stuctural diversity – resolving herbig ae/be circumstellar ...€¦ · stuctural diversity –...
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Stuctural diversity – resolving Herbig Ae/Be circumstellar Disks at 10-150 AU using PDI
Henning AvenhausInstitute for Astronomy, ETH Zürich2013 ROCKS! Conference, Hawaii
Sascha Quanz, Hans Martin Schmid, Antonio Garufi, Michael Meyer, Sebastian Wolf and others
Stuctural diversity – resolving Herbig Ae/Be circumstellar Disks at 10-150 AU using PDI
Henning AvenhausInstitute for Astronomy, ETH Zürich2013 ROCKS! Conference, Hawaii
Sascha Quanz, Hans Martin Schmid, Antonio Garufi, Michael Meyer, Sebastian Wolf and others
NACO
Why image protoplanetary disks?
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SED can give a lot of information, but is degenerate w.r.t. fine disk structures
Information from scattered light:• Extent, orientation, inclination,
eccentricity, ...
• Sub-structures within the disk
• Signatures of planet formation
We need resolved, high-resolution images!
ROCKS! 2013, Hawaii - Henning Avenhaus, ETH Zürich
We want to do: High-resolution imaging…
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Say we want to do 0.1” imaging, then we need a telescope of…
We want to do: High-resolution imaging…
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Say we want to do 0.1” imaging, then we need a telescope of…
mm / sub-mm
~1mm
> 2.5km
ALMA
We want to do: High-resolution imaging…
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Say we want to do 0.1” imaging, then we need a telescope of…
Mid-infrared
~20µm
> 50m
Not possible
(wait for E-
ELT/TMT/GMT or
use interferometry)
mm / sub-mm
~1mm
> 2.5km
ALMA
We want to do: High-resolution imaging…
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Say we want to do 0.1” imaging, then we need a telescope of…
Mid-infrared
~20µm
> 50m
Not possible
(wait for E-
ELT/TMT/GMT or
use interferometry)
Near-IR / VIS
~1µm
> 2.5m
VLT, Keck, Hubble
Problem:
star is very bright
mm / sub-mm
~1mm
> 2.5km
ALMA
8ROCKS! 2013, Hawaii - Henning Avenhaus, ETH Zürich
Near-IR / VIS
… in the near-IR with small inner working angle
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9ROCKS! 2013, Hawaii - Henning Avenhaus, ETH Zürich
Near-IR / VIS
Grady et al. 2007
Coronagraphy
+ PSF subtraction
… in the near-IR with small inner working angle
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10ROCKS! 2013, Hawaii - Henning Avenhaus, ETH Zürich
Near-IR / VIS
Grady et al. 2007
Coronagraphy
+ PSF subtraction
Quanz, Avenhaus et al. 2013
Polarimetric
differential imaging
… in the near-IR with small inner working angle
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11ROCKS! 2013, Hawaii - Henning Avenhaus, ETH Zürich
Near-IR / VIS
Grady et al. 2007
Coronagraphy
+ PSF subtraction
Quanz, Avenhaus et al. 2013
Polarimetric
differential imaging
… in the near-IR with small inner working angle
Can probe planet-forming zones (0.1” at 100 pc is 10 AU)
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Polarimetric Differential Imaging (PDI) explained
Light from star
Wol
last
on
pris
m
Detector Data reduction
Stokes Q
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Polarimetric Differential Imaging (PDI) explained
Light from star
Wol
last
on
pris
m
Detector Data reduction
Stokes Q
Stokes U
P
What we see: An overview
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HD100546 HD97048 HD169142
SAO206462 HD142527 HD163296
What we see: An overview
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HD100546 HD97048 HD169142
SAO206462 HD142527 HD163296
What we see: An overview
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HD100546 HD97048 HD169142
SAO206462 HD142527 HD163296
HD142527: An intensively studied Herbig star
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F6 star of 2-12 Myr at ~145pc
Outer disk with very large scale height
Asymmetric inner hole out to ~100-130 AU
Inner, self-shadowed disk
Verhoeff et al. 2011
HD142527: A large inner hole
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Ks-band polarized flux (scaled with r^2)
Avenhaus et al. 2013 (in prep.)
HD142527: A large inner hole
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Sub-mm continuum emission
Casassus et al. 2013
Ks-band polarized flux (scaled with r^2)
Avenhaus et al. 2013 (in prep.)
HD142527 inner hole: How empty is empty?
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HD142527 inner hole: How empty is empty?
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Enhance
(factor 15)
HD142527 inner hole: How empty is empty?
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Enhance
(factor 15)
Weak evidence for dust scattering within the hole, but no “streamers” can be seen (scattering >100x weaker than in outer disk)
Too faint? Shadowed by inner disk? No streamers?
HD142527: Sub-structures in the disk
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Six spiral arms (at least two of these were known before)
Prominent holes in the disk: In northern direction,
PA ~0° In southeastern direction,
PA ~150°
All substructures seen in both H and Ks filters (and we have colors)
Avenhaus et al. 2013 (in prep.)
HD142527: An asymmetry in the north?
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Sub-mm continuum emission
Casassus et al. 2013
Ks-band polarized flux (scaled with r^2)
Avenhaus et al. (in prep.)
VISIR Q-band 18.7μm(deconvolved)
Verhoeff et al. 2011
Simulations of planet shadows in disks
Jang-Condell 2009
Sub-mm continuum is highly asymmetric in northern direction (dust trapping?) Verhoeff et al (2011) argue for planet at PA ~0° based on “trojans” seen in mid-IR A hole is seen in scattered light in the northern direction
Planet? Maximum mass a few MJup based on planet searches (Rameau et al. 2012, Casassus et al. 2013)
HD142527: Estimating disk parameters
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Well-resolved inner rim allows to fit a phenomenological model for the inner rim
Direct, self-consistent estimates: Inclination Eccentricity (~0.14) Semi-major axis of inner rim Scale height of inner rim
(~50 AU)
But: Inner rim scale height and inclination highly degenerateAvenhaus et al. 2013 (in prep.)
HD142527: Conclusions
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HD142527 is a very interesting disk: Large inner hole, large scale height Variety of substructures in outer disk Different substructures at different wavelengths
What we learn: Only weak evidence for very faint dust scattering in inner hole No trace of “streamers” No trace of inner disk or halo (likely self-shadowed) Disk parameters can be directly estimated
SAO206462 (also known as HD135344B)
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~3-12 Myr F4 star at ~140pc
Detections: Double-armed spiral structure Inner hole inside of ~25 AU Inner working angle: 0.07”
Questions to answer: Origin of spiral arms? Spiral
density waves? Origin of gap? Structures are on the surface of
the disk! (Optically thick)
Simulations and further observations (ALMA) required
Garufi, Avenhaus et al. 2013 (in prep.)
HD169142
A7 star at ~145pc, ~3-12 Myr
Disk features: Bright ring at ~25
AU featuring a dip Gap at ~30-60 AU Outer disk with
steep SB profile
What is the origin of thegap?
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Quanz, Avenhaus et al. 2013
ROCKS! 2013, Hawaii - Henning Avenhaus, ETH Zürich
HD169142: What causes the gap?
Possibility one:
Puffed up inner rim anddisk shadow
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Possibility two:
Annular gap in the disk (opened by planet?)
ALMA can answer this question!
PDI: Some thoughts
PDI can give us access to the inner parts of a disk:
High resolution (short wavelength on big telescope) High contrast (uses its own PSF for subtraction) Otherwise unreachable inner working angle of ~0.1” Same resolution as ALMA, complimentary information
But, we have to be aware:
We are probing scattered light, thus surface of disk (optically thick) Polarimetric efficiency variations can mimic structure
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Conclusions
To understand planet formation, we need to have imaging that is
High-resolution (to resolve the structures we are interested in) (For scattered light): High-contrast (bright central star) Small inner working angle (to probe planet-forming zones)
Few techniques are able to do this:
In (sub)-mm, ALMA is now able to achieve required resolution In the mid-IR, we have no telescope big enough In scattered light (visible, near-IR), only PDI can get the inner working
angle
Scattered light and sub-mm observations are complimentary to probe both surface and mid-plane of protoplanetary disks
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Future prospects
Visible / near-IR
Further disk studies and follow-up observations using VLT/NACO
Higher resolution, better contrastusing VLT/SPHERE
Sub-mm / mm
Find out whether the spirals / rings we see translate to mid-plane structures
ALMA at similar resolution (Cycle 2)
Modelling
Translate models to scattered-light images using radiative transfer code Try to understand the surfaces of disks
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BACKUP
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Polarimetric Differential Imaging (PDI) explained
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Qr
Ur
tangential
radial
Light from star
Wol
last
on
pris
m
Detector Data reduction
Stokes Q
Stokes U
Example: PDI vs. Coronagraphic imaging
4/11/13 35Departement/Institut/Gruppe
Casassus et al. 2012 Avenhaus et al. 2013 (in prep.)