SMA and ALMA Studies of Disk- and PlanetFormation around Low-mass Protostars
Shigehisa Takakuwa (Kagoshima U. / ASIAA)
Image Credit: ESO/L. Calçada
Collaborators
Hsi-Wei Yen (ASIAA —> ESO)
Nagayoshi Ohashi (NAOJ / ASIAA)
Yusuke Aso (U. of Tokyo)
Ti-Lin Chou (NTU —> U. Chicago)
Patrick Koch (ASIAA)
Ruben Krasnopolsky (ASIAA)
Paul T. P. Ho (ASIAA)
Hauyu Baobab Liu (ESO)
Naomi Hirano (ASIAA)
Pingao Gu (ASIAA)
ChinFei Lee (ASIAA)
Evaria Puspitaningrum (ITB)
Yuri Aikawa (Kobe U.)
Masahiro N. Machida (Kyushu U.)
Kazuya Saigo (Osaka Prefecture U.)
Masao Saito (NRO / SOKENDAI)
Kengo Tomida (Osaka U. / Princeton U.)
Kohji Tomisaka (SOKENDAI / NAOJ)
0. Introduction
Keplerian Disks are ubiquitous around T-Tauri Stars.
(Rkep 100 - 800 AU, Disk Mass 0.0001 - 0.1 Msun)
Sites of Planet Formation ̶> ``Protoplanetary Disk
(ALMA HL Tau Image)
How the Disks form around
protostars, embedded
in protostellar envelopes ?
Our group ̶> Systematic SMA
and ALMA Observations of
Protostars.
Table of Contents
1. SMA and ALMA Observations of Class I Protostars
—> Ubiquity of Keplerian Disks embedded
in Infalling Envelopes around Class I
2. High-Resolution ALMA Observations of Class 0 Protostars
—> No Keplerian Disk or Large Keplerian Disk
3. ALMA Observations of Gas Gaps in HL Tau
—> Evidence for planet formation in the Class I stage
1. SMA and ALMA Observations of Class I Protostars
SMA+ASTE CS (7-6) Observations of L1551 IRS 5 (Chou, Takakuwa et al. 2014)
!"#$%&'()*"+,
-).%&'()*"+,
140 AU
Gray: 0.9-mm Continuum
High velocity ̶> Northwest - Southeast velocity gradient along
the major axis of the continuum emission.
Low velocity ̶> Extended, slight North - South velocity gradient.
High-Velocity CS Emission in L1551 IRS 5
̶> Keplerian Circumbinary Disk
!"#$
M* 0.5 Msolar
%&'()
*(#$
!"#$
%&'()
*(#$
rkep 64 AU
Low-Velocity CS Emission in L1551 IRS 5
̶> Infalling Envelope slower than the free-fall
(<̶ M* derived from the Keplerian rotation)
SMA+ASTE CS (7-6) P-V Diagrams of L1551 IRS 5
Inner Keplerian Disk
̶> Kep. Rot along maj
̶> No minor vel. grad.
Outer Envelope
̶> r-1 Rotation
(Momose et al. 1998)
connect to inner Kep.
@r 64 AU
̶> Slight minor vel. grad.
Slower Infall than free-fall.
Summary: SMA and ALMA Observations of Class I Protostars
Tbol (K)
M*(solar
mass)
Envelope
L1551 NE
91
0.8
Slow Infall,
Slow rotation
L1551 IRS 5
92
0.5
Protostars
TMC-1A
172
L1489 IRS
238
Slow Infall,
r-1 rotation
Rkep (AU) Our Publications
300 AU
64 AU
Takakuwa et al. 2012, 2013, 2014,
2015
Takakuwa et al. 2004;
Chou et al. 2014
0.64
Slow Infall,
r-1 rotation
100 AU
Yen et al. 2013; Aso et al. 2015
1.6
Freefall,
r-1 rotation
300 AU
Yen et al. 2013, 2014
•
Large-Scale (r>~100 AU) Keplerian Disks.
•
r-1 rotation in the Infalling Envelopes, Envelope rotation
connects smoothly to the Keplerian rotation in the disks.
•
Infalling velocity ~3 times slower than free-fall.
Keplerian Disks are well developed at the Class I stage.
2. High-Resolution ALMA Observations of Class 0 Protostars
B335 in C18O (2-1) (Yen, Takakuwa, et al. 2015)
Contour mom0
Color mom1
Clear Velocity gradient along the envelope minor axis
̶> Infalling Motion.
No Velocity gradient along the major axis at 0.35 beam.
P-V Modeling of the C18O (2-1) Emission in B335
Contour: Obs
Color: Model
Infall (Freefall) to the Protostar with 0.05 Msun
(Vinfall 2.0 km s-1 at r = 10 AU)
No Rotation, Upper limit of Rkep < 3 AU.
B335 is an early Class 0 source.
̶> Disk Formation has not proceeded much ?
(a)
12
CO (2-1)
(a)
12
CO (2-1)
Our Latest ALMA Observations of Class 0 Protostars at ~0.4” resolution
(Yen et al. 2016b)
IRAS 16253-2429 IRAS 15398-3559
(d) C18O (2-1)
No clear velocity gradient
along the major axis,
but along the minor axis
(e)
-45)
(d)SO
C18(5
O 6(2-1)
Clear velocity gradient
both along the major and
minor axis
Lupus 3 MMS
(e)(d)
SOC18
(5O
(2-1)
6-4
5)
Velocity gradient primarily
along the major axis
P-V Diagrams along the major axis & the Rotational Profiles
(a)
(b)
r-0.5 —> Keplerian!!
Lupus 3 MMS
Lupus 3 MMS
(c)
(d)
r-1 —> Conserved Specific
Angular Momentum
IRAS 15398-3559
(e)
IRAS 16253-2429
IRAS 15398-3559
Observed (black) and Model (Red) P-V Diagrams
Major axis
(a)
Minor axis
(b)
—> Keplerian Disk
Lupus 3 MMS
(c)
(d)
—> Infall + r-1 Rotation
IRAS 15398-3559
(e)
(f)
—> Infall only
IRAS 16253-2429
Our ALMA Results of Class 0 Protostars
Protostars
Tbol (K)
M*(solar
mass)
Envelope
Rkep (AU) Our Publications
B335
31
0.05
Infall,
slow rotation
<3
Yen et al. 2010, 2011, 2013, 2015a, b
IRAS
16293-2429
36
0.03
Infall,
slow rotation
<6
Yen et al. 2016
Lupus 3 MMS
39
0.3
Keplerian Disk
only
130
Yen et al. 2016
L1527 IRS
59
0.3
Slow Infall,
r-1 rotation
54
0.01
Infall,
r-1 rotation
<20
IRAS
15398-3559
61
Class 0 with Keplerian Disks
Yen et al. 2013, 2015a;
Ohashi et al. 2014
Yen et al. 2016
Keplerian Disk Radii v.s. Protostellar Mass
L1455 IRS 1
Class 0 VLA1623 Lupus 3 MMS
HH212
L1527 IRS
IRAS 15398-3559
Class I
Rd~M*
IRAS 16293-2429
B335
unresolved, inferred disks
Rd~M*3
Our results
+ the other literatures
Two groups of Class 0: with r~100 AU scale disks,
without any disks (r< 20 AU)
—> Rapid Growth of Disks within the Class 0 phase ?
Summary: High-Resolution ALMA Observations of Class 0 Protostars
Two Groups of Class 0 with large (~100 AU) Keplerian Disks,
and without any Keplerian Disks (r< 20 AU).
The radii of the identified Keplerian Disks around Class 0
appear to be comparable to those around Class I,
while the protostellar mass larger in Class I.
Well-developed Keplerian Disks, i.e., protoplanetary Disks,
have already been formed in the Class 0 stage ?
Planet Formation starts at Class I ?
3. ALMA Observations of Gas Gaps in HL Tau
(Yen et al. 2016a; ALMA press release May 25, 2016)
The dust gaps in the disk induced numerous discussions.
Sub-Jovian Planets (Dipierro et al. 2015; Kanagawa et al. 2015;
Tamayo et al. 2015; Jin et al. 2016).
Secular Gravitational Instability (Takahashi & Inutsuka 2014)
Pebble growths (Zhang et al. 2015)
Dust aggregates (Okuzumi et al. 2015)
Gas Distribution (~100×dusts) must be a key!!
ALMA partnership et al. 2015
Obtaining High-Resolution HCO+ (1-0) Radial Profile in HL Tau
(from the same ALMA Long Baseline Data)
Intensity
radius１
radius２
radius３
3
Annular Averaging
̶>Higher S/N Ratio
2
1 radius
Annular Averaged
Image
with the high resolution
Note: Azimuthal information has been lost.
HCO+ Radial Profile at 0.07 (= 10 AU) resolution in HL Tau
N (HCO+) (1016 cm-2)
Dust Gaps
Blue: HCO+; Red: Dust
2-color image
Dust Rings
69 AU
28 AU
( Neptune Orbit)
Gas Gap
Gas Gap
Radius (AU)
Two Gas Gaps at similar locations to those of Dusts
—> The Gaps are “real” gaps of materials, not just
change of dust properties.
In particular, around the inner gap at ~Neptune orbit,
the surface density is high enough to produce planets.
From the depths and widths,
0.8 MJ planet
2.1 MJ planet
Direct Imaging of Gas Gaps without annular averaging
(Our submitted Cycle 4 Proposal)
(a)
(b)
HCO+ (3-2)
HCO+ (4-3)
HCO+ (1-0)
HCO+ (3-2)
HCO+ (4-3)
At the same resolution, brightness sensitivities of the higher
transitions are better (i.e., TB~freq-2×S).
2 mJy / 0.07”—> 62.7 K for (1-0), 7.0 K for (3-2), & 3.9 K for (4-3)
Direct Imaging of the Gas Gaps Feasible!!
Concluding Remarks: SMA and ALMA Studies of Diskand Planet-Formation around Low-mass Protostars
Rapid (<106 yr) formation of Keplerian Disks in the Class 0
stage. Class I Keplerian Disks are ubiquitous.
Infalling Envelope often exhibits r-1 rotation,
and the rotation connects smoothly to the Keplerian Disks.
The infalling velocity ~3 time slower than free-fall.
Planet formation may start at the Class I stage.
Imaging of gas gaps in Class I Disks, promising
sign of planet formation, is feasible.