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Josep Miquel Girart Institut de Ciències de l’Espai (CSIC-IEEC) Catalonia

SMA Legacy Project: DR 21(OH): a Highly Fragment , Magnetized , Turbulent and Rotating Dense Core. Josep Miquel Girart Institut de Ciències de l’Espai (CSIC-IEEC) Catalonia. P. Frau (OAN, CAB-CSIC) Q. Zhang ( CfA ) K. Qiu ( MPIfR ) S.P. Lai (NHTU) Y.-W. Tang (ASIAA)

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Josep Miquel Girart Institut de Ciències de l’Espai (CSIC-IEEC) Catalonia

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  1. SMA Legacy Project: DR 21(OH): a HighlyFragment, Magnetized, TurbulentandRotating Dense Core Josep Miquel Girart Institut de Ciències de l’Espai (CSIC-IEEC) Catalonia P. Frau (OAN, CAB-CSIC) Q. Zhang (CfA) K. Qiu (MPIfR) S.P. Lai (NHTU) Y.-W. Tang (ASIAA) P. Koch (ASIAA) Paul Ho (ASIAA)

  2. Motivation: Aperture synthesis mm polarimetricobs W51 e2/e8 Lai et al. 2001 NGC1333 IRA4A Girart et al. 1999 NGC224 FIR 5 Lai et al. 2002 • BIMA: pioneer instrument that allowed for the first time to resolve the magnetic fields in star forming dense cores • … though the number of observed targets were small

  3. Motivation: Aperture synthesis submmpolarimetricobs NGC1333 IRAS4A Girart et al. 2006 G31.41 Girart et al. 2009 • SMA has already provided hints of the role of magnetic fields in SFRs • ALMA would open a revolution of polarization data • Simulations already available to the community (RAMSES: Commmerçon et al. 2011) • ARTIST already available to the community (ARTIST: Padovani et al. 2011)

  4. SMA Legacy Project: Filaments, Star Formation & MagneticFields • Filamentary molecular clumpsfrom: • SurveysofIRDCs • Cygnus-X region • GalacticPlanewith BOLOCAM • polarizationwith SCUBA • Continuum flux limitof 0.5 Jy/beam (interfero.) • Most of sources in a relatively nearby distances (<2 kpc) • Earliest stages of star formation: avoid HII regions • Several cores observed for some of the filaments • Frequency tuning to observe good molecular tracers of: • the core’s kinematics (H13CO+ 4-3, SO lines), • hot core lines (CH3OCH3, CH3CH2CN)) • outflow activity (CO 3-2, SiO 8-7) Image from Hennemann et al. 2012 DR 21, NGC6334, NGC2264C, G14.2, G34.4

  5. Cygnus X - DR21(OH) region (Reipurth & Schneider 2008) Motte et al.2007 Schneideret al.2010 One of the most active star forming regions in the Milky Way

  6. The DR21(OH) region (Reipurth & Schneider 2008) Zapata et al. 2012 Schneideret al.2010 DR21(OH) is a very active massive star forming core. D = 1.5 kpc L ~2 104 L Mcore ~350 M Msubcore ~5-25 M

  7. DR21(OH): previous polarization observations • The vertical filament has a total pressure composed about equally of turbulent energy and magnetic energy. • The magnetic field in the vertical filament appears to go across the filament and has an estimated strength offew hundreds μG in the sky plane Vallee & Fiege(2006) DR21(OH): previous BIMA observations detected both the dust and CO 2-1 linear polarization Lai et al. (2003)

  8. DR21(OH): Zeeman CN observations Blos = 0.4, 0.7 mG Lai et al. (2003), Cortes et al. (2005) Crutcher et al. (1999)

  9. DR21(OH): SMA observations 880 μmspectro-polarimetric observations using all the available configurations between June & October 2011

  10. DR21(OH): Kinematics of the dense core. Rotation 880 μm dust emission • H13CO+ 4-3 gas traces fairly well the dust emission • Clear velocity gradient in the NE-SW direction

  11. DR21(OH): A Keplerian-like rotating envelope Mass embedded in SMA 6 & SMA 7: ~60 M Keplerian rotation curve: ~10/cos(i) M … therefore: i ~ 80o DR21(OH) is almost face-on

  12. DR21(OH): Hot cores and outflows

  13. DR21(OH): Outflows driving sources

  14. DR21(OH): BIMA vs SMA polarization maps • Shown: • Contour maps of 878 μm continuum Stokes I from the SMA • Blue bars: SMA B segments • Red bars: BIMA B segments • 878 μm SMA map at the • same angular resolution as • the 1.2mm BIMA

  15. DR21(OH): B-field maps from pc to 0.1 pc SCUPOL-JCMT & SMA

  16. DR21(OH): B-field maps at 104 to 1000 AU • Complex B morphology but NE and W polarized regions in agreement with the large scale B field • High fragmentation observed, compared with other star forming cores observed at similar spatial scales (see Palau et al. 2013, ApJ, 762, 120). Needed a mass-to-flux ratio of 100? (Commerçonet al. 2011)

  17. DR21(OH): Statistical analysis for the SMA Hezareh et al. (2010): from the correlation of the velocity dispersion of H13CN and H13CO+ 4–3 lines: δ = 9 mpc !!!!!!!!!!! Bpos = 1.7 mG !!!!!!!!!!! Bpos = 0.36 mG derived from CN Zeeman by Crutcher et al. (1999, se also Crutcher 2012)

  18. DR21(OH): Mass-to-magnetic flux ratio @ core Mass-to-magnetic flux ratio in terms of the critical value (Crutcher et al. 2004) N(H2)=1.6 1024 cm-2 … the M/Φ measured values is 6 times the ciritical value!

  19. DR21(OH): Statistical analysis for SCUPOL δV and are larger in the core than in the filament: due to the very active star formation activity in the core In agreement with the value derived by Vallee & Fiege (2006) Bpos = 0.7 mG derived from CN Zeeman by Crutcher et al. (1999, se also Crutcher 2012)

  20. Mass-to-magnetic flux ratio @ filament N(H2) = 4.2 1023 cm-2 (Hennemann et al. 2012): the M/Φ measured values is 3 times the ciritical value, in agreement with evinde of infall motions in the filament (Schneider et al. 2010)

  21. DR21(OH): Gravitation vs Magnetic tension FB: Magnetic tension FB: Gravitational pull to know more about the concept of this technique, please check: Koch et al. 2012, ApJ, 747, 79 Blue-colored patches: mass-to-flux ratios of about 2 to 3 times the critical value Red patches: magnetic tension still out weightsgravity

  22. DR21(OH): Magnetic diffusion due to turbulence? The increase of the magnetic field is smaller than the value expected for ambipolar diffusion or for a weak field The magnetic field flux diffusion at core scales could be due to magnetic reconnection in the presence of turbulence (Lazarian & Vishniac 1999; Santos-Lima et al. 2010). Indeed: Leão et al (2013) predicts:

  23. DR21(OH): Angular momentunvsmagnetic fields DR21(OH) is a core almost face-on (i~80º) with a toroidal magnetic field: shaped by rotation? Machida et al. (2005) estimates the critical value between the angular momentum and the magnetic field strength: For the DR21(OH), the estimated ratio is so centrifugal energy is dynamically as important as the magnetic energy.

  24. DR21(OH) Summary • 878 μm SMA polarimetricand line observations • The dense core exhibits an overall velocity gradient in a Keplerian-like pattern • The core appear to be face-on • The dust polarization shows a complex magnetic field, compatible with a toroidal configuration. • We found evidence of magnetic field diffusion at the core scales, far beyond the expected value for ambipolar diffusion • The dynamics of the DR 21(OH) core appear to be controlled energetically in equal parts by the magnetic field, turbulence and the angular momentum. • Yet, gravitation overwhelms all the forces, making this a clear supercritical core with a mass–to–flux ratio of ≃ 6 times the critical value

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