(Sub)mm & Infrared Spectroscopy of Circumstellar Disks

1. (Sub)mm & Infrared Spectroscopy of Circumstellar Disks HD 141569A (HST ACS) Geoffrey A. Blake Div. Geological & Planetary Sciences 59th OSU Symposium 25June2004

2. People Really Doing the Work! Caltech: -Jacqueline Kessler (now at UT Austin), Joanna Brown -Adwin Boogert, Chunhua Qi (now at the SMA/CfA) Leiden w/Ewine van Dishoeck & Michiel Hogerheijde: -Klaus Pontoppidan, Gerd Jan van Zadelhoff, Wing-Fai Thi (now at ESO) • Why study disks? • Mm-wave interferometry of protoplanetary disks. • High resolution IR spectroscopy of disks. • Conclusions 25June2004

3. How are isolated Sun-like stars formed? outflow x1000 in scale infall Cloud collapse Rotating disk Planet formation Mature solar system Picture largely derived from indirect tracers, especially SEDs. Adapted from McCaughrean

4. Spitzer Space Telescope - IRAC (mid-IR cameras, 3.6 4.5, 5.8, 8.0 mm) - MIPS (far-IR cameras, 24, 70 160 mm, R=20 SED mode) - IRS (5-40 mm long slit,R=150, 10-38 mm echelle, R=600) August 2003 launch, >5 year lifetime. • - GTO observations • - Legacy program • - General observations Evans et al., c2d ~170 YSOs first look + follow up of mapping. Meyer et al. Photometry~350 sources, IRS follow up (Class III). 25June2004

5. Ices toward young low mass stars Boogert et al. 2004, ApJS special issue HH 46 w/IRAC, IRS Keck/VLT +Spitzer 25June2004

6. Study Isolated Disks (Weak/No Outflow) Planet building phase Beckwith & Sargent 1996, Nature383, 139-144. 25June2004

7. Why study disks? Star-disk-planet interactions: Radial velocity surveys are sensitive to ~Jupiter/Saturn mass planets out to >5 AU. From whence hot-Jupiters?

8. The answer lies at earlier times… Disk-star- and protoplanet interactions lead to migration while the disk is present. Theory 1 AU at 140 pc subtends 0.’’007. Jupiter (5 AU): V_doppler = 13 m/s V_orbit = 13 km/s Simulation G. Bryden Observation?

9. Spectroscopy of “Disk Atmospheres” G.J. van Zadelhoff 2002 Chiang & Goldreich 1997 IR disk surface within several – several tens of AU (sub)mm disk surface at large radii, disk interior 25June2004

10. The 1-Baseline Heterodyne Interferometer: • HST resolution at 1mm • D=10 km! Use array. • Can’t directly process 100 – • 1000 GHz signals. • Heterodyne receivers detect • |V| and f, noise defined by • the quantum limit of hn/k. • Positional information is • carried by the PHASE. • Spectral coverage depends • on the receivers, while the • kinematic resolution is • determined by correlator. Geometrical delay 25June2004

11. The n-Element Heterodyne Interferometer: • n(n-1)/2 baselines, imaging performance depends on the array geometry, but • For small to moderate n, the (u,v) plane is sparsely filled. • For a given array, the minimum detectable temperature varies as (resolution = qS)-2 : qP = primary telescope beam 25June2004

12. CO traces disk geometry, velocity field: CO 3-2 CO 2-1 Qi et al. 2004, ApJL, in press. TW Hydra w/SMA

13. Disk Ionization Structure: CO and Ions Disk properties vary widely with radius, height; and depend on accretion rate, etc. (Aikawa et al. 2002, w/ D’Alessio et al. disk models). Currently sensitive only to R>80 AU in gas tracers, R<80 AU dust. CO clearly optically thick, isotopes reveal extensive depletion, poor mass tracer! The fractional ionization is >10-8, easily sufficient for MRI transport. HD & H2D+ (Ceccarelli et al. 2004) in midplane?

14. Chemical Imaging of Outer Disk? Qi et al. 2004 & in prep HDO formed via H2D+, possible tracer of H3+? Kessler et al. 2004, in prep (6 transits) CO well mixed, while [CN]/[HCN] traces enhanced UV fields. Is LkCa 15 unusual? Photodesorption?

15. For models: Using scaled H density distribution with varying inner radius cutoff NT R0 Rout Molecular Distribution Models LkCa 15 HCN observations Ro=50AU Ro=100AU Ro=300AU Ro=200AU

16. Transitional/Debris Disks? HD141569 & Vega w/PdBI: Vega, Wilner et al. 2002 CO 2-1 from HD141569 J.-C. Augereau & A. Dutrey astro-ph/0404191

17. Future of the U.S. University Arrays – CARMA CARMA = OVRO (6 10.4m) + BIMA (9 6.1m) + SZ Array (8 3.5m) telescopes. March 27th , 2004 SUP approved! 2004 SZA at OVRO 2004 move 6.1m 2004 move 10.4m 2005 full operations Cedar Flat 7300 ft. June 15th, 2004

18. How can we probe the planet-forming region? (pre-ALMA) The size scales are too small even for the largest current & near-term arrays. Spectroscopy to the rescue! Theory Jupiter (5 AU): V_doppler = 13 m/s V_orbit = 13 km/s Observation?

19. AB Aur HD 163296 High Resolution IR Spectroscopy & Disks R=10,000-100,000 (30-3 km/s) echelles (ISAAC,NIRSPEC, PHOENIX,TEXES) on 8-10 m telescopes can now probe “typical” T Tauri/Herbig Ae stars: Keck CO M-band fundamental NIRSPEC R=25000

20. Orientation is Pivotal in the IR! Edge-on absorption. L1489: Gas/Ice~10/1, accretion. CRBR2422.8: Gas/Ice~1/1, velocity field? Elias 18 Gas/Ice<1/10 (Shuping et al.) H2, H3+ in absorption? 25June2004

21. Spitzer Enables the Study of Edge-on Disks! VLT VLT The small molecules in ices are similar in protostars and disks. Flux (Jy) ISAACS 25June2004

22. What about other species w/echelles? NGC 7538 IRS9 Boogert et al. 2004, ApJ, in press 25June2004

23. Edge-on Disks & Comets? N7538 W33A Hale-Bopp Water 100 100 100 CO 10 1 23 CO2 16 3 6 CH4 1 0.7 0.6 H2CO 3 2 1 CH3OH 9 10 2 HCOOH 2 0.5 0.1 NH3 10 4 0.7 OCS 0.1 0.05 0.4 IR studies of edge on disks will map out both gas phase & grain mantle composition, compare to that found in massive YSOs, comets. 25June2004

24. In older systems, CO disk emission is common: Herbig Ae stars, from ~face-on (AB Aur) to highly inclined (HD 163296). CO lines correlated with inclination and much narrower than those of H I Disk! CO lines give distances slightly larger than K-band interferometry, broad H I traces gas much closer to star (see also Brittain & Rettig 2002, ApJ, 588, 535; Najita et al. 2003, ApJ, 589, 931). Can do ~30-40 objects/night. Pf b

25. Systematic Line Width Trends: • Objects thought to be ~face on have the narrowest line widths, highly inclined systems the largest. • As the excitation energy increases, so does the line width (small effect). • Consistent with disk emission, radii range from 0.5-5 AU at high J. • Low J lines also resonantly scatter 5 mm photons to much larger distances. • Asymmetries (VV Ser)? Blake & Boogert 2004, ApJL 606, L73. 25June2004

26. How is the CO excited in these disks? CO and 13CO rotation diagrams show curvature as a result of t>1. Still, small amounts of gas since N(H2)~5 x 1022 leads to dust opacities near unity. CO 13CO Collisional excitation important, but cannot explain line widths at low J values (too broad). Resonant IR scattering at larger radii! The vibrational excitation is highly variable, likely due to variations in the UV field. Disk shadowing? 25June2004

27. Where does the CO emission come from? Flared disk models often possess 2-5 micron deficiency in model SEDs, where a “bump” is often observed for Herbig Ae stars. Dullemond et al. 2002 Explanation: Dust sublimation near the star exposes the inner disk to direct stellar radiation, heating the dust and “puffing up” the disk. 25June2004

28. CO Emission from Disks around T Tauri Stars For dust sublimation alone, the lines from T Tauri disks should be broader than those from Herbig Ae stars+disks. Often observed, but… Calvet et al. 2002 The TW Hya lines are extremely narrow, even for a disk with i~7 degrees, imply R>2 AU. Gap tracer?

29. AB Aur HD 163296 Disk Spectroscopy - Conclusions (Sub)mm-wave instruments can only study the outer reaches of large disks at present in lines; even at these wavelengths the disk mid-plane is largely inaccessible due to molecular depletion. Expanded arrays (CARMA, eSMA, ALMA) will provide access to much smaller scales, lines should selectively highlight regions of planet accretion/formation. Midplane w/H2D+? High resolution IR spectroscopy just starting, is immensely powerful, and provides unique access to the 0.5-50 AU disk surface before advent of ALMA, large IR interferometers. Spectra are esp. sensitive to disk geometry. Spitzer is providing beautiful spectrophotometric SEDs and many new targets! 25June2004

30. Arrays everywhere! PdBI VLA BIMA SMA ATCA OVRO Typically ntel≤ 6-10. 25June2004

31. Embedded disks? 3mm: HCO+, HCN, 13CO, C180 (1-0)  2000 AU radius, 0.02 M disk 1mm: HCO+ (3-2)  infall (disk not quite fully rotationally supported) 0.65 M M  1.4 M disk collapse to 300 AU in 2 x 104 yrs? L1489, a disk in transition? Padgett et al 1999 Hogerheijde 2001 See also: Hogerheijde et al 1997, 1998; Looney 2000; Chandler & Richer 2000, Shirley et al 2000 HCO+ 3-2 HCO+ 1-0

32. OVRO CO(2-1) Survey of T Tauri stars (Koerner & Sargent 2003) • stellar ages 1 - 10 Myrs • stellar masses ~ 1 M • selection by 1 mm flux, SED characteristics • Taurus 19/19 detections • Ophiuchus 4/6 detections • resolution ~ 2” 20 objects radii  150 AU masses  0.02 M (from SEDs) See also Dutrey, Guilloteau, & Simon, Ohashi

33. Chemical / Radiative Transfer Modeling Physical model: D'Alessio et al. 2001 Chemical model: Willacy& Langer 2001 Radiative transfer: Hogerheijde & vander Tak 2000 Understanding Disk Chemistry Molecular line survey UV fields grain reactions disk ages and evolution

34. MM-Wave CO Traces Dynamics, Others? D. Koerner & A. Sargent OVRO, in Qi et al. (2004). Measure: R_disk M_star Inclination w/resolved images. LkCa 15 LkCa 15 Dutrey et al. 1997, IRAM 30m 25June2004

35. Star Sp Type d(pc) Teff(K) R(Rsun) L(Lsun) M(Msun) Age(Myr) LkCa 15 K5:V 140 4365 1.64 0.72 0.81 11.7 GM Aur K5V:e 140 4060 1.78 0.8 0.84 1.8 HD 163296 A0 120 9550 2.2 30.2 2.3 6.0 MWC 480 A3 130 8710 2.1 32.4 2.0 4.6 LkCa 15 OVRO+CSO/JCMT MM-Wave Disk Survey The Sample (drawn from larger single dish + OVRO CO survey): MWC 480 Mannings, Koerner & Sargent 1997 Koerner & Sargent 1995 25June2004

36. OVRO+CSO/JCMT MM-Wave Disk Survey II van Zadelhoff et al. 2001 Combine 3/1.3 mm array images w/higher J spectra to constrain OUTER disk properties, chemical networks. 25June2004

37. Source L*(L ) CN/HCN Hdust/hgas LkCa 15 0.72 ~ 10 1.0 GM Aur 0.80 << 1 4.0 MWC 480 30.2 ~ 4 1.7 HD 163293 35.2 >> 50 - UV Fields: HCN and CN  [CN]/[HCN] traces enhanced UV fields (Fuente et al. 1993, Chiang et al. 2001) LkCa 15 Molecular distribution ring-like? Photochemistry or desorption? Qi et al., in prep 25June2004

38. 8.9 8.2 7.6 6.9 6.3 9.5 5.0 5.6 4.3 3.0 3.7 LkCa15 ___ model - - - CO 2-1 fit Modeling the effects of (uv) Sampling Model Parameters i = 58°, Vturb= 0.1 km/s Ro= 5 AU, Rout= 430 AU nCO = 10-4 nH (D'Alessio 2001) qsyn = 3.6” x 3.6” Infinite resolution, complete UV coverage Observed UV sampling, uniform weighting

39. Are these large disks unusual? CO, HCO+ (and NNH+) chemistry well predicted by disk models. Other species, esp. CS, CN, HCN, much more intense, with unusual emission patterns in some cases (LkCa 15). MM-continuum surveys do not reveal such large, massive disks in similarly aged clusters (IC348) and clouds (NGC 2024, MBM12). Environment? Need better (sub)mm-wave imaging capabilities. SMA! and… 29Aprn03

40. CARMA – Site Monitoring

41. Disk Observations w/CARMA+ALMA CARMA ALMA Md=0.01Msun Rout=120AU Ro=20AU HDO: rms (3sigma) = 0.05-0.1 K (CARMA w/D config. in 4 hrs) Dust simulation (L.G. Mundy), unrealistic phase errors, but no CLEAN/MEM.

42. Atmospheric Phase Correction (mm Adaptive Optics) • Atm. fluctuations (mostly • H2O)can vary geom. delay. • |V|eif decorrelation • if Ef>p (each baseline). • If the fluctuations vary • systematically across the • array, phase errors ensue. • Problem is NOT solved. OVRO WLM System

43. Enter ALMA: Dust simulation (L.G. Mundy), unrealistic phase errors, but no CLEAN/MEM. Superb site & large array exceptional performance (64 12m telescopes, by 2012). Llano de Chajnantor; 5000 m, good for astronomy, tough for humans!

44. Ices in the disk of L1489 IRS • Prominent band of solid CO detected toward L1489, originating in large, flaring disk. • CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures: • 'polar' H2O:CO • 'apolar' CO2:CO [NEW!] • 'apolar' pure CO (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

45. Variations in CO M-band Spectra: Nearly all spectra observed to date have emission from very high J levels (J>30-35), but… The degree of vibrational excitation is highly variable! 25June2004

46. SED Fits versus IR Interferometry Fits to AB Aur SED yield an inner radius of ~0.5 AU (and 0.06 AU for T Tau). (Monnier & Millan-Gabet 2002, ApJ) Dullemond et al. 2002 This model can now be directly tested via YSO size determinations with K-band interferometry. Intense dust emission pumps CO, rim “shadowing” can produce moderate T_rot.

47. Future “Near”-IR (1-5 mm) Spectroscopy Brittain & Rettig 2002, Nature Many other species and disk types (transitional, debris, etc.) should be examined in both absorption (edge-on disks) and emission, but extremely high dynamic range will be needed. Protoplanet tracers? H2, H3+, CH4, H2O, OCS... Line profile asymmetries?