ALMA/45m/ASTE Users’ Meeting
19th Dec. 2016, NAOJ

Protoplanetary Disk
Observations with ALMA
Takayuki Muto(Kogakuin University)

Contents• Introduction• Survey of Protoplanetary Disks• Imaging Observations of Individual Targets• Polarization Observations• SummaryDisclaimer• I will cover:– Scientific motivations of observing with ALMA and ali l bi
littlebit off modelingd li workk– A tiny fraction of recent observation (papers publishedin 2015‐2016) results• But I do NOT cover:– Chemistry (does not mean chemistry is less important)– ManyMththeoreticalti l works
k ththatt ttry tto connectt
observations with planet formation• Introduction• Survey of Protoplanetary Disks• Imaging Observations of Individual Targets• Polarization Observations• SummaryProtoplanetary Disk and Planet Formation• Protoplanetary disks arebirthplace of planets• Mixture
Mioff gas anddddust• Dust ggrains growgtoplanets

From NASA

Overview of Protoplanetary Disk

•Cold, thin disk
•Many are located at >~140 pc (the closest one at ~50 pc)
Dullemond and Monnier 2010

Fundamental Questions• What are protoplanetary disks?
– Gas mass,, dust mass,, temperature,p, size …

• What happens in protoplanetary disks?
– HowH dod grains
i grow, ini whath time
iscale?
l ?
– What happens when planets are form?
– When and how does gas dissipate?

• Need observational evidences

Recent ALMA Results(to be covered in this talk)• Survey• Individual Targets– High resolution observations– Gas
G andd dustd structures• New science with new capabilitypy– Polarization• Introduction• Survey of Protoplanetary Disks• Imaging Observations of Individual Targets• Polarization Observations• SummarySurvey• What is the overall pproperties
pofprotoplanetary disks?
– Dust mass
– gas mass
– gas‐to‐dust ratio• Lupusp Surveyy (Ansdell(et al. 2016))– Continuum + 13CO(3‐2) + C18O(3‐2)• UScoUS Survery
S(B(Barenfeldtf ldt ett al.l 2016)– Continuum + 12CO(3‐2)

Lupus Survey Overview• 89 sources ini Lupus I‐IV
• 0.3 asec resolution– 45 AU @ d=150 pc• Sensitivity– ~0.3 Mearth dust
– ~ 1MJ gas• Only 30sec – 1min on source• 62 detected in dust continuum• 36 detected in 13CO,
13CO 11 detected in C18O
Ansdell et al. 2016

Lupus Continuum Image Gallery

Ansdell et al. 2016

Dust and Gas Mass

•Dust mass spans over ~ 3 orders of magnitude•GasG mass iis ttypicallyi ll ~1 MJ
Ansdell et al. 2016

Gas to Dust Ratio
Gas‐to‐DustSignificantly lower gas‐to‐dust ratio than ISM

Ansdell et al. 2016

Stacking of Non
Non‐Detections
Detections• Continuum Non‐Detections– Non‐detection even afterstacking– (Dust mass) < 6 Lunar mass

• Gas Non‐Detections– Gas‐to‐Dust <~ 10•Quick evolution from protoplanetary to debris disk phase?
•Very small gas‐to‐dustgas to dust ratio
Ansdell et al. 2016

Comparison with Other Region• Lupus and Taurus are similar, while USco shows lower Mdust• Similar distribution for three regions

Ansdell et al. 2016
Barenfeld et al. 2016

• Introduction• Survey of Protoplanetary Disks• Imaging Observations of Individual Targets• Polarization Observations• Summary

High Resolution Imaging Observations• “Ring World” revealed– Highg resolution ((<0.1 asec)) observations for dustcontinuum• HL Tau, TW Hya– Gas+dust rings• HD 163296• And another spiral…
– Elias 2‐27

Why high resolution?
• Key to understand dynamical structure– Important scale: disk scale height– H ~ (sound speed) * (Kepler time) ~ 10 AU at r=100 AU– Need to resolve ~ 0.1 asec structures at d=140 pc* If you really want to resolve “Earth‐Forming” regions, you needmuch longer baseline

Flockk ett al.l 2011
FlFARGO simulation

HL Tau• ALMA longlbaselineb licampaign• Multiple ring structurein dust continuum in B3,B6, B7– 0.025‐0.075 asec
resolutionl• Gas emission alsoddetected
d in HCO+• 139 citations!
ALMA Partnership 2015

Dust + Gas Modeling

Dust settled in the disk midplane
Pinte et al. 2015

Morphological Signature of DustSettling

No settlingintermediate settling

Highly settled

Young (1‐2(1 2 Myr) disk showing dust settling
Pinte et al. 2015

Gas Gaps?
“integratedintegrated and azimuthally averagedaveraged” HCO+ profiles

Yen et al. 2016

TW Hya• 0.02 asec resolution in B7– ~1AU resolution due to its proximity to the Sun• Inner hole + multiple rings

Andrews et al. 2016

TW Hya High‐Res.
High Res Multiband

Tsukagoshi et al. 2016

Gap and Grain Properties• Reasonably optically thinemission• Spectral index peaks
inside the 20AU gap– “large grain deficit gap”

Tsukagoshi et al. 2016

HD 163296• Continuum + 12CO +13CO + C18O
– ~ 0.2 asec resolution• Ring structures in dust
• No prominent ring ingas, but yet no‐gas‐gap model does not fit
the observations
Isella et al. 2016

G/D Ratio Estimates Based on Simple
Modeling

dust distribution

gas distribution

g/d ratio•Both dust and gas gaps are necessary
G/ ratioat o iss not
ot coconstant
sta t overo e thet ed
disks•G/DIsella et al. 2016

Spiral in Elias 22‐2727• Spiral‐likeS i l lik structurest t
ini a young massive
i diskdi kPerez et al. 2016

• Introduction• Survey of Protoplanetary Disks• Imaging Observations of Individual Targets• Polarization Observations• SummaryPolarization• New features in ALMA
• Can be used to observe:– Magnetic field structures– Dust size when ring‐like structures are presentDust Self‐Scattering
Self Scattering• Dust thermal radiation scattered by dust particles• Requires:– Ring‐like structure and/or inclination– Dust particles with appropriate size
si e
– Relatively large amount of dust (optical depth ~ 1)

• Polarization can be a measure of dust grain size

Kataoka et al. 2015

Polarization Image of HD 142527

Kataoka et al. 2016

Polarization Flip

• Polarization flip occurs– when a ring‐like dust distribution is present– when dust size is appropiate
pp p((150 um in this case))
Kataoka et al. 2016

Summary and Outlook• ALMA is revealing (and will reveal) the nature of
protoplanetary disks with great details– Survey is indicating gas‐to‐dust
gas to dust ratio is different from thatof ISM– High resolution observations are revealing ring and spirallike structures both in gas and dust
– Polarization observations may constrain the state of grain
growth• New
N id
ideas off iinterpreting
tti ththe ddata?
t ?
• How do we integrate the data to construct a planet
formation scenario BASED ON OBSERVATIONS?