The Earliest Stages of Planet

Transcription

1 The Earliest Stages of Planet Formation The Clumps That Failed Some partners in crime: Galvagni, M., Hayfield, T., Mayer, L.,Roškar, R., and Saha, P. Shabram, M. and Ford, E. Michael, S. and Durisen, R. Douglas, T., Ilee, J. D., Caselli, P., Hartquist, T. W., and Rawlings, J. M. C. Stars To Life, April 2013 Aaron C. Boley

2 Topics Timing in the Meteoritic Record The constraints for the Solar System Consequences of Massive Disks Why instabilities matter for solids and disk chemistry What Happens when Fragments Fail? 2

3 Major Questions for Planet Formation When does planet formation begin? When does tdisk =0 correspond to t solid =0? What are the environments of planet formation? What modes of planet formation are possible? 3

4 Disk Evolution and Planet Formation We can think of disk evolution in three rough evolutionary phases Newly-forming disks Class 0 to Class 1 systems. Roughly few X 10 5 yr. Established disks Your typical disk ~ few X 10 6 yr. Debris disks Leftovers banging together. Ongoing and bright for >10 8 yr. 4

5 What Is This Talk About Focusing on the early disk early epoch, i.e., the Newly-Forming Disks. Mass infall period Embedded Denser, hotter than other stages of disk evolution What are consequences of this phase of disk evolution for planet formation throughout the disk s lifetime? 5

6 THE HISTORY OF THE SOLAR SYSTEM IS WRITTEN IN STONE Allende

7 Food For Thought Ca-Al-rich Inclusions (CAIs) 4567 Myr [1] Iron meteorite parent body formation for ~1.5 Myr [2] Mars half assembled by 1.8 Myr [3] Most chondrules are younger than CAIs, iron meteorite parent bodies, and maybe planetoids [1] Amelin et al. 2002; [2] Schersten et al. 2006; [3] Dauphas & Pourmand

8 Why Worry About Newly-Forming Disks? CAIs are old, and clustered around yr of each other 8

9 A Cinematic Approach Credit: Advanced Visualization Lab, Kritsuk & Norman, and Boley 9

10 Why Should The Disk Become Unstable? Infall should mass load a disk 10

11 Simple EOS. Includes B fields. 2D. Vorobyov & Basu 2006

12 Vorobyov & Basu 2006

13 Inutsuka et al Magnetic decoupling at n = /cc. Simple EOS

14 Zhaohuan Zhu 65 AU 200 AU M Sun /yr M Sun /yr 2D simulations. Variation in accretion rate and infall radius. Form of radiative cooling See also Kratter et al. 2010

15 Shocks Give Localized Heating Boley & Durisen

16 Fluid element histories from Boley & Durisen 2008

17 Log Σ (g cm -2 ) AU AU Ilee et al Base simulation

18 Ilee et al. 2011

19 Ilee et al Chemical models based on simulations.

20 Douglas et al., submitted

21 0.5 Even edge-on has strong signatures! -0.5 T. A. Douglas et al., submitted

22 Consequences of Spiral Shocks Spiral shocks repeatedly create changes in environment Heating profiles can have rapid rise, followed by protracted cooling, or rapid rise and rapid cooling Many near-sonic heating events (Boley & Durisen 2008; Cossins et al. 2009) Everything is processed to some degree Very strong shocks are rare Spiral pitch angles are ~10 o (in WKB tan i ~ " h/r ~ " cs /v # ) But, spirals are not the only thing that can heat... 22

23 Log Σ (g cm -2 ) AU AU

24 A Clump From A Global Sim g AU Surface Density log10(g/cm 2 ) AU

25 Clumps Are Fragile Initial clump size will be multiple AU in size RHill = a (M c /(3M Star )) 1/3 For q=mc /M Star =10-3, R Hill ~ 0.07a For q = 10-2, R Hill ~0.15a Eccentric orbits, clump-clump interactions, clump-disk interactions clump can overflow its Hill sphere 25

26 Log10 Density (g/cc) Including The Internal States of H2 Log10 Temperature Survival of a clump is a race to H2 dissociation See also poster by Marina Galvagni

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28 ANATOMY OF A CLUMP T~Density 1/2.75 Each clump is a mini nebula

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31 Consequences of Clump Destruction Each clump is a mini nebula Release processed solids into the nebula Solid and chemical alteration Could in principle form cores before destruction Tidal stripping/tidal downsizing (Boley et al. 2010; Nayakshin 2010) 31

32 Shabram & Boley 2013

33 Overall and Future Direction Multiple mechanisms for heating the disk during very early times Does anything make it through unscathed? Processing throughout the disk Significant work to be done before the regime of CAI formation is modeled We have only scratched the surface, and the studies are largely insufficient Other ideas for early solid alteration and large solid formation? 33