Title CO surveys of disks around stars from 0.3 to 3 msun Pi A. Dutrey Time 2760 hrs 1) CO surveys of disks around stars from 0.3 to 3 msun Authors: A.Dutrey, S.Guilloteau 2. Science goal: Study the gaseous disk structure (temperature, density, Rout(CO), = turbulence) and kinematics from the CO lines. Measure the stellar mass of the = central object. Correlate disk properties with stellar properties. Needed: 12CO 2-1, 3-2, trace the temperature distribution at the disk surface 13CO 1-0, 2-1, 3-2, trace the temperature/density 1-2 scale heights = above the mid-plane C18O 2-1, 3-2, trace the temperature/density in the mid-plane according to Dartois, Dutrey, Guilloteau 2003 3. Number of sources: Roughly 40. 4. Coordinates: 4.1. 5 sources in Hyd (RA= , DEC=-60) 15 sources in ChaI (RA=11, DEC=-70) 20 sources in Oph (RA=16:30, DEC=-24) 4.2. Moving target: no 4.3. Time critical: no 5. Spatial scales: 5.1. Angular resolution: 0.2-0.4 arcsec 5.2. Range of spatial scales/FOV: up to 8 arcsec 5.3. Single dish: no 5.4. ACA: no 5.5. Subarrays: no 6. Frequencies: 6.1. Receiver band: Band 3, Band 6, Band 7 6.2. Lines: 12CO 2-1, 3-2, 13CO 1-0, 2-1, 3-2, C18O 2-1, 3-2 A. Frequency: 110, lines 13CO & C18O 1-0, + 12CO 1-0 (if possible) B. Frequency: 219-220/230, lines 13CO & C18O 1-0 + 12CO 2-1 (required) C. Frequency: 329-330, lines 13CO & C18O 3-2 D. Frequency: 345, line 12CO 3-2 6.3. Spectral resolution (km/s): 0.1km/s (0.05 km/s to estimate the = turbulence) 6.4. Spectral coverage (km/s or GHz): ~30-40 km/s disk 7. Continuum flux density: 7.1. Typical value: 10-500 mJy, varying as nu^3 7.2. Continuum peak value: 0.2-5 mJy/beam, varying as nu^2 (resolving the disk) 7.3. Required continuum rms: Band dependent 7.4. Dynamic range in image: intrinsic range of order 1000, not required for this study. 8. Line intensity: limited by 13CO 1-0 & C18O 2-1, 3-2 8.1. Typical value: 0.5-40 K (depending on lines) 8.2. Required rms per channel: 0.5 K 8.3. Spectral dynamic range: low (in each channel...) 9. Polarization: YES if possible (12CO line + continuum) (integration time not based on polarization) 10. Integration time per setting: A (110 GHz) at 0.4", rms 1.8 K in hour, required 13 hrs per source B (220 GHz) at 0.2", rms 2.6 K in hour, required 27 hrs per source C (330 GHz) at 0.2", rms 2.7 K in hour, required 29 hrs per source 11. Total integration time for program: 69 hours per source X 40 sources = 2760 hours 12. Notes Time estimate can only be reduced by degrading angular resolution. At 1" (110 GHz) and 0.5" (220 and 330 GHz) as done currently at IRAM = PdB, required total time is 440 hours ************************************************************************* Review Phil Myers: Science case okay, but requested time for resolution 0.2-0.4 arcsec is equivalent to 345 8-hour tracks - impractical! -------------------------------------------------- Review v2.0: 1) CO surveys of disks around stars from 0.3 to 3 msun Authors: A.Dutrey, S.Guilloteau Reviewer: John Bally Too many transitions and sources are proposed. I recommend the selection of fewer targets. You could pick the closest disks associated with central-star masses of say 0.3, 1, and 3 Msol. In each mass-range, pick a nearly face-on example, and a nearly edge-on one. Why do we need to observe 40 sources? Reply: If you take sources at different ages, you very rapidly need 40 sources to sample reasonnably the astrophysical problems. Some specific targets such as the IRN in Cha I, or VLA1623 in rho-Oph should be emphasized. The line list should be pruned; do you really need three transitions in each isotopic variant of CO? Should the observations be obtained in scaled-arrays that produce matched beams? I would emphasize the highest frequency lines to maximize angular resolution. Reply: Only the generic distance (~150 pc = Taurus distance) is important since it is not a real proposal In addition to measuring scale-heights, rotation curves, and the disk and stellar masses, these ALMA observations should enable searches for second-second order structure parameters of the disks such as spiral density waves, gaps, and radial variations in the abundances of the various isotopes and observed molecular species by referencing the line-strengths to the continuum produced by dust. Multi-wavelength dust continuum fluxes and polarization may provide constraints on radial (and azimuthal) variations in grain sizes and magnetic field geometry. Reply: Of course, you are right! This is not a real proposal but a time estimate for a well define problem: CO surveys in TTauri disks. Rapid switching between sources should enable multiple targets to be observed within each 8-hour shift, contrary to the Phil Myers comment (DRSP 1.0 review). Reply: YES