Gas & Ice in Protoplanetary and Debris Disks Geoffrey A. Blake Div. Geological & Planetary Sciences 15 th UMd Symposium 11Oct2004 HD A (HST ACS)

Study Isolated Disks (Weak/No Outflow) 11Oct2004 Beckwith & Sargent 1996, Nature 383, Planet building phase

Disk-star- and protoplanet interactions lead to migration while the gas is present. Core- accretion & ice? Why do we care about gas & ice in disks? Theory Observation? 1 AU at 140 pc subtends 0.’’007. Jupiter (5 AU): V_doppler = 13 m/s V_orbit = 13 km/s Simulation G. Bryden

Spectroscopy of “Disk Atmospheres” 11Oct2004 IR disk surface within several – several tens of AU (sub)mm disk surface at large radii, disk interior G.J. van Zadelhoff 2002 Chiang & Goldreich 1997

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 , noise defined by the quantum limit of h /k. Positional information is carried by the PHASE. Spectral coverage depends on the receivers, while the kinematic resolution is determined by correlator. 11Oct2004 Geometrical delay

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 =  S ) -2 : 11Oct2004  P = primary telescope beam

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

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 -9, easily sufficient for MRI transport. Disk Ionization Structure: CO and Ions

If depletion is extensive, what species might be able to probe the disk midplane? One possible route involves deuterated ions such as H 2 D + : The abundances of these ions may be difficult to quantify, however, and so SOFIA/Herschel studies of HD J=1-0 at 112  m are eagerly awaited! Are there gas probes of the disk midplane? Ceccarelli et al. 2004, ApJ 607, L51 TW Hya v LSR (km/s) T MB (K) Van Dishoeck et al. 2003, A&A 400, L1

CO well mixed, while [CN]/[HCN] traces enhanced UV fields, esp. Ly  Is LkCa 15 unusual? Photodesorption? Qi et al & in prep Chemical Imaging of Outer Disk? HDO formed via H 2 D +, possible tracer of H 3 + ? Kessler et al. 2004, in prep (6 transits)

CO 2-1 from HD J.-C. Augereau & A. Dutrey astro-ph/ Transitional/Debris Disks? HD & Vega w/PdBI: Vega, Wilner et al (dust)

Future of the University Arrays – CARMA CARMA = OVRO (6 10.4m) + BIMA (9 6.1m) + SZA (8 3.5m) arrays SUP approved! 2004 SZA at OVRO 2004 move 6.1m 2004 move 10.4m 2005 full operations Cedar Flat 7300 ft. March 27 th, Oct2004

HDO: rms (3sigma) = K (CARMA w/D config. in 4 hrs) ALMACARMA M d =0.01M sun R out =120AU R o =20AU Disk Observations w/CARMA+ALMA Dust simulation (L.G. Mundy), realistic phase errors, but no CLEAN/MEM.

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

High Resolution IR Spectroscopy & Disks CO M-band Keck NIRSPEC R=25,000 R=10, ,000 (30-3 km/s) echelles (ISAAC,NIRSPEC, PHOENIX,TEXES) on 8-10 m telescopes can now probe “typical” T Tauri/Herbig Ae stars: TW Hya L1489 IRS

Spitzer can study edge-on disks! 11Oct2004 VLT ISAACS Flux (Jy) The small molecules in ices are similar in protostellar envelopes and disks.

What about other gaseous species w/echelles? 11Oct2004 NGC 7538 IRS9 Boogert et al. 2004, ApJ, in press

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 ~20-30 objects/night. In older/inclined systems, CO disk emission: Herbig Ae stars, from ~face-on (AB Aur) to highly inclined (HD ). CO lines correlated with inclination and much narrower than those of H I Disk! Pf 

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 AU at high J. Low J lines also resonantly scatter 5  m photons to much larger distances. Asymmetries (VV Ser)? 11Oct2004 Blake & Boogert 2004, ApJL 606, L73.

CO and 13 CO rotation diagrams show curvature as a result of  >1. Still, small amounts of gas since N(H 2 )~5 x leads to dust opacities near unity. 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? How is the CO excited in these disks? 11Oct2004 CO 13 CO

Explanation: Dust sublimation near the star exposes the inner disk to direct stellar radiation, heating the dust and “puffing up” the disk. Flared disk models often possess 2-5 micron deficiency in model SEDs, where a “bump” is often observed for Herbig Ae stars. Where does the CO emission come from? Dullemond et al Oct2004

Calvet et al For dust sublimation alone, the lines from T Tauri disks should be broader than those from Herbig Ae stars+disks. Often observed, but… CO Emission from Transitional Disks? The TW Hya lines are extremely narrow, with i~7 ° R≥0.4 AU. Similar for SR 9 and DoAr 44, but gas radius << dust radius (SED)? Recall h CO ≥ eV to dissociate.

Calvet et al Controversial ISO SWS studies were in LARGE beams, truly disk emission? Gas Tracers in Debris Disks? What about H 2 ? TEXES/IRTF ground based follow up has now detected H 2 in cTTs, narrow & point-source like. Debris disks studies need 8-10m! (2005B) TEXES, Richter et al. (2004), in preparation. Spitzer IRS?

(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 may selectively highlight regions of planet formation. Midplane w/H 2 D + and HD? High resolution IR spectroscopy just starting, is immensely powerful, and provides unique access to the 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! Disk Spectroscopy - Conclusions 11Oct2004 AB Aur HD

OVRO CO(2-1) Survey of T Tauri stars stellar ages 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) (Koerner & Sargent 2003) See also Dutrey, Guilloteau, & Simon, Ohashi

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

MM-Wave CO Traces Dynamics, Others? 11Oct2004 Dutrey et al. 1997, IRAM 30m D. Koerner & A. Sargent OVRO, in Qi et al. (2004). Measure: R_disk M_star Inclination w/resolved images. LkCa 15

Combine 3/1.3 mm array images w/higher J spectra to constrain OUTER disk properties, chemical networks. van Zadelhoff et al OVRO+CSO/JCMT MM-Wave Disk Survey II 11Oct2004

Source L * (L ) CN/HCN H dust /h gas LkCa ~ GM Aur 0.80 << MWC ~ HD >> 50 - [CN]/[HCN] traces enhanced UV fields ( Fuente et al. 1993, Chiang et al ) Molecular distribution ring-like? Photochemistry or desorption? Qi et al., in prep UV Fields: HCN and CN LkCa 15 11Oct2004 

Infinite resolution, complete UV coverage Observed UV sampling, uniform weighting CO 2-1 fit LkCa15 ___ model Model Parameters i = 58°, V turb = 0.1 km/s R o = 5 AU, R out = 430 AU n CO = n H (D'Alessio 2001)  syn = 3.6” x 3.6” Modeling the effects of (uv) Sampling

Atm. fluctuations (mostly H 2 O) can vary geom. delay. |V|e i f decorrelation if Ef>  each baseline). If the fluctuations vary systematically across the array, phase errors ensue. Problem is NOT solved. OVRO WLM System Atmospheric Phase Correction (mm Adaptive Optics)

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

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: 1'polar' H 2 O:CO 2'apolar' CO 2 :CO [NEW!] 3'apolar' pure CO (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

Boogert et al. 2004, ApJS 154, Oct2004 HH 46 w/IRAC, IRS Ices toward young low mass stars Keck/VLT +Spitzer

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. Fits to AB Aur SED yield an inner radius of ~0.5 AU (and 0.06 AU for T Tau). SED Fits versus IR Interferometry (Monnier & Millan-Gabet 2002, ApJ) Dullemond et al. 2002

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? H 2, H 3 +, CH 4, H 2 O, OCS... Line profile asymmetries? Future “Near”-IR (1-5  m) Spectroscopy Brittain & Rettig 2002, Nature