Conference Summary Outstanding questions: a personal view

1. Conference SummaryOutstanding questions: a personal view Zooming in on Star Formation, Nafplio, June 14, 2019

2. Galactic Scale Star Formation What we know for sure now: • Feedback, and vertical pressure (im-)balance is crucial • The role of radial and vertical net mass transport is poorly understood Speculations – in 5-10 years • We will have a solid understanding of the topic • Radial and vertical average mass transport is integrated into the picture

3. Molecular Cloud Formation & Properties What we know for sure now • The ISM is a complex system, but is statistically in balance • It is supersonic and super-Alfvénic on average • On average it obeys several “statistical” (Larson-) relation Speculations – in 5-10 years • We will be on top of this

4. Molecular Cloud Fragmentation – filaments / cores What we know for sure now • Star formation relies fundamentally on fragmentation • Sheets • Filaments • Cores Speculations – in 5-10 years: • We will all be referring to “turbulent fragmentation”  • We will be on top of both the question of the IMF, and • .. on the topic of at what scale gravity takes over from inertia • That scale is of course mass dependent, but < 1-2 pc even for high mass star

5. Low Mass Star Formation, Disks, non-ideal MHD, … What we know for sure • An apparent self-similarity of the Salpeter branch • The IMF has a turn-over, maximum, and steep drop Speculation, in 5-10 years: • We will understand what is important and what is not for the turn-over • It will be understood basically as a “failure to collaps” – decreasing chance to reach collapse density • Hence, we will understand how to scale this to other circumstances • Early Universe … • Star Bursts …

6. Solar / Stellar Physics, connections to Star Formation What we know for sure now • Abundance determinations have reached an important limit, where we can see abundance differences btw otherwise “identical” stars – and not because of Galactic Evolution and systematic gradients • The are“large” (10-20%) differences, which depend mainly on condensation temperatures Speculations: In 5-10 years • We will understand what the abundance differences tell us about the birth environments • We will know where the Sun was formed • M67?

7. High Mass Star Formation What we know for sure: • High mass star formation is crucial for the ISM – feedback • SNe • Winds • UV • High mass stars have no problem forming • They basically adhere to the Salpeter IMF • The “only” problem is our understanding of how this works Speculations: In 5-10 years • We will be on top of this • Massive star formation will be a standard component in SF simulations

8. Planet / Solar System Formation What we know for sure: • The understanding of the formation of planet systems is going to advance tremendously during the next 5-10 years • New observations: Planet atmospheres (bio-signatures) • New modelling: “ab initio” modeling of dust-gas interaction Speculations – in 10 years: • Planetesimals are out • MRI is out – large scale mag fields are in • Streaming instability is out • Pebble accretion, pressure traps (in-side out?) is in

9. Code Development What we know for sure: • Computational modelling can, and is going to, contribute to advances in understanding of all of the previously mentioned topics