The Growth Mechanisms of Macroscopic Bodies in Protoplanetary Disks
HD 100453 An Evolutionary Link Between Protoplanetary Disks and Debris Disks.
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Transcript of HD 100453 An Evolutionary Link Between Protoplanetary Disks and Debris Disks.
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HD 100453HD 100453An Evolutionary Link Between An Evolutionary Link Between
Protoplanetary DisksProtoplanetary Disksand Debris Disksand Debris Disks
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Journal Paper Co-authorsJournal Paper Co-authors
Karen Collins Master's Thesis Defense 4/24/2008
Co-authors(s) Affiliation ContributionC. A. Grady Eureka Scientific and NASA GSFC overall direction, science mentor, HST and Chandra PI, and day-to-day support
K. Hamaguchi & R. Petre X-ray Astrophysics Laboratory NASA/GSFC
Chandra observations, data reduction, and results
J. P. Wisniewski NASA/GSFC, NPP Fellow HST ACS HRC observations, data reduction, and results
S. Brittain Clemson University Gemini South observations of warm CO, data reduction, and results
M. Sitko & W. J. Carpenter SSI, University of Cincinnati SED and modeling data, general support
G. M. Williger University of Louisville FUSE observations, data reduction, results, and general day-to-day support
R. van Boekel Max-Planck-Institut für Astronomie VLT NACO NIR observations, data reduction, common proper motion results, and related photometric results
A. Carmona Max-Planck-Institut für Astronomie,ESO, ISDC & Geneva Observatory
VLT SINFONI NIR spectroscopy, data reduction, spectral typing, and other related results.
M. E. van den Ancker European Southern Observatory VLT SINFONI NIR spectroscopy, data reduction, spectral typing, and other related results.
G. Meeus Astrophysikalisches Institut Potsdam FEROS Ca II spectroscopic data
J. P. Williams, G. S. Mathews
University of Hawaii JCMT HARP CO spectroscopic observations, data reduction, dust mass calculations, gas mass calculations, and related results
X. P. Chen Max-Planck-Institut für Astronomie VLT NACO Brγ common proper motion data reduction
B. E. Woodgate NASA/GSFC overall scientific interpretation
Th. Henning Max-Planck-Institut für Astronomie overall scientific interpretation
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Karen Collins Master's Thesis Defense 4/24/2008
Star Formation OverviewStar Formation Overview
Start with molecular cloud Four phases of collapse
dense rotating core forms collapses from inside out bipolar outflows
carry away angular momen. (L) star and disk revealed
Conservation of L cloud rotates slowly star rotates more rapidly
High L material forms disk disk accretes onto star
Shu et al. 1987
Wood 1997
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Pre-Main Sequence StarsPre-Main Sequence Stars
Pre-main sequence (PMS) stars fully revealed stars still gravitationally contracting toward main sequence hydrogen fusion not started yet
PMS stars are called T Tauri if 0.1 M < M < 2 M (M, K, G, F type stars)
Herbig Ae/Be if 2 M < M < 8 M (F, A, B type stars)
higher mass stars emerge from cloud on main sequence
Observable characteristics Balmer emission lines in stellar spectrum (Hα, Hβ, Hγ, …)
transition (32, 42, 52, …) infrared excess due to circumstellar dust (next slides)
Karen Collins Master's Thesis Defense 4/24/2008
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Karen Collins Master's Thesis Defense 4/24/2008
Spectral Energy DistributionSpectral Energy Distribution Spectral Energy Distribution (SED)
plot of radiated energyvs. wavelength
Stellar photosphere~blackbody peaks in optical
Sun
5778 K A-type stars
7500-10,000 K M-type stars
3000-4000 K
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Infrared ExcessInfrared Excess
IR excess total emission − stellar contribution
stellar contribution determined from a model fit to UV and Optical data source is circumstellar dust
dust absorbs stellar radiation re-radiates as thermal emission
IR excess source inner disk
NIR (1 - 7 μm) outer disk
MID to FIR (10 - 50 μm) disk midplane
FIR to mm (>50 μm)
Karen Collins Master's Thesis Defense 4/24/2008
adapted from M.Sitko simulation
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Disk EvolutionDisk Evolution
Protoplanetary Disks (initial phase) gas rich + small dust grains (submicron) gas:dust ~100:1 (as in interstellar medium (ISM)) high accretion rates (> ~1108 M yr1)
gas and dust well mixed hydrostatic equilibrium dust material supported above midplane
disk can maintain scale height disk expected to “flare”
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Flared Disk Flared Disk
"bowl" shaped disk h r, where > 1.0 relatively flat SED in IR inner rim NIR BB disk surface MIR - FIR disk midplane FIR - mm
Karen Collins Master's Thesis Defense 4/24/2008
Dullemond et al. 2006 Dullemond et al. 2006
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Disk Vertical StructureDisk Vertical Structure
inner-most part of the disk is dust free beyond sublimation temperature
the inner rim is illuminated face-on from the star, the gas heats up more and causes an increased scale height (i.e. it "puffs up")
as the disk ages, the dust grains grow in size
disk becomes vertically stratified larger grains in midplane smaller grains in upper layers
Karen Collins Master's Thesis Defense 4/24/2008
Dullemond et al. 2006
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Disk Evolution ContinuedDisk Evolution Continued
Transitional Disks (intermediate phase) accretion rates ~10 - 100x lower than
protoplanetary disks
IR excess similar to pp disk at >10 μm
IR excess significantly less at <10 μm
result of less dust, or optically thin dust,in the inner disk photoevaporation
grain growth until optically thin
gap creation by massive planet
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Disk Evolution ContinuedDisk Evolution Continued
Debris Disks (final phase) accretion has stopped
moderate IR excess at >10 μm
very little to no IR excess at <10 μm
no inner disk at all
primordial dust has grown to rocks,protoplanets, and terrestrial planets
remaining dust is second generationfrom collisions of massive bodies
gas-poor
Karen Collins Master's Thesis Defense 4/24/2008
Van
den
Anc
ker
1999
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Meeus GroupsMeeus Groups
Meeus et al. (2001) divided 14 Herbig stars into two groups Group I
blackbody in MIR high fraction of IR excess (LIR/L* ~ 0.5)
steep submm slope (i.e. small grains) Group II
no blackbody in MIR low fraction of IR excess (LIR/L* ~ 0.2)
shallow submm slope (i.e. larger grains)
Meeus et al. suggested Group I sources evolve to Group II sources
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Meeus Physical ModelMeeus Physical Model
3 components disk midplane - optically thick inner disk with scale height outer disk
Group I inner disk optically thin
outer disk is directly illuminated outer disk heats & flares creates MIR BB
Group II inner disk optically thick
outer disk shielded outer disk stays flat no MIR BB
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Thesis GoalThesis Goal
Test idea that Meeus Group I sourcesevolve to Meeus Group II sources
at time of Meeus et al. (2001) paper, many age estimates were not available
accretion rates were not considered
(recall that accretion rate is tied to disk evolution)
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Thesis ApproachThesis Approach
Compare ages and accretion rates between the groups we focus on HD 100453 in this work because:
Herbig AeBe stars are difficult to date after about 5 Myr low-mass stars are easier to date and often form together with A-stars we can determine the age of the A-star from a companion low-mass star a candidate low-mass companion was recently reported for HD 100453A
(Chen et al. 2006)
determine age and accretion rate for HD 100453A (this work) determine age and accretion rate for other stars from the
literature
Karen Collins Master's Thesis Defense 4/24/2008
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HD 100453AHD 100453A
Karen Collins Master's Thesis Defense 4/24/2008
Southern Hemisphere(Lower Centaurus-Crux Assn)
Distance 114 pc v=7.78
(not visible by naked eye)
Spectral Type A9Ve Age > ~10 Myr
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Summary of ObservationsSummary of Observations
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Test of Companion Status Test of Companion Status
To date an A-star from a low-mass companion, we need to know that they are physical companions
Two tests: determine motion of A-star & candidate companion
If motion through space is common, they are likely physical companions
determine spectral type of companion for the brightness contrast between the two stars,
a physical companion would be a low-mass star
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The Candidate CompanionThe Candidate Companion
HST optical direct image B located 1.05 @ 126° east of north
mv = 15.87 (A:B = 1500:1 contrast)
Karen Collins Master's Thesis Defense 4/24/2008
optical
HST ACS HRC F606W
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Candidate Companion Spectral TypeCandidate Companion Spectral Type
Need high spatial resolution spectroscopyto separate the light from the two stars
Optical Spectroscopy is first choice need A/O for ~1 separation none available
NIR is good second choice SINFONI on VLT with A/O Integral Field Spectrograph 0.8 x 0.8 field of view J, H, K band gratings (NIR)
Karen Collins Master's Thesis Defense 4/24/2008
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Candidate Companion Spectral TypeCandidate Companion Spectral Type
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Relative Proper MotionRelative Proper Motion
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Candidate ConfirmationCandidate Confirmation
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Companion PhotometryCompanion Photometry
Object Mode Filter magnitude Notes(prime)
HD 100453B Direct mF606W 15.6 HST HRC(J. Wisniewski)
HD 100453B Coron mF606W 15.8 HST HRC(J. Wisniewski)
HD 100453B Combined mF606W 15.7 0.2(J. Wisniewski)
HD 100453B Direct Ks 10.66 0.1(Chen et al. 2006)
HD 100453B Coron L 10.13 0.1 VLT NACO(R. van Boekel)
HD 100453B Coron M 9.99 0.1 VLT NACO(R. van Boekel)
HD 100453B Calculated V 15.87 0.2(K. Collins)
HD 100453B Calculated K 10.64 0.1(K. Collins)
HD 100453B Calculated L 10.27 0.1(K. Collins)
Karen Collins Master's Thesis Defense 4/24/2008
• Key Point: Candidate companion has NO IR Excess Can use K-band in H-R diagram for age estimate
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Age Determination (from A-star)Age Determination (from A-star)
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Age Determination (from Age Determination (from Companion)Companion) Note wider separation of isochrones for low-mass stars
HD 100453B (input data) mK = 10.64 ± 0.1 M4.0V – M4.5V
Teff = 3300 K – 3400 K
Results (Siess Model) age: 10 15 Myr mass: 0.21 0.23 M
Results (Baraffe Model) age: 11 18 Myr mass: 0.24 0.30 M
Results (Combined) age: 14 ± 4 Myr mass: 0.21 0.30 M
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Mass Accretion onto A-starMass Accretion onto A-star
Mass accretion rate gives insight into theevolutionary phase of the disk
We investigate the following accretion indicators: enhanced FUV continuum Herbig-Haro knots in Lyα enhanced emission of
Ca II λ8662 Å Hard X-rays Hα (6563 Å) Brγ (2.166 μm)
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Accretion - FUV ContinuumAccretion - FUV Continuum
FUV continuum upper limit from FUSE spectra <1.51015 ergs s1 cm2 Å1 (1σ)
(-14.8 in log space)
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Accretion - FUV ContinuumAccretion - FUV Continuum
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Accretion - FUV ContinuumAccretion - FUV Continuum
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Accretion - Herbig-Haro Knots Accretion - Herbig-Haro Knots
Karen Collins Master's Thesis Defense 4/24/2008
HST ACS SBC F122M
FUV
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Accretion- Ca II Accretion- Ca II 8662 Å emission 8662 Å emission
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Accretion - HαAccretion - Hα
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Accretion - X-rayAccretion - X-ray
Karen Collins Master's Thesis Defense 4/24/2008
Chandra
red 0.35 − 0.70 keVgreen 0.70 − 0.90 keVblue 0.90 − 2.00 keVenergy (keV) 1 2
Chandra X-ray
HD 100453AHD 100453B
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Accretion Rate SummaryAccretion Rate Summary
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Constraints on Disk StructureConstraints on Disk Structure
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M. Sitko, private communication
Habart et al. (2006)
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HST ACS CoronagraphyHST ACS Coronagraphy Need ~1x106 contrast to image disk around A star Use coronagraph to block light from central star Use psf-subtraction to reduce remaining stray light ACS HRC provides contrast of:
~1x105 in direct mode ~1x106 in coronagraphic mode ~1x107 in coronagraphic mode with psf-subtraction
HRC has 0".9 radius spot size, but psf-subtraction residuals out to ~2-3"
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Clampin et al. 2003
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Constraints on Disk StructureConstraints on Disk Structure
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HST ACS HRC Coron w/psf-sub
HD 100453
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Constraints on Disk StructureConstraints on Disk Structure
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HST ACS - 2003 (red)VLT NACO - 2006 (blue)
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Disk Structure SummaryDisk Structure Summary
Karen Collins Master's Thesis Defense 4/24/2008
C
B
A
Gap (SED dip)?
i ?
Inner Rim<0.5 AU (NIR BB)
Outer Radius>40 AU (PAH)
Outer Edge Optically Thin<90 proj. AU (star C)
Companion120 proj. AU
Scattered LightOuter Radius <250 AU
Line of Sight
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Gas and Dust in Inner DiskGas and Dust in Inner Disk
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(after Brittain et al. 2007)
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Gas and Dust in Outer DiskGas and Dust in Outer Disk
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Where Does It Belong?Where Does It Belong?
14 ± 4 Myr transitional disk character High NIR excess protoplanetary disk character Low accretion rate transitional or debris disk character Gas-poor disk debris disk character High total IR excess flared disk? requires gas?
HD 100453A does not fit in anyclassically defined disk group(protoplanetary, transitional, debris)
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Thesis ResultsThesis Results
Karen Collins Master's Thesis Defense 4/24/2008
Recall we set out to test idea that Meeus Group I sources evolve to Group II ...
by comparing ages & accretion between the groups determine for HD 100453 collect new and updated data from literature
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Thesis ResultsThesis Results
Karen Collins Master's Thesis Defense 4/24/2008
Group I sources areslightly older than Group II on average(but are within 1σ)
Group I accretion rates are slightly lower than Group II accretion rateson average(but are within 1σ)
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Thesis ResultsThesis Results
Age range significantlyoverlaps between the twogroups
Accretion slows as star agesin both groups
Meeus suggested star and diskevolution may be decoupledfor this sample
We find that the star, accretion rate, and disk evolve together. We conclude that the hypothesis suggesting Meeus Group I
sources evolve to Meeus Group II sources does not hold.
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Possible Physical ExplanationPossible Physical Explanation
HD 100546 example (Group I) cavity confirmed by interferometry & STIS (Lui et al. 2003) (Grady et al. 2005)
inner rim of inner and outer disk createsNIR and MIR blackbody components in SEDand high Lexcess/L*
possible giant planet in gap is causingcollisional cascade
collisions produce small dust grains radiation pressure blows the grains onto
surface of cold outer disk small grains cause steep submm slope
Meeus groups may be more representative of differences in disk structure rather than differences in disk evolution.
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after Bouwman et al. 2003)
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Future DirectionsFuture Directions
To lift disk structure degeneracy allowed by SED need high contrast, high spatial resolution imaging high spatial resolution interferometry
We can do this with existing instrumentation NICMOS on HST (coron. imaging, 0.075 pixel1 , 0".3 hole)
My collaborators have submitted a proposal (March 2008) for NICMOS observations of several T Tauri and Herbig Ae/Be stars, including HD 100453.
Near-term prospects HST SM4 (8/2008) set to repair other key instruments
ACS (down since June 2006) coron. imaging mode, 0.025 pixel1, 0".9 radius spot
STIS (down since 2004) coron. imaging mode, 0.05 pixel1, 0".5-2.8" wedges
Karen Collins Master's Thesis Defense 4/24/2008
HD
141
569
(f
rom
Kris
t 20
04)
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Long -Term ProspectsLong -Term Prospects
Atacama Large Millimeter Array (ALMA) 0.3 - 9.6 mm (cold dust and gas) 0".01 resolution, no occulter needed 64 x 12-meter antennas completion expected in 2012
Simulation 0.5 M star
1 MJ planet
5 AU orbit Mdisk = 10 MJ
Karen Collins Master's Thesis Defense 4/24/2008
Wolf & D'Angelo 2005
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Karen Collins Master's Thesis Defense 4/24/2008
A possible view of the HD 100453 system?A possible view of the HD 100453 system?
adapted from NASA/JPL-Caltech/T. Pyle (SSC)
Thank You!Thank You!