hd 100453 an evolutionary link between protoplanetary disks and debris disks

HD 100453HD 100453An Evolutionary Link Between An Evolutionary Link Between

Protoplanetary DisksProtoplanetary Disksand Debris Disksand Debris Disks

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


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

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)



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

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)


adapted from M.Sitko simulation

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”


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


Dullemond et al. 2006 Dullemond et al. 2006

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


Dullemond et al. 2006

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


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


Van

den

Anc

ker

1999

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


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


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)


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


HD 100453AHD 100453A


Southern Hemisphere(Lower Centaurus-Crux Assn)

Distance 114 pc v=7.78

(not visible by naked eye)

Spectral Type A9Ve Age > ~10 Myr

Summary of ObservationsSummary of Observations


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


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)


optical

HST ACS HRC F606W

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)


Candidate Companion Spectral TypeCandidate Companion Spectral Type


Relative Proper MotionRelative Proper Motion


Candidate ConfirmationCandidate Confirmation


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)


• Key Point: Candidate companion has NO IR Excess Can use K-band in H-R diagram for age estimate

Age Determination (from A-star)Age Determination (from A-star)


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


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)


Accretion - FUV ContinuumAccretion - FUV Continuum

FUV continuum upper limit from FUSE spectra <1.51015 ergs s1 cm2 Å1 (1σ)

(-14.8 in log space)


Accretion - FUV ContinuumAccretion - FUV Continuum


Accretion - Herbig-Haro Knots Accretion - Herbig-Haro Knots


HST ACS SBC F122M

FUV

Accretion- Ca II Accretion- Ca II 8662 Å emission 8662 Å emission


Accretion - HαAccretion - Hα


Accretion - X-rayAccretion - X-ray


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

Accretion Rate SummaryAccretion Rate Summary


Constraints on Disk StructureConstraints on Disk Structure


M. Sitko, private communication

Habart et al. (2006)

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"


Clampin et al. 2003



HST ACS HRC Coron w/psf-sub

HD 100453



HST ACS - 2003 (red)VLT NACO - 2006 (blue)

Disk Structure SummaryDisk Structure Summary


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

Gas and Dust in Inner DiskGas and Dust in Inner Disk


(after Brittain et al. 2007)

Gas and Dust in Outer DiskGas and Dust in Outer Disk


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)


Thesis ResultsThesis Results


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



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)


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.


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.


after Bouwman et al. 2003)

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


HD

141

569

(f

rom

Kris

t 20

04)

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


Wolf & D'Angelo 2005


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!

hd 100453 an evolutionary link between protoplanetary disks and debris disks

Documents

midplane disk

material forms disk

pp disk

size disk

disk ages

scale height disk

outer disk mid

disk vertical structure