Title Gaps in nearby protoplanetary disks Pi S.Guilloteau Time 13 hrs Gaps in nearby protoplanetary disks ================================== Authors: S.Guilloteau, A.Dutrey 2. Science goal: image gaps created by protoplanets in nearby dust protoplanetary disks. The goal is to measure the gap radius and the brightness contrast gap/disk in order to constrain hydrodynamics models of planet formation in disks. See also predictions by Wolf et al., 2002. We have to image to a significant brightness level at the highest possible angular resolution. For a proto-Jupiter, the gap width is about 1-2 AU. The highest possible angular resolution (0.013", i.e 1.8 AU at 140 pc) is therefore required. The proposed observed frequency is 345 GHz, high enough to provide high angular resolution, but not too high because otherwise even the gap would be optically thick to dust emission. At 5 AU from the star, the dust opacity at 345 GHz will be of order 8 to 20, but since the surface density contrast is expected to be of order 100, the gap will still be optically thin. A secondary goal would be to detect ``CO gaps'' in these disks at the sensitivity limit provided by the main goal (the continuum). 3 Number of sources: 5 objects 4.Coordinates: 4.1 2 sources in Taurus (RA=04, DEC=+25) 1 in Hya (TW Hya) (RA=11, DEC=-34) 2 sources in ChaI (RA=11, DEC=-70) 4.2 Moving target: no 4.3 Time critical: no 5. Spatial scales: 5.1. Angular resolution: 0.035 arcsec 5.2. Range of spatial scales/FOV: up to 1 arcsec 5.3. Single dish: no 5.4. ACA: no 5.5. Subarrays: no 6. Frequencies: 6.1. Receiver band: Band 7 6.2. Lines: CO (3-2) line Frequency: 345 GHz 6.3. Spectral resolution (km/s): 1 km/s 6.4. Spectral coverage (km/s or GHz): >=100 km/s 7. Continuum flux density: 7.1. Typical value: N/A 7.2. Continuum peak brightness: 50 - 200 K 7.3. Required continuum rms: 1 K 7.4. Dynamic range in image: > 100:1 8. Line intensity: sensitivity limited by continuum goals 8.1. Typical value: 50 - 200 K (optically thick) 8.2. Required rms per channel: N/A 8.3. Spectral dynamic range: N/A 9. Polarization: no 10. Integration time per setting: rms in continuum : 1.6 K in 1 hour, so 2.6 hours required. in line. Note that this gives at 1 km/s resolution a brightness rms of 80 K. 11. Total integration time for program: 5 sources at 2.6 hours = 13 hours *********************************************************************** Review Phil Myers: for gap imaging, candidate disks should be more nearly face-on than edge-on, authors do not say how they would select face-on candidates (other than TW Hya). Time requested is remarkably short -- a bargain! -------------------------------------------------- Review v2.0: Gaps in nearby protoplanetary disks ================================== Authors: S.Guilloteau, A.Dutrey Reviewer: J. Bally I would add higher frequency data as well. Thought it is possible that gaps may become optically thick, we do not know for sure. The highest possible resolution should be sought for in this experiment. Furthermore, I would expect that the inner edge of a gap may be in shadow, and therefore colder than the outer edge which may be illuminated, and therefore warmer. Planets opening gaps are expected to be surrounded by circum-planetary disks and spiral waves. These features may be picked-up by the highest resolution ALMA images of the closest sources. Accreting proto-giant planets are also expected to have photospheres nearly an AU in diameter. ALMA may directly detect such objects as compact point sources within a gap. They may be hotter than surrounding dust due to accretion heating.