Title Structure and properties of disks around high-mass (proto-)stars Pi L. Testi Time 190 hrs Structure and properties of disks around high-mass (proto-)stars ================================================================ Authors: L. Testi, ... 2. Science goal: Study disk-outflow systems in the high-mass regime with the aim of comparing the results with better studied low-mass objects, to constrain competing formation mechanisms (coalescence vs.accretion) and infer disks dispersal timescales. To this effect one needs to observe suitable tracers for disks in these systems and suitable tracers for outflows. One will have to observe a sample of objects from embedded high mass protostars to young stars. Number of objects: 5/5/5/5/5 among cold protostars, warm massive cores, hot cores, UCHII regions, early Be stars and/or O stars in resolved UCHII. Total 25 objects. The disk tracers are continuum for dust (2 frequencies: 220 and 345 GHz), and rare molecules to probe the inner regions of the high-mass star forming cores [CH3CN for warm/hot cores (e.g. Cesaroni et al.), something fancier may be required for colder objects, deuterated molecules (suggestion by Caselli/Cesaroni). CO may probe disks around newly formed stars. The outflow tracers are: CO or isotopomers for embedded objects. [CO(1-0) or (2-1) from Beuther/Zhang/Molinari] 3. Number of sources: Roughly 25. 4. Coordinates: 4.1. Scattered, all on the galactic plane, most in the central regions of the Galaxy. 4.2. Moving target: no 4.3. Time critical: no 5. Spatial scales: 5.1. Angular resolution: 0.2-0.1 arcsec for disk; 2-4 arcsec for outflow 5.2. Range of spatial scales/FOV: up to 5 arcsec for disk; >20 arcsec for outflow 5.3. Single dish: yes for outflow 5.4. ACA: yes for outflow 5.5. Subarrays: no 6. Frequencies: 6.1. Receiver band: Band 3, Band 6, Band 7 6.2. Lines: CO(1-0) for outflow, CH3CN(12-11)/N2D+(3-2), CO(3-2) Frequency: 115, 220/230, 345 GHz 6.3. Spectral resolution (km/s): 0.5km/s outflow; <=0.2 km/s disk 6.4. Spectral coverage (km/s or GHz): ~150 km/s outflow; <=20 km/s disk 7. Continuum flux density: 7.1. Typical value: several mJy 7.2. Continuum peak value: 1 mJy/beam (resolving the disk) 7.3. Required continuum rms: 0.1 mJy/beam 7.4. Dynamic range in image: Low in general, may be ~1000 in a few regions 8. Line intensity: 8.1. Typical value: outflow: >100 Jy (single dish); disk: few Jy (interf core) 8.2. Required rms per channel: outflow: 0.1K disk: ~1K (in both cases one will be interested in the line wings). 8.3. Spectral dynamic range: low (in each channel...) 9. Polarization: YES for continuum. 10. Integration time per setting: outflow (Band 3, low res, ACA, single dish): 10 min/pointing, typical size of these outflows may require up to 10 pointing = mosaics (see Shepherd/Gueth works): ~1.5 hrs/src (+ACA/+SD) disk (Band 6 and Band 7): 3hr/source/freq (single pointing) 11. Total integration time for program: 190h 25(src)x(1.5h+3h+3h)=~190h ********************************************************************** Review Phil Myers: Interesting for imaging of high-mass systems and their outflows, yet it seems unlikely to tell us much about disk dispersal timescales with only 5 members in each group. -------------------------------------------------- Review v2.0: Structure and properties of disks around high-mass (proto-)stars ================================================================ Authors: L. Testi, ... Reviewe John Bally: The nearest sources - those within 1 kpc need to be given top priority because these are where the highest resolution will be achieved. OMC1, OMC1-S, and Cepheus A (HW2 and HW3c) should be done in detail first. "Second tier" sources located within 1 to 3 kpc should be the second priority. Existing data already shows that all nearby bigh-mass SFRs that have suspected disks also contain multiple stellar sources within the projected extents of their disks. The highest AND lowest continuum frequencies should be used to search for point sources that may indicate companion stars. Spectral indices will be needed to distinguish dust emission from hyper-compact HII regions expected to surrounding stars more massive than 10 Solar masses. Continuum frequencies need to be selected carefully to minimize contamination from line emission. In regions like Orion it may be difficult to find portions of the spectrum that are truly emission-line free!