POLARIZATION IN FORMING STARS

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15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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POLARIZATION IN
FORMING STARS


PROBING SMALL SCALES WITH
CARMA

Chat Hull

UC
Berkeley, Radio Astronomy Laboratory


27
August 2012


NSF CARMA site visit

Cedar Flat, CA


Progress overview


Testing: Feb.


Oct., 2010


Tested polarizers, mixers, and
orthomode

transducers


Progress overview


Installation: Oct. 2010


Installed dual
-
polarization modules
on all 15 six
-

and ten
-
meter
antennas


1 inch

Progress overview


Commissioning: Oct. 2010


Oct. 2011


Jan. 2011:

first dual
-
polarization data (Orion)


Feb. 2011:

full
-
Stokes
correlator

completed


May 2011:

first full
-
Stokes data (
IRAS 4A
)


May 2011:
XY phase calibration method developed


Oct.



Nov. 2011:

commissioning data taken


IRAS 4A

Progress overview


Science: Feb. 2012




Full
-
Stokes system available to outside
users



The
TADPOL key project


Goals


To understand the role
of B
-
fields in
star formation


in the collimation of bipolar
outflows, in particular


Understand the importance of B
-
fields from large to small scales


Results


20
sources
mapped


17
detections
at
3
-
sigma or higher;
some as
high as 30
-
sigma!



Other
polarization projects


M82 polarization (
Bolatto

et al.
)


Eagle Nebula polarization (Pound
et al.
)


Protostellar polarization (Kwon
et al.
)


Saturn polarization (
Princeton
)

TADPOL survey

28 targets

Triples number of low
-
mass, forming stars published to date


280 observing hours

CARMA C, D, & E arrays


1


4
"
resolution

10


higher resolution than CSO

& JCMT

Probes intermediate region between ~1 pc (single
-
dish) and ~100 AU (ALMA)


1 mm wavelength

Ideal for dust polarization, as well as CO(2
-
1)

TADPOL collaboration


UC Berkeley

Chat Hull (PI),
Dick
Plambeck
, Meredith Hughes, Mel Wright,
Carl Heiles, Geoff Bower



University of Maryland

Marc Pound, Alberto
Bolatto
, Katherine Jameson, Lee Mundy



Caltech

Thushara

Pillai
, John Carpenter, James Lamb,
Nikolaus

Volgenau



University of Illinois, Urbana
-
Champagne

Ian Stephens, Leslie Looney,
Woojin

Kwon, Dick
Crutcher
,
Nick
Hakobian



University of Chicago

Roger Hildebrand



Other

Jason
Fiege

(Manitoba), Erica
Franzmann

(Manitoba), Martin
Houde

(UWO, Caltech), Dan Marrone (Arizona), Brenda
Matthews (NRC
-
CNRC), John
Vaillancourt

(USRA
-
SOFIA)


Credit: Bill Saxton
,

Harvard
-
Smithsonian
Center for Astrophysics

Canonical model
of SF with B
-
fields

Girart
+ 2006

Rao
+ 2009

Holland+ 1996

Misalignment of B
-
fields and outflows

Outflow

B
-
field

IRAS 16293

IRAS 4A

VLA 1623

Isolated cores

L1157

Isolated cores

IRAS 4A

IRAS 2A

Isolated cores

IRAS 4B

Ser
-
emb

8

4B1

4B2

High
-
mass star
-
forming regions

G034 MM1

High
-
mass star
-
forming regions

DR 21(OH)

Outflow vs. B
-
field: distribution

Hull+ 2012, in prep.

Simulation:

outflows &
B
-
fields aligned within a
20º cone (takes into
account projection
effects)

Simulation:

outflows &
B
-
fields are randomly
oriented

KS test results:


20º cone
ruled out
(p
-
value ~ 10
-
6
)



Random orientations
cannot be ruled out
(p
-
value ~ 0.5)



Conclusions


Hardware status


CARMA polarization system is fully functional



TADPOL survey status


~50% complete; should be complete by winter ‘12



Polarization science status


Full
-
Stokes system available to entire community


Several polarization projects in progress


TADPOL: L1157 & outflow
-
vs.
-
B
-
field papers in prep.

Fin