Sma observations of magnetic fields in low mass star forming regions
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SMA Observations of Magnetic Fields in Low Mass Star Forming Regions. Ramprasad Rao (ASIAA), Josep Miquel Girart (IEEC-CSIC), and the SMA Polarimetry Team. And what these observations tell us about B. B-Field Ambipolar Diffusion Regulated star formation. Crutcher 2006.

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Sma observations of magnetic fields in low mass star forming regions

SMA Observations of Magnetic Fields in Low Mass Star Forming Regions

Ramprasad Rao (ASIAA), Josep Miquel Girart (IEEC-CSIC),

and the

SMA Polarimetry Team

And what these observations tell us about B.



Sma observations of magnetic fields in low mass star forming regions

Simulations of polarized dust emission Regions

Goncalves et al. 2005


Sma observations of magnetic fields in low mass star forming regions

R=0.02 pc ~ Regions

4000 AU

Bethell et al. 2007


Tool of choice submm mm polarimetry
Tool of Choice: Submm/mm Polarimetry Regions

  • Advantages of emission polarimetry

    • emission is optically thin

    • no contamination from scattering, absorption etc.

  • Single dish measurements (CSO/Hertz/SHARP, JCMT/SCUBA)

    • good sensitivity to large scale structure

    • Dust emission strong at submm

    • Resolution is low ~10”

  • Highly sensitive interferometer array observations are needed. OVRO and BIMA earlier, currently SMA and CARMA, future with ALMA

  • BUT, cannot directly give strength of B


Polarization targets
Polarization Targets Regions

  • Low Mass: NGC 1333, IRAS 16293 A/B, HL Tau, L1551IRS5, VLA1623, Barnard 1c, Serpens Molecular cloud etc.

  • High mass: G5.89, G30.79 FIR10, IRAS20126, G31.41, Orion-KL etc.

  • SMA High Mass Legacy project: See Talk by Zhang Q. PI


Ngc 1333 cloud
NGC 1333 RegionsCloud

Sandell & Knee 2001

SCUBA 850 m


Ngc 1333 iras 4a
NGC 1333 IRAS 4A Regions

C-F method gives

B~ 5 mG; B fields

likely to be

dominant over

turbulence

B Field

Girart et al. 2006


However what is missing is the connection to large scale fields
However, what is missing is the connection to Regionslarge scale fields …!!!


Large scale
Large scale Regions

SHARP

Matthews+ 2009; SCUPOL

combination of both small scale and large scale structure is needed

SMA

Attard+ 2009; Slide courtesy Giles Novak


Ngc 1333 iras 4b
NGC 1333 IRAS 4B Regions

SMA

SCUPOL


Ngc 1333 iras 2a
NGC 1333 IRAS 2A Regions

SMA

SCUPOL IRAS2


Ophiuchus
Ophiuchus Regions

Bolocam 1.1mm

31” resolution

Young et al. 2006


Iras 16293
IRAS 16293 Regions

Outflow

Line joining

Aa, Ab

B-field


Iras16293 scuba
IRAS16293: SCUBA Regions

E Field

Matthews et al. (2009)


Vla1623

SCUPOL Regions

VLA1623

SMA

JCMT

Holland et al. 1996


Serpens molecular cloud
Serpens Molecular Cloud Regions

Enoch et al. (2011)

Bolocam 1.1mm

Spitzer 24 micron

Distance ~ 415 pc


Serpens
Serpens Regions

In prep.


Taurus class i sources
Taurus: Class I sources Regions

HL Tau

L1551 IRS 5

Pmax~less than 1+/-0.5% at the center

Tamura et al. 1995

JCMT


Low mass stars summary
Low Mass Stars: Summary Regions

  • Some Class 0 sources show resolved and ordered magnetic fields e.g. NGC 1333 IRAS 4A

  • Other Class 0 sources show none or disordered e.g. VLA 1623

  • Class I sources show weak or undetected polarization


Conclusions
Conclusions Regions

Magnetic fields appear to be dominant in quite a few of the objects

Sensitivity is still an issue - improvements made at the SMA

ALMA will be great when it comes online for polarization observations - but need short spacing data

"If the sun didn't have a magnetic field, then it would be as boring a star as most astronomers think it is.” – quote attributed to R. Leighton

“Magnetic fields are to astrophysicists what sex is to psychoanalysts.” - H. C. van de Hulst

Thank You!!