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Chat Hull University of California, Berkeley Radio Astronomy Laboratory 4 June 2014 PowerPoint Presentation
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Chat Hull University of California, Berkeley Radio Astronomy Laboratory 4 June 2014

Chat Hull University of California, Berkeley Radio Astronomy Laboratory 4 June 2014

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Chat Hull University of California, Berkeley Radio Astronomy Laboratory 4 June 2014

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  1. Does turbulencecause the misalignmentof outflows and magnetic fields in protostellar cores? Chat Hull University of California, Berkeley Radio Astronomy Laboratory 4 June 2014 The Early Phase of Star Formation (EPoS) Turbulence Focus Group Ringberg Castle, Kreuth, Germany

  2. What is the role of magnetic fields in star formation? Incidental? Fundamental?

  3. LARGE SCALE B-field ⟂ filament Musca dark cloud 10 pc E,B Pereyra & Magalhães 2004

  4. LARGE SCALE B-field ⟂ filament Taurus: B211/B213/L1495 Palmeirim+ 2013

  5. B-field consistency over multiple scales

  6. Multi-scale comparisons: B-fields >1 pc 0.1 pc 1000 AU 100 AU • CONSISTENT • Hua-bai Li+ 2009

  7. Ambient 𝜽B-field (deg) (deg) 100 pc  0.1 pc : Consistent B-fields 0º 180º 90º 90º Core 𝜽B-field (deg) 0º Li+ 2009 -90º H.-b. Li+ 2009

  8. Multi-scale comparisons: B-fields >1 pc 0.1 pc 1000 AU 100 AU • CONSISTENT • Hua-bai Li+ 2009

  9. Multi-scale comparisons: B-fields 1 pc 0.1 pc 1000 AU 100 AU • CONSISTENT • Hull+ 2014

  10. Cores with consistent large-to-small B-fields HH 211

  11. • Core ⨉ Star-forming region Alignment vs. polarization fraction Hull+ 2014, ApJS, in press 90º Consistent B-fields from 0.1  0.01 pc 𝜽small– 𝜽large (deg) 45º 0º Polarization % 3% 8% 1%

  12. So B-fields are consistent over 4 orders of magnitude… • …but outflows and • B-fields are • randomly aligned!

  13. Credit: Bill Saxton, NRAO/AUI KALYPSO project, Harvard/CfA

  14. B-fields random w.r.t. outflows IRAS 4A HH 211 Ser-emb 8 B-field Outflow OMC3-MMS6

  15. Outflow vs. B-field: distribution 1 0 – 20º Random 0 – 45º CDF 70 – 90º • KS-test results: • 20º cone ruled out ( p-value ~ 10-15 ) • Misaligned ( 0.33 ) and random ( 0.33 ) cannot be ruled out Hull+ 2013, ApJ, 768, 159 (plot updated Feb ‘14) 0 0º 90º 𝜽outflow– 𝜽B-field (deg)

  16. Potential reason #1: • TURBULENCE • Star formation = billiards?? • (like planet formation) Mark A. Garfick, space-art.co.uk

  17. B-field || filament but... Small scale turbulence? Chen & Ostriker2014

  18. Potential reason #1: • TURBULENCE • EPoS discussion: • Richard Klein: current simulations • Arce: turbulence in outflow simulations • Rowan Smith: sub-filaments (~0.1 pc) could be created by turbulence

  19. But… • How can B-fields maintain their integrity over 4 OOM in regions of such turbulence?

  20. Potential reason #2: • Binary interactions

  21. But can binaries twist outflows by >10-20º ? Stapelfeldt et al. 2014 Proc. IAUS 299

  22. Potential reason #3: • Episodic accretion over time

  23. HerbigAe/Be stars aren’t random • They evolve more quickly • Circumbinary disk is coplanar with individual disks (Wheelwright+2011) • Younger Ae/Be stars are aligned with B-fields (Rodrigues+2009)

  24. But… • Outflows don’t wildly change direction • Which we might expect if misalignment takes place slowly in low-mass protostars

  25. Summary • Why are B-fields and outflows randomly aligned? • Possible reasons: • Turbulence • But how are B-fields consistent over 4 OOM? • Binary interactions • But angular change isn’t large enough • Episodic accretion • But outflows don’t twist enough • TADPOL data release (ApJS, in press): arXiv:1310.6653 • TADPOL outflows vs. B-fields: 2013,ApJ, 768, 159 • TADPOL survey: tadpol.astro.illinois.edu

  26. Fin