Structure in Debris Disks

Jane Greaves SUPA, St Andrews resolved disk examples

Žaround 10 Myr beta Pic, HR 4796 A, HD 141569, AU Mic

Ža few 100 Myr Vega, Fomalhaut, HD 139664, HD 107146

Ž~1 Gyr onwards epsilon Eri, eta Crv, HD 53143, tau Ceti a rogues gallery

SCUBA images, 1998-2004 types of

Žfirst discoveries mainly A- luminous, short-lived Žemphasis now on F/G/K… potential Solar analogues past/future compared to Solar System at 4.5 Gyr ŽM stars, brown dwarfs? kinds of structure

Žextent Žcavity Žhalo Žoffset Žwarp Žspiral Žclump epochs

Ž10 Myr: end of 'proto-planetary disk' large, massive disks… still some gas… shaped by newly-formed giant planets? Ž100's Myr: completing terrestrial planets debris frequent… planet migration? … cataclysms? ŽGyr's: main for Solar analogues steady grinding … impacts on planets relevance to planets

Žzones where planetesimals grew

Žlate-growing Plutos?

Žperturbations: Neptunes and up

Žvery distant planets typical or atypical?

ŽNB, the resolved examples are at the large, bright end of the population 10" at 10 pc ↔ 100 AU many times dust ŽMANY more unresolved examples… and NO debris seen for most stars Ž hence, potentially odd view of ease of forming distant planets, etc. HD 30495 with SCUBA G3 V star at 13 pc ~10 Myr epoch

Žwell known A-stars beta Pic HD 141569 HR 4796 A

ŽAU Mic M0 star in beta Pic association beta Pictoris Žhuge disk: >1000 AU Žwarped: multiple planes Žouter rings: stellar flyby? Žmultiple belts… - herded by planets? Žmid-IR asymmetry… - resonance / break-up? Ždistant submm feature Ž'falling evaporating bodies' Žgas (atomic, ionic… C-rich)

Golomowski et al. 2006; Telesco et al. 2005; Okamoto et al. 2004; Kalas et al. 2000; Holland et al. 1998;Smith & Terrile 1984 AU Mic Žvs. beta Pic: smaller disk (r ~ 200 AU) several clumps similar gas-to-dust ratio? up to ~ 5:1 Žsurprisingly similar to beta Pic dynamical times should

differ (2 vs. 0.5 Msun) Kalas Liu & Matthews 2004; Liu 2004; Metchev et al. 2005; Roberge et al. 2005 HR 4796 A

Žanother luminous star in the TW Hya group, ~10 Myr old, A0 V but TW Hya (K8 V) is counted as a T Tauri star Žforced asymmetries suggest perturbing planets

Wyatt et al. 1999; Scheider et al. 1999; Koerner et al. 1998; Jayawardhana et al. 1998 HD 141569

Žanother arguably pre-ms system B9.5 V, ~5 Myr

rdisk > 1000 AU Ždisk spirals due to: external companion star…or internal but very distant planet? (~200 AU)

Wyatt 2005; Clampin et al. 2003; Weinberger et al. 1999 summary: young systems

Žcomplex dynamics going on remnant gas involved? Žepoch of building giant-planets over? disk central regions cleared but systems probably still evolving Žno smooth disks: planetary perturbers very distant planets surprising? Žknow v. little about Solar analogues! Dent, Greaves & Coulson 2005: gradual shrinking of gas disks up to ~ 20 Myr? summary: young systems

Žcomplex dynamics going on remnant gas involved? Žepoch of building giant-planets over? disk central regions cleared but systems probably still evolving Žno smooth disks: planetary perturbers very distant planets surprising? Žknow v. little about Solar analogues! 100's Myr epoch

ŽA-stars: Vega (A0, 350 Myr) Fomalhaut (A3, 300 Myr) Ž-like stars: HD 139664 (F5, ~300 Myr) HD 107146 (G2, ~150 Myr) ŽNB in clusters: ~20% debris rate? major epoch of planetesimal collisions? Gorlova et al. 2004, Stauffer et al. 2005: B5-K1 debris disks at 100 Myr in M47& the Pleiades…

… F2-G1 disks in the Ursa Major group, ~300-500 Myr Spangler et al. 2001 Vega Žarchetype - but not typical structure? Žhalo of blown-out grains (mid-IR)… to distinct clumps (mm) effects of planetary migration, stirring of planetesimals, and trapped vs escaping particles

Holland et al. 1998; Su et al. 2005; Wyatt 2003, 2006 Žchoice of wavelength strongly affects what is seen (and interpreted)

850 microns

Marsh et al. 2006; Wilner et al. 2002; Koerner et al. 2001; Holland et al. 2003, 1998 Fomalhaut

Žunlike Vega no halo Žnarrow ring system ~25 AU at 140 AU Žsingle distant clump suggests a planet at ~ 100 AU?

Kalas et al. 2005; Marsh et al. 2005; Stapelfeldt et al. 2004; Wyatt & Dent 2002; Holland et al. 2003, 1998 HD 139664 and HD 107146

ŽF5 star with narrow belt: ~25 AU wide at 100 AU

Kalas et al. 2006

ŽG2 star with wider belt Williams et al. 2004; > 55 AU wide at 150 AU Ardila et al. 2004 summary: 'terrestrial' epoch

Žgas-less disks… smaller and simpler narrow rings, big cavities, clumps Žmany systems have debris ~ 50% for A stars… less for F/G/K? large dust masses: … cataclysms? completion of exo-Earths? Židentifiable resonances supporting presence of distant planets planet detection

Žoutwards planet migration increases planetesimal collisions plus traps dust hence, plot position of planets… sensitive at tens of AU example: a Neptune- mass planet at 65 AU around Vega Marsh et al. 2006, from model of Wyatt (2003) Gyr epoch

ŽA stars: ~ 1 Gyr on main sequence but a random nearby star typically a fraction of ~10 Gyr age of Galactic Disk Žresolved images only at 1 & 10 Gyr! none for Sun-like age but many exist…

Bryden et al. 2006 eta Crv

ŽF2 V, ~ 1 Gyr old inclined ring, or ring with 2 clumps? plus hot dust near star

850, 450, 450 (high res.) - Wyatt et al. 2005 HD 53143

ŽK1 V, 1 ± 0.2 Gyr wide ring similar to archetype epsilon Eri

Kalas et al. 2006 100 AU epsilon Eri

ŽK2 V, 0.85 Gyr central cavity to ~30 AU multiple clumps only system with time- resolved motion

(a) 850 microns (b) 450 microns (+850 contours); Greaves et al. 1998, 2005 Ž2-sigma rotation detection… nominally ~2.5 deg/ clumps dragged by planet at edge of cavity?

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Sim A Sim B 3.5 Sim C Sim D Sim E Observed 3

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Poulton, Greaves & Cameron 2006 tau Ceti

ŽG8 V, 10 Gyr 850μm most like Solar System in size but 20x dust flux of Kuiper Belt many more comets, at twice age of Sun no analogue to Size of Pluto’s orbit Jupiter… many

infalling comets? Greaves et al. 2004 summary: mature epoch

Ždisks mostly larger than Solar System r ~ 100-150 AU (but biased) mostly comet (not asteroid) belts smoother than younger disks? Žalso much dustier systems -4 Mdust > 10 MEarth (Mcomets > 1 MEarth) Ždiverse sculpting by planets? not generally Doppler-planet systems Gyr dust levels

Žextrapolation of excesses: most Sun-like stars could be 2-5x duster than the Solar System

0.03 0.1 0.3 1 3 10 30 100% excess (bins x3)

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Solar trends

Žto first order every system ≠ every other system! Žlittle pattern emerges if grouped by age spectral type rotation companions / planets Žhence, no 'predictor' of outcome?? common features

Žrings, not filled disks also from SED's of unresolved systems not necessarily cleared by planets Žbut many perturbed disks indicate planets at tens of AU… outwards migration? Ždisks larger than Solar System typical descendants of T Tauri disks? metallicity

Žonly known for ~Gyr Solar-analogues but clear influence on 'success' explain no-giant / many-comet systems, etc.

debris debris + planet hot Jupiter cool Jupiter no debris or planet 1.00

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cumulative function cumulative 0.30

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0.00 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 [Fe/H] future aims

Žmore resolved examples & better S/N make sense of zoo basics of why dust is where identify resonances correctly Žtime resolved imaging exploit rotation as planet detection tool Žbigger parameter space in models not just single matches to single systems ALMA JCMT

Survey speed × 5000 Resolution ×10

Herschel

Sensitivity × 10 – 1000 True image fidelity z=4 Quasar SOFIA

1mJy SCUBA z=2 Vega disk SCUBA-2 Herschel VLA ALMA z=10 Galaxy LSTLSD Flux density 1μJy

HST NGST

1m 1mm 1μm Wavelength summary

Žhuge advances via imaging Žprospects of understanding the planet connection! Žeffects of debris on exo-Earths and life?

1984… 1998… 2010?