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Glenn Schneider Steward Observatory, University of Arizona (NICMOS/IDT) Dusty Circumstellar Disks and Substellar Companions
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Glenn Schneider Steward Observatory, University of Arizona (NICMOS/IDT) Substellar Companions and Dusty Circumstellar Disks … and, what’s happening @ ~ 100 AU? @ ~ 100 AU?
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Diffraction Limited Imaging in Optical/Near-IR > 98% Strehl Ratios @ all s Highly STABLE PSF Coronagraphy: NICMOS STIS, ACS NIR High Dynamic Range Sampling NICMOS/MA: mag=19.4 (6 x 4m) Background Rejection 1.6 m: ~10 -6 pix -1 @ 1” 1.1 m: ~10 -5 in 2”-3” annulus Intra-Orbit Field Rotation HST Provides a Unique Venue for High Contrast Imaging
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H-Band (F160W) Point-Source Detectability Limits Two-Roll Coronagraphic PSF Subtraction 22m Total Integration H(5 ) = 7.14 + 3.15 ” - 0.286 ” 2. Read Noise DominatedPhoton Noise Dominated H=6.9
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Extra-Solar Planet & Brown Dwarf Companions Circumstellar Disks Scientific Areas of Investigation via PSF-Subtracted Coronagraphic Imaging
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HST/NICMOS Coronagphic Imaging Surveys Carried Out by the IDT’s Environments of Nearby Stars (EONS) Team 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.
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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. few megayears to a few tens of megayears 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.
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Collapsing protostar forms proto- planetary disk Rocky cores of giant planets form Terrestrial planets form Clearing of inner solar system, formation of a Kuiper cometary belt? 10 6 yrs 10 8 yrs 10 9 yrs accrete gaseous atmospheres Era of heavy bombarment by comets Current age of the Sun: 5x10 9 yrs. Persei Sun TW Hydrae Taurus, Ophiuchus star forming regions Hyades Tucanae Assoc Pleiades Primary Dust (≤ m) Secondary Dust (≥ m) Locked to Gas Collisional erosion Clearing Timescales: P-R drag few 10 6 Rad. Pressure: ~ 10 4 rys 10 7 Assoc Giant planets From: R. Webb Planet-Building Timeline
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.. 0 6 7 8 9 10 Log 10 Age (years) 80M jup 14M jup JUPITER SATURN STARS (Hydrogen burning) BROWN DWARFS (Deuterium burning) PLANETS 200M jup GL 503.2B GL577B/C HR 7329B CD -33° 7795B TWA6B ? Evolution of M Dwarf Stars, Brown Dwarfs and Giant Planets (from Adam Burrows) -10 -8 -6 -4 -2 Log 10 L/L sum sun Cooling Curves for Substellar Objects
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DIRECT DETECTION OF YOUNG PLANETS MECHANICS& A PRIME CANDIDATE (TWA 6 ‘B’)
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CORONAGRAPHICCOMPANIONDETECTION 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 Roll = 30° Time = 20 minutes
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Above: Coronagraphic Images Roll: 30° Above: Coronagraphic Images Roll: 30° Left: Difference Image Same display dynamic range At =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. H companion = 20.1 H = 13.2
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Minimize local residuals in region near companion image while constraining background to be statistically zero...
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PositiveImageExtracion
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NegativeImageExtraction(Inverted)
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RotateNegativeExtractionAboutOccultedTarget And Add AfterInversion
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Model and RemoveDiffractionSpikeResiduals**DSPK Is it a Point Source?
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Radial Profile, Photocentric Moment & Gaussian Fitting Is it a Point Source?
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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...
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Sensitivity: Noise Equavalent Background Assessment
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Detectability and Spatial Completeness ( ) Dependence via Model PSF Implantation ( ) Dependence via Model PSF Implantation Observed Model * Nulled Implant * TinyTim 5.0 HST+NICMOS Optical Model - Krist
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Detectability: ( ) Dependence via Model PSF Implantation
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. 4 8 12 16 20 25 % Recovered Flux S/N (Positive Implant Only) Photometric Efficacy & Statistical Significance
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TWA6B Detection Illustrates Performance Repeatability Two-Roll Coronagraphic PSF Subtraction 22m Total Integration H(5 ) = 7.14 + 3.15 ” - 0.286 ” 2.
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TW Hya Assn K7 primary, D = 55pc Age = 10 Myr =2.54”, 140AU H =13.2 (L B/A )[H]=5 x 10 -6 Habs = 16.6 Implies: Mass ~ 2 Jupiter Mass ~ 2 Jupiter T eff ~ 800K T eff ~ 800K IF Companion... S/N TWA6B = 35 TWA 6A/B
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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)
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Is it, or Isn’t It? Undetected in NICMOS 0.9 m 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 Band Bandpass Mag NICMOS/C2 F160W 1.40—1.80 20.1 NICMOS/C2 F090M 0.80—1.00 >23.1 STIS/G750L I extract 0.81—0.99 ~25.4 STIS/G750L R extract 0.63—0.77 >27.2 If NOT a hot young planet, it must be a Highly exotic object!
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Is it, or Isn’t It? Undetected in NICMOS 0.9 m Followup Observation I-H > 3 Marginally Detected in 6-Orbit Binned STIS G750L Spectrum Colors Consistent with 2 Mjup, 10 Myr, “Hot” Giant Planet* 20.1 >23.1 ~25.4 >27.2 Keck/AO Astrometric (PM) Follow-up Thus-Far Inconclusive * Sudarsky et al., 2000Spectrum from A. Burrows
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Is it, or Isn’t It? We have requested 12 HST Orbits to attempt PSF-subtracted NICMOS G141 (1.1—1.9 m) grism spectrophotometry to obtain what might be the first spectrum of an extra-solar planet. 20.1 >23.1 ~25.4 >27.2 This observation will also yield a Differential Proper Motion Measure.
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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.
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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. Observing scattered light from circumstellar debris has been observationally challenging because of the very high Star:Disk contrast ratios in such systems. 1984 - B.A. Smith & R.J. Terrile 6" radius coronagraphic mask, Las Campanas (discovery image) Until very recently the large, and nearly edge-on disk around Pictoris remained the only such disk imaged. Pictoris Resolved imaging spatial distribution of dust/debris. Direct (Scattered Light) Imaging of Dusty Debris
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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.
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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. A 400AU radius disk, with a broad, partially filled asymmetric gap containing a “spiral” arclet. HD 141569A (Herbig Ae/Be) ~ 5 Myr
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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”).
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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”). and, possibly, a radially and azimuthally confined arc-like depression.
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HR 4796A
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1991 - Jura (ApJ, 383, L79) inferred presence of large amount of circumstellar dust from IRAS excess. Estimated dust = Ldisk/Lstar = 5x10-3 (~2x Pictoris). 1995 - Jura et al. (ApJ, 445, 451) noted earlier 110K estimate of dust temperature indicated lack of material at 3 m to be bound gravitationally at 40 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 20.8 m 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 1.6 m) 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. Koerner et al. (1998) Observation Model 2" 12.5 + 20.8 m 20.8 m Schneider et al. (1999) HR 4796A - Observational Chronology
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N E B A 2" AB = 7.7" ≥500 pc HR 4796B (late M) Likely PMS Star H , H , Ca H&K emission J-H = 0.75 HR 4796A - Has an M-Dwarf Companion … which could help to truncate the outer portion of the disk
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NICMOS Observations of the HR 4796A Circumstellar Debris Ring E N 020406080100 Arc Seconds (Y) -0.5 0.0 0.5 1.0 0.5 -0.5 0.0 1.0 020406080 1.5 1.0 0.50.0-0.5-1.5 Arc Seconds (X) E N F160W F110W mJy/pixel GEOMETRY PA = 26.8°±0.6° i = 73.1°±1.2° a = 1.05”±0.02” MORPHOLOGY r = 70AU width < 14AU “abrupt” truncation “clear” @ r < 50 AU FLUX DENSITY 12.8±1.0mJy @ 1.1 m 12.5±2.0mJy @ 1.6 m H(F160W) = 12.35± J(F110W) = 12.92±0.08 0.16 0.19 T dust ~ L disk /L * 1.4±0.2x10 -3 @ 1.1 m 2.4±0.5x10 -3 @ 1.6 m NIR scattered flux in good agreement with visible absorption & mid-IR re-radiation.
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E N 020406080100 Arc Seconds (Y) -0.5 0.0 0.5 1.0 0.5 -0.5 0.0 1.0 020406080 1.5 1.0 0.50.0-0.5-1.5 Arc Seconds (X) E N F160W F110W mJy/pixel Implications Possible dynamical confinement of particles by one or more unseen bodies. Mean particle size > few m. debris origin, not I.S. dust. Anisotropies NE ansa ~ 15% brighter than SW ansa. Suggestion of preferential (forward) scattering to SE. NICMOS Observations of the HR 4796A Circumstellar Debris Ring
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Deep OSCIR images of the HR 4796A disk Telesco et al. (1999, A&A) indicate comparable sizes of 10.8 and 18.2 m emitting regions. They find central 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 18.2 m 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. 020406080100 E N Arc Seconds -2.0-1.5-0.50.00.51.01.52.0 1.0 0.5 0.0 -0.5 E N -1.5-0.50.00.51.01.52.0 020406080100 -2.0 Top: OSCIR 18.2 m Bottom: NICMOS 1.1 m Star-subtracted scans along the disk major axis. Models for different grain sizes (Telesco, et al. 1999) HR 4796A - Thermal IR Imaging
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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. 1999 - Greaves et al. obtain JCMT/SCUBA 450 and 850 m 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. HR 4796A - Observational Chronology
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z=0.5AU, R=5AU, NIR =0.25 z=5AU, R=10AU, NIR =0.2 z=1AU, R=20AU, NIR =0.1 NICMOS 1.1 m image Monte Carlo runs constrain geometry & dust Produce observed dust distibution in 10 Myr Minitial: 10-20x minimum-mass solar nebula Assume: isotropic scattering and, = 0.3 (Augereau et al, 1999) Adust to obtain ~ 1.5x10 -3 a e 0 = 10 -3 e 0 = 10 -3 m 0 = 10 MMSN CONCLUSIONS: Planet formation @ 70 AU in 10 Myr possible with initial disk mass =10—20M MMSN. Dust production associated with planet formation is then confined to a ring with a = 7—15 AU. Optical depth in ring satisfies constraints on scattered light at 1—2 m and on thermal emission at 10—100 m if the dust size distribution is N ~ r i with q ≥ 3 for r i ≤ 1 m. Models with disk masses smaller than 10 MMSN fail to produce planets and an observable dusty ring in 10 Myr. -q Kenyon & Luu (1999, ApJ) HR 4796A - Kenyon & Wood (2000) Dynamical Evolutionary Model
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Cold annulus + hot dust (~0.2Jy) Simulated disk at 20.8 m, assuming grain properties and surface density derived from the SED fitting and a Pic like vertical structure, with 0.14" pixels like observations by Koerner et al. (1998) and convolved 10m telescope PSF. Full SED fitting with two dust populations. HR 4796A - Augereau et al. (1999) Physical Model Simulatated images of the cold annulus peaked at 70 AU in scattered light at 1.1 m (with 0.076" pixels as in NICMOS) for two asymmetry factors considered assuming a Henyey- Greenstein 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. 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 > 10 m 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. ~0.2Jy cold annulus+hot dust
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HR 4796A The quest for higher resolution
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HR 4796A HR 4748 (PSF) Orient #1 Orient #2 Orient = 16° STIS Observations of the HR 4796A Circumstellar Debris Ring
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HR 4796A HR 4748 (PSF) Orient #1 Orient #2 __ STIS Observations of the HR 4796A Circumstellar Debris Ring
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Better Focus Match Better Focus Match PSF Orient #1 PSF Orient #2 Varience Minimized (Flux & Position Adjusted) PSF Subtractions Better Position Match Better Position Match STIS Observations of the HR 4796A Circumstellar Debris Ring
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PSF Orient #1 PSF Orient #2 N E 2-rolls samples regions otherwise obscured by wedge & spikes STIS Observations of the HR 4796A Circumstellar Debris Ring Varience Minimized (Flux & Position Adjusted) PSF Subtractions
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Weighted Image Combination - Resampled STIS Observations of the HR 4796A Circumstellar Debris Ring
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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 RING GEOMETRY (Least-Squares Isophotal Ellipse Fit)
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Brightness (Normalized to NE Ansa) HR 4796A Circumstellar Debris Ring - WIDTH FWHM ring = 0.192” FWHM: 12.9±0.7AU 9.6% D ring 1-e -1 = 0.126” PSF point source = 0.043” Measured = 0.197” WIDTH AT NE ANSA 1-e -1 : 7.5±0.4AU 11.9% R ring * Slightly asymmetric *
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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" RING GEOMETRY - Least-Squares Isophotal Ellipse Fit
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“FACE-ON” PROJECTION - With Flux Conservation
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Spatially Resolved Relative PHOTOMETRY of the Ring
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Photometric Error Estimation
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N-Sigma Brightness Ratio (Percent) NW:SE Surface Brightness Anisotropy
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N-Sigma Brightness Ratio (Percent) Front:Back Surface Brightness Anisotropy
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STIS( eff 0.58 m): F(ring[unobscured])/F(star) = 0.00049 ± 0.000036 (7.3%) NICMOS ( eff 1.10 m): F(ring[unobscured])/F(star) = 0.00083 ± 0.00012 (14.3%) Aperture Photometry NICMOS ( eff 1.60 m): F(ring[unobscured])/F(star) = 0.00140 ± 0.00029 (20.8%)
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Wavelength Dependent Scattering Efficiency (Color)
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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. “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. Characteristic width ~ 10% of 70AU radius ring. Ring is uniformly RED from “V” to H with 1:1.7:2.9 spectral reflectance in CCD50(“V”):F110W(1.1 m):F160W(H). Spatially resolved photometry of ring with ±2% uncertainty at ansae (1”), and ±6—8% uncertainty at 0.6—0.5”.
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Brightness Anisotropies, Confinement & Color Consistent with Dynamical Interactions with Co-Orbital Unseen Planet-Mass Bodies
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HD 141569A
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1" HD 141569 PSF STAR 12.5 17.9 20.8 0.26" FWHM 0.37" FWHM 0.43" FWHM HD 141569A - Thermal IR Disk Detected/Imaged by Silverstone B9V Herbig Ae/Be Star, H = 6.89 d = 100 pc, Age ~ 5 Myr, 2.3M sun
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1" Face-on Projection Unsharp Masking Gradient Enhancement 1.1 m NICMOS Coronagraphic Image Disk Radius = 400 AU Gap Radius = 245 AU Gap Width ~ 40 AU HD 141569A - NICMOS Coronagraphic Imaging Scattering by cold dust is OUTSIDE region of thermal emission.
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Surface Density of Scatterers 100200300400500 Radius (AU) 0.01 x 500AU (5") NICMOS F110W HD 141569A - Circumstellar Disk & Gap 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. Gap may be partially cleared of material by unseen planetary companion. Gap Width:Radius implies planetary mass of ~ 1.2 M jup (2Mjup detection limit @ gap, where w=0.35±0.05). Hieracrchial triple system d A ( BC ) = 8.3”, d BC = 1.3” (projected) M-Dwarf companions may influence disk dynamics.
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DENSITY OF SCATTERERS = 4 r 2 F(r) = albedo = optical depth to scattering But, in the outer portion of disk: absorbed < 8.4x10 -3 ==> scattered ~ 0.4 total = scattered + absorbed If scattered + absorbed = L IR /L = 8.4x10 -3, then scattered = scattered / total = 0.25 * (Weinberger, et al., 1999) HD 141569A - Albedo of the Grains
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Location 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( a/a 3 ) where c~ 0.1 (Lissauer 1993) for a = 50 AU, a = 240 AU ->M = 0.9 M jup, below detection threshold. Note: For a gaseous disk (not this case) time to clear gap ~ 300 orbits (Lin et al 1999). HD 141569A - Can a Planet “Hide” in the Gap?
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A – B Sep = 7.”57 PA = 311.5° B – C Sep = 1.”38 PA = 301.9° 1998 NICMOS 1934 Rossiter Differential Proper Motions 0 1 2 3 4 5 6 7 8 012345678 Arcseconds (West) Arcseconds (North) 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)- A Triple System
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TiO LiI H Flux Density (x10 3 ) 5 0 10 15 640066006800700072007400 B A 0.50 ± 0.05 -1.70 ± 0.05 C 0.50 ± 0.05 -0.50 ± 0.05 B Li H EW HD 141569 B & C ~ 5 Myr ± 3 Spectral Types: B = M2V, C= M4V Companions: Young, Hot, M-Dwarfs HD 141569 (A, BC)- Age-Dating the System
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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 141569 (A, BC) - Dynamical Sculpting by Companions?
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HD 141569A NICMOS (0.11” Resolution) Knowing the Flux Desnisity, Orientation, Size, etc., Allowed Planning an Effective Follow-up...
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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.
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HD 141569A NICMOS (0.11”) STIS (0.05” ) NICMOS (0.11”) STIS (0.05” ) Gradient Enhancement + Mild Smoothing (@ Pixel Scale)
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TW Hydrae
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K7Ve (Rucinski & Krautter, 1983) Distance: 56±7 pc (Hipparchos) Age: ~ 6 Myr H and UV Excesses Isolated Classical T-Tauri Star Member TW Hya Association (TWA ~ 10 Myr, 60 pc) Long Wavelength Excesses ~ L disk /L star ~ 0.3 (IRAS) CO emission (Zuckerman et al. 1995) TW Hydrae
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Gray scattering: F110W - F160W = 0.96 mag (same as star) Flared Disk + Hole Thin Disk 1.1 m 1.6 m ln Surface Brightness (mJy arcsec -2 ) TW Hydrae - NICMOS Coronagraphic Imaging Face-On, Optically Thick, 190 AU radius Flared Disk
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SURFACE BRIGHTNESS (mJy arcsec -2 ) TW Hydrae - Is it Real? YES
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YES Also seen in HST Optical Band-Passes STIS (0.5 m)WFPC-2 (0.8 m)
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TW Hydrae - Surface Brightness Profile Flux density Power Law: r -2.6±.0.1 @ 35 AU < r < 135 AU Break @ 100 AU
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TW Hydrae - Surface Brightness Profile “Zone 2-3 Break” may implicate sculpting by grains
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Radially and azimuthally confined arc-like depression? TW Hydrae - Optical Assymetry
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ABSOLUTE MAGNITUDE TW Hydrae - Companion Detection Limits
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Peak: Amorphous (~9.6 m) & Crystaline (~11.2 m) Silicates. TW Hydrae - Mid-IR (8—13 m) Spectrum (Spatially Unresolved @11.7 & 17.9 m) Wavelength (microns) F (Jy) Keck I LWS ~ 120 Weinberger, Becklin, Schneider, 2001
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Log F [erg s -1 cm -2 ] Wavelength [microns] TW Hydrae - SED Model from All Spectral Bands ala Chaing et al. (2001) Surface grains < 2 m Interior grains < 12mm Grain Size Distribution dN/dr (interior) ~ r -1 dN/dr (surface) ~ r -3.5 Dust Surface Mass Density 10 (r/AU) -1 cm -2 Disk Radii: Inner = 0.05 AU Outer = 200 AU
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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 M jup @ 40—100 AU limit. Disk Mass: ~ few x10 2 Earth Masses of Condensed Silicates & Ices. Dust mass few times > “typical” Taurus & Ophiuchus TTS Disks. Good evidence for grain growth within the disk.
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PHYSICAL SIZES
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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. We look forward to the re-incarnation of NICMOS, to continue the search. Today, we have only a handful of spatially resolved images of dusty debris disks and extra-solar planet companion candiates.
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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: gschneider@as.arizona.edu http://nicmosis.as.arizona.edu:8000/
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