Imaging of Protoplanetary and Debris Disks

1. Imaging of Protoplanetary and Debris Disks Karl Stapelfeldt Jet Propulsion Laboratory PALM 3000 Requirements Review

2. 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 PALM 3000 Requirements Review

3. “Transiting” Disks: The Orion Silhouettes • 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 HST/ACS Hα; N. Smith et al. 2005 PALM 3000 Requirements Review

4. V 376 Cas Stapelfeldt et al. 2008 WFPC2 RI CB 26 Sauter et al. 2008 NICMOS JHK ‘Gomez Hamburger’- PPN Padgett et al. 2008 NICMOS JHK Edge-on disks : 13 + 4 now imaged “Nature’s coronagraph” PALM 3000 Requirements Review

5. Variable nebulosity in the HH 30 disk 18 epochs 1994-2005 Watson & Stapelfeldt 2007 If asymmetry is periodic, few days < P < 300 days Stochastic flaring events ? Periodic disk illumination from hotspots on a rotating star ? (Wood & Whitney 1998). Moving inner disk inhomogeneities that shadow the outer disk ? PALM 3000 Requirements Review

6. Young disks detected against direct starlight GG Tau I band Krist et al. 2005 GO Tau R band GO Tau H band • 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 ! TW Hya H band Weinberger et al. 2002 AB Aur UI bands Grady et al. 1999 PALM 3000 Requirements Review

7. Most YSO disks remain undetected in scattered light Disk detectability in WFPC2 images • 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 ? Noise floor Stapelfeldt et al. 2008 PALM 3000 Requirements Review

8. 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) PALM 3000 Requirements Review

9. 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 ? PALM 3000 Requirements Review

10. 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 PALM 3000 Requirements Review

11. Fomalhaut’s Eccentric RingA3V star, age 200 Myrs, distance 8 pc CSO (Marsh et al. 2005) HST (Kalas et al. 2005) New Spitzer (in prep) 0.6 μm MIPS 70 μm deconvolved 350 μm PALM 3000 Requirements Review

12.  * 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 edge Kalas et al. 2005 PALM 3000 Requirements Review

13. Good AO images ugly AO images 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 isdetected in scattered light • Effective contrast limit is ~ 1000x our own Kuiper Belt PALM 3000 Requirements Review

14. 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 PALM 3000 Requirements Review

15. 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 Requirements Review

16. 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 PALM 3000 Requirements Review