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Gas in Protoplanetary Disks

Gas in Protoplanetary Disks. Thomas Henning Max Planck Institute for Astronomy, Heidelberg. Frontiers Science Opportunities with JWST, Baltimore, 2011. Planet Formation: Stages. In presence of gas. In absence of gas. dust. Star & circumstellar (or protoplanetary ) disk. Dynamical

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Gas in Protoplanetary Disks

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  1. Gas in Protoplanetary Disks Thomas Henning Max Planck Institute for Astronomy, Heidelberg Frontiers Science Opportunities with JWST, Baltimore, 2011

  2. Planet Formation: Stages In presence of gas In absence of gas dust Star & circumstellar (or protoplanetary) disk Dynamical restructuring

  3. This Talk • How much time do we have to form planets? • Can we find water and organic molecules in disks? • What can we do with JWST? __________

  4. The Disk Structure __________ Small Structures – Low Mass – Low line/continuum ratio

  5. The Gas Disks • Angular momentum and mass transport • Dynamics of dust and planets (Coagulation/Migration) • Reservoir for the formation of molecules __________ • Water on Earth • „Wet“ Formation • (Drake 05) • „Dry“ Formation • (Morbidelli et al. 00)

  6. 3D Global Stratified MHD Simulation __________ Radius:1-10 AU 8 pressure scale heights Blue Gene/P and Pluto code: Flock et al. (2011)

  7. (Semenov, Wiebe, Henning, 2004, A&A, 417, 93) __________ Ionization structure of a T Tauri disk Mixed grains (dead zone) Sedimentation See also Ilgner & Nelson (2006, 2007) „Layered“ vertical structure

  8. Disk mass and planet mass Mplanet=0.5 Mdisk Planet mass [Jovian masses] Maximal planet mass increases with disk mass. Log(Mdisk/MMSN) Mordasini et al. , submitted.

  9. PAHs in Protoplanetary Disks __________ (Geers et al. 2007, RR Tau) (Acke, Bouwman, Juhasz, Henning et al. 2010)

  10. Dust and GasDisk Lifetimes __________ Haisch et al. (2001), Hernandez et al. (2008), … Fedele et al. (2010), …

  11. Gas Disk Lifetimes < 10 Myr __________ FEPS Spitzer Legacy IRS survey • 20 stars with ages 3-100 Myr => No gas rich disks (> 0.1 MJup) detected. Hollenbach et al. (2005), Pascucci et al. (2006) See also: Ingleby et al. (2009)

  12. Different stages of disk evolution H V(km/s) log(/ m) Typical CTTS H ~ 10 Myr ~1 Myr V(km/s) log(/ m) Flattened, accreting disk H V(km/s) log(/ m) Non-accreting TO

  13. A molecular disk at its edge HD 141569A • CO emission at 4.7 μm • Gas in Keplerian orbit • Inner cavity (r~11 AU) • Coming closer to the star than HST Goto et al. (2006)

  14. LkCa 15 – The SEEDS Collaboration Offset between nebulosity center and star suggests eccentric outer disk; this is expected from dynamical influence of planets, and hard to explain otherwise. What physical object is it that we see as a bright crescent? Two possibilities: Illuminated wall of the disk on the far side. Forward-scattering on near-side disk surface. Thalmann et al. 2010 Thalmann et al. 2010 Espaillat et al. 2008

  15. Disk Chemistry __________ • Large range of temperatures and densities • Importance of stellar and interstellar radiation fields Ionization and heating sources: Cosmic rays, UV radiation, X-rays, extinct radionuclides • Strong coupling between chemistry and dynamics (ionization, temperature structure, cooling) Dust and gas strongly coupled … __________

  16. Observable region with interferometers IS UV, cosmic rays accretion Disk Structure ~1000 AU hν, UV, X-rays Snowline (T=100K) photon-dominated layer warm mol. layer 0 cold midplane puffed-up inner rim turbulent mixing 0.03 AU 100 AU ~500 AU

  17. radiative association reactions with C How to produce simple hydrocarbons? __________ Gas-phase chemistry allows to build up simple molecules that can later freeze out or are ‘used’ to form larger species

  18. Spectroscopy - An Essential Tool ISO SWS disk spectrum of the Herbig Ae star HD 100546 (Malfait et al. 1998) and comet Hale-Bopp (Crovisier et al. 1997) for comparison DRM Documents, MISC Report, August 22nd, 2001 (Background) Apai et al. (2005); Flux at mJy level Pontoppidan et al. (2005)

  19. H2 is a challenging molecule to detect Rotational lines between 5.05 µm and 28.22 µm Bitner ea. (2007, AB Aur) Martin-Zaidi ea. (2009, HD 97048) See also Carmona ea. (2008) Not sensitivity, but disk structure! We use tracers for obtaining information about the gas.

  20. The Disk Tracers • Atomic and ionic fine structure lines ([NeII], [SiII], [SI], …) • Diagnostic features of PAHs (11.3 microns) and dust grains • Molecular lines (H2, H2O, CO2, …) (Gorti and Hollenbach 2008, Star of 1 Ms)

  21. Observational constraints • UV: H2 emission from hot inner disks • Optical wavelengths: [OI] emission • IR: H2, CO, H2O, OH, … in warm inner disk (1-10 AU) and molecular ices in outer disk, key organic species CH4 (7.7 µm), C2H2 (13.7 µm), HCN (14.0 µm) • FIR: CO, OH, … in warm outer disk surface • (Sub)mm:CO and isotopes, HCO+, DCO+, CN, HCN, • DCN, HNC, N2H+, H2CO, CS, HDO (?), CH3OH, CCH • in cold outer disks (»10 AU) __________

  22. Spectroscopy at sub-mm wavelengths __________ Dutrey et al. 1997 CID @ PDBI: Dutrey ea. 07, Schreyer ea.08, Henning ea. 10, …. DISCS @SMA: Öberg ea. 10, 11 Thi et al. 2004; Kastner et al. 1997

  23. Molecular Abundances in Disks __________ Strong depletion of gas-phase species: radiation or freeze-out?

  24. IR Spectroscopy Reveals Complex Chemistry __________ 700 K 400 K 300 K (Lahuis et al. 2006 IRS 46 in Ophiuchus; Variable) see also Gibb et al. 2008 for GV Tau) • HCN and C2H2 detected around a young low-mass star • T ≳350 K • Abundances several orders of magnitude higher than ISM dark clouds • Production in inner (< 6 AU) disk or wind

  25. Organic Molecules and Water Pascucci et al. (2009) Carr & Najita (2008) N atoms from photodissociation of N2 Diversity in inner disk atmosphere chemistry (e.g. Pontoppidan ea. 10, Carr & Najita 11, Teske ea. 11)

  26. Water in Protoplanetary Disks • Dominant line-cooling of inner disk surfaces (~10-4 Lsun) • (Pontoppidan et al. 2010) • No H2O, but OH detection in Herbig Ae/Be disks – • Photodissociation of water by FUV photons • (Pontoppidan et al. 2010, Fedele et al. 2011) • Mid-infrared lines come from ~1 AU • with rotional temperatures between • 500 and 600 K • No detection of colder water vapor in • outer disk regions with Herschel • (Bergin et al. 2010) VLT/VISIR: Pontoppidan ea. (10)

  27. Dust Evolution and Water Abundance Vasyunin, Henning et al. (2011) Abundance of water is getting higher in mid-plane and in intermediate warm disk layer. Maximum of abundance shifts deeper into the disk which may prevent water vapor from being observed.

  28. HD 100456 with Herschel CO, [OI], [CII], CO, H2O, CH+, … Sturm, Bouwman, Henning et al. (2010; see also Thi et al. 2011)

  29. Key Science Questions for JWST • Inner Gaps and Radial Structure of Outer Disks • Vertical Disk Structure (Gas-Dust Physics and Chemistry) • Content of Water and Organic Molecules in Disks Fukagawa et al. 2004

  30. Disk structure Spectroscopy Imaging

  31. Dust settling revealed by imaging PAH Image in PAH and dust continuum bands

  32. Imaging gaps in transitional disks VLT VISIR image 8.6 PAH 11.3 PAH 19.8 mm large grains IRS48 SR 21 Geers et al. 2007 Ratzka et al. 2007 Brown et al. 2008. 2009 Pontoppidan et al. 2008 Eisner et al. 2009 Thalmann et al. 2010 Examples of disks known to have big enough gaps (~40 AU) to resolve with MIRI imaging and IFU

  33. Vertical Protoplanetary Disk Structure Mid-IR gas lines trace various depths in the disk (temperature and density profiling) Gas-dust physics (e.g. sedimentation) and thermal structure Key factors: Stellar irradiation characteristics, grain/PAH evolution, chemistry Surface density and disk mass kept constant; Dashed lines: AV=1, 10 mag contours

  34. Uniqueness of MIRI/MRS High spectral resolution, high sensitivity, continuous  coverage: • line-to-continuum ratio sufficient to detect minor species (res: 2000-3700) • extend studies to faint brown dwarf disks (mJy @ 10m) [Fred Lahuis]

  35. Inventory of Organic Molecules in Disksof Various Evolutionary Stages • Key organic molecules such as CH4, C2H2, HCN, … • Sample can be based on previous characterization with • Spitzer/IRS, Herschel/PACS and Herschel/HIFI HNC, CH4, CH3, C2H6, CH3OH, … to be detected with MIRI

  36. The Water Reservoir MIRI water lines come from an inner dense region Woitke et al. (2009) The Power of the MIRI IFU F. Lahuis

  37. Conclusions • Rapid dust and gas evolution • Rich molecular chemistry in planet-forming disks • Diversity in abundance of organic species • Transition disks and exoplanets • Bright future: ALMA, 30-40m class telescopes, JWST __________ __________

  38. MIRI Science Disk Team Imaging and Spectroscopy of PP Disks M. Barlow, D. Barrado, W. Benz, J. Blommaert, A. Boccaletti, J. Bouwman, L. Decin, A. Glauser, M. Güdel, Th. Henning, I. Kamp, P.-O. Lagage, F. Lahuis, G. Olofsson, E. Pantin, J. Surdej, T. Tikkanen, E. van Dishoeck, H. Walker, R. Waters, B. VandenbusscheISO+Spitzer+HST+Chandra+Herschel+VLT/VLTI+IRAM/JCMT/SMA/VLA+Modeling

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