morains
for
al.
hed
few
cult
ion

Millimeter-wave polarization of
protoplanetary disks: alignment or scattering?

The Astrophysical Journal Letters, 844:L5 (5pp), 2017 July 20

Kataoka et al.

ALMAdependenceBand 7 of(870µm)
ALMA Band 3 (3.1 mm)
527 essential. The wavelength
the polarization
any fraction is not strong in the case of the grain alignment,
isk. while it is strong in the case of the self-scattering because
HL Tauisk,
the scattering-induced polarization is efﬁcient only when theeld,
ra- maximum grain size is around l 2p where λ is theter- wavelengths (Kataoka et al. 2015).
To obtain the wavelength-dependent polarimetric images, weterarts observe the HL Tau disk with the Atacama Large Millimeter/nta- submillimeter Array (ALMA) using Band 3. HL Tau is a younglete star in the Taurus molecular cloud with a distance of 140pc(Rebull et al. 2004). The circumstellar disk is around in
y at ∼100 au scale (Kwon et al. 2011). The disk has several ringion and gap structures with tens of au scales (ALMA Partnershipwith et al. 2015). The observed band corresponds to wavelengths offol- 3.1 mm, which is sufﬁciently longer than the previous CARMA
with polarimetric observations at 1.3 mm (Stephens et al. 2014).
undhich
2. Observations
Stephens et al. 2017
Kataoka et al. 2017
cuFigure 1.
ALMA polarimetric observations at 3 mm (top,al.
Kataoka
et al.observed2017), 1.3by
mmALMA(middle),µm (bottom),
HL
Tau wason and2016870October
12,
where
red 4vectors
show(2016.1.00115.S,
the >3 polarization
morphology(i.e.,
ent during
its theCycle
operation
PI:
A.
Kataoka).
vectors
have
not
been
rotated).
Vectorlengthsarelinearly
proporAlignment.” The antenna conﬁguration ScatteringwasC40-6,
and 41 intensity,
antennaswhichwere istional to P . The color scaleshows
the polarizedved operating.
masked to
onlycorrelator
show 3 detections.
each panel
The
processedStokes
fourI contours
spectral inwindowsmm
are shownfor [3,
10, 25,50, 100,
325, GHz
500, 750,
1000]⇥ I , where
92.5,
102.5,
and200,104.5
witha bandwidth
centered
at 90.5,1
thefor 3 mm, 1.3 mm, and 870 µm,
I is 44, 154, and 460 µJy bm
of
1.75
GHz
each.
The
bandpass,
amplitude,
and phase wererespectively.
de(NAOJ)
MA calibrated by observations of J0510+1800, J0423-0120, andand the polarization calibration was
ons J0431+1731,
of 0.00 3 andrespectively,
0.00 4, respectively.
performed by observations of J0510+1800. The raw data were
T. theMuto(Kogakuin
reduced by
EA-ARC
staff. U.), M. Momose, T. Tsukagoshi (Ibaraki U.), H.Nagai (NAOJ), M. Fukagawa (Nagoya U.),We
further (Osaka
performU.),
theT.iterative
H. Shibai
HanawaCLEAN(Chiba deconvolutionU.), K. Murakawa (Osaka-S.), Kees Dullemond, Adriana Pohl (Heidelberg)
imaging with self-calibration to improve the image quality. We

Akimasa Kataoka

accretion process, with an accretion rate of about for a large, rotationally supported disk in this class 0 protostellar sysolar masses per year. If it has been accreting at that rate tem. Such a disk at this early phase may be inconsistent with some disk
ch of its life, its age is approximately 300,000 years, formation models that consider strong magnetic braking12,13; however,ory suggests larger accretion rates earlier6, so it may large disks can form at this stage in models with weak magnetic
14,15$%&&%'(fields&) *+&,'%
or if the magnetic field is not aligned with the rotation axis16.
The presence of a rotationally supported disk is con33333333333333333333333333333333333333333333333333333333333333333
Assumingthat the disk is rotationally supported and that the mass
significantly more mass may be addedto ^]its
planet89G3 ..X3 K58458B
5DD958C
6; L9 D586 ;G 5 C68E4I ;G
B94C9 :A;7BC
VK58458B ^]N ^- 54B \,X A;:569B 2E6HE4 5 29AA O4;24 C7D98L7LLA9 ;G!"#$%"&'(#%)*#)%$-&%. itselfH;6inI5CNthe(years)R ES
E A RCH the| R Eposition–velocity
PO R TSthe2E4BC
protostaris dominant, we
canuse
informaontime
as wellasto +,the& *+'protostar*;;D aNfuture.
:89569B LF 6H9 :;<LE49B 5:6E;4of;G C69AA58
54B
molecular
G8;< 9J6E4:6 <5CCEP9 C658C 2HE:H 2989
C7D984;P5 9JDA;CE;4C
envelope + disk/+'$*)'&%,%+/
tion#HECfrom
star
L1527*'+)IRS 0",$%%$(hereafter
L1527), at;4:9a D586
distanceof about;G 6H9 U:;8DE;[b9465787C)K 5CC;:E56E;43:A;7B AE9Cthe molecular line data to determine the protostellar mass.
E4 6H9 BE89:6E;4 ;G 6H9 :94689 ;G 6H9 c5A5JF L76 5L;P9 6H9 c5A5:6E:#1$+, class
3&*.4%+)"(#&%'041#
parent molecular cloud (22), accretes materialof $2#0"*#0+"
the nearest
0 protostars;
this is the earliest
phase
cloud
core
from its surrounding disk with a mass accretion
5+&6+ 78 9':$(=;<1&%'$( 58 =&-&> 2
=&-&?
-10^6
rate of 8 × 10−8 M⊙ year−1 (25). Previous obrmation
process>,?'0@&3$#1
and 98weshow a schematic diagram of a
= !"#$%&'( )$"*+&#( ,-.&#/'*$#01 2'#34)5+6'#7.5+839 )*#':& ;1
servations at 0.6″ to 1.1″ angular resolution wereystem
in-CFig.
1.A&#F'(0Observations of dust continuum emission<4=>?@= A'#5+8(BD"E(5+&(1well describedby a smooth and axisymmetric
Infalling> G'#/'#94)F8*+.$(8'( H&(*&# I$# J.*#$%+0.85.1 KL A'#9&( )*#&&*1 H'F-#89B&1
distributionofmaterial
D'..'5+".&**.
O)J27
wereL;MN=1obtainedwith the Submillimeter Array (SMA)
envelope in the disk that extends? J.*#$($F0 <&%'#*F&(*1 O(8/&#.8*0 $I P3$#89'1 A'8(./833&1 P3$#89' N;KL=1 O)J
near the stellar photosphere and decreases monoed Array for Millimeter-wave Astronomy (CARMA) at
tonically with distance from the star (20, 23).
"#$%& $'( )*$'+#& ,-%. /0#10' ($%2 .-*+34*$% 3*-4(&5 64# *0##*+ 0&
To estimate the optical depth of the observed
4'(+%&#--($6-4# #1+
0'#+%'$*#1+&+mm,
3*-4(&5 following$'(of
870 mm,1.3
mm&#%43#4%+
and-,3.4
up indications
dust
continuum emission, we performed radi3-'&+74+'#*8 $6-4# #1+ 0'0#0$* 3-'(0#0-'& #1$# 90:+ %0&+ #- &#$%
5$'()*$'+# ,-%.$#0-'!
;1+ 3*-4(&$%+ )%0.$%0*8-,
s Gemini
results
that
L15273-.)-&+(
harbouredan edge-on disk.
ative transfer calculations using RADMC-3D (26).-*+34*$% 18(%-9+'5 /1031 0& :0%#4$**8 0'$33+&&06*+ #- (0%+3#
at 1.3 mm (17), using the previous surface den-10^5-6&+%:$#0-'!
<4# #1+ 3*-4(&$*&- 3-'#$0'/1031 0& in/+** Fig. 2 with sufficientand 3.4-mm
data
are (4&#5
shownsity constraint found for the Elias 2-27 disk (20).
.0=+( /0#1 #1+ 9$& $'( /1031 1$& /+** 4'(+%&#--( +,,+3#& -'#1+#%$'&.0&&0-'the-, *091#!
>+%+ /+ 4&+ &+'&0#0:+'+$%?0',%$%+(
Outflow
OutflowThis model reproduces
the azimuthally averaged
resolveemission
from
the
disk
midplane,finding.+$&4%+.+'#& -, #1+ *091# ,%-. 6$329%-4'( &#$%& $& 0# 0& $6&-%6+(
radial profile of the observed ALMA 1.3-mm con$'( &3$##+%+(
68 #%$3+ $.-4'#& -, (4&#0'#+%'$*
B68,The~10^4AUndednorth–south,
like#- )%-6+
the #1+3.8-mm
dark lane.
obElias2016)
Fig. 2-24
1. Thermal (Perez+
dust emission fromthe protoplanetinuum emission (fig. S1) (17). At a radial distance&#%43#4%+ -, #1+ ($%2 3*-4( <$%'$%( @A /0#1 4')%+3+(+'#+( (+#$0*!
B+
C'(
#1+
3*-4(D&(+'&0#8&#%43#4%+
#6+
:+%8
/+**
(+&3%06+(
imagedatawavelength
of
1.3
mm,
with
ALMA reaching
from
the
star
(hereafterreferredtoasradiusand,180 6 12 astronomical units (AU) in diameter(radius2001)(Alves+68 #1+ +74$#0-'& ,-% $ )%+&&4%+?3-'C'+(5 &+*,?9%$:0#$#0'9 0&-?
by the ellipse in the bottom left corner), which corresp
denoted by R) larger than R ≈ 10 AU, the emis#1+%.$* &)1+%+ #1$#
0& 3%0#03$**8&#$6*+ $33-%(0'9#- #1+ <-''-%E
measuredfrominsidetheoutercontourplottedinFig.
2;
The field-of-view center (at 0, 0) corresponds to the disk esion
isoptically
thin
and
thus
tracesthedensity
F6+%# 3%0#+%0$ ! I& $ %+&4*# /+ 3$' )%+30&+*8 &)+30,8 #1+ )18&03$*
16 hours 26 min 45.024 s, declination (J2000) = –24
ofsolidmaterial
down
to
the
midplaneoftheprotostar3-'(0#0-'&0'&0(+
$
($%2
3*-4(
-'
#1+
:+%9+
-,
3-**$)&+#,-%.
$
ssion appears smaller than the mid-infrared dark lane&#$%!
the position of the star Elias 2-27. (A) 1.3-mm dus
disk. At the location of the spiral structures (from@;A9:7A58 :A;7BC 589 D8E<58EAF:;<D;C9B;G<;A9:7A58
HFB8;I94
Infallingower-density
outer
disk
is
fainterthanthesensitivity
limit.
planetary disk over a 4″ by 4″ area. The color scale rep
R
=
100
to
300
AU),
the
azimuthally
averaged<EJ9B
2E6H 685:9 E<D78E6E9C E4:A7BE4I E4698C69AA58 B7C6 I85E4C 54B
formation
13
envelope
per beam (1 Jy = 10
W m Hz ). (B) Increased co
optical
depth
t
of
the
dust
continuum
emission
8589;8I54E:
54B
E4;8I54E:<;A9:7A9C3
K9:57C9;G
E6C
CF<<968E:
stance from the Earth to the Sun, 1.496 3 10 cm.) Other
C687:6789 6H9 HFB8;I94 <;A9:7A9 D;CC9CC9C 4; BED;A9 <;<946 54B
observations shown in (A) with an unsharp masking fi
is t = 0.1 at R = 100 AU, decreasing to t = 0.02
:544;6
D8;B7:9 5 895BEAF B969:65LA9
CEI45A 74B98
6H9 :;4BE6E;4C
6H56 L1527 and other classot
conclusively
detectdisks
aroundat R = 300 AU (fig. S1B), which is consistent:H585:698EM9 :;ABN B58O :A;7BC3 #H9 685BE6E;45A <96H;BC 7C9B 6;with the measured peak brightness temperaB98EP9 6H9 L5CE:
DHFCE:5A
D8;D986E9Cresolution;G C7:H <;A9:7A58was:A;7BC too low to distinguishbecausethespatial~25,000
tureon the AU
spirals of 1.2 K at R = 150 AU.
H989G;89 <5O9 7C9 ;G ;LC98P56E;4C ;G 685:9 Q C788;I569CN 45<9AF
7,8
H;C9
8589
<;A9:7A9C
2E6H
C7GR:E946
BED;A9<;<946C
6;L9
95CEAF
The
spiralstructures are even more evident
sionfrom the envelope and/or the disks were too small .
B969:69B LF 85BE; CD9:68;C:;DE: 69:H4ES79CN 54B E4698C69AA58 B7C6N
in Fig. 2A, in which the data has
been projectedenvelope:10^4AU,
6H98<5A
9<ECCE;4L9 B969:69B
LF 85BE; :;46E477<
a2H;C9disk
mass
of:540.007
6 0.0007
M[ from the 870-mm flux Figure 1 | CartoonL1527,
of a protostellar
rotatedgridtothat
match
thefororientation
into asystempolar coordinate
accounts
9:H4ES79C3 Q;29P98N 6H9 E4698D89656E;4 ;G 89C7A6C B98EP9B G8;<
H9C95
<96H;BCEC
4;6
5A25FC
C685EIH6G;8258B
3
U9P985A
D;;8AFthe viewing
geometry
disk. In polarAU) coordiinfallinghighlights
the(Tobin+large(Rof<the12,500
213.6
6 8.1 mJy); details are given in Supplementary of L1527. Green shading
10^5mm
disk:10^2
AU
2012):;4C685E49B 9GG9:6C
E4H98946 E4 6H9C9 69:H4ES79C VC7:H 5C B9PE56E;4C
nates, a ring with zero eccentricity would have HL Tau (ALMA+ 2015)
8;< A;:5A 6H98<;BF45<E:
9S7EAEL8E7<N ;D5:E6F
P58E56E;4CN
and disk; the envelope geometry on
section3. We consider
thismass:H9<EW
a lower limit because the envelope surrounding the protostar
a constant radius for all polar angles. However,:5A 9P;A76E;4N C<5AAWC:5A9 C687:6789N B9DA96E;4 ;G <;A9:7A9CN
27
21 B7C6 69<W
L14-2
M. F
9
complex
than
shown
here
. Becausethe
10,000-AU scales is generally more
74O4;24 9<ECCEPE6F D8;D986E9C ;G 6H9 B7C6N274O4;24
shown
in Fig. 2A
are twobright structuresthat
opacity
is
large
(3.5
cm
g
at
850
mm)
,
and
we
have
not
D9856789X <5O9 6H9 :;4C687:6E;4 ;G 54 745<LEI7;7C DE:6789 ;G 6H9grow in radius
fromonto~100 toa 300
AUdue
as theto
polar
infallingmaterial
hasThesome net rotation,
it falls
disk
conservation
C687:6789 ;G 6H9C9 ;LY9:6C 5 P98F BEGR:7A6 65CO3 #H9 B9DA;FW
November 23 and 0.7
mm on the latter
two executions.
rDHFCE:5A
spatialfilteringbytheinterferometer.
angle
increases.
The
brightest
of
these
two
struc/, 0'*('*) 123
4/56 )&&5 06!67
total on-target
integration
time$'()
was893::∼2 !-6hr.
<946 ;G C94CE6EP9N A58I9WG;8<56 E4G8589B 5885F :5<985C ;4 A58I9 !"#$%& ' !"#"$%& '() (&'*+"(,*'*&) "-'.&#
of 0'*('*)
angularmomentumdirectly
ontoofthe
The disk is
13 H5C 5A6989B 6HEC CE6756E;4 LF 945LAE4I 6H9 BE89:6 93;; !-6 93<9 protoplanetaryraw
data B%/C)
were
calibrated
NRAO staff. After rather thantureslies northwest
the protostar.
star, labeled “NW”;!-= "-'.& 8!>! ! >!=These/, ?@& )'*A-/%&BC%'*
12 ?'A&(byD"?@
9A9C:;D9CN H;29P98N
disks
ed
the
CO
(
J
5
2
R
1)
molecular
line
transition
withapplying
phase
corrections
from
water
vapor
radiometer
4@& B%/C) "# #&&( "(<95C789<946 ;G 6H9 B7C6 9J6E4:6E;4 V6H56 ECN 6H9 ;P985AA BE<E476E;4 EFGH# !&*I J'*.& 4&%&#B/5& 8!J4= %/B'?&) "( ?@& K@"%&'( L()&#3
the spiralstructureto
southeastof the Keplerianstar is labeled rotation
colouredwith a red-to-blue velocity
gradient
illustratemeasurements,
the data
were
L? ?@&#& /5?"B'% D'O&%&(.?@#?@&
B%/C)time-averaged"# B/-5%&?&%I into 2 s integraB79 6; 6H9 :;<LE49B 9GG9:6C ;G 5LC;8D6E;4 54B C:56698E4I 5*/M&B?"/( '.'"(#? ?@& N'%'B?"B $C%.&3
“SE.”
In
Fig.
2B,
we
present
thesurfacebrightness
a;GLFC658AEIH6
wavelength
of
1.3
mm.
This
line
tracestheoutflow
intions andﬂaggedproblematic
antennas and times. The#?'*%".@?
B'C#&)for$Iaround#-'%%"(?&*#?&%%'*the)C#?
B7C6X 6;258B 6H;7C54BC ;G E4BEPEB75A L5:OI8;74B C658C ;LC98P9B /5'PC& /D"(. ?/ &Q?"(B?"/( /, $'BA.*/C()
protostar.
Massistransported
fromtheenvelope
to the disk andbandpass
responseof
each
spectralwindow
wascalibrated
13
contrast of the NW and SE arms, defined as the
10 :A;7B3 U7:H <95C789<946C 589 G899 G8;< 6H9 5'*?"B%&# ?@'? 5&*-&'?& ?@& B%/C)3 4@& B/-5%&?& '$#&(B& /, ,/*&.*/C() #?'*# 5*/M&B?&)
H8;7IH 5 <;A9:7A58
Fig. 2. Polar projection of disk emission and measu
using the observations of J1058+0133. The amplitude scalerotostars;
however,
Fig.
3
shows
that
the
CO
emissionthenis5B=3accreted
throughthe disk
ontothetheTheand/, ?@& B%/C) ?/ ?@&F/%'*
FI#?&-it
8RS;
4@& J1107–4449.
10^6:;<DAE:56E;4C
6H56 DA5I79 <;A9:7A58WAE49 ;8 B7C6 9<ECCE;4 B565 54B /(?/ ?@& B%/C) "# ' *&#C%? /, ?@& 5*/Q"-"?I
ratioandbetweenpeakprotostar.
of emission at
the protostar
arm
protoplanetary
disk. (A) Projection onto polar coord
was determinedfrom
J1037–2934
andThe/C?&* *')"C# /, ?@& B%/C) "# B/-5'*'$%&?/ ?@& "((&*#"T&/, ?@& G/*?
B%/C)/, B/-&?#was?@'? calibrated using the945LA9 B965EA9B <5DC ;G :A;7B C687:6789 6; L9 :;4C687:69B 3
10complexgain
responseofthesystemandthebackgroundsurface brightness(17). We the
ces
the
inner
envelope
and
disk
in
L1527.
The
outflow
distancetothecentralstar R) of the dust continuum obthatevacuates
polar
disk
both
work
together
and
drive
a
bipolaroutflow
8!R9 =3 4@&-'##/, ?@&
B%/C)"# '$/C?
?D"B& ?@'?
?@& FC(3 0/??/-6 Although%9:946AF 29 D98G;8<9B P98F C94CE6EP9 4958WE4G8589B E<5IE4I #C**/C() ?@& FC(
e.g.,
TW
Hya
(Andrews+
2016)
frequent
observationsof /, J1103–3251.
images
found
that
both
arms
have
similarcontrasts–1O4;24 )&&5 0676V $'() "-'.& /, ?@& B%/C) generated
has
been
scaledbyRinorder to aid visualization, and th
B/(#?*CB?&) $I
B/-$"("(.
'("(,*'*&)
V
$'()
8S3S
!;LC98P56E;4C 6; <5D 6H9 C687:6789 ;G 5 6FD9 ;G B58O :A;7B
from these data are relatively free of artifacts andregionsofEFGH#target
the (1.5
envelope.
less
61 km
s , butdoes"-'.&notD"?@ ?@& affect
0 '() 7recover"-'.&#3 our4@&$'() "-'.&ﬂux
D'# density/$?'"(&) D"?@
the Vintegratedof theJy), folding
5C velocities
5 K;O IA;L7A9 N ;49;G 6H9 than
A95C6 :;<DAE:569B:;4RI7856E;4C;G D'O&%&(.?@=
ranging between values of 1.3 and 2.5. The spiraltoward east. Curves correspond to the best-fit model sp

Star and disk formation
.1N.T

Disk

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Disk~300 AU

G5H

−26

−2

−1

1

TN+

The Astrophysical Journal Letters, 820:L40 (5pp), 2016 April 1

Andrews et al.

Z[\

:

]N-

LU

2

HD 142527 (Fukagawa+ 2013)

ALMA
observations
with a ?@&higher density of short
K@"%&'( L()&#3
L? (&'*+"(,*'*&)
D'O&%&(.?@#<;A9:7A58 I5C 6H56 EC O4;24 6; G;8< C658C3 #H9 658I96 :A;7B G;8 ;78 W&D 4&B@(/%/.I 4&%&#B/5& 8W44= "(in?@&additionalarms reach their highest contrast at R = 150 AU,
their constraint at the 3s level (solid lines). (B) Surface br
spacings
the imagereconstruction.
#?'*# %/B'?&)$&@"() improves?@& B%/C) B%&'*%I'55&'* "(?@&C67BFN K58458B ^]N EC E6C9AG ;49 ;G 6H9 R49C6 9J5<DA9C ;G 5 K;O B%/C) $&B/-&#2 ?*'(#5'*&(? '() ?@&antenna
3 location in the disk wherecoinciding
with
the
To
that
end,
we
calibrated
threearchival
ALMA
data
tronomyObservatory,
Charlottesville,
Virginia
22903,
USA.
DepartmentofAstronomy,
UniversityofMichigan,Ann
Arbor,
Michigan
48109,
USA.
DepartmentofAstronomy,
Universityof arm, defined as the ratio between the peak oeach spiral
IA;L7A9N 54B 25C C9A9:69B L9:57C9 E6 EC 5 4958LFN 89A56EP9AF EC;A569B "-'.&3 0&B'C#& ?@&#& #?'*# '*& /$#&*O&) /(%I "( ?@& %/(.&#? /, ?@& ?@*&& D'O&%&(.?@
of TW
Hya,
from
May 20, 2012 November
4 <;A9:7A58 :A;7B 2E6H BEC6E4:6 L;74BW
5 the most influence over thermal presgravity
has$'()#6 ?@&I '55&'* O&*I *&) "( ?@"#observations?@*&&+B/%/C* "-'.&3
4@&#&'*& ?@&#?'*#2012?@'? 5*/O")&
54B<;8DH;A;IE:5AAF
CE<DA9(17), which is computed at increasing radial distance fronois 61801, USA. Institute for Astronomy and NASA Astrobiology Institute,
University
Manoa,
Hilo, Hawaii 96720, USA. Harvard-Smithsonian Center for Astrophysics,
20, and 2014
Decemberof
31,Hawaii
using 16,at25,
and 34 antennas?@*/C.@ ?@& B%/C)3
58E9CN 5 O4;24 BEC654:9 V.1Z D:_ 89G3 .,XN 54B 69<D9856789 V.^ `_ -&'#C*&-&(?# /, )C#? &Q?"(B?"/( )"*&B?%I
sure and shear forces, that is, where the Toomre
spanning baselines from 15 to 375 m. The ﬁrst two observa-

chusetts 02138, USA. 6Centro de Radioastronomı́a y Astrofı́sica, UNAM,
Apartado
3-72(Xangari),Morelia, Michoacán,
Mexico. 7lowest
Max-Planck-Institutfür Radioastronomie,
tions
had four 59Postal
MHz wide
spectralwindows 58089
centered at
Q parameter(fig. S2)
(17).
Figure 1. Synthesizedimage of the 870 is
μm continuum emission
from theTW However,!"#$%& ' ()* +,- ' .. /"!$"%0 1,,. ' 22234567893:;<!"#333.8,
335.4,
345.8,
and
347.4
GHz.
The
latterhad
two© 2001 Macmillan Magazines Ltd
disk with a 30
mas FWHM(1.6minimumau) circular beam.value
The rms noiselevel is Q is well
53121 Bonn, Germany.
Akimasa KataokaHya(NAOJ)
even
at itsToomreconstrained the geometry of these structures by
235 MHz windows (at 338.2 and 349.4 GHz), one 469 MHz∼35 μJy beam−1. The inset shows a 0 2 wide (10.8 au) zoom using an imagew

area of 33 square arc sec, where there is adequate sion (dqosensitivity to measure the polarization. Assum- whereas t
ing optically thin emission, a dust temperature of larization
50 K (19), a gas-to-dust ratio of 100, and a dust intrinsic
opacity of 1.5 cmj2 gj1 (20), we estimate the estimate
total mass
Envelope, ~10^4
AU traced by the dust to be 1.2 d3002 regardedsolar masses Ed300 K (d/300 pc), where d is the function iBB
adopted distanceto the NGC 1333 cloud^. We magnetic
If we
can make an estimate of the averaged column
density EN(H2)^ and volume density En(H2)^ of tion angle
the region traced by the dust as follows: N(H2) 0 by Alfv2n
M/(Amm) and n(H2) 0 M/(Vmm), where M is the then the s
dust mass, mm is the average mass per par- in the pla
ticle, A is the area of the dust emission, and V 0 from the13(4/3)p– / 2 A / 2 is the volume. Adopting a helium- where r ito-hydrogen mass ratio of 30%, we find that the line-of-sig
mean column density is N(H2) 0 8.2 ! 1023 dispersion
cmj2 and the mean volume density is n(H2) 0 which is t
4.3 ! 107 d300j1 cmj3; both are similar to the Q is a dim
IRAS 4A(Girart et al. 2006)
Ser-emb 8 (Hull et al. 2017)
the cloudexpectedvalues for the observed scales (19).
Fig. 1. (A) Sketch of the axis directions: red/blueWith the array configuration and frequency inal equat
arrows show the direction of the redshifted/
blueshifted lobes of the molecular outflow, used, these SMA observations are not sensitive Simulatio
embeddeddisks,~10^2
AUsolid lines show toprotoplanetarydisks,~10^2
AUor 0.50 (25)
dust emission on scales
largerthan 10¶¶probably driven
by IRAS
4B (8);
the main
B axis of the magnetic field; and dashed 3000 AU, where models of magnetized collaps- value oflines show the envelope axes. The solid triangles ing clouds expect the magnetic field to be data, n(H2E field has been (correctedshow the positions of IRAS 4A1 and 4A2. TheEcross uniform. Therefore, the magnetic
shows the center of the magnetic field symmetry. modeled by a family of parabolic functions by (26),(B) Contour map of the 877-mm dust emission(Stokes I) superposed with the color imageof the of the driven2.
Table 1. v is the velocity Fig.
turbulentmotions in
et al.of2016).
The method uses a Harten–Lax–van-LeerHistogram
thediscontinuities (HLLD) Riemann solver to accurately capturev º B 4pr is the Alfvénic wave speed.
the box, and thatpolarized flux intensity. Red vectors indicate
shocks.
The moving-mesh method greatly reduces advection
AREPO’s base scheme polarization
solves the equations ofangle
ideal
residuals
errors compared with traditional adaptive reﬁnement meshhydrodynamics with a ﬁnite-volume approach using alengthis
proportional
tofractionalpolarization,
L1527 (Segura-Cox+ 2015)
due to its quasi-Lagrangian nature. We also couple
second-order unsplit Godunov scheme. In order to maintainfor the best parabolicmethods
magnetself-gravity to the MHD equations, which is calculated using a
the divergence-free property of the magnetic ﬁeld on an
and the direction is the position angleunstructuredof linear
Tree–Particle–Mesh scheme. Solenoidal turbulence is driven inmesh, we have implemented a constrained
shown
in Fig.
1.the largest spatial scales using an OrnsteinFourier
space attransport solver in terms ofic
the field
magneticmodel,
vector potential
topolarization. Contour levels are 1, 3, 6, evolve
9,I30! of idealThe
Uhlenbeck process (Federrath & Klessen 2013).
the equations
magnetohydrodynamics (Mocz
mean and the standard
100 AU
65 mJy per beam. The synthesized beam is shown deviation of100
3
theAUpolarizationin the bottom
left corner.
(C)SMA
Contour and image angle residuals are –1.1- andcf) non-detectionof disks
withmap
the dust
emission.
the 8.0-, respectively.
HD 142527
HL TauHD 163296,
TWofHya,
GM Aur,
DG RedTau bars show
measured magnetic field vectors. Gray bars
(Hughes etcorrespondal. 2009,to2013)(Kataoka(Kataoka et al. 2017)
the best-fit parabolic magnetic
field et al. 2016b)
model. The fit parameters are the position angle of
Akimasa Kataoka (NAOJ)
the magnetic field axis q 0 61- T 6-; the center

Polarization of star-disk systemtime (years)
-10^6

-10^5

protostarformation

The Astrophysical Journal Letters, 842:L9 (10pp), 2017 June 20

Hull et al.

Figure 1. Multi-scale view of the magnetic ﬁeld around Ser-emb8 (aJ2000 =18:29:48.089, dJ2000 =+1:16:43.32). Line segments represent the magnetic ﬁeld
orientation, rotated by 90 from the dust polarization (the length of each segment is identical and does not represent any other quantity). Grayscale is total intensity(Stokes I) thermal dust emission. Panel (a) shows 870 μm JCMT observations (Matthews et al. 2009), (b) shows 1.3 mm CARMA observations (Hull et al. 2014), and(c) shows 870 μm ALMA observations, revealing the magnetic ﬁeld morphology with ∼10,000, 1000, and 140 au resolution, respectively. For the ALMA data, line
segments are plotted where the polarized intensity P > 3sP; the rms noise in the polarized intensity map sP = 25 μJy beam−1. The dust emission is shown starting at
3×σI, where the rms noise in the Stokes I map σI=50 μJy beam−1. The peak polarized and total intensities in the ALMA data are 0.693 mJy beam−1 and102 mJy beam−1, respectively (the two peaks do not coincide exactly). The red and blue arrows indicate the redshifted and blueshifted lobes of the bipolar outﬂow(Hull et al. 2014). The text below each of the panels indicates the physical size of the image at the 436 pc distance to the Serpens Main region (Ortiz-León et al. 2017;see earlier results by Dzib et al. 2010, 2011). The black ellipses in the lower left corners of the ALMA and CARMA maps represent the synthesized beams (resolution
elements). The ALMA beam measures 0. 35 ´ 0. 32 at a position angle of −63°; the CARMA beam measures 2. 89 ´ 2. 43 at a position angle of 13 . The JCMT
data have a resolution of 20 .
(The data used to create this ﬁgure are available.)

The Astrophysical Journal Letters, 798:L2 (6pp), 2015 January 1

Segura-Cox et al.

Table 1
Initial Parameters of the Four Simulations Carried Out with AREPO

10^5

sim.

b mean ‐ field

Bmean ‐ field (μG)%A,mean ‐ field%sComment

1
2
3
4

25
0.25
0.028
0.0025

1.2
12
36
120

35
3.5
1.2
0.35

10
10
10
10

very weak ﬁeld (super-Alfvénic)weak ﬁeld (super-Alfvénic)moderate ﬁeld (trans-Alfvénic)strong ﬁeld (sub-Alfvénic)Note. b mean ‐ field indicates the initial plasma β, i.e., the ratio of gas pressure to magnetic pressure. Bmean ‐ field is the initial magnetic ﬁeld strength in the 5.2 pc box.
%A,mean ‐ field indicates the initial Alfvén Mach number, and %s º vturb cs is the initial sonic Mach number.

turb

A

Figure 1. Polarimetric map (polarization vectors rotated by 90◦ to show inferred magnetic field orientation) of the L1527 disk from CARMA data with a0.′′ 39×0.′′ 31 beam. Fractional polarization vectors !3σ displayed. Contours are Stokes I data with levels of [−6, −4, −3, 3, 4, 6, 10, 20, 40, 60, 80, 100]×σ ,σ = 0.45 mJy beam−1 . Grayscale shows the polarized intensity !3σ . Outflows in the plane of the sky are marked by red and blue arrows.

10^6

5.544 GHz. We used the MIRIAD software package (Sault et al.
1995) to reduce the data. The polarization calibration followed
the standard process for CARMA (Hull et al. 2014). The phaseand polarization leakage calibrator for all tracks was 0510+180.
The preferred bandpass calibrator was 3C84, and 3C454.3 wasused when 3C84 was unavailable. For most tracks, the flux
calibrator was MWC349 with a calibration accuracy estimationof ∼15%, but only statistical uncertainties are considered inthis Letter. When this calibrator was not observed, the flux wasinterpolated from the observations of MWC349 in other tracks.
To maximize sensitivity, maps of the four Stokes parameters(I, Q, U , and V) were created using natural weighting. Fromthese, we derive the polarization position-angle (P.A.) andintensity maps. We also generated new maps of L1527 datafrom the TADPOL survey (Hull et al. 2014). The data include
five tracks between 2011 May and 2013 April in D and E arrays.
3. RESULTS

The 1.3 mm dust emission map of L1527 is presented in
Figure 1 and is consistent with the known edge-on disk (Tobin
et al. 2013b). The disk has been resolved previously at 3.4 mm
and 870 µm (Tobin et al. 2012) and also has been shown tohave Keplerian motion and a radius of 54 AU (Ohashi et al.
2014). Our observations are the first resolved detection of the

96 mJy, respectively), which is congruent with our measured
1.3 mm fluxes when taking account a 20% extrapolating andamplitude uncertainty. Based on this evidence, our observations
are dominated by disk emission of the L1527 system, with little
contamination from the large-scale envelope emission.
We detect dust polarization of the young disk over two
synthesized beams with an average polarization of 2.5% ± 0.6%
and a P.A. of 5◦ ± 5◦ measured counterclockwise from north,aligning well with the Stokes I elliptical Gaussian fitted P.A.
of 5.◦ 2 ± 0.◦ 4. The inferred magnetic field (with polarization
vectors rotated by 90◦ ) is shown in Figure 1. The morphologyof the inferred field is parallel to the disk axis, as is expectedfrom an edge-on toroidal field—uniform and aligned with the
disk. We compare a uniform field at a 5◦ P.A. (the same as
the dust emission) to the data and find a reduced χ 2 < 1.
The polarization fraction of the circumstellar disk of L1527 islarger than the 1.4% polarization fraction found in the faceon candidate disk of IRAS 16293-2422 B (Rao et al. 2014),
although the lower polarization fraction of IRAS 16293-2422
B may be due in part to beam-averaging; due to orientation,
an edge on toroidal field is less beam-averaged as the vectors
are more uniform. Our polarization percentage is similar to thetheoretically predicted 2%–3% polarization fraction found insimulations of magnetized disks (Cho & Lazarian 2007). On theother hand, observations of the disks of older T Tauri systems

SED of a protoplanetary disk

J. Menu et al.: TW Hya: multiwavelength interferometry of a transition disk
• TW Hya (Mstar = 0.6 M⊙, Teff = 4000 K)
MIR

Scattered Light(sub-)mm

star

1

2

3
4

a
b
d

c

Distance in AU
1 Turbulent Mixing (radial or vertical)

disk

10.35 mm

2 Vertical Settling
3 Radial Drift4 a) Stickingb) Bouncingc) Fragmentation with mass transferd) Fragmentation

10

100

3.0 mmALMA
VLTI/MATISSE

10 µm
2 µm

10 µm

EELT
JWST/MIRI

Fig. 1.— Illustration of the structure, grain evolution processes and observational constraints for protoplanetary disks. On
the left side we show the main grain transport and collision mechanism properties. The different lengths of the arrows
illustrate the different velocities of the different grains. On the right hand side, we show the areas of the disk that can beprobed by the various techniques. The axis shows the logarithmic radial distance from the central star. The horizontal
bars show the highest angular resolutions (left edge of the bars) that can be achieved with a set of upcoming facilities andinstruments for at the typical distance of the nearest star forming regions.

Menu et al. 2014

Testi et al. 2014

• The millimeter emission is thermal dust emission from the disk.

• How can wepolarizetheemission?
with respect
to the gas.
The thermal
force exerted ondustthem depends
a dimensionless number, which relates the stopping time to
not only on the relative motion
betweengas (NAOJ)
and dust, but
Akimasa
Kataoka

the orbital period ⌦K . The concept of the Stokes number isPolarization mechanisms
1. Alignment of elongated dust grains with magnetic fields
Magnetic Field

Linearpolarizatione.g., Lazarian and Hoang 2007

2. The self-scattering of thermal dust emission
Kataoka et al. 2015

3. Alignment of elongated dust grains with radiation fields
Tazaki, Lazarian et al. 2017
Akimasa Kataoka (NAOJ)

Dust is big in disks
0.1μm

1m

1mm

102-4kmdust opacity

510

amax=1 µm, κabs
amax=1 µm, κsca
amax=100 µm, κabs
amax=100 µm, κsca

410

κabs,sca [cm2/g]

1km

3

10

102

scattering> absorption

1

10

100
-1

10

10-2
10

-3

100

101

102
λ [µm]

Akimasa Kataoka (NAOJ)

103

104

Light source of scattering
IR scattered light
The circumstellar disk HD 169142: gas,

example (face-on, PI)

disk

Infraredradio scattered light(self-scattering)

Pohl et al. 2017

Figure 1. Left: J-band azimuthally polarized intensity image Q
in linear scale with annotations for the gap and ring structures.
to the star, r2 , to compensate for the stellar illumination drop-o
brightest pixel along the inner ring. The region masked by the cpoints towards left.

?

millimeter

Akimasa Kataoka (NAOJ)

Polarization due to scattering
incident light(unpolarized)
a dust grain

an observer

an observer
an observer
http://sites.sinauer.com/animalcommunication2e/chapter05.02.html

Akimasa Kataoka (NAOJ)

Polarization due to scattering
thermal dust emissionof other dust grainsa dust grain

The observer is you.

Horizontal Polarization(the line of sight isperpendicular to the planeof this slide)

Akimasa Kataoka (NAOJ)

Polarization due to scattering

Horizontal Polarization

Akimasa Kataoka (NAOJ)

Polarization due to scattering

Unpolarized

Akimasa Kataoka (NAOJ)

Polarization due to scattering

Unpolarized

Akimasa Kataoka (NAOJ)

Polarization due to scattering

Vertical Polarization

Akimasa Kataoka (NAOJ)

Protoplanetary disks

The highly asymmetric crescent-shaped dust
dust grains
zes to rocky structure revealed by the 0.44-mm ALMA conThe Astrophysical Journal Letters, 783:L13 (6pp), 2014 March
MEarth) within tinuum (Fig. 1) traces emission from millimeterL14-2 sized dust grains and is located between 45 and M. Fukagawa et al.
[Vol. 65,
ircumstellars is stymied 80 AU (T9 AU) from the star. The azimuthal
al drift and extent is less than one-third of the ring, with no
A IRS 48(2.4 mJy per beam) inintermediate detected flux at a 3s levelHD142527
U) (1 AU = the northern part (fig. S1). The peak emission
to the Sun), has a very high signal-to-noise ratio of ~390, andacquire high the contrast with the upper limit on the opposite
espect to the side of the ring is at least a factor of 130. The
problems for complete absence of dust emission in the north ofty collisions IRS 48 and resulting high contrast make theft velocities crescent-shaped feature more extreme than earlier
if particles dust asymmetries (10, 13). The spectral slope
rapidly drift a of the millimeter fluxes Fn [0.44 mm comA&A proofs: manuscript no. hd97048-gap
before they bined with fluxes at lower frequencies n (14)]BaFukagawa
al. 2013
van der Marel et al. 2013
Perez et al. 2014
l size. This is only 2.67 T 0.25
(Fn º n ), etsuggestingthat
st persistentgrains(15)
thethe disk of
Fig. 1.millimeter-sized
Dust continuum map
at 336
GHzdominate(890 !m) for
The Astrophysical Journal Letters, 820:L40 (5pp), 2016 April 1
Andrews et al.
A possible
0.44-mmcontinuum
However,temperaturetheHD 142527.
The
color scale emission.
shows the brightnesson12
uvclip/superuniform
MEM model
Novemberandmm lineon thelatter two=same
5, 10, The15,superuniform
anda logarithmic
scale.
contours
denoteT
ed pressure
gas traced
by Thethe23black
CO0.7
6-5
from
the
b executions.
HD
97048
total on-target integration time was ∼2 hr.
20 K,ALMA
while thedata
white
denotesthe5 " level. The
sizestaff.
of theAftersyntheere the dust
setoneindicates
a Keplerian
These
raw
data were
calibrated by disk
NRAOproHL
Tau
TW Hya 1.0
sized beam is shownat theleftcorrections
corner of fromthe imagewithwhite ellipse
applying
phasewater 1.0
vapor aradiometer
Fig. 2. Moment 0 (left) and 1 (right) maps in 13 CO1.0(upper) and C18 O
essure bump 00 file characteristic
of
a
gas
disk
with
an
inner
ı
the au)datawith
were atime-averaged
into 2 s integra(= 55 au ! 48
major-axis
of 0: 39 ! 0:00 34 measurements,
J = 3–2 (lower). The contours in the left panels show the 5 " levels.
12 PA of 57 .
tions andproblematic
antennasCOand 6-5times. The
an trap dust cavity aroundthe ﬂagged
centralforstar(Fig. 1B).
0.5 was calibrated
0.5
In the right0.5panels, the first moment maps are presented
for the emisbandpass response of each spectral window
6–10).
emission using
is detected
down
to a 20 AU
the observationsof J1058+0133.
Theradius,
amplitude scalesion detected above 5 ". The contours for the integrated intensity are
Cycle 0. The maximum
and minimum
baselines were380 m
was determined
andatJ1107–4449.
The
Millimeter/ which is consistent
withfrom
the J1037–2934
hot CO ring
30
AU
overplotted,
0.0
0.0 starting from 5 " and increasing by 5 "0.0steps. The crosscomplex gain responseof the lattersystem wascalibratedusing the to theand 20(14).
m, respectively,
andtherethecorresponded
eport a highThisfrequent
indicatesthatisindeed
still
some
in
each
panel
denotes the position of the central star. The synthesized
observations of J1103–3251. Although images 00.
Thelargestangular
scale
of
the
detectablecomponentof10
generated
from
these
data
are
relatively
freeof
artifactsandbeam size−0.5
is displayed with a white ellipse in each−0.5panel, and is 0:00 43−0.5 drop
imeter-sized CO insiderecover
the dust
hole, with a significant
the integrated ﬂux density of the target (1.5 Jy), foldingC
inALMA
this letter
consistedfour! 0:00 37 with a PA of 50ı for both 13 CO and C18 O.
additional density
observations
with~25
a higher
shortof theobservations
star of the reported
gasinsurface
insideofTof5density
AU.ofschedulingspacings
improves
theJuneimage toreconstruction.
the antenna
periodfrom2012
August.
The corre−1.0
−1.0
−1.0
GHz) blocks
con- over
The simultaneous
ALMA
line
and
continuum
To that end,
we calibrated
three archival
ALMA data
configured
to storedual
polarizations
inNovember
four separate
observations
ofno
TW doubt
Hya, from2012 May
2012
that thislator
can wasobservations
leave
about
the20,relative
20, and 2014 December 31, using 16, 25, and 34 1.0
antennas
0.5
0.0
−0.5
−1.0
1.0
0.5
0.0
−0.5
−1.0
1.0
0.5
0.0
−0.5
−1.0
spectralposition
windows
withadust.
bandwidthof 469 MHz
andwith
ust trapping
of
gas
and
spanningbaselines
from 15 to 375 m. The ﬁrst two observa- ∆α [arcseconds]∆α [arcseconds]∆α [arcseconds]
Figure 1. ALMA observations of dust and gas emission for the disks su
tions
had four 59athus
MHzchannel
wide
spectralwindows
centeredat MHzprovidingspacingof
0.122
disk. 3840 channels,
The observations
indicatethat
large
Figure 1. Synthesized image of the 870 μm continuum emission from the TW
Table 1. Left panels:vandust continuum
emission
scale) and dust br
333.8,
335.4,
345.8,
and
347.4
GHz.
The
latterhad
two
Andrews
et
al.
2016
ALMA
Partnership2015
der Plaset (coloral. 2016
Hya disk with a 30 mas FWHM (1.6 au) circular beam. The rms noise level is
Note
that
the
effective
spectralresolution(0.11 kms"1 ). 235
RS 48 [dismillimeter-sizedarein
an asymMHzgrains
windows(at distributed
338.2
and 349.4
GHz),
one 469MHz∼35is
μJy beam . The inset shows a 0 2 wide (10.8 au) zoom using an image
moment0map,
contours
start
and
are
spacedby
3σ,where σ is the rm
Fig.
2.MHz
Reconstructed
HD97048(24×18
for theband
7 data.
The intensity scale for−1all images is in units of Jy beam 1 . To highlightwithofﬁner
resolution
mas,ALMA
or 1.3×1.0
au, FWHMbeam).
"1
window (at 352.0 GHz), and one
1875
window (atimages
1
kms.
becauseof Hanninglower
a factorof #2 that(#0.2
kms the)micrometer1 pc = 3.1
× bymetricstructure,butthewassmall
small-scale
structure
we show (from left to right) images reconstructed with progressively smaller beams. The left panel shows the image
338.4 GHz).
J1037–2934
employed
as a gain calibrator,
color versionof this figure
is available
the clipping
online journal.)andTitanspreadand
3C throughout
279 (Mayfor
20),
Ceres
and ToJ0522-364
reconstructedusingsuperuniform
reconstructedimage
resulting infromsizedThe
grains
are
the
ring.
with a largesmoothing.
centralfrequencies
these
four
windows
are weighting. The central panel shows the superuniformly(Aweighted(November 20), or Ganymede and J0158+0133(December
31) k . Finally, the right panel shows the MEM model image. The di↵erence in dynamic range between the panels is due toall baselines
below 160
knowledge,
known
mechanism
thatfore inner 330.588,
disk our329.331,
andcalibrators.
342.400
GHz,
respectively,
served 342.883,
as theﬂux onlyor bandpass
thesefluxThelossweather
incurredbyclipping the shortest baselines for the central panel, and due to the smaller reconstructed beam for the right panel.
13
observations
wasexcellent,
with
PWV
levels
of
0.5–1
mm.
The
could
generate
thisseparation
inthedistribution
Mid-infrared
allowing us to combined
observemolecular lines of CO J = 3–2,
Image Properties for D
on-target integration time was 95 minutes. The basic
18
of
the
large
and
small
grainsisalong-lived
gasring inCthe
above. results
As a check,of
we thecompared
O J = 3–2, calibration
and CSwas
J as=described
7–6. TheCS obserof ⇡ 1200 and a RMS of 0.20 mJy beam 1 . We 2.3. ALMA Cycle
Target1 band 3 data R.A.a
Deca
the amplitudes from each individualdynamical
data set on range
overlappingpressure
bump
in
the
radialandazimuthal
diission atanvations will be spatial
reportedelsewhere.
The279
frequencies
and found exceptional
consistency.
shift quasars
all images3C
using
theandproper motion correction found in vanSν bThecalibrated
visibilities
from each observation
were shifted
rection.
The
reasonthat
dust
particles
gettrappedAU radius
or
Fig.
1.
IRS
48
dust
and
gas
observations.
The
Leeuwen(2007)
and
these
are
shown
in
Figs.
1
and
2
for
the
QSO J1924"2914
weretargetedasbandpass
calibrators,
whereasAkimasa Kataoka (NAOJ)
to account for the proper motion of the target and then(J2000)(J2000)(Jy)(
ally resolved in pressure bumps is their drift with respect to the
0.15

0.20

−1

0.00

0.02

0.04

0.06

0.08

wnloaded from www.sciencemag.org on June 6, 20130.10

∆δ [arcseconds]

0.05

0.00

0.01

0.02

Anisotropic thermal emission at mm wavelengths

0.03

0.04

self-scattering in a protoplanetary disk

Akimasa Kataoka (NAOJ)

self-scattering in a protoplanetary disk

Akimasa Kataoka (NAOJ)

Theoretical prediction
P[%]fraction [%]Polarization

2
StokesI (continuum)
I [mJy/arcsec
]

3

3.00

10

ring @ 170AU, d=140pc

2102[arcsec][arcsec]

1
0

101

-1
-2

λ=870µm-2-1

01[arcsec]

2

2.50

1

2.00

0

1.50

-1

1.00

-2

0.50

λ=870µm

100

0.00
-2

2

-1

0
1
[arcsec]2

The polarization degree is ashigh as 2.5%→detectable with ALMA
Anisotropy → net polarization
Akimasa Kataoka (NAOJ)

Kataoka, et al., 2015

ALMA observation of HD 142527
flip

100 AU•

100 AU

Flip of polarization vectors•

Change of the direction of radiative flux - evidence of the selfscattering (Kataoka et al. 2015)
Kataoka, et al., 2016b
Akimasa Kataoka (NAOJ)

Conditions of dust grains for polarization
・For efficient scattering

λ=870 µm (ALMA Band 7)
1.4(grain size) >~ λ1.2
1(grain size) <~ λThere is a grain size which
contributes most to thepolarized emission

P・For efficient polarization

P90

1.4

P
ω
Albedo

1.2
1

0.8

0.8

0.6

0.6

0.4

0.4

0.2

0.2

0

0

-0.2
0.001

-0.2
0.01
0.1
Maximum grain size [cm]grain size [cm]If (grain size) ~ λ/2π, the polarized emission due
to dust scattering is the strongest
Akimasa Kataoka (NAOJ)

1

d the albedo ! = sca /(abs + sca ) as a function of maximum grain size.
a 3.5 . The wavelengths are assumed to be 1.3 mm for the left panel andgrain size which has the most efficient polarization by 90 scattering.

0
he
2)
).

Grain size constraints by polarization
1.2

Expected polarization degree (scalable)

1

Pω

0.8

3.1 mm0.87 mm (Band 3)(Band 7)7 mm
(Band 1)0.34 mm(Band 10)

0.6
0.4
0.2
0
0.001

0.01
0.1
Maximum grain size [cm]1
Kataoka, et al., 2015

Multi-wave polarization → constraints on the grain size
Fig. 4.— The polarization
times
Akimasa
Kataoka the(NAOJ)albedo P ! against the max-

2.7 mm. It is in
ed from ALMA
nership: Brogan
the typical ISM
ken as evidence
et al. 2014), almple, Ricci et al.
e obtained withally thick. Somelly resolved dish shows β ∼ 0continuum peakogan et al. 2015,
dex β is sensigrains. Indeed,
spectral energyh β ∼ 1 in theto only 2.5 µm;
hollow spheres
ed in our modelTau disc have aens of microns).
veraged) opacity
ar and/or part ofhis possibility isor the relativelys natural to ask
hat matches thecause the key ton degree of thelimit), and thiss. For example,a), the polarizain the scattering
ion fraction but
0.87 mm for all
hes a (negative)m (see the rightself-scattering in an inclined disk

See also Kataoka et al. 2016aof the disc closer to the observer (the right half) brighter. The polarization fraction is, however, higher on the far side (especiallytowards the outer part of the disc) because the polarization degreeof the scattered light is higher for backward scattering than forforward scattering (see Fig. 6). The most striking difference between this case and the Rayleigh scattering case shown in Fig. 5lies in the polarization direction. The difference comes from thepolarization reversal in the large grain case, which yields an intrinsic (or face-on) polarization direction in the radial (as opposed toazimuthal) direction and an inclination-induced polarization along
the major (rather than minor) axis. The interplay between the intrinsic and inclination-induced polarization leads to polarization
directions in the region of high polarized intensity (the most easily

Akimasa Kataoka (NAOJ)

Yang, Li, et al. 2016(disk, edge-on view)

Figure 7. Scattering-induced polarization by large grains. As in Fig. 5,plotted are the polarized intensity (colour map) and polarization vectors(line segments, with length proportional to the polarization fraction). Notethe strong asymmetry with respect to the major axis in both the polarized
intensity and the polarization vectors. The polarization along the major axis
in the central region is due to polarization reversal, which may be a robust
indicator of scattering by large, mm/cm-sized, grains. The near side of thedisc is on the right.

i=45°

HL Tau pol. - prediction
λ=870µm•i = 47° (ALMA Partnership 2015)•

The polarization vectors are parallel to the minor axis
Kataoka, et al., 2016a (see also Yang et al. 2016)
Akimasa Kataoka (NAOJ)

HL Tau polarization with ALMA

100 AU•

100 AUWe find the azimuthal polarization vectors at 3.1 mm wavelength
Kataoka, et al., 2017
Akimasa Kataoka (NAOJ)

HL Tau polarization

polarization
AASTEXAAST
wavelength-dependent
polarization
EX wavelength-dependent

100 AU

100 AUdata from Stephens et al., 2014

Kataoka, et al., 2017

mparisonof the polarization
images between= 1.3 mm=(CARMA
Stephens etal. 2014)= 3.1
e 2. Comparisonof the polarization
images between
1.3 mm (CARMA
Stephens
et andal. 2014)an• The polarization vectors at 1.3 mm are parallel to the minor axis
bservation).
The ALMA
is smoothed
to have thebeamsizebeamof CARMA
the where
beam ts
A, this observation).
Theimage
ALMA
image is smoothedto samehave thesame
size of where
CARMA
ith0.56
the00 PA
79.5PAdegrees.
color The
scalecolor
represents
the polarized
the grey⇥
withoftheof 79.5The
degrees.
scale represents
the intensity
polarized while
intensity
whilecontours
the greyrepr
con
mission. emission.
levelsof thegreyofcontours(3,3.16, 12,
24,
96)in
⇥ the
2.1 mJy/beamfor the CAf•The
I whereThe
polarization
vectorsatmmare
azimuthaldirectionntinuumThelevelsthegrey arecontours
are(3,48,
6,
12,
24,
48,
96)
⇥ II =whereI = 2.1 mJy/beam
4.9 mJy/beam
ALMA data.
nd
ALMA data.
I = 34.9 mJy/beamwavelength-dependent polarization in mm range
Akimasa Kataoka (NAOJ)

ALMA observation: HL Taue Astrophysical Journal Letters, 808:L3 (10pp), 2015 July 20

The Astrophysical Journal Letters,
808:L3 (10pp),
ALMA Partnershipet 2015
al. July 205), the Class 0 disk candidate of NGC 1333 IRAS 4A
x et al. 2015), the Herbig AE late-stage protoplaney disk HD 142527 (Kataoka et al. 2016), and the disk
didate of the high-mass protostar Cepheus A HW2
nández-López et al. 2016). Polarization toward diskse also been detected at mid-infrared wavelengths of
10.3, and 12.5 µm (Li et al. 2016, 2017). However,arized emission at mid-infrared wavelengths can occur
to absorption, emission, and sometimes scattering,
sing difficulty in interpreting the polarization morlogy.
espite these detections, the polarization morpholousually were not consistent with what would be exted from magnetically aligned dust grains. In particuStephens et al. (2014) used the Combined Array forearch in Millimeter-wave Astronomy (CARMA) tosure the 1.3 mm polarization morphology in HL Tau.2
morphology was inconsistent with grains aligned2015), the Class 0 disk candidate of NGC 1333 IRAS 4A
h the commonly-expected toroidal magnetic fields(Cox et al. 2015), the Herbig AE late-stage protoplanearization/E-field vectors distributed radially in thetary disk HD 142527 (Kataoka et al. 2016), and the disk). Instead, the E-vectors were oriented more or lesscandidate of the high-mass protostar Cepheus A HW2
ng the minor axis of the disk. Kataoka et al. (2015,(Fernández-López et al. 2016). Polarization toward disks
6) and Yang et al. (2016) suggested that the polarizahave also been detected at mid-infrared wavelengths ofmorphology is actually consistent with that expected
8.7, 10.3, and 12.5 µm (Li et al. 2016, 2017). However,m self-scattering (also see Pohl et al. 2016; Yang etemission at mid-infrared wavelengths can occur2017). Indeed, several disks where polarization polarized
is
due
to
absorption,
emission, and sometimes scattering,ected show consistency with the polarization morcausing difficulty in interpreting the polarization morlogy expected from self-scattering rather than grains
phology.
ned with the magnetic field. However, except for
ALMA observations of HD 142527 (Kataoka et al. Despite these detections, the polarization morphologies usually were not consistent with what would be ex6) and HL Tau (Kataoka et al. 2017), the published
pected from magnetically aligned dust grains. In particuervations are too coarse to resolve more than a few
lar,Stephens
et al.
(2014)
used theCombined
ependent
beams
the
disk,
it difficult), and (c) show
2.9,across
1.3, and0.87
mm making
ALMA continuum
imagesof HL Tau.
Panel(d) showsthe 1.3mm PSFArrayfor the forsame FOV as the otherResearchinMillimeter-wave
Astronomy(CARMA)toistinguishbetweenscattering
and
other
polarization
t with an enlarged view of the inner 300 mas centered on the PSF’s peak (the other bands show similar patterns). Panels (e) and (f) show themeasure the 1.3 mm polarization morphology in HL Tau.
xhanisms.
maps resulting from the combination of the 1.3 and 0.87 mm data. The spectral index (α) map has been masked where α αerror < 4 . The
The morphology was inconsistent with grains aligned
he high-resolution
ALMAof Table
HD 142527
hown
in the lower leftof eachobservations
panel; also see
1. The range of the color bar shown for panel (b) at 1.3 mm corresponds to −2× rms towith the commonly-expected toroidal magnetic fields
Kataoka
et al. (2016)
polarization
many
singFigure
the values
Tableresolved
1. The color
scales forforpanels(a), (top,(c), and (e) are thesame distributed
except using radiallythe values
1. in
ALMA
polarimetricobservations
at 3Stephensmm(polarization/E-field
vectors
in oftherms and image peak
et
al.
2017
of independent
resolution
elements
acrossthedisk.
espective
wavelength
in
Table
1.
Kataoka et al. 2017), 1.3 mm (middle), and 870 µm disk).
(bottom),
Instead, the E-vectors were oriented more or lesspolarization
wasradialthroughout
most of thedisk, (i.e.,
where the red
vectors
show
the >3 polarization
morphology
along
the minor axis of the disk. Kataoka et al. (2015,
have notrotated).
Vectorare linearly
proporch isvectors
expectedfor beengrainsalignedwithlengths
a toroidal
field,
2016)
andYang etdisk
al. (2016)
suggestedpolarizational
to
P
.
The
color
scale
shows
the
polarized
intensity,
which
towardthewasmorphology
from ra- theisaverage
itionof theeachedges
point
moved tochanged
the nearest
geometry
over thatlargethescales.
However, the bestmasked to only show 3 detections. Stokes I contours in each
panel
tion
morphology
isactually
consistent
with
that
expected
Akimasa
Kataoka
to areazimuthal,is 50,
morewithscatterum(orshown
minimumdarkrings).
Toavoid
ﬁt ellipses have
theircenters(NAOJ
offsetfellow)
with respect to the peak offor which[3, 10, for25,
100,consistent200,
325, 500,
750,
1000]
⇥ , where
I

ALMA Partnership 2014

Kataoka et al. 2017

Polarization mechanisms
1. Alignment of elongated dust grains with magnetic fields
Magnetic Field
Thermal emission

Linearpolarizatione.g., Lazarian and Hoang 2007

2. The self-scattering of thermal dust emission
Kataoka et al. 2015

3. Alignment of elongated dust grains with radiation fields
Tazaki, Lazarian et al. 2017
Akimasa Kataoka (NAOJ)

Alignment with radiation fields
a~100 µmaligned withrad. fields

azaki et al.

Figure 5. Timescales relevant to RAT alignment. Top and bottom panels show the an of E-vector is plotted as the white bar. Left and right panels represent mid-infrared
panels correspond to the two diﬀerent locations in the disk, (R, z) = (50 au, 0 au), a
vely. The dust grains are assumed to be magnetically poor ( f p = 0.01 and φ
sp = 0). the timescale of the gaseous damping (trepresentgas ) and the RAT alignment times−3 and f-parameterareassumed
to
be
α
=
10
=
0.5,
respectively.
−Jhigh−J
precession timescale (t). Green and blue lines show the Larmor precession tirrad, p

Tazaki, Lazarian et al. 2017

inclusions ( f p = 10%, φsp = 3%, Ncl = 2 × 103 ), respectively. The dashed line in th
grain size does not strongly aﬀect on the resultant polarization
Akimasa Kataoka (NAOJ)

Polarization mechanismsalignment with B-fields• Toroidal magnetic
fields are assumed

self-scattering• Inclination-induced
scattering -> parallelto the minor axis
• Grain size is a ~λ/2π:
strong wavelength
dependence
Akimasa Kataoka (NAOJ)

alignment with radiation• Grains are needed tobe big (~>100um)• Radiation gradient isin the radial direction.

Wavelength dependencealignment with B-fields

self-scattering

the Class 0 disk candidate of NGC 1333 IRAS 4A
al. 2015), the Herbig AE late-stage protoplanek HD 142527 (Kataoka et al. 2016), and the disk
ate of the high-mass protostar Cepheus A HW2
ndez-López et al. 2016). Polarization toward disks
so been detected at mid-infrared wavelengths of
3, and 12.5 µm (Li et al. 2016, 2017). However,ed emission at mid-infrared wavelengths can occur
absorption, emission, and sometimes scattering,difficulty in interpreting the polarization mory.
te these detections, the polarization morpholoually were not consistent with what would be exfrom magnetically aligned dust grains. In particuphens et al. (2014) used the Combined Array for
h in Millimeter-wave Astronomy (CARMA) toe the 1.3 mm polarization morphology in HL Tau.2
orphology was inconsistent with grains aligned2015), the Class 0 disk candidate of NGC 1333 IRAS 4A
he commonly-expected toroidal magnetic fields(Cox et al. 2015), the Herbig AE late-stage protoplanezation/E-field vectors distributed radially in thetary disk HD 142527 (Kataoka et al. 2016), and the disk
nstead, the E-vectors were oriented more or lesscandidate of the high-mass protostar Cepheus A HW2
he minor axis of the disk. Kataoka et al. (2015,(Fernández-López et al. 2016). Polarization toward disks
nd Yang et al. (2016) suggested that the polarizahave also been detected at mid-infrared wavelengths ofrphology is actually consistent with that expected
8.7, 10.3, and 12.5 µm (Li et al. 2016, 2017). However,lf-scattering (also see Pohl et al. 2016; Yang etemission at mid-infrared wavelengths can occur
7). Indeed, several disks where polarization polarizedisdue to absorption, emission, and sometimes scattering,d show consistency with the polarization morcausing difficulty in interpreting the polarization mory expected from self-scattering rather than grains
phology.
with the magnetic field. However, except for
MA observations of HD 142527 (Kataoka et al. Despite these detections, the polarization morphologies usually were not consistent with what would be exnd HL Tau (Kataoka et al. 2017), the published
pected from magnetically aligned dust grains. In particutions are too coarse to resolve more than a fewlar, Stephens et al. (2014) used the Combined Array forndent beams across the disk, making it difficult
Research in Millimeter-wave Astronomy (CARMA) tonguish between scattering and other polarization
measure the 1.3 mm polarization morphology in HL Tau.
isms.
The morphology was inconsistent with grains aligned
high-resolution ALMA observations of HD 142527
with the commonly-expected toroidal magnetic fields
aoka et al. (2016) resolved polarization for many
Figure 1.
ALMA polarimetric observations at 3 mm
(top,(polarization/E-field
vectors
distributed
ndependent
elements
acrossdisk.
Akimasa
Kataoka radially(NAOJ) in the
Kataoka
et al.resolution2017), 1.3 mm(middle),and the870 µm(bottom),disk). Instead, the E-vectors were oriented more or lessself-scattering

mixturealignment with radiationalignment with radiation

Stephens et al. 2017 (see also Kataoka et al. 2017)

Total polarization fraction
AASTEX wavelength-dependent polarization

100 AU

5100 AU

integrating

Figure 2. Comparison of the polarization images between= 1.3 mm (CARMA Stephens et al. 2014) and= 3.1 mm
(ALMA, this observation). The ALMA image is smoothed to have the same beam size of CARMA where the beam size is
0.6500 ⇥ 0.5600 with the PA of 79.5 degrees. The color scale represents the polarized intensity while the grey contours represent
the continuum emission. The levels of the grey contours are (3, 6, 12, 24, 48, 96) ⇥ I where I = 2.1 mJy/beam for the CARMA
data and I = 34.9 mJy/beam ALMA data.

no polarization
0.5%

<0.1%

We can extract the self-scattering components
Akimasa Kataoka (NAOJ)

HL Tau polarization

Kataoka, et al., 2017
The maximum grain size is ~ 70 µm
Akimasa Kataoka (NAOJ)

Star and disk formation
Molecular
cloud cores

Timescale~104-6 years

Protostar andprotoplanetary disk

~106-7 years~0.1 pc
Spatial scale=20,000 AU~100 AU~ 200 arcsec~1 arcsec

magnetic fields
Key physics
or turbulence?

grain growth

Akimasa Kataoka (NAOJ)

A.Isella10µm polarization
Magnetic Field in AB Aur Disk

-0.5

Surface brightness (log[Jy/arcsec2])
0.0
0.5
1.0
1.5
2.0

-200

-100

Offset (AU)
0

100

•

200

-100

2%
04h 55m 45.95s

45.85sRight Ascension (J2000)

45.75sDan Li, et al., 2016

Figure 1. The polarization map of the AB Aur protoplanetary
disk at 10.3 µm. Displayed in color is the total intensity
image of
Akimasa Kataoka (NAOJ)

1

-0.5

-200

0

30° 33′ 03″

2

120

0

0.5

04″

Outer part - the selfscattering-induced
polarization

tion at 1.6 µm (i.e., Fig. 3 inRing
Hashgap
implying that, at least for the outerDfrom scattering probably contributes
E
total polarization we observed there
pected result, contradicting most, i
studies on mid-IR polarization P3in Y
ization due to scattering is found, or aligible near 10 µm (e.g., NAitken et al
2000; Aitken et al. 2002;
Barneset al
Inner ringE
To test our conclusions that the ob
0.5
0
0
-0.5
-1
of the 0.5
protoplanetary
disk
of
AB
A
R.A. offset (arcsecond)
dichroic emission and scattering, we
Hashimoto
al.,
2011
10
(mJy/arcsec)
transfermodels ofetthe
disk
that
take
of these polarization mechanisms in t

Dec. offset (arcsecond)
-0.5
0
0.5

•

Offset (AU)and the empirical relation between a
AB Aur @ 10 µm
tion and the optical depth (Smith et
200• Inner part - grains are aligned• Outerthelevelself-scatteringmatepartthat -thisof visual extinct
polarization
values of ∼0.04% at 10.3
with poloidal B-fields at
inducedpolarization
The Astrophysical Journal
2011 March 10 value (0.44%).
lessLetters,
than729:L17
the(6pp),observed
05″ surface
100
The centrosymmetric component
AU
cf)
NIR
polarization
Aur’s
disk
remarkably
simi0
100 outer50
0-50is -100
-150 10050
1Declination (J2000)

06″

(ISM)
(Acke
et al. are
2004;aligned
Mariñas et a
Inner
part
- grains
ing this conclusion is that the visua
with
B-fields
at (Roberge
ABpoloidal
Aur is only
0.25 magthe interstellar extinction law fromsurface

Total

Current understandings
1µm

10µm

2

100µm

1mm

2015), the Class 0 disk candidate of NGC 1333 IRAS 4A(Cox et al. 2015), the Herbig AE late-stage protoplanetary disk HD 142527 (Kataoka et al. 2016), and the disk
candidate of the high-mass protostar Cepheus A HW2(Fernández-López et al. 2016). Polarization toward disks
have also been detected at mid-infrared wavelengths of
8.7, 10.3, and 12.5 µm (Li et al. 2016, 2017). However,polarized emission at mid-infrared wavelengths can occur
due to absorption, emission, and sometimes scattering,causing difficulty in interpreting the polarization morphology.
Despite these detections, the polarization morphologies usually were not consistent with what would be expected from magnetically aligned dust grains. In particular, Stephens et al. (2014) used the Combined Array for
Research in Millimeter-wave Astronomy (CARMA) to2
measure the 1.3 mm polarization morphology in HL Tau.
The morphology was inconsistent with grains aligned2015), the Class 0 disk candidate of NGC 1333 IRAS 4A
with the commonly-expected toroidal magnetic fields(Cox et al. 2015), the Herbig AE late-stage protoplane(polarization/E-field vectors distributed radially in thetary disk HD 142527 (Kataoka et al. 2016), and the diskdisk). Instead, the E-vectors were oriented more or lesscandidate of the high-mass protostar Cepheus A HW2along the minor axis of the disk. Kataoka et al. (2015,(Fernández-López et al. 2016). Polarization toward disks
2016) and Yang et al. (2016) suggested that the polarizahave also been detected at mid-infrared wavelengths oftion morphology is actually consistent with that expectedfrom self-scattering (also see Pohl et al. 2016; Yang 8.7,
et 10.3, and 12.5 µm (Li et al. 2016, 2017). However,
emission at mid-infrared wavelengths can occur
al. 2017). Indeed, several disks where polarization polarizedisdue to absorption, emission, and sometimes scattering,detected show consistency with the polarization morcausing
difficulty
in interpreting the polarization morphology expected from self-scattering rather than grains
phology.
aligned with the magnetic field. However, except for
Despitethese
detections,the polarization morpholothe ALMA observations of HD 142527 (Kataoka et al.
gies usually were not consistent with what would be ex2016) and HL Tau (Kataoka et al. 2017), the published
pected from magnetically aligned dust grains. In particuobservations are too coarse to resolve more than a fewlar, Stephens et al. (2014) used the Combined Array forindependent beams across the disk, making it difficult
Research in Millimeter-wave Astronomy (CARMA) toto distinguish between scattering and other polarization
measure the 1.3 mm polarization morphology in HL Tau.2
mechanisms.
The morphology was inconsistent with grains aligned
The high-resolution ALMA observations of HD 142527
2015), the Class 0 disk candidate of NGC 1333 IRAS 4A
with the commonly-expected toroidal magnetic fields
by Kataoka et al. (2016) resolved polarization for many
(Cox et al. 2015), the Herbig AE late-stage protoplane(polarization/E-field vectors distributed radially in the
10s of independent resolution elements across the disk.
tary disk HD 142527 (Kataoka et al. 2016), and the diskdisk). Instead, the E-vectors were oriented more or less
The polarization was radial throughout most of the disk,
candidate of the high-mass protostar Cepheus A HW2
along
the
minor
axis
of
the
disk.
Kataokaetal.
(2015,
which is expected for grains aligned with a toroidal field,(Fernández-López et al. 2016). Polarization toward disks
2016) and Yang et al. (2016) suggested that the polarizabut toward the edges the morphology changed from rahave also been detected at mid-infrared wavelengths oftionmorphology
isactually
consistent
with
that
expected
dial to azimuthal, which is more consistent with scatter8.7, 10.3, and 12.5 µm (Li et al. 2016, 2017). However,from self-scattering (also see Pohl et al. 2016; Yang eting. Models in Kataoka et al. (2016) found that scatterpolarized emission at mid-infrared wavelengths can occur
al. 2017). Indeed, several disks where polarization ising can broadly reproduce the features observed in partsdue to absorption, emission, and sometimes scattering,detectedshow
consistency
withthepolarization
morof the disk – especially where the polarization orientacausing
difficulty in interpreting the polarization morThe Astrophysical Journal, 832:200 (8pp), 2016 December phology
1
Fernández-López
et al.
expected from self-scattering rather than grains
tions change sharply – but not everywhere. A complete
phology.
alignedwiththemagnetic
field.
However,
exceptforunderstanding of this interesting case is still missing.
Table 1
Astrophysical Journal, 832:18 (9pp), 2016 November 20
Li et al.
ALMAof HD 142527 (Kataoka et al. Despite these detections, the polarization morpholoParameters
Cepheus 1observations
mm Continuum Sources
HL Tau is one of the brightest Class I/II in thesky theatof thegies usually
were not consistent with what would be ex2016) and HL Tau (Kataoka et al. 2017),
the publishedc(sub)millimeterpolarization
P%bSource wavelengths,
R.A. and thus theDecl.
Stokes I Peak
Stokes I Flux
Pa
pectedP.A.
from magnetically aligned dust grains. In particu−1
observationsaretoocoarseto resolve
main-sequence The
stars of
2–4M
)
at
the
distanceof144
pc
can be determinedwith (mJy beam )J2000 at high resolution
J2000
(mJy)
(mJy) more than(%)a fewe
circumstellar
disk HD 169142: gas, dust and planets acting in concert?
5 morphology
lar,Stephens
et al. (2014) used the Combined Array forindependent beams across the disk, making it difficult
reasonable integration
times.
et62 al.
(2017)
folWarf et al. 2003). At 4±1 Myr old, this source still shows
01¢49.
60
22h56 m17.sKataoka
989423±10863±209±1
2.0±0.4 Research
57±6 in Millimeter-wave Astronomy (CARMA) to
HW2
to distinguishbetweenscattering andother polarization
lowed up onHW3c
the Stephensetm17.
al.s 976(2014) observations
with
−7
−1
22h56
62 01¢46. 10
68±10160±6
L
L
L
measure the 1.3 mm polarization morphology in HL Tau.
ence of signiﬁcant accretion (∼10 Meyr ; DeWarf
mechanisms.
3 mm observations of HL Tau. Surprisingly, they foundThe morphology was inconsistent with grains aligned
l. 2003; Tang et al. 2012). AB Aur is surrounded by aNotes.
that the polarization
morphology was azimuthal, whichThe high-resolution ALMA observations of HD 142527
awith the commonly-expected toroidal magnetic fields
Polarized
intensity
ﬂux.
byKataokaetal.
(2016)
resolved
polarizationformanysuggests grainsaligned with their long axes perpendicub
minent disk, with mid-IR and 1.3 mm dust emission
Figure1.
ALMApolarimetricobservations
at
3
mm
(top,
(polarization/E-field
vectors distributed radially in the
Fraction of polarized emission (percentage average).
10s of independent
resolution elements across the disk.
lar to the radiation
field, as predicted by Tazaki et al.
c
Kataoka et al. 2017), 1.3 mm (middle), and 870 µm disk).
(bottom),
Position angles of the polarized emission are measured counterclockwise.
Instead, the E-vectors were oriented more or lesscted out to ∼280 au and CO line emission detected out toThepolarization
wasradialthroughout
most
of
the
disk,
where the red vectors show the >3 polarization morphology (i.e.,(2017). Henceforth, we will call this grain alignment
along
the
minor
axis
of the disk. Kataoka et al. (2015,
expectedalignedVector
withlengths
a toroidal
field, proporhave for
not grains
been rotated).
are linearly
0 au from the star (Mariñas et al. 2006; Tang et al. 2012).
mechanism “alignment with the radiation anisotropy.”which isvectors
2016)
tionalthe
to Pedges. The color
scale shows thechanged
polarized from
intensity,
whichandis Yang et al. (2016) suggested that the polarizabut toward
the morphology
raThe very di↵erent polarization morphologies observed
oth CO and near-IR scattered-light images, the disk is richmasked
to
only
show
3
detections.
StokesI
contours
in
each
panel
tion morphology is actually consistent with that expecteddial to azimuthal,
which is more consistent with scatterat 1.3 mm (0.00 6 resolution, Stephens et al. 2014) and 3 mm
are shown for [3, 10, 25, 50, 100, 200, 325, 500, 750, 1000] ⇥fromI , where
self-scattering (also see Pohl et al. 2016; Yang etmorphological features such as spiral arms and gaps,
ing. Models
in Kataoka et al. (2016)
found
that
scatter1 for(0.00 4 resolution, Kataoka et al. 2017) suggest that the
3 mm,
1.3 mm,and 870 µm,
I is 44, 154, and 460 µJy bm
al. 2017). Indeed, several disks where polarization ising
canbroadly
reproducethefeaturesobservedinparts
respectively.
gesting a dynamical disk environment and, perhaps,morphology of the polarization emission is strongly dedetectedshow consistency with the polarization morof the disk – especially where the polarization orientapendent on the wavelength. This Letter presents ALMA
oing planet formation (Piétu et al. 2005; Hashimoto
phology expected from self-scattering rather than grains
tions change
but not everywhere. A complete
observations at both 1.3 mm and 870 µm at resolutionsof 0.00 3sharply
and 0.00 4,– respectively.
. 2011; Tang et al. 2012). Previous observations at various
understanding of this interesting case is still missing. aligned with the magnetic field. However, except for
the ALMA observations of HD 142527 (Kataoka et al.
HL Tau is one of the brightest Class I/II in the sky atelengths gave a fairly consistent disk inclination of 27°2016) and HL Tau (Kataoka et al. 2017), the published(sub)millimeter wavelengths, and thus the polarization
ere 0° corresponds to pole-on), with the major axis of theobservations are too coarse to resolve more than a few
morphology can be determined at high resolution withindependent beams across the disk, making it difficult
oriented at a position angle (P.A.) of 70° (measured E
reasonable integration times. Kataoka et al. (2017) folto distinguish between scattering and other polarization
lowed up on the Stephens et al. (2014) observations withm N) (Piétu et al. 2005; Tang et al. 2012; Rodríguez
mechanisms.
3 mm observations of HL Tau. Surprisingly, they found. 2014). H-band (1.6 μm) polarization of the AB Aur diskthat the polarization morphology was azimuthal, which The high-resolution ALMA observations of HD 142527
by Kataoka et al. (2016) resolved polarization for manysuggests grains aligned with their long axes perpendicubeen imaged by Hashimoto et al. (2011), showing a clear
1.
ALMA
polarimetricobservations
3 mm (top,10s of Figure
independent
resolution
elements
across theat disk.
lar to the radiation field, as predicted by Tazaki et al.
Kataoka et al. 2017), 1.3 mm (middle), and 870 µm (bottom),rosymmetric pattern indicative of scattering, as expected at
The polarization
wasradialthroughout
most of thedisk, (i.e.,
where the red
vectors
show
the >3 polarization
morphology(2017). Henceforth, we will call this grain alignment
e short IR wavelengths.
is expected
forbeengrainsalignedwithlengths
a toroidal
field, proporhave notrotated).
Vectorare linearlymechanism “alignment with the radiation anisotropy.” which vectors
tional to
The colorshows the changed
polarized intensity,
but toward
theP .edges
the scalemorphology
from ra-which is
The very di↵erent polarization morphologies observed
he paper is organized as follows. Section 2 describes ourmasked to only show 3 detections. Stokes I contours in each panel
00
dial
to
azimuthal,
which
is
more
consistent
with
scatterFigure 2. Left: polarimetric map (polarization E-vectors) of theat
CepheusAHW2
structure. Fractionalpolarization
vectorsover33s
displayed. Black
1.3 mm (0.disk-like
6 resolution,
Stephens
et al. red
2014)
and
mm
are shown for [3, 10, 25, 50, 100, 200, 325, 500, 750, 1000] ⇥ I , whereacquisition and reduction, with results presented ining.
in 154,
Kataokaet µJyal. bm(2016)
found
scattercontours are Stokes I data with the same levels as in Figure 1. Green
correspond toKataoka
the VLA Cband
emissionshowingthat
the radiothejetat −6,Models−3, 3,is 44,
1 for(0.00contours
4 resolution,
et continuumal. 2017)
suggestand 460
3 mm,that
1.3 mm,and 870 µm,
Ithe6, 10, 20, 40, 80, 100, and 140 times the rms noise level of the 6 cm radio map, 28 m Jy beam-1) associated with the HW2 massive protostar. The color scale
ing showscanrespectively.
broadly reproduce the features observed in partsion 3. Disk models are presented in Section 4. The
Figure 1. Polarization map of the AB Aur protoplanetary disk at 10.3 μm.
morphology
theobservations
polarization
emissionstronglyde(gray) and VLAof(green)are shownat the bottomisleft
corner. Right:
same map as inpolarized intensity over 3s . The synthesized beam of both CARMA
of
the
disk
–
especially
where
the
polarization
orienta2
Displayed
in
color
is
the
total
intensity
image
of
the
disk,
superimposedbypendentonthewavelength.
This
Letterpresents
ALMA
left panel but including orange vectors between 2s and 3s . The polarized intensity (color scale) also shows emission over 2s .
ications 1.
of ourare discussed
in Section
5, with
our image Q in logarithmic scale for better visualization. Right: Q ⇥ r
FigureLeft:study
J-bandazimuthally
polarized
intensity
tions change
sharply
but not everywhere. A complete
observations at both 1.3 mm and 870 µm at resolutionsof 0.00 3 and0.00 4,–respectively.
white contours of polarized intensities at 20, 40, 80, 160, 320, and 640 mJy
ngs
summarized
in Section
6.
nlinearscale withannotations
for the gap and ring structures.
pixel
is ismultiplied
the squareof its distance
4.2.1. Uniform Magnetic Field Model
4.2.2. Toroidal Magnetic Field Model understanding of this interesting case is still missing.
. Each image
polarization
vectorderived fromwith
an apertureof 3×3 pixels
arcsec−2Each
2
HL
Tau
is
one
of
the
brightest Class I/II in the sky at
the original
image.
Polarization
only plotted
where the signal-toto the star, r , to compensate for the stellar illumination in
drop-o↵withradius.
Allvectors
flux arescalesare normalized
to half of the
The ﬁrst model that we test is one with grains aligned with a
The second model that we test is a simple one, (sub)millimeterwith grains
wavelengths, and thus the polarization(S/N) is higher
than 150 in by
the thetotal intensity
image, North
yielding isa up, Eastaligned with a toroidal magnetic ﬁeld. Toroidal ﬁelds are
uniform magnetic ﬁeld threading the disk-like structure
brightest pixel along the inner ring. The region masked by noise
the ratio
coronagraphis indicatedgray circle.
morphology can be determined at high resolution withproposed for MRI (magneto-rotational instability) dominatedapproximately along its major axis, which would cause amaximum uncertainty in the degree of polarization (p) of ∼1%. Near the disk
2. OBSERVATIONSAND DATA REDUCTION
pointstowards left.
disks of low-mass protostars (e.g., Cho & Lazarianreasonable2007). It is integration times. Kataoka et al. (2017) foldistribution of polarization vectors perpendicular to the ﬁeld
center, where the highest S/N is reached, the typical uncertainty in p is ∼0.1%.
lowed
up on the Stephens et al. (2014) observations withtherefore an appropriate model to test against the
CARMA(i.e.,
northeast–southwest,
along
the
minor
axis).
This
distribuThe angular resolution of the observation is 0 35, as shown in the bottom-left
We observed AB Aur on 2015 February 6 UT using the3
mm observations of HL Tau. Surprisingly, they foundobservations.
tion of vectors has the same morphology as the large-scalecorner.
The
upper-leftsketchshows
theprojected
spin
axis(thick
line)
and
that
the
We ﬁt the observations (orientation of the polarizationpolarization morphology was azimuthal, which
m band dual-beam polarimetry mode of CanariCam. We
850 m m polarization observations (Matthews et al. 2009),

scattering ofphotons ofcentral star

Alignmentwith B-field?

Alignment with rad-fields

scattering (?)

scattering

Stephens et al. 2017 (see also Kataoka et al. 2017)

Pohl, et al., 2017

Li, et al., 2016

Fernández-Lopez et al., 2016

Akimasa Kataoka (NAOJ fellow)

What’s missing in theory?
•

Alignment - What’s the condition for the transition from thealignment with B-fields to that with rad. fields. Grain size? Is
the iron inclusion necessary? Conditions for the gas
turbulence?

•

Scattering - Scattering properties of porous dust aggregatesis missing. Is the grain growth significant even at Class 0
Disks in Taurus, Ophiuchus, and C
stages?
4.0

mm

3.5

= 3.7 (ISM)

TaurusChamaeleon
Ophiuchus

3.0
2.5
2.0

mm =2 (

=0)

1.5
101

Testi et al., 2014

102

103

F1mm [mJy]
Ribas et al., 2017

Figure5. Predicted
1 mm (scaled
to 140 pc in theFig. 5.— Left panel: Spectral index between 1.1 and 3 mm plottedagainstthe flux at fluxes
1.1 mmat(scaled
for a common
Akimasa Kataoka(NAOJ)
casespectralof Chamaeleon
indicesin the millimedistance of 140 pc) for disks around single stars (or wide binaries) withtypes earlyI)Mvs.
to Kspectral
in nearbystar forming

Draine 2
sumptiodisks wi2016) mflatter sl
ily as M
in Fig.
of themportant
dwarfs,and smastars, anthick antions areof their
2014; TeConclusions•

We propose that the self-scattering of thermal dust emission can produce
millimeter-wave polarization. The conditions are:
1. The intensity has anisotropic radiation fields
2. The maximum grain size is comparable to the wavelengths(Kataoka et al., 2015, ApJ)•

We have detected the polarization of HD 142527 with ALMA•

The orientations of polarization vectors are consistent with the self-scatteringmodel.
(Kataoka et al. 2016b, ApJL)•

We have observed polarization of HL Tau with ALMA•

3.1 mm polarization vectors are dominated by explained by the grainalignment, while 1.3 mm pol. vectors by the self-scattering.

•

The maximum grain size is constrained to be ~70 µm(Kataoka et al. 2016a ApJ, Kataoka et al. 2017 ApJL)
Akimasa Kataoka (NAOJ)