Observational Properties of Protoplanetary Disks Leonardo Testi - ESO/Arcetri [email protected]; [email protected] • Today: • • • Tracing water, deuteration and link with Solar System Complex Organic Molecule Transition disks Questions from this morning • • CO Snowlines: why are so hard to see? • • • Close to the star and traced by *faint* molecules! Need ALMA sensitivity! We can observe directly only gas-phase molecules How can we probe the cold midplane gas? • • Need molecules that do not condense on the grains (hard/faint) Moderate desorption due to CR&induced UV possible Part X Water and Complex Molecules (van Dishoeck+2014) The complex chemistry of YSOs and disks • Tracing water in protostars and disks • Systematic difference between HD, HDO and other molecules • Need resolved measurements (Ceccarelli+2014) (Ceccarelli+2014) Deuteration (Cleeves+2014) Models of Deuteration in Disks • Disk is not capable to produce the deuteration => ices Can we detect water with ALMA in disks? ! (Brinch et al. 2010) è Herschel (Hogerheijde et al. 2011) detects much less water than originally expected in protoplanetary disks è Freeze out and dust settling expose only a tiny fraction of the water ice to stellar radiation è Deuterium fractionation and water isotopes accessible (van Dishoeck 2013) Chemical complexity • Complex molecules are formed on the ices and then can be released in the gas phase as ices sublimate Chemical complexity • Climbing the ladder of chemical complexity (Sanchez-Monge+2014) Hot molecular cores • This process is commonly observed in hot molecular cores where young massive stars evaporate the icy mantles (Jorgensen+2012) Chemical complexity • Simple sugar (glycolaldehyde) in low mass protostar (van der Marel+2014) (Belloche+2014) Chemical complexity - Future • • H2CO Full ALMA sensitivity required (Jimenez-Serra+2014) Very hard to detect complex molecules in disks 5 min pause • How can we explain the radial distribution of [D]/ [H] in our own Solar System? • Are we focusing too much on a chemistry of life tuned on what we have on Earth? • What about chirality? Take home points • Molecular spectroscopy is potentially a very powerful tool to study disk kinematics, physics and chemistry • • Complex modelling Missing/uncertain key data: collision rates, reaction rates • ALMA will be the prime tool to study gas in disks • kinematics, physics and chemistry of disks • The Chemical heritage of the Solar System may be linked to a pre-disk evolution Part XI Transitional Disks and Disk Dissipation What if we carve a hole? νFν ν(4q-2)/q ν3+β νFν λ λ Transition disks Williams&Cieza2011 • ~10-20% of disk population, likely represent a variety of evolutionary patterns Transition disks • Lack of dust opacity in the inner disk • • • Grain growth? Photoevaporated hole Dynamically carved hole • • • Fast! Early growth in protostars Evolution??? (Pinilla et al. 2014) Grain properties in TDs (Armitage) Disk photoevaporation • • Energetic stellar radiation heats the disk surface Unbound material flows away from the system EUV+FUV+X-rays (Gorti+2009) Simple Theory of Photoevaporation from in • Outer disk inflow maintains inner disk, when Macc fades a gap is created and the inner disk is removed • Fast removal of inner disk Monday, 7 May 2012 Evidence of photoevaporation EUV – M ~ 10-10M⊙ (Pascucci+2011) X-ray – M ~ 10-8M⊙ / Ercolano & Owen 2010 • Blueshifted [NeII] line from the wind Monday, 7 May 2012 (Alexander+2014) Scenario (Andrews+2011) Dust depleted inner regions • mm continuum images reveal inner cavity (Rosotti+2013) Accretion in TDs • Accretion phase should be very short (Manara+2014) Accretion in TDs • There is a relatively large population of TDs with large inner holes that show accretion compatible with classical disks (Perez+2015) ALMA results on TDs (Perez+2014) (Fukagawa+2013) ALMA results on TDs • Vortices or planet-induced azimuthal asymmetries in the gas distribution that lead to particle confinement Take home points • Photoevaporation alone has troubles in explaining transition disks • Especially the accreting disks with large inner holes • A combination of various effects may conspire to explain the characteristics of transition disks • Combination of planet formation and photoevaporation? • ALMA reveals asymmetries in the large grains distribution in the outer disk • may promote formation of large bodies in the outer disk
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