Transcript High Contrast - University of Arizona

High Contrast Imaging
and
The Disk/Planet Connection
Glenn Schneider
Steward Observatory, University of Arizona (NICMOS/IDT)
Direct (Scattered Light) Imaging of Dusty Debris
Observing scattered light from circumstellar
debris has been observationally challenging
because of the very high Star:Disk contrast
ratios in such systems.
Until very recently the large, and nearly
edge-on disk around b Pictoris remained the
only such disk imaged.
Resolved imaging
1984 - B.A. Smith & R.J. Terrile
6" radius coronagraphic mask,
Las Campanas (discovery image)
b Pictoris
spatial distribution of dust/debris.
Asymmetries (radial & azimuthal):
• May implicate low-mass perturbers (planets) from:
Rings, Central Holes, Gaps, Clumps, Arcs, Arclets
• Help Elucidate the scattering & physical properties of the grains.
The HUBBLE Legacy
Breaking the Low Contrast Paradigm
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are needed to see this picture.
TODAY HST Provides a Unique Venue for High Contrast Imaging
• Diffraction Limited Imaging in Optical/Near-IR
•> 98% Strehl Ratios @ all ls
Background Rejection
• Highly STABLE PSF
1.6mm: ~10-6 pix-1 @ 1”
1.1mm: ~10-5 in 2”-3” annulus
• Coronagraphy: NICMOS
STIS, ACS
HST is a stepping
• Intra-Orbit
stone for superField
high contrast *
Rotation
imaging
*
NIR High Dynamic Range Sampling
NICMOS/MA: Dmag=19.4 (6 x 4m)
Background
Rejection
109—1010
Planet-Building Timeline
HST Vis/NIR
Taurus,
Ophiuchus
star forming
regions
HST Vis/NIR
High Contrast
TW Hydrae Tucanae
Hyades
Assoc Pleiades
Assoc
a Persei
106
yr s
Collapsing
protostar
forms protoplanetary disk
Beyond HST Vis/UV
Super-High Contrast
107
yr s
108
yr s
Giant planets
accrete
gaseous
atmospheres
Rocky cores
of giant
planets form
Era of heavy
bombarment
by comets
Terrestrial
planets
form
Primary Dust (≤ mm) Secondary Dust (≥mm)
Locked to Gas
Collisional erosion
Clearing Timescales: P-R drag few 10 6
Rad. Pressure: ~ 104
Sun
109
yr s
Current
age of
the Sun:
5x109 yrs .
Clearing of
inner solar
system,
formation of a
Kuiper
cometary
belt?
From: R. Webb
Scientific Areas of Investigation Enabled
With Today’s Capabilities on HST
via PSF-Subtracted Coronagraphic Imaging
Young Extra-Solar Planet* &
Brown Dwarf
Companions
1"
Circumstellar Disks
fdisk/f* > few x 10-3 at 1”
q > 50 mas
* < few x 106 yr at 1”
Moving Beyond HST into the Super-High Contrast Regime
Exosolar Planet Imaging & Spectroscopy:
few x 106 Myr at 1”
> 109 yr (solar age) at 1”
Disk Imaging & Spectroscopy:
fdisk/f* > few x 10-3 at 1”
≤ 10-6 at 1”
q > 50 mas
a few mas (sub-AU at 200pc)
OPTICAL CONFIGURATIONS
TECHNOLOGICAL CHALLENGES
•Coronagraphy
•Polarimetric Nulling
•Nulling Interferometry
•Wavefront Correction
•Station-Keeping Occulters
•Interferometric Arrays
•Micro-Roughness of Optical Surfaces
•Particulate/Contamination Control
•Stray Light Management & Control
•Pupil Apodization (and Shaping)
•Metrological Tolerancing & Stability
•Wavefront/Mirror Sensing & Control
The Dusty Disk/Planet Connection
Current theories of disk/planet evolution suggest a
presumed epoch of planet-building via the formation
and agglomerative growth of embryonic bodies, and the
subsequent accretion of gaseous atmospheres onto hot
giant planets, is attendant with a significant decline in
the gas-to-dust ratios in the remnant protostellar
environments.
In this critical phase of newly formed (or forming)
extra-solar planetary systems, posited from a few
megayears to a few tens of megayears, the circumstellar
environments become dominated by a second-generation
population of dust containing larger grains arising from
the collisional erosion of planetesimals.
< 1Myr
Proplyds
in Orion
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and…
Substellar
Objets to
~ 10 Mjup
HH30 Obscured
GM AUR Unembedded
Coronagraph +
PSF Subtraction
Direct Image
~ 1— few Myr
Radius (Pixels) from Hole Center
5
7
9
11
13
16
Coronagraphic Background Reduction
15
14
13
12
11
10
9
8
INTENSITY (AZIMUTHAL AVERAGE)
10 0
5
17
19
21
23
25
27
29
31
33
35
37
REDUCTION IN BACKGROUND FLUX FROM F160W PSF
10-1
Unocculted F160W PSF
PSF + Coronagraph
PSF + Coronagraph + Roll
10-2
1
pixel
10-3
10-4
Coronagraph +
10-5
7
6
15
10-6
0
Coronagraphic
Hole
PSF Subtraction
Radius = 0.3"
0.075 0.15 0.225
0.3 0.375 0.45 0.525
0.6 0.675 0.75 0.825
0.9 0.975 1.05
ARCSECONDS
4
Averages, 1-Pixel Wide Annular Zones
3 Azimuthal
(69:69, 208:209) and (77, 205) Glint Features Excluded
2
0.3 0.45 0.6 0.75 0.9 1.05 1.2 1.35 1.5 1.65 1.8 1.95 2.1 2.25 2.4 2.55 2.7 2.85
Radius (Arcsec) from Hole Center
Planet-Building Timeline
Taurus,
Ophiuchus
star forming
regions
106
yr s
Collapsing
protostar
forms protoplanetary disk
HH 30
Planet-Building Timeline
Taurus,
Ophiuchus
star forming
regions
106
yr s
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Collapsing
protostar
forms protoplanetary disk
Rocky cores
of giant
planets form
Planet-Building Timeline
TW Hydrae
Assoc
Taurus,
Ophiuchus
star forming
regions
107
yr s
106
yr s
Giant planets
accrete
gaseous
atmospheres
Collapsing
protostar
forms protoplanetary disk
141569A
Planet-Building Timeline
Taurus,
Ophiuchus
star forming
regions
TW Hydrae Tucanae
Hyades
Assoc Pleiades
Assoc
a Persei
106
yr s
Collapsing
protostar
forms protoplanetary disk
107
yr s
108
yr s
Giant planets
accrete
gaseous
atmospheres
Rocky cores
of giant
planets form
Era of heavy
bombarment
by comets
Terrestrial
planets
form
Primary Dust (≤ mm) Secondary Dust (≥mm)
Locked to Gas
Collisional erosion
Sun
109
yr s
Current
age of
the Sun:
5x109 yrs .
Clearing of
inner solar
system,
formation of a
Kuiper
cometary
belt?
Clearing Timescales: P-R drag few 10 6
Rad. Pressure: ~ 104
From: R. Webb
Examples of Dusty Disks with Radial and Hemispheric Brightness
Anisotropies and Complex Morphologies, Possibly Indicative of
Dynamical Interactions with Unseen Planetary Mass Companions,
Spatially Resolved and Imaged Around Young (< 10 Myr) Stars by HST.
HR 4796A (A0V), ~ 8 Myr
A 70AU radius ring, ~ 12
AU wide ring of very red
material, exhibiting strong
forward scattering and
ansally asymmetric
hemispheric flux densities.
Examples of Dusty Disks with Radial and Hemispheric Brightness
Anisotropies and Complex Morphologies, Possibly Indicative of
Dynamical Interactions with Unseen Planetary Mass Companions,
Spatially Resolved and Imaged Around Young (< 10 Myr) Stars by HST.
HD 141569A
(Herbig Ae/Be)
~ 5 Myr
A 400AU radius disk, with a broad, partially filled
asymmetric gap containing a “spiral” arclet.
Examples of Dusty Disks with Radial and Hemispheric Brightness
Anisotropies and Complex Morphologies, Possibly Indicative of
Dynamical Interactions with Unseen Planetary Mass Companions,
Spatially Resolved and Imaged Around Young (< 10 Myr) Stars by HST.
TW Hya (K7)
“Old” PMS Star
Pole-on circularly symmetric disk with a break in
its surface brightness profile at 120 AU (2”).
Examples of Dusty Disks with Radial and Hemispheric Brightness
Anisotropies and Complex Morphologies, Possibly Indicative of
Dynamical Interactions with Unseen Planetary Mass Companions,
Spatially Resolved and Imaged Around Young (< 10 Myr) Stars by HST.
TW Hya (K7)
“Old” PMS Star
and, possibly, a
radially and
azimuthally confined
arc-like depression.
Pole-on circularly symmetric disk with a break in
its surface brightness profile at 120 AU (2”).
HR 4796A
1.1mm
0.58mm
HR 4796A RING GEOMETRY
(Least-Squares Isophotal Ellipse Fit)
Ansal Separation (Peaks)
=
2.107”
± 0.0045”
Major Axis of BFE
=
2.114”
± 0.0055"
P.A. of Major Axis (E of N)
= 27.06°
± 0.18°
Major:Minor Axial Length
= (3.9658
± 0.034): 1
Inclination of Pole to LOS
= 75.73°
± 0.12°
Photocentric Offset from BFE(Y) = -0.0159" ± 0.0048"
Photocentric Offset from BFE(X) = +0.0031" ± 0.0028"
HR 4796A Circumstellar Debris Ring - WIDTH
NE ANSA CROSS-SECTIONAL PROFILE
1.1
WIDTH AT NE ANSA
FWHM: 12.3±0.7AU
8.7% Dring
1-e-1:* 17.7±10.1AU
0.9
0.8
Brightness (normalized to NE Ansa)
Brightness (Normalized to NE Ansa)
1
NE ANSA CROSS-SECTIONAL PROFILE
1.1
1
0.7
12.5% Dring
0.9
0.8
0.6
0.7
0.197"
0.6
0.5
0.197"
0.5
Measured
PSF point source
FWHM ring
1-e-1 *
0.4
0.4
0.3
0.2
0.3
0.1
0
-1.6
-1.5
0.2
-1.4
-1.3
-1.2
-1.1
-1
-0.9
-0.8
-0.7
20% inner:outer
fall-off asymmetry
Distance (Arc Seconds)
-1.5
-1.4
-1.3
-1.2
0.197”
0.070”
0.184”
0.265”
-0.6
0.1
0
-1.6
=
=
=
=
-1.1
-1
-0.9
Distance (Arc Seconds)
-0.8
-0.7
-0.6
RING GEOMETRY - Least-Squares Isophotal Ellipse Fit
Ansal Separation (Peaks)
=
2.107”
± 0.0045”
Major Axis of BFE
=
2.114”
± 0.0055"
P.A. of Major Axis (E of N)
= 27.06°
± 0.18°
Major:Minor Axial Length
= (3.9658
± 0.034): 1
Inclination of Pole to LOS
= 75.73°
± 0.12°
Photocentric Offset from BFE(Y) = -0.0159" ± 0.0048"
Photocentric Offset from BFE(X) = +0.0031" ± 0.0028"
“FACE-ON” PROJECTION - With Flux Conservation
Spatially Resolved Relative PHOTOMETRY of the Ring
NW:SE Surface Brightness Anisotropy
Front:Back Surface Brightness Anisotropy
170
160
NE % FRONT:BACK
SW % FRONT:BACK
MEAN FRONT:BACK
1 + 0.73*COS(theta)
150
140
130
120
110
100
6
5
4
3
2
1
0
0
(NE Front-Back) : SIGMA(Front/Back)
(SW Front-Back) : SIGMA(Front/Back)
(MEAN Front-Back) : SIGMA(Front/Back)
10
20
30
40
Angle from Major Axis (Degrees)
50
60
Broad Colors of the HR 4796A Debris Ring
[50CCD]-[F110W]=0.55±0.09
[50CCD]-[F160W]=1.14 +0.20
-0.17
Intrinsically red grains
•Consistent with collisionally
evolved population of particle sizes
> few microns
•Not primordial ISM grains
•Similar intrinsic colors to TNOs
in our solar system [V]-[J]=+1.07*
•Consistent with laboratory*
irradiation experiments on a variety
of organics to study reddening of
D & P type asteroids with distance
From Sun.
*Barucci et al (1993); Andronico et al (1987)
Planet-Building Timeline
Taurus,
Ophiuchus
star forming
regions
TW Hydrae Tucanae
Hyades
Assoc Pleiades
Assoc
a Persei
106
yr s
Collapsing
protostar
forms protoplanetary disk
107
yr s
108
yr s
Giant planets
accrete
gaseous
atmospheres
Rocky cores
of giant
planets form
Era of heavy
bombarment
by comets
Terrestrial
planets
form
Primary Dust (≤ mm) Secondary Dust (≥mm)
Locked to Gas
Collisional erosion
Sun
109
yr s
Current
age of
the Sun:
5x109 yrs .
Clearing of
inner solar
system,
formation of a
Kuiper
cometary
belt?
Clearing Timescales: P-R drag few 10 6
Rad. Pressure: ~ 104
From: R. Webb
Cooling Curves for Substellar Objects
0
Evolution of M Dwarf Stars, Brown Dwarfs
and Giant Planets (from Adam Burrows)
-2
200M jup
80M jup
sun
Log
10L/Lsum
-4
-6
14M jup
-8
STARS (Hydrogen burning)
BROWN DWARFS (Deuterium burning)
JUPITER
PLANETS
-10
6
7
SATURN
8
Log10 Age (years)
9
10
CORONAGRAPHIC
COMPANION
DETECTION
(Multiaccum) Imaging
at two S/C orientations
(in a single HST
visability period).
Background objects
rotate about occulted
Target. PSF structures
and optical artifacts
do not.
TWA6. Two Integrations:
Median of 3 Multiaccum Each
D Roll = 30°
D Time = 20 minutes
H “companion” = 20.1
DH = 13.2, r=2.5”
At r=2.5” background
brightness is reduced
by an ADDITIONAL
factor of 50 over raw
coronagraphic gain (of
appx 4).
Each
independent
image of TWA6“B” is
S/N ~20 in difference
frame.
Above: Coronagraphic
Images
D Roll: 30°
Left:
Difference
Image
Same display dynamic range
Imperfections in
PSF-subtractions
result in residuals
expected from pure
photon noise.
Systematics:
OTA “Breathing”
Target Re-centration
Coron. Edge Effects
Mechanical Stability
Detectability and Spatial Completeness
(r,q) Dependence via Model PSF Implantation
Observed
Model*
*TinyTim
Nulled
Implant
5.0 HST+NICMOS Optical Model - Krist
Detectability: (r,q) Dependence via Model PSF Implantation
.
Photometric Efficacy & Statistical Significance
25
% Recovered Flux
20
16
12
8
4
Detectability:
(1”,q) Dependence via Model PSF Implantation
2.0
1.0
0.0
1.0
Arc Seconds
2.0
PSF FWHM = 0.16"
TWA6 Image
Combination:
S/NTWA6B = 35
NICMOS
F160W
25 OCT 1998
Camera 2 (0.076"/pixel)
Coronagraph (0.3" radius)
Integration Time =1280s
H-Band (F160W) Point-Source Detectability Limits
Two-Roll Coronagraphic PSF Subtraction 22m Total Integration
DH(5s) = 7.14 + 3.15r” - 0.286r” 2 {M&K Stars}
..
..
9
Photon Noise Dominated
Read Noise Dominated
4
10
11
12
0
-2
-4
-4 -2 0
14
2
4
0.0 0.2 0.4 0.6 0.8 1.0
Normalized Intensity
7x7 Pixels
71% Ensquared Energy
DH
M
ag
ni
tu
de
13
2
H=6.9
5s
15
1s
16
0
1
2
3
4
5
6
Radius (Arc seconds)
7
8
9
10
2.0
1.0
0.0
1.0
Arc Seconds
PSF FWHM = 0.16"
2.0
TWA 6A/B
TW Hya Assn
K7primary, D = 55pc
Age = 10 Myr
r=2.54”, 140AU
DH =13.2
(LB/A)[H]=5 x10-6
Habs = 16.6
NICMOS
F160W
25 OCT 1998
Implies:
• Mass ~ 2Jupiter
S/NTWA6B = 35 • Teff ~ 800K
Camera 2 (0.076"/pixel)
Coronagraph (0.3" radius)
Integration Time =1280s IF
Companion...
Confirmation (or Rejection) by Common Proper Motion
2.0
1.0
0.0
1.0
Arc Seconds
… possible via groundbased adaptive optics
imaging with a sufficiently
long temporal baseline.
2.0
PSF FWHM = 0.16"
NICMOS
F160W
25 OCT 1998
Camera 2 (0.076"/pixel)
Coronagraph (0.3" radius)
Integration Time =1280s
Keck II + AO imaging.
Courtosy of B.Macintosh, LLNL
Anomaly or Bias? A Jovian Planet @ > 140 AU?
• RV Surveys suggest ~ 5% MS *s have 0.8—8 Mjup companions
@ d < 3AU from their primaries.
• NOT Where Giant Planets are found in our own Solar System
WHY ARE THEY THERE?
Posited*: Mutual interactions within a disk can perturb one young
planet to move into a < 1AU eccentric orbit (as inferred
from RV surveys), and the other…
Ejected (but bound) to very large separations, > 100AU
Cannot be observationally tested with HST-like capabilities,
requires “Super-High” contrast imaging.
* e,g., Lin & Ida (ApJ, 1997); Boss (2001, IAU Symp 202)
Inner Regions of Evolved Disks
Cannot yet be probed in scattered light. Yet, as inferred from mid-IR:
An inner tenuous component
of warm zodi-like dust may
be confined within a few AU
of HR 4796A.
12–20mm thermal emission
is contained completely
within the large inner “hole”
of HD 141569A.
What evolutionary and dynamical interactions may be going on between
unseen planets and unseen dust which will shape these systems?
Requires “Super-High” contrast and resolution.
HST Has Sampled Only the Low-Hanging Fruit
in the Disk/Planet Orchard.
200M jup
TWA6B ?
80M jup
sun
10L/Lsum
-4
Log
GL 503.2B
GL577B/C
-2
HR 7329B
CD -33° 7795B
0
-6
14M jup
-8
STARS (Hydrogen burning)
BROWN DWARFS (Deuterium burning)
JUPITER
PLANETS
-10
6
7
SATURN
8
Log10 Age (years)
9
10
Anomaly or Bias? A Jovian Planet @ > 140 AU?
• RV Surveys suggest ~ 5% MS *s have 0.8—8 Mjup companions
@ d < 3AU from their primaries.
• NOT Where Giant Planets are found in our own Solar System
WHY ARE THEY THERE?
Posited*: Mutual interactions within a disk can perturb one young
planet to move into a < 1AU eccentric orbit (as inferred
from RV surveys), and the other…
Ejected (but bound) to very large separations, > 100AU
* e,g., Lin & Ida (ApJ, 1997); Boss (2001, IAU Symp 202)
UV/Optical imaging and spectroscopy of collisionally evolved
circumstellar debris and co-orbital bodies will play a pivotal role in
furthering our understanding of the formation and evolution of exosolar
planetary systems. To study physical processes acting over sub-AU
spatial scales and time scales comparable to the age of our solar system
will require a 3—4 order of magnitude improvement in instrumental
stray light rejection over the performance obtainable with HST.
GLENN SCHNEIDER
NICMOS Project
Steward Observatory
933 N. Cherry Avenue
University of Arizona
Tucson, Arizona 85721
HUBBLE SPACE T ELESCOPE
Phone: 520-621-5865
FAX: 520-621-1891
e-mail: [email protected]
http://nicmosis.as.arizona.edu:8000/
Is it, or Isn’t It?
• Undetected in NICMOS 0.9mm Followup Observation
I-H > 3
• Marginally Detected in 6-Orbit Binned STIS G750L Spectrum
• Colors Consistent with 2 Mjup, 10 Myr, “Hot” Giant Planet
Instrument
NICMOS/C2
NICMOS/C2
STIS/G750L
STIS/G750L
Band
F160W
F090M
I extract
R extract
Bandpass
1.40—1.80
0.80—1.00
0.81—0.99
0.63—0.77
If NOT a hot young planet, it must be a
Highly exotic object!
Mag
20.1
>23.1
~25.4
>27.2
Is it, or Isn’t It?
• Undetected in NICMOS 0.9mm Followup Observation
I-H > 3
• Marginally Detected in 6-Orbit Binned STIS G750L Spectrum
• Colors Consistent with 2 Mjup, 10 Myr, “Hot” Giant Planet*
~25.4
>27.2
>23.1
Spectrum from A. Burrows
20.1
* Sudarsky
et al., 2000
• Keck/AO Astrometric (PM) Follow-up Thus-Far Inconclusive
Is it, or Isn’t It?
A differential proper motion measure will be obtained with NICMOS.
If common proper motions are confirmed we will request time for
NICMOS grism spectrophotometry to obtain a near-IR spectrum.
~25.4
>27.2
>23.1
20.1