)millimeter images had limited resolution Epsilon Eridani HD 95086 Tau Ceti Beta Pictoris HR 4796A HD 107146 AU Mic 30 70 µ m 20 Offset / arcsec 10 0 -10 -20 -30 30 20 10 0 -10 -20 30 Offset / arcsec Greaves+ (2014) Su+ (2015) Lawler+ (2014) Vandenbussche+ (2010) Hughes+ (2011) Matthews+ (2015) Koerner+ (1998) 49 Ceti HD 181327 HD 21997 Fomalhaut HD 10647 (q1 Eri) Eta Corvi HR 8799 Roberge+ (2013) Liseau+ (2010) Matthews+ (2014) Lebreton+ (2012) Moor+ (2015) Acke+ (2012) Lebreton+ (2016) HD 115617 (61 Vir) HD 207129 HD 139664 HD 38858 HD 15115 HD 61005 HD 32297 Ricarte+ (2013) Wyatt+ (2012) Herschel DEBRIS Lohne+ (2012) Kennedy+ (2015) MacGregor+ (2015a) Maness+ (2008) Steele+ (2016)

MacGregor ALMA has revealed a wealth of detailed substructure Epsilon Eridani HD 95086 Tau Ceti Beta Pictoris HR 4796A HD 107146 AU Mic Ricci+ (2015) MacGregor+ (in Su, MacGregor+ (2017) MacGregor+ (2016) Dent+ (2014) Kennedy+ (2018) MacGregor+ (2013) Marino+ prep.) (2018) 49 Ceti HD 181327 HD 21997 Fomalhaut HD 10647 (q1 Eri) Eta Corvi HR 8799 Booth+ (2016) Lieman-Sifry+ (2015) MacGregor+, Wyatt+ Marino+ (2016) Marino+ (2016) Moor+ (2013) MacGregor+ (2017b) Wilner, Hughes+ (2017) (in prep.) MacGregor+ (in MacGregor+ (2018) prep.) HD 115617 (61 Vir) HD 207129 HD 139664 HD 38858 HD 15115 HD 61005 HD 32297 Marino+ (2017) MacGregor+ (in MacGregor+ (in MacGregor+ (in MacGregor+ (in MacGregor+ (2018) MacGregor+ (2018) MacGregor+ (in prep.) prep.) prep.) prep.) prep.)

MacGregor Debris disks show structure due to the influence of planets Planets orbiting a star can gravitationally perturb an outer debris disk Can produce a variety of structures: warps, clumps, eccentricities, sharp edges, etc. Goal: Probe for wide separation planets using debris disk structure Kuiper Belt β Pictoris Warp Resonance Inclined orbit of ! Pictoris b Outward migration of Neptune Credit: Lagrange+ (2010), Jewitt+ (2009)

MacGregor Some disks appear eccentric and/or asymmetric Fomalhaut (440 Myr) First image from Hubble showed narrow belt with possible planet (Kalas et al. 2005, 2008, 2013) planet? disk center ALMA Cycle 3 project imaged disk with uniform sensitivity using a 7-pointing star mosaic (PI Paul Kalas, MacGregor et al. 2017, Matrà et al. 2017) Credit: Kalas+ (2013), MacGregor+ (2017)

MacGregor Model visibilities to derive disk structure and geometry F belt [mJy] = 24.7 ± 0.1 F star [mJy] = 0.75 ± 0.2 R belt [AU] = 136.3 ± 0.9 Δa [AU] = 13.5 ± 1.6 incl [°] = 65.6 ± 0.3 PA [°] = 337.9 ± 0.3 Steps to modeling an eccentric ring within an MCMC framework: e f = 0.12 ± 0.01 1. Compute true anomaly and orbital positions for ~10 4 particles e p = 0.06 ± 0.04 2. Create 2D histogram by binning at pixel resolution ω f [°] = 22.5 ± 4.3 3. Assume r -0.5 temperature profile, compute flux in each pixel 4. Account for disk geometry (inclination, PA), offsets, etc Credit: MacGregor+ (2017)

MacGregor New data could reveal properties of sculpting planet If disk is shaped by a planet, theory predicts azimuthal variations in the disk width New high resolution observations are able to resolve this variation Unpublished- don’t share! Credit: MacGregor+ (in prep.)

MacGregor Systems with both disks and planets are important test cases HR 8799 (30 Myr) System consists of: 1. Four 5—10 M Jup directly- imaged companions with projected separations of 14, 24, 38, and 68 AU 2. Warm inner belt (T ~ 150 K) 3. Cold outer belt (T ~ 35 K) 4. Extended halo of small grains out to ~1000 AU Credit: Jason Wang/ Christian Marois, Marley+ (2012), Wilner, MacGregor+ (2018)

MacGregor Disk geometry provides independent constraints on planet masses Translate constraint on disk inner edge into constraint on mass of Normalized Counts planet b (Pearce & Wyatt 2014): ✓ M pl ◆ 1 / 3 R in = a pl + 5 a pl 3 M ∗ R in = 104 +8 � 12 AU Adopting: a pl = 68 AU M pl [M Jup ] M ⇤ = 1 . 56 M � M pl = 5 . 8 +7 . 9 Yields: Provides an independent constraint − 3 . 1 M Jup on current mass estimates derived from evolutionary models Credit: Wilner, MacGregor+ (2018)

MacGregor Some systems have multiple Kuiper Belts Two rings separated by a gap at 59 AU HD 15115 (45 Myr) resolved by ALMA and possibly sculpted by a 0.2 M Jup planet ���� surface density ( Σ ) Gaussian Gap Model Data Model Residuals ���� ���� W gap ���� ���� Σ ∝ r x ���� ���� ���� ���� ∆ gap ���� �� �� �� �� �� �� ��� ���� ���� ���� R in R gap R out ���� distance ( r ) ���� ���� �� �� �� �� �� �� ��� �� �� �� �� �� �� ��� �� �� �� �� �� �� ��� R out R in R gap Credit: MacGregor+ (2019)

MacGregor Models predict the presence of currently unseen planets A handful of other debris disks show similar structure with multiple rings Implies population of ice giant REBOUND simulations reproduce structure planets currently undetected by other techniques Credit: MacGregor+ (2019), Marino+ (2018, 2019)

MacGregor A growing sample of debris disks now have gas detections HD 32297 (30 Myr) Dust and gas are co-located Secondary origin through collisions of cometary bodies Credit: MacGregor+ (2018)

MacGregor But, this is still a small (biased) sample of disks More gas (CO) has been detected in disks surrounding stars that are… Young (< 50 Myr old) More massive (A and B type) Credit: Hughes+ (2018)

MacGregor ALMA and JWST complement each other ALMA can… 1. Resolve structure in cold Kuiper Belt analogues 2. Detect molecular gas lines (e.g., CO isotopologues) planetesimal(belts( terrestrial(planets( giant(planets( disk(halo( Increasing…+ ~1500(K( ~300(K( ~150(K( ~50(K( distance( Terrestrial( Asteroidal( Kuiper(Belt( wavelength( Zone( Zone( Zone( Decreasing…+ ~10$μm$ ~24$μm$ >60$μm$ temperature( JWST$ ALMA$ JWST can… 1. Resolve structure in debris disks with multiple components 2. Probe grain composition (silicates) and atomic gas lines

MacGregor Debris disks are the fossil record of planet formation Planetesimals (and grains) are the leftover material from earlier planet formation The properties of planets reflect the properties of the material they formed from Goal: Use debris disks to constrain planet formation models (and compositions)

MacGregor Infrared observations can resolve structure in terrestrial zones ε Eridani (400 Myr) ALMA SOFIA Unresolved hot dust within 25 AU Marginally resolved by FORCAST at 35 µm from Herschel DUNES Credit: MacGregor+ (in prep.), Su+ (2017)

MacGregor Mid-IR observations probe composition of disk solids η Corvi (1.5 Gyr) Spitzer ALMA Unresolved hot dust at a few AU 10 μm silicate emission feature Credit: Marino+ (2016), Lisse+ (2012)

MacGregor The grain size distribution constrains collisional models Current measurements for both warm dust (blue) and cold dust (orange) favor shallower size distributions Most consistent with models of porous grains not dominated by material strength Hughes+ (2018) (sub)mm spectral index (orange): Matthews+ (2007, 2015), Donaldson+ (2013), Olofsson+ (2013), Marshall+ (2014, 2017), Pawellek+ (2014), MacGregor+ (2016) from Herschel DUNES spectral shape of the mid-infrared silicate features (blue): Mittal+ (2015)