1. HD 100453 An Evolutionary Link Between Protoplanetary Disks and Debris Disks

2. Journal Paper Co-authors Karen CollinsMaster's Thesis Defense4/24/2008 Co-authors(s)AffiliationContribution C. A. GradyEureka Scientific and NASA GSFCoverall direction, science mentor, HST and Chandra PI, and day-to-day support K. Hamaguchi & R. PetreX-ray Astrophysics Laboratory NASA/GSFC Chandra observations, data reduction, and results J. P. WisniewskiNASA/GSFC, NPP FellowHST ACS HRC observations, data reduction, and results S. BrittainClemson UniversityGemini South observations of warm CO, data reduction, and results M. Sitko & W. J. CarpenterSSI, University of CincinnatiSED and modeling data, general support G. M. WilligerUniversity of LouisvilleFUSE observations, data reduction, results, and general day-to-day support R. van BoekelMax-Planck-Institut für AstronomieVLT NACO NIR observations, data reduction, common proper motion results, and related photometric results A. CarmonaMax-Planck-Institut für Astronomie, ESO, ISDC & Geneva Observatory VLT SINFONI NIR spectroscopy, data reduction, spectral typing, and other related results. M. E. van den AnckerEuropean Southern ObservatoryVLT SINFONI NIR spectroscopy, data reduction, spectral typing, and other related results. G. MeeusAstrophysikalisches Institut PotsdamFEROS Ca II spectroscopic data J. P. Williams, G. S. Mathews University of HawaiiJCMT HARP CO spectroscopic observations, data reduction, dust mass calculations, gas mass calculations, and related results X. P. ChenMax-Planck-Institut für AstronomieVLT NACO Brγ common proper motion data reduction B. E. WoodgateNASA/GSFCoverall scientific interpretation Th. HenningMax-Planck-Institut für Astronomieoverall scientific interpretation

3. Karen CollinsMaster's Thesis Defense4/24/2008 Star 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

4. Pre-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 (3 2, 4 2, 5 2, …) infrared excess due to circumstellar dust (next slides) Karen CollinsMaster's Thesis Defense4/24/2008

5. Spectral Energy Distribution Spectral Energy Distribution (SED) plot of radiated energy vs. wavelength Stellar photosphere ~blackbody peaks in optical Sun 5778 K A-type stars 7500-10,000 K M-type stars 3000-4000 K

6. Infrared 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 CollinsMaster's Thesis Defense4/24/2008 adapted from M.Sitko simulation

7. Disk Evolution Protoplanetary Disks (initial phase) gas rich + small dust grains (submicron) gas:dust ~100:1 (as in interstellar medium (ISM)) high accretion rates (> ~1 10 8 M yr 1 ) gas and dust well mixed hydrostatic equilibrium dust material supported above midplane disk can maintain scale height disk expected to flare Karen CollinsMaster's Thesis Defense4/24/2008

8. 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 CollinsMaster's Thesis Defense4/24/2008 Dullemond et al. 2006

9. Disk 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 CollinsMaster's Thesis Defense4/24/2008 Dullemond et al. 2006

10. Disk 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 Karen CollinsMaster's Thesis Defense4/24/2008

11. Disk 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 generation from collisions of massive bodies gas-poor Karen CollinsMaster's Thesis Defense4/24/2008 Van den Ancker 1999

12. Meeus Groups Meeus et al. (2001) divided 14 Herbig stars into two groups Group I blackbody in MIR high fraction of IR excess (L IR /L * ~ 0.5) steep submm slope (i.e. small grains) Group II no blackbody in MIR low fraction of IR excess (L IR /L * ~ 0.2) shallow submm slope (i.e. larger grains) Meeus et al. suggested Group I sources evolve to Group II sources Karen CollinsMaster's Thesis Defense4/24/2008

13. Meeus 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 Karen CollinsMaster's Thesis Defense4/24/2008

14. Thesis Goal Test idea that Meeus Group I sources evolve 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) Karen CollinsMaster's Thesis Defense4/24/2008

15. Thesis 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 CollinsMaster's Thesis Defense4/24/2008

16. HD 100453A Karen CollinsMaster's Thesis Defense4/24/2008 Southern Hemisphere (Lower Centaurus-Crux Assn) Distance 114 pc v=7.78 (not visible by naked eye) Spectral Type A9Ve Age > ~10 Myr

17. Summary of Observations Karen CollinsMaster's Thesis Defense4/24/2008 InstrumentPrimeDirect Image Coron. Image SpectraWavelengthScientific Purpose ChandraK. Hamaguchi X-rayAccretion Rate HST ACS HRCJ. Wisniewski OpticalCompanion Location & Photometry HST ACS HRCJ. Wisniewski OpticalDisk Detection & Photometry HST ACS SBCC. Grady K. Collins FUVCompanion Detection VLT NACOR van Boekel NIRCompanion Proper Motion & Photometry VLT SINFONIA. Carmona NIRSpectral Type of Companion FUSEG.M. Williger FUVAccretion Rate PhoenixS. Brittain NIRWarm Gas Limits JCMT HARPJ. Williams G. Mathews SubmmCold Gas Limits FEROSG. Meeus K. Collins OpticalAccretion Rate

18. 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 Karen CollinsMaster's Thesis Defense4/24/2008

19. The Candidate Companion HST optical direct image B located 1.05 @ 126° east of north m v = 15.87 (A:B = 1500:1 contrast) Karen CollinsMaster's Thesis Defense4/24/2008 optical HST ACS HRC F606W

20. Candidate Companion Spectral Type Need high spatial resolution spectroscopy to 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 CollinsMaster's Thesis Defense4/24/2008

21. Candidate Companion Spectral Type Karen CollinsMaster's Thesis Defense4/24/2008

22. Relative Proper Motion Karen CollinsMaster's Thesis Defense4/24/2008

23. Candidate Confirmation Karen CollinsMaster's Thesis Defense4/24/2008

24. Companion Photometry ObjectModeFiltermagnitudeNotes (prime) HD 100453BDirectm F606W 15.6HST HRC (J. Wisniewski) HD 100453BCoronm F606W 15.8HST HRC (J. Wisniewski) HD 100453BCombinedm F606W 15.7 0.2 (J. Wisniewski) HD 100453BDirectKsKs 10.66 0.1 (Chen et al. 2006) HD 100453BCoron L 10.13 0.1 VLT NACO (R. van Boekel) HD 100453BCoron M 9.99 0.1 VLT NACO (R. van Boekel) HD 100453BCalculatedV 15.87 0.2 (K. Collins) HD 100453BCalculatedK 10.64 0.1 (K. Collins) HD 100453BCalculatedL 10.27 0.1 (K. Collins) Karen CollinsMaster's Thesis Defense4/24/2008 Key Point: Candidate companion has NO IR Excess Can use K-band in H-R diagram for age estimate

25. Age Determination (from A-star) Karen CollinsMaster's Thesis Defense4/24/2008

26. Age Determination (from Companion) Note wider separation of isochrones for low-mass stars HD 100453B (input data) m K = 10.64 ± 0.1 M4.0V – M4.5V T eff = 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 Karen CollinsMaster's Thesis Defense4/24/2008

27. Mass Accretion onto A-star Mass accretion rate gives insight into the evolutionary 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) Karen CollinsMaster's Thesis Defense4/24/2008

28. Accretion - FUV Continuum FUV continuum upper limit from FUSE spectra <1.5 10 15 ergs s 1 cm 2 Å 1 (1σ) (-14.8 in log space) Karen CollinsMaster's Thesis Defense4/24/2008

29. Accretion - FUV Continuum Karen CollinsMaster's Thesis Defense4/24/2008 Plot accretion rate vs. FUV continuum accretion rates based on Brγ (Garcia Lopez et al. 2006) FUV values from literature note power law trend except HD 100453

30. Accretion - FUV Continuum Karen CollinsMaster's Thesis Defense4/24/2008

31. Accretion - Herbig-Haro Knots Karen CollinsMaster's Thesis Defense4/24/2008 HST ACS SBC F122M FUV

32. Accretion- Ca II 8662 Å emission Karen CollinsMaster's Thesis Defense4/24/2008

33. Accretion - Hα Karen CollinsMaster's Thesis Defense4/24/2008

34. Accretion - X-ray Karen CollinsMaster's Thesis Defense4/24/2008 Chandra red0.35 0.70 keV green0.70 0.90 keV blue0.90 2.00 keV energy (keV) 1 2 Chandra X-ray HD 100453A HD 100453B

35. Accretion Rate Summary Accretion IndicatorAccretion LevelSignificance FUV Continuum< 2.5×10 10 M yr 1 1 Lack of Ca II 8662 Å emission line < 1.0×10 10 M yr 1 4 Lack of HH Knots in Ly < ~6×10 11 M yr 1 factor of 10 H weak accretor X-raynot strong accretor Karen CollinsMaster's Thesis Defense4/24/2008

36. Constraints on Disk Structure Karen CollinsMaster's Thesis Defense4/24/2008 M. Sitko, private communication Habart et al. (2006)

37. HST ACS Coronagraphy Need ~1x10 6 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: ~1x10 5 in direct mode ~1x10 6 in coronagraphic mode ~1x10 7 in coronagraphic mode with psf-subtraction HRC has 0".9 radius spot size, but psf-subtraction residuals out to ~2-3" Karen CollinsMaster's Thesis Defense4/24/2008 Clampin et al. 2003

38. Constraints on Disk Structure Karen CollinsMaster's Thesis Defense4/24/2008 HST ACS HRC Coron w/psf-sub HD 100453

39. Constraints on Disk Structure Karen CollinsMaster's Thesis Defense4/24/2008 HST ACS - 2003 (red) VLT NACO - 2006 (blue)

40. Disk Structure Summary Karen CollinsMaster's Thesis Defense4/24/2008 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) Companion 120 proj. AU Scattered Light Outer Radius <250 AU Line of Sight

41. Gas and Dust in Inner Disk Karen CollinsMaster's Thesis Defense4/24/2008 (after Brittain et al. 2007)

42. Gas and Dust in Outer Disk Karen CollinsMaster's Thesis Defense4/24/2008

43. 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 any classically defined disk group (protoplanetary, transitional, debris) Karen CollinsMaster's Thesis Defense4/24/2008

44. Thesis Results Karen CollinsMaster's Thesis Defense4/24/2008 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

45. Thesis Results Karen CollinsMaster's Thesis Defense4/24/2008 Group I sources are slightly older than Group II on average (but are within 1σ) Group I accretion rates are slightly lower than Group II accretion rates on average (but are within 1σ)

46. Thesis Results Age range significantly overlaps between the two groups Accretion slows as star ages in both groups Meeus suggested star and disk evolution may be decoupled for 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. Karen CollinsMaster's Thesis Defense4/24/2008

47. Possible 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 creates NIR and MIR blackbody components in SED and high L excess /L * possible giant planet in gap is causing collisional 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. Karen CollinsMaster's Thesis Defense4/24/2008 after Bouwman et al. 2003)

48. Future 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 pixel 1, 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 pixel 1, 0".9 radius spot STIS (down since 2004) coron. imaging mode, 0.05 pixel 1, 0".5-2.8" wedges Karen CollinsMaster's Thesis Defense4/24/2008 HD 141569 (from Krist 2004)

49. Long -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 M J planet 5 AU orbit M disk = 10 M J Karen CollinsMaster's Thesis Defense4/24/2008 Wolf & D'Angelo 2005

50. Karen CollinsMaster's Thesis Defense4/24/2008 A possible view of the HD 100453 system? adapted from NASA/JPL-Caltech/T. Pyle (SSC) Thank You!