Imaging of Protoplanetary and Debris Disks

Nov. 12 2007 PALM 3000 Requirements Review

Imaging of Protoplanetary and Debris Disks

Karl StapelfeldtJet Propulsion Laboratory


What is Learned fromHigh Resolution Disk Imaging?

• Confirms basic disk morphology of dust distribution– position angle– major and minor axes (outer radius of disk)

• Measurable disk parameters– Radial disk structure (gaps, rings)– Azimuthal disk structure (asymmetries)– Vertical thickness (if close to edge-on)

• Derivable disk parameters via image modeling– Inclination– Radial surface brightness profile vertical flaring vs. radius– Vertical disk structure if nearly edge-on scale height– Disk mass-opacity product– Dust properties : κ(λ), phase function, polarizability

• Some of the derivable properties are degenerate


“Transiting” Disks: The Orion Silhouettes

HST/ACS Hα; N. Smith et al. 2005

• Disks backlit by the M42 H II region, d= 450 pc

• Clearly seen in the optical (Hα, …), but difficult to study in the near-IR

• 26 clean examples to date; more coming ?

• Not seen towards other H II regions


Edge-on disks : 13 + 4 now imaged

V 376 CasStapelfeldt et al. 2008

WFPC2 RI

CB 26Sauter et al. 2008

NICMOS JHK

‘Gomez Hamburger’-PPN

Padgett et al. 2008NICMOS JHK

“Nature’s coronagraph”


Variable nebulosity in the HH 30 disk

Stochastic flaring events ?

Periodic disk illumination from hotspots on a rotating star ? (Wood & Whitney 1998).

Moving inner disk inhomogeneities that shadow the outer disk ?

18 epochs 1994-2005Watson & Stapelfeldt 2007

If asymmetry is periodic, few days < P < 300 days


Young disks detected against direct starlight

• PSF artifacts make these disks more difficult to analyze

• 3+5 T Tauri disks are detected• 5 Ae star disks are detected• Beware envelope nebulosity !

GG Tau I bandKrist et al. 2005 GO Tau R band GO Tau H band

TW Hya H bandWeinberger et al. 2002

AB Aur UI bandsGrady et al. 1999


Most YSO disks remain undetected in scattered light

• Only 1/3 have detectable nebulosity

• < 10 % have disk nebulosity

• Many resolvable CO disks not detected

• Some disks must be much darker than others:– Depletion of

small grains ?– Dust settling ?

Stapelfeldt et al. 2008

Disk detectability in WFPC2 images

Noise floor


Imaging Comparison : HD 141569A (courtesy of John Krist)

STIS Coronagraph (U→I)NICMOS Coronagraph (J) ACS Coronagraph (V)

• Important transition object between optically thick protoplanetary disks and optically thin debris disks

• Radial zones with decreased surface density – dynamical clearing by planets at r > 100 AU ?

• Spiral arm induced by stellar encounter ?(Weinberger et al. 1999; Mouillet et al. 2001; Clampin et al. 2003)


Recent debris disk discoveries: Rings

• HD 107146 ACS R band– Ardila et al. 2004– Young G2 V star– Broad density peak at 130 AU

radius– Micron-sized grains inferred

• HD 181327 NICMOS J band– Schneider et al. 2006– Young F5 V star– R= 86 AU, R= 36 AU– Faint optical dust halo extending

out several hundred AU ?


Recent debris disk discoveries: edge-on systems

• HD 139664 ACS R band– Kalas et al. 2005– Young F5 star 17 pc distant– 110 AU measured outer radius– 83 AU inferred inner radius

• HD 32297 NICMOS J band– Schneider et al. 2005– A0 star at 113 pc distance– Detected radius ~ 300 AU– Optical groundbased images

(Kalas et al. 2005) show much 1600 AU radius, “bent” disk


Fomalhaut’s Eccentric RingA3V star, age 200 Myrs, distance 8 pc

HST (Kalas et al. 2005)

MIPS 70 μmdeconvolved

CSO (Marsh et al. 2005)

350 μm

0.6 μm

New Spitzer (in prep)


Eccentric ring model (Wyatt et al. 1999)

• Outer ring is perturbed by eccentric interior planet

• Produces brightness asymmetry in thermal emission from the Fomalhaut disk

• Models predict mass of perturber: – 0.06 to 0.3 MJ, if located at ring

inner edge (Quillen 2006)– Higher planet mass required if it

is located well inside ring

• Spitzer imaging later this month could detect 1-2 MJ

planet at radii > 5″ (40 AU)

*

Sharpness of ring inner edgeKalas et al. 2005


Debris disks detected in scattered light

• 11 published detections; 3 more are coming

• Half of these have ring morphology

• Many other IRAS/Spitzer disks observed but not detected

• No object with Ld/Lstar < 10-4 is

detected in scattered light

• Effective contrast limit is ~ 1000x our own Kuiper Belt

Source Name

Sp Type

Dis (pc)

Ld/Lstar

HD 141569 B9 100 0.008

HR 4796 A0 67 0.005

HD 32297 A0 113 0.003

HD 181327 F5 51 0.003

beta Pic A5 20 0.002

HD 107146 G2 28 0.001

AU Mic M0 10 0.0006

HD 15115 F2 45 0.0005

HD 53143 K1 18 0.0003

HD 139664 F5 18 0.0001

Fomalhaut A3 8 0.00008

Good AO images ugly AO images


http://www.circumstellardisks.orgOnline database for spatially resolved disks

• Built at JPL by Caer McCabe• Catalogs peer-

reviewed results on disks at optical, infrared, and (sub)millimeter wavelengths

• 100 disks in current working catalog

• Key references and images are included

http://www.circumstellardisks.org/


PALM 3000 Disk Science Niches 1.

• Will achieve 2x better resolution & IWA than HST/NICMOS; more stochastic image residuals

• Bright NGS targets: V < 5 for 95% strehl at K band– Potential to exceed HST/NICMOS contrast floor

by a factor of 10, down to Ld/Lstar ~ 3x10-5

– ~4/17 stars with Spitzer-detected debris disks have a high enough dust content, and are bright enough & visible from Palomar

– Debris disks will extend outside AO control radius

– No YSOs are bright enough


PALM 3000 Disk Science Niches 2.

• Fainter NGS targets: V < 10 for 80% strehl at K band– Only 12 YSOs bright enough & visible from

Palomar, primarily Ae stars– 7 additional stars with existing debris disks

images are bright enough and visible from Palomar

• 20 W LGS: Would open up huge near-IR sample; large surveys of Spitzer-selected YSOs in nearby molecular clouds

• Optical: low/variable strehl suitable only for discoveries of backlit or edge-on systems

Imaging of Protoplanetary and Debris Disks

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