Transcript M - University of Arizona

Dusty Circumstellar Disks
and
Substellar Companions
Glenn Schneider
Steward Observatory, University of Arizona (NICMOS/IDT)
Substellar Companions
and
Dusty Circumstellar Disks
Glenn Schneider
Steward Observatory, University of Arizona (NICMOS/IDT)
… and, what’s happening
@ ~ 100 AU?
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
• Intra-Orbit
Field
Rotation
NIR High Dynamic Range Sampling
NICMOS/MA: Dmag=19.4 (6 x 4m)
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
10-5
7
6
15
10-6
0
Coronagraphic
Hole
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
H-Band (F160W) Point-Source Detectability Limits
Two-Roll Coronagraphic PSF Subtraction 22m Total Integration
DH(5s) = 7.14 + 3.15r” - 0.286r” 2
..
..
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
Scientific Areas of Investigation
1"
via PSF-Subtracted Coronagraphic Imaging
Extra-Solar Planet &
Brown Dwarf
Companions
Circumstellar Disks
HST/NICMOS Coronagphic Imaging Surveys Carried Out
by the IDT’s Environments of Nearby Stars (EONS) Team
HUBBLE SPACE T ELESCOPE
DISK Candidates: 22 young (< 100 Myr) unembedded (largely
unobscured by primordial material) K-A stars within ~ 100 pc
with with known far-IR exceses.
PLANET/BROWN
DWARF Candidates:
38 young ‘High’
Proper Motion within
~ 50 pc with, including all
(but one) of the then-know
Members of the TW Hya Assn.
BROWN DWARF/
VLM Star Candidates:
32 HighProper Motion
Late M-Dwarf Stars
within ~ 10 pc.
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.
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
Evolution of M Dwarf Stars, Brown Dwarfs
and Giant Planets (from Adam Burrows)
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
DIRECT DETECTION OF YOUNG PLANETS
MECHANICS
&
A PRIME CANDIDATE (TWA 6 ‘B’)
CORONAGRAPHIC
COMPANION
DETECTION
Multiaccum Imaging
at two S/C orientations
In a single 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
At r=2.5” (where image
of companion emerges),
background brightness
is reduced by an
ADDITIONAL factor
of 50 over raw
coronagraphic gain (of
appx 4).
Each image of TWA6B
is S/N ~20 in difference
frame.
Above: Coronagraphic
Images
H companion = 20.1
DH = 13.2
Left:
D Roll: 30°
Difference
Image
Same display dynamic range
Minimize local
residuals in
region near
companion
image while
constraining
background to
be statistically
zero...
Positive
Image
Extracion
Negative
Image
Extraction
(Inverted)
Rotate
Negative
Extraction
About
Occulted
Target
And Add
After
Inversion
Model and
Remove
Diffraction
Spike
Residuals*
*DSPK
Is it a Point Source?
Radial Profile, Photocentric Moment & Gaussian Fitting
Is it a Point Source?
Residuals from 2D
Gaussian Model
Subtracted from Data
Are Identical to Those
Expected from
NICMOS Camera 2
F160W PSF at the
Coronagraphic Focus.
How Deep?
Sensitivity
Completeness...
Sensitivity: Noise Equavalent Background Assessment
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
Detectability: (r,q) Dependence via Model PSF Implantation
.
Photometric Efficacy & Statistical Significance
25
% Recovered Flux
20
16
12
8
4
TWA6B Detection Illustrates Performance Repeatability
Two-Roll Coronagraphic PSF Subtraction 22m Total Integration
DH(5s) = 7.14 + 3.15r” - 0.286r” 2
..
9
..
NICMOS F160W
N
4
PSF FWHM = 0.16"
E
2
10
0
-2
-4
11
H = 6.9
DH = 13.2
r = 2.5"
S/N = 35
12
TWA6"B"
20 May 1998
0
1
2
Arc Seconds
3
-4 -2 0
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
14
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"
N
2.0
E
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...
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)
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?
We have requested 12 HST Orbits to attempt PSF-subtracted
NICMOS G141 (1.1—1.9mm) grism spectrophotometry to obtain
what might be the first spectrum of an extra-solar planet.
~25.4
>27.2
>23.1
20.1
This observation will also yield a Differential Proper Motion Measure.
Is it, or Isn’t It?
Time will tell…
But, if not TWA6 ‘B’, the
technical capability to image such
young planets is no longer in the
future.
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.
Dusty Disks with Radial and Hemispheric Brightness Anisotropies
and Complex Morphologies, Possibly Indicative of Dynamical
Interactions with Unseen Planetary Mass Companions Were Spatially
Resolved and Imaged Around Three Young (< 10 Myr) Stars.
HR 4796A (A0V), ~ 8 Myr
A 70AU radius ring, ~ 10
AU wide ring of very red
material, exhibiting strong
forward scattering and
ansally asymmetric
hemispheric flux densities.
Dusty Disks with Radial and Hemispheric Brightness Anisotropies
and Complex Morphologies, Possibly Indicative of Dynamical
Interactions with Unseen Planetary Mass Companions Were Spatially
Resolved and Imaged Around Three Young (< 10 Myr) Stars.
HD 141569A
(Herbig Ae/Be)
~ 5 Myr
A 400AU radius disk, with a broad, partially filled
asymmetric gap containing a “spiral” arclet.
Dusty Disks with Radial and Hemispheric Brightness Anisotropies
and Complex Morphologies, Possibly Indicative of Dynamical
Interactions with Unseen Planetary Mass Companions Were Spatially
Resolved and Imaged Around Three Young (< 10 Myr) Stars.
TW Hya (K7)
“Old” PMS Star
Pole-on circularly symmetric disk with a break in
its surface brightness profile at 120 AU (2”).
Dusty Disks with Radial and Hemispheric Brightness Anisotropies
and Complex Morphologies, Possibly Indicative of Dynamical
Interactions with Unseen Planetary Mass Companions Were Spatially
Resolved and Imaged Around Three Young (< 10 Myr) Stars.
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
HR 4796A - Observational Chronology
1991 - Jura (ApJ, 383, L79) inferred presence of large amount of circumstellar dust from IRAS
excess. Estimated tdust = Ldisk/Lstar = 5x10-3 (~2x b Pictoris).
1995 - Jura et al. (ApJ, 445, 451) noted earlier 110K estimate of dust temperature indicated lack
of material at < 40 AU. Required grains > 3mm to be bound gravitationally at 40<r<200 AU. No
close companions with M* > 0.125 Msun seen (speckle).
1998 - Koerner et al. (ApJ, 503, L83) and Jayawardhana et al. (ApJ, 503, 79) independently
image mid-IR disk. Inner depleted region evident in high resolution 20.8mm image reproduced
with a model suggesting: i=72° (+6°, -9°), PA = 28°±6°, Rin ~ 55AU, Rout ~ 80AU -> Kuiper
belt-like dust ring.
1999 - Schneider et al. (ApJ, 513, L127) report on morphology and photometry of well-resolved
NIR images in two NIR colors (1.1 and 1.6mm) of a narrowly confined ringlike circumstellar
disk, with characteristic properties predicted by Koerner et al, from ~ 0.1" resolution NICMOS
coronagraphy obtained contemporaneously with 1998 mid-IR images.
Schneider et al. (1999)
Koerner et al. (1998)
Observation
20.8mm
Model
12.5 + 20.8mm
2"
HR 4796A - Has an M-Dwarf Companion
N
AB = 7.7"
≥500 pc
E
A
HR 4796B (late M)
Likely PMS Star
Hb, Hg, Ca H&K emission
J-H = 0.75
2"
B
… which could help to truncate the outer portion of the disk
Arc Seconds (Y)
NICMOS Observations of the HR 4796A Circumstellar Debris Ring
GEOMETRY
-1.0 F160W
PA = 26.8°±0.6°
i = 73.1°±1.2°
-0.5
a = 1.05”±0.02”
MORPHOLOGY
0.0
N
r = 70AU
width < 14AU
0.5
E
“abrupt” truncation
mJy/pixel
“clear” @ r < 50 AU
1.0
0
20
40
60
80
FLUX DENSITY
-1.0 F110W
12.8±1.0mJy @ 1.1mm
12.5±2.0mJy @ 1.6mm
-0.5
H(F160W) = 12.35± 0.16
0.19
J(F110W) = 12.92±0.08
0.0
N
Tdust ~ Ldisk/L*
1.4±0.2x10-3 @ 1.1mm
0.5
E
-3 @ 1.6mm
mJy/pixel 2.4±0.5x10
1.0
0
20 40 60 80 100 NIR scattered flux in good
agreement with visible
1.5
1.0
0.5
0.0 -0.5 -1.0 -1.5
Arc Seconds (X)
absorption & mid-IR re-radiation.
NICMOS Observations of the HR 4796A Circumstellar Debris Ring
-1.0
F160W
Anisotropies
NE ansa ~ 15% brighter
than SW ansa.
-0.5
0.0
N
Arc Seconds (Y)
0.5
E
mJy/pixel
1.0
0
-1.0
20
40
60
80
F110W
Implications
Possible dynamical
confinement of particles by
one or more unseen bodies.
-0.5
0.0
N
0.5
E
mJy/pixel
1.0
0
1.5
1.0
Suggestion of preferential
(forward) scattering to SE.
20
40
0.5
0.0 -0.5
Arc Seconds (X)
60
-1.0
80
100
-1.5
Mean particle size > few mm.
debris origin, not I.S. dust.
HR 4796A - Thermal IR Imaging
Deep OSCIR images of the HR 4796A disk Telesco et al. (1999, A&A) indicate comparable sizes
of 10.8 and 18.2 mm emitting regions. They find tcentral zone ≤ 3% of main part of the disk
(confirming that the central hole is largely cleared). Inward fall-off from the ring is shallower at
18.2mm then inferred from the NICMOS images. Moreover, they report on a possible brightness
asymmetry in the OSCIR images (similar to NICMOS) which might implicate the existence of a
gravitational perturber causing this "pericenter glow" (Wyatt, et al 2000) from particles in the NE
side of the disk shifted closer to the star.
Top: OSCIR 18.2 m m
Bottom: NICMOS 1.1 mm
Star-subtracted scans
along the disk major axis.
1.0
0.5
N
E
-2.0
-1.5
-1.0
0
-0.5
0.0
N
20
0.0
-0.5
E
40 60 80 100
0.5 1.0 1.5 2.0 -2.0 -1.5
Arc Seconds
-1.0
0
20
40
-0.5
0.0
0.5
60
1.0
80
-1.0
100
1.5
2.0
Models for different grain
sizes (Telesco, et al. 1999)
HR 4796A - Observational Chronology
1999 - Greaves et al. obtain JCMT/SCUBA 450 and 850mm flux excess measures of 0.18 and
0.019 Jy, respectively, and estimate total gas mass < 1–7 Earth masses.
1999 - Augereau et al. re-reduce K' observations of Mouillet et al. and find excess in agreement
with Schneider et al at ~1" in low S/N image showing extension in NE/SW directions. They
estimate a lower limit for dust mass of ~ 4 Earth masses.
NICMOS
Additional processing
recovered ring flux
closer in and
suggested somewhat
higher inclination
(~76°).
“Clumpiness” due
to residuals in PSF
subtraction, not
attributed to
structure of ring.
HR 4796A - Kenyon & Wood (2000) Dynamical Evolutionary Model
Monte Carlo runs constrain geometry & tdust
Produce observed dust distibution in 10 Myr
Minitial: 10-20x minimum-mass solar nebula
Assume: isotropic scattering and,
w = 0.3 (Augereau et al, 1999)
Adust to obtain t ~ 1.5x10-3
Kenyon & Luu (1999, ApJ)
e0 = 10-3
NICMOS 1.1mm image
z=0.5AU, R=5AU,
twNIR=0.25
e0 = 10-3
m0 = 10MMSN
a
CONCLUSIONS:
• Planet formation @ 70 AU in 10 Myr possible with initial
disk mass =10—20MMMSN.
• Dust
production associated with planet formation is then
confined to a ring with Da = 7—15 AU.
• Optical depth in ring satisfies constraints on scattered light
at 1—2 mm and on thermal emission
at 10—100 mm if the
-q
dust size distribution is N ~ ri with q ≥ 3 for ri ≤ 1 m.
z=5AU, R=10AU,
twNIR=0.2
z=1AU, R=20AU,
twNIR=0.1
• Models with
disk masses smaller than 10MMSN fail to
produce planets and an observable dusty ring in 10 Myr.
HR 4796A - Augereau et al. (1999) Physical Model
Two-component model reproduces all then-available observations: "the full spectral energy
distribution from the mid-infrared to the millimeter wavelengths, resolved scattered light and
thermal emission observations".
a) cold amorphous (Si and H20 ice) grains > 10mm in size (cut-off in size by radiation pressure),
with porosity ~0.6, peaking at 70AU.
b) hot dust at ~ 9AU of "comet-like" composition (crysatlline Si and H20), porosity ~ 0.97.
Collisions are common in both populations.
Bodies as large as a few meters are required.
Model gives rise to a minimum mass
of a few Mearth with gas:dust < 1.
Simulated disk at 20.8mm,
assuming grain properties and
surface density derived from
the SED fitting and a b Pic
like vertical structure, with
0.14" pixels like observations
by Koerner et al. (1998) and
convolved 10m telescope PSF.
~0.2Jy
annulus+hot
dust
Coldcold
annulus
+ hot dust (~0.2Jy)
Full SED fitting with
two dust populations.
Simulatated images of the cold annulus peaked at 70 AU in
scattered light at 1.1mm (with 0.076" pixels as in NICMOS)
for two asymmetry factors considered assuming a HenyeyGreenstein phase function (The inner hot dust not observable
has not been added). The NICMOS observation suggests |g| <
0.15. The flux density predicted in the region outside r > 0.65"
is 5.2mJy, in good agreement with the 7.5±0.5mJy observed
with HST.
HR 4796A
The quest for
higher resolution
STIS Observations of the HR 4796A Circumstellar Debris Ring
Orient #1
Orient #2
DOrient = 16°
STIS Observations of the HR 4796A Circumstellar Debris Ring
Orient #1
Orient #2
+
_
STIS Observations of the HR 4796A Circumstellar Debris Ring
PSF Orient #1 PSF Orient #2
Better
Focus
Match
Better
Position
Match
Better
Position
Match
Better
Focus
Match
Varience Minimized (Flux & Position Adjusted) PSF Subtractions
STIS Observations of the HR 4796A Circumstellar Debris Ring
PSF Orient #1 PSF Orient #2
2-rolls
samples
regions
otherwise
obscured
by wedge
& spikes
N
E
Varience Minimized (Flux & Position Adjusted) PSF Subtractions
STIS Observations of the HR 4796A Circumstellar Debris Ring
Weighted Image Combination - Resampled
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:
0.9
0.8
Brightness (normalized to NE Ansa)
Brightness (Normalized to NE Ansa)
1
NE ANSA CROSS-SECTIONAL PROFILE
1.1
1-e-1:* 7.5±0.4AU
11.9% Rring
1
0.7
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
-1.4
-1.3
-1.2
0.197”
0.043”
0.192”
0.126”
Slightly asymmetric
Distance (Arc Seconds)
-1.5
=
=
=
=
-0.6
0.1
0
-1.6
12.9±0.7AU
9.6% Dring
-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
Photometric Error Estimation
1s Noise (% of peak)
..
10
8
6
4
2
0
-2
-4
-6
-8
-10
0.5
1.0
Radius (arcseconds)
1.5
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
Aperture Photometry
STIS(leff 0.58 mm):
F(ring[unobscured])/F(star) = 0.00049 ± 0.000036 (7.3%)
NICMOS (leff 1.10 mm): F(ring[unobscured])/F(star) = 0.00083 ± 0.00012 (14.3%)
NICMOS (leff 1.60 mm): F(ring[unobscured])/F(star) = 0.00140 ± 0.00029 (20.8%)
Wavelength Dependent Scattering Efficiency (Color)
HR 4796A SUMMARY
Ring geometry/astrometry defined by NICMOS improved by
higher resolution STIS observations. Notably, i 2.6° larger than
original (published) NICMOS solution.
Spatially resolved photometry of ring with ±2% uncertainty at
ansae (1”), and ±6—8% uncertainty at 0.6—0.5”.
Characteristic width ~ 10% of 70AU radius ring.
“Left/Right” brightness anisotropy or ~20% along at least 50°
wide diametrically opposed arcs centered on ansae.
“Front/Back” brightness anisotropy, roughly symmetric in both
L/R “hemispheres”, increasing with longitudinal distance from
ansae to 35% difference at 30° from ansae.
Ring is uniformly RED from “V” to H with 1:1.7:2.9 spectral
reflectance in CCD50(“V”):F110W(1.1mm):F160W(H).
Brightness Anisotropies, Confinement & Color
Consistent with Dynamical Interactions with
Co-Orbital Unseen Planet-Mass Bodies
NICMOS F110W (0.8—1.4mm)
STIS 50CCD (0.2—1.0mm)
N
E
1"
0 10 20 30 40 50 60 70 80 90 100
% Peak Surface Brightness
HD 141569A
HD 141569A - Thermal IR Disk Detected/Imaged by Silverstone
HD 141569
PSF STAR
12.5
1"
17.9
0.26" FWHM
20.8
0.37" FWHM
0.43" FWHM
B9V Herbig Ae/Be Star, H = 6.89
d = 100 pc, Age ~ 5 Myr, 2.3Msun
HD 141569A - NICMOS Coronagraphic Imaging
Disk Radius = 400 AU
Gap Radius = 245 AU
Gap Width
~ 40 AU
1.1mm NICMOS Coronagraphic Image
1"
Face-on Projection
Unsharp Masking Gradient Enhancement
Scattering by cold dust is OUTSIDE region of thermal emission.
HD 141569A - Circumstellar Disk & Gap
NICMOS F110W
Total Flux Density = 8±2mJy @ r>0.6”
Peak SB = 0.3mJy arcsec-2 @ 185AU
Inclination to LOS = 51°±3°
Intrinsic Scattering Function results in
Brightness Anisotropy in ratio 1.5±0.2:1
in direction of forward scattering.
500AU (5")
Gap may be partially cleared of material
by unseen planetary companion.
0.01 xtw
Gap Width:Radius implies planetary
mass of ~ 1.2 M jup (2Mjup detection
limit @ gap, where w=0.35±0.05).
Surface Density of Scatterers
100
200
300
400
Radius (AU)
500
Hieracrchial triple system
dA(BC) = 8.3”, dBC = 1.3” (projected)
M-Dwarf companions may influence
disk dynamics.
HD 141569A - Albedo of the Grains
DENSITY OF SCATTERERS
tw = 4pr2F(r)
w = albedo
t = optical depth to scattering
ttotal = tscattered + tabsorbed
If tscattered + tabsorbed = LIR/L*= 8.4x10-3,
then wscattered = twscattered/ttotal = 0.25
But, in the outer portion of disk:
tabsorbed < 8.4x10-3 ==> wscattered ~ 0.4
(Weinberger, et al., 1999)
HD 141569A - Can a Planet “Hide” in the Gap?
Locat ion
of gap
R = 240 AU, M = 2.3Msun, so P = 2450 yr. For Age = 5x10 6 -> 2000 orbits
Limiting F110W magnitude for a point source in the gap is 20.3 -> M ~ 3 jup
Mass of Planet to Clear Gap: M/M * ~ c(Da/a3) where c~ 0.1 (Lissauer 1993)
for Da = 50 AU, a = 240 AU ->M = 0.9 Mjup, below detection threshold.
Note: For a gaseous disk (not this case) time to clear gap ~ 300 orbits (Lin et al 1999).
HD 141569 (A, BC)- A Triple System
Arcseconds (North)
vA – B
Sep = 7.” 57
PA = 311.5°
vB – C
Sep = 1.” 38
PA = 301.9°
Differential
Proper Motions
1998 NICMOS
1934 Rossiter
8
7
6
5
4
3
2
1
0
0
1
2
3
4
5
6
7
8
Arcseconds (West)
Predicted 1998 position from 1934
measures and Hipparcos proper motions
Also, consistent radial velocities
==> Common Space Motion
(Weinberger, et al, 2000, ApJ)
HD 141569 (A, BC)- Age-Dating the System
HD 141569 B & C ~ 5 Myr ± 3
3
Ha
yr)
Ti O
5
0.6
0.5
0.45
0.35
16
)
0.25
MJ
C
A
0
6.3
8
0.7
r
la
So
B
3.2
4
Baraffe, et al. (1998)
s(
as
4
Ag e (M
Li I
10
2 0.8
.
M
Flux Density (x10 3 )
15
5
0.2
0.15
6400 6600 6800 7000 7200 7400
EW
Ha
Li
B
C
-0.50 ± 0.05 -1.70 ± 0.05
0.50 ± 0.05 0.50 ± 0.05
6
7
Spectral Types: B = M2V, C= M4V
3.60
3.55
Teff
3.50
Companions: Young, Hot, M-Dwarfs
HD 141569 (A, BC) - Dynamical Sculpting by Companions?
2
3
4
5
6
7
8
9
• Density of Scatters:
Equal at 200 AU and 360 AU.
If non-coplaner companions can
excite vertical velocities in disk.
• Circular 50 AU-wide Gap @ 250AU
Continual clearing to remove P-R
and RP driven transiting particles.
• Gap circularity implies dynamical
stability on long time-scales.
• If co-planer Lindblad resonances
from 1053AU distant CoM (BC)
(9:1) @ 243 AU, (8:1) @ 263AU
closest to gap.
HD 141569A
NICMOS (0.11” Resolution)
Knowing the Flux Desnisity, Orientation, Size, etc.,
Allowed Planning an Effective Follow-up...
HD 141569A
STIS (0.05” Resolution)
Global strcture better described by “concentric ring” morphology.
“Gap” broader and partially filled.
“Spiral arclett” structure seen in disk gap.
HD 141569A
NICMOS (0.11”)
STIS (0.05” )
Gradient Enhancement
+ Mild Smoothing (@ Pixel Scale)
TW Hydrae
TW Hydrae
• K7Ve (Rucinski & Krautter, 1983)
• Distance: 56±7 pc (Hipparchos)
• Age: ~ 6 Myr
• Ha and UV Excesses
Isolated Classical T-Tauri Star
• Member TW Hya Association
(TWA ~ 10 Myr, 60 pc)
• Long Wavelength Excesses
t ~ Ldisk /Lstar ~ 0.3 (IRAS)
CO emission (Zuckerman et al. 1995)
TW Hydrae - NICMOS Coronagraphic Imaging
Face-On, Optically Thick, 190 AU radius Flared Disk
Flared Disk
+
Hole
1.1mm
1.6mm
-2)
ln Surface Brightness (mJy arcsec
• Gray scattering:
F110W - F160W = 0.96 mag (same as star)
Thin Disk
SURFACE BRIGHTNESS (mJy arcsec-2)
TW Hydrae - Is it Real?
YES
TW Hydrae - Is it Real?
Also seen in HST Optical Band-Passes
YES
STIS (0.5mm)
WFPC-2 (0.8mm)
TW Hydrae - Surface Brightness Profile
Flux density Power Law: r-2.6±.0.1 @ 35 AU < r < 135 AU
Break @ 100 AU
TW Hydrae - Surface Brightness Profile
“Zone 2-3 Break” may implicate sculpting by grains
12
Zone 1
2
14
3
4
NICMOS- Weinberger et al. 1999
WFPC-2 - Krist et al. 2000
16
18
F160W
F110W
F814W
F606W
50CCD (uncalibrated)
20
22
0.6
0.8
1
2
Radius (Arc Seconds)
3
4
TW Hydrae - Optical Assymetry
Radially and azimuthally confined arc-like depression?
ABSOLUTE MAGNITUDE
TW Hydrae - Companion Detection Limits
TW Hydrae - Mid-IR (8—13mm) Spectrum
(Spatially Unresolved @11.7 & 17.9 mm)
Fn (Jy)
Peak: Amorphous (~9.6mm) & Crystaline (~11.2mm) Silicates.
Keck I LWS Dl/l ~ 120
Weinberger, Becklin, Schneider, 2001
Wavelength (microns)
TW Hydrae - SED Model from All Spectral Bands
ala Chaing et al. (2001)
Log lFl [erg s-1 cm-2]
-9
Surface grains < 2mm
Interior grains < 12mm
-10
Grain Size Distribution
dN/dr (interior) ~ r-1
dN/dr (surface) ~ r-3.5
-11
-12
Dust Surface Mass Density
10 (r/AU) -1 cm-2
-13
-14
-15
1
10
100
1000
Wavelength [microns]
10000
Disk Radii:
Inner = 0.05 AU
Outer = 200 AU
TW Hydrae - Summary
TTS surrounded by Optically Thick dust disk.
Disk must be Flared given scattered light radius and thermal SED.
“Break” in Surf. Brightness @ ~ 95AU may be due to dynamical effects.
No Companions found to 10—2 Mjup @ 40—100 AU limit.
Disk Mass: ~ few x102 Earth Masses of Condensed Silicates & Ices.
Dust mass few times > “typical” Taurus & Ophiuchus TTS Disks.
Good evidence for grain growth within the disk.
PHYSICAL SIZES
HD 141569
TW HYDRAE
300 AU
TWA6 A/B
HR 4796A
140 AU
370 AU
490 AU
800 AU
PEAK
GAP
140 AU
The first-epoch NICMOS mission
ended on 4 January 1999. But, just as
dust is reprocessed around young stars,
NICMOS will get a new lease on life
after HST SM3B (14 Feb 2002) when a
a reverse Brayton cycle cooler will be
installed and interfaced with NICMOS,
returning it to service.
HUBBLE SPACE T ELESCOPE
We look forward to
the re-incarnation
of NICMOS, to
continue the search.
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Today, we have only a handful of
spatially resolved images of
dusty
debris disks and
extra-solar
planet
companion
candiates.
GLENN SCHNEIDER
NICMOS Project
Steward Observatory
933 N. Cherry Avenue
University of Arizona
Tucson, Arizona 85721
Phone: 520-621-5865
FAX: 520-621-1891
e-mail: [email protected]
http://nicmosis.as.arizona.edu:8000/
HUBBLE SPACE T ELESCOPE