Thomas Henning Max Planck Institute for Astronomy, Heidelberg Conference Summary

Grain Growth, Heidelberg, July 2013 Cumber01.ppt 30.5.2001 The Facts

• Silicates and carbonaceous ISM dust • Broad size distribution • Additional materials in circumstellar envelopes (carbides, nanodiamonds, fullerenes, …) • Molecular ices in cold clouds • Grain growth in pp disks • Crystalline silicates and molecular ices in pp disks

(For silicates: Henning, ARAA, 48, 21, 2010) Onion-like presolar graphite particle - Murchison meteorite

1µm

Clayton et al. Forsterite crystals from Comet Wild 2

2 µm-sized particle from Stardust mission Crystals in motion in EX Lupi: Juhasz et al. (2012) My personal ( biased) view … • Topic becomes rich in data (Herschel emission/NIR extinction maps, Spitzer coreshine, Herschel spectroscopy & photometry, AO-based NIR & MIR images, ALMA data, e-VLA projects, Stardust mission)

• Experimental data available (Jena legacy: dust optical properties, collisional behaviour : Braunschweig, Duisburg, HD, Jena)

• New avenues for dust growth in pp disks (observational constraints needed – turbulence & gas and dust distribution, companions)

• Connection to light scattering, solid-state Parallelogram, Not a banana physics and statistics community needed (ß discussion (Henning et al. 1995) , features = f(a, m, shape, agglomeration), DDA discussion (Michel et al. 1996) , size distributions Dohnanyi (1969), MRN, Biermann & Harwit (1980), fitting, fluid dynamics) N(H2) from Herschel + Spitzer + UKIRT

Kainulainen, Ragan, Henning, Stutz (2013) NearNear--infraredinfrared Extinction Law

Fritz et al. 11 Extinction Spectra of Carbonaceous Materials

Quinten, Kreibig, Henning, Mutschke (2002) ∅ µµµ Boudet ea. 2005 SiO2 ~1.5 m β(T, ν) Break in the absorption law ~30cm-1: r SiO 1.5 µµµm 2 Different § SiO fumed 2 frequency + MgSiO sol-gel 3 dependence Í MgSiO 3 glass

500 µµµm- 1mm 100 µµµm- 200 µµµm Anticorrelation T-β β(T)~ const. QuestionsQuestions:: Diffuse ISM/CloudISM/ Cloud Cores

• Q1: What is the observational evidence for accretion vs. coagulation in denser regions of the diffuse ISM?

• Q2: How can we explain the near-IR extinction curve in the diffuse ISM and in denser regions?

• Q3:What happens during the accretion process and in shocks?

• Q4: How old are cores and how long are we allowed to grow particles?

• Q5: How can we best measure the external radiation field? Can we use the gas as a tracer for grain growth?

• Q6: What is the nature of the VSG population? QuestionsQuestions:: Protoplanetary disks

• Q1: How is the initial grain distribution for GI produced?

• Q2: Heating events vs. Coagulation?

• Q3: Where is the Fe/FeS? Where are the carbonaceous grains?

• Q4: Are all group I sources transition disks ? ( Maaskant et al. 13)

• Q5: What is the radial and vertical grain distribution? What is the best analysis tool for multi-λ data?

• Q6: How fluffy are fluffy grains?

• Q7: Can we find evidence for aligned grains? Absorption, scattering, and emission by interstellar material produces enough puzzles, even of identification, to keep the proverbial seven spectroscopists with seven brooms busy for at least seven years. Trimble & Aschwaden (1998)