Title   Structure of Debris disks  & Vega-type objects. 
Pi     A. Dutrey
Time   690 hrs

 Structure of Debris disks  & Vega-type objects.
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  Authors: A.Dutrey, S.Guilloteau

  2. Science Goals: search for large dust particles (~mm - cm size)
  and ``cold gas'' in nearby debris disks in order to characterize
  their physical properties and evolutionary scheme, taking into account
  the Mid-IR to optical properties of these systems.
  Needed: CO and dust mapping (mosaic for nearby systems, D< 30pc)

  3. Number of sources: 5

  4. Coordinates
  4.1. Scattered in the sky - 5 objects (all famous)
  eg, Vega, Beta Pic, E Eri, etc...
  4.2. moving target: no
  4.3. Time critical: no

  5. Spatial scales
  5.1 angular resolution:  0.5 -- 1.5" (minimum possible)
  5.2 mosaicing in most cases -  3-15 fields - depending on distance, =
ang.size, inclination angle
  5.3 total power: yes
  5.4 ACA yes
  5.5 subarrays: no

  6. Frequencies
  6.1 Frequency band: 6 (cold extended  gas), 7, 9
  6.2 Line and Frequencies (GHz)
  A. 230 GHz 12CO(2-1) and continuum GHz (and if possible 13CO(2-1) =
220.4 GHz)
  B. 345 GHz 12CO(3-2) and continuum
  C. 670 GHz continuum at 0.5 mm
  6.3 Spectral resolution: 0.2 km/s
  6.4 Bandwidth/Spectral coverage: 40 km/s

  7. Continuum flux density
  7.1 Typical value (Jy)  5- 10 mJy (over 100 -- 800 clean beams)
  7.2 Required rms:
      A. 5 microJy/Beam - resolved
      B. 10 microJy/Beam
      C. 40 microJy/Beam
      (using a pessimistic SED in nu^2)
  7.3 Dynamic range within image: standard

  8. Line intensity
  8.1 typical value: in 12CO(2-1):   unknown! < 0.1  Jy.km/s ?
  8.2 required rms per channel: as given by continuum requirement:
      A. 11 mK brightness for 0.2 km/s resolution
      B. 20 mK brightness for 0.2 km/s resolution
      C. N/A (no line)
  8.3 spectral dynamic range: standard

  9. polarisation: no (too weak)

  10. integration time per setting  / per object
      A. 7 hrs per field,  total of 20--30 fields for the 5 objects
      B. 6 hrs per field,  total of 40--60 fields for the 5 objects
      C. 10 hrs per field, total of 80--120 fields for the 5 objects
      for a blind search.

  11. total integration time for program
      The number of fields can be more accurately specified once the
      part A. (Band 6) has been observed. We shall count in total 30
      fields for A, 30 fields for B and C.
      Total 30 x (6+7+10) = 690 hours.

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Review Phil Myers: Useful goal to image nearby debris disks in several
bands.  But the authors say the typical 12CO line intensity is
"unknown" and yet they request 690 hours or the equivalent of 86
8-hour periods.  Too vague and an impractical time request.


Comment Ewine: I expect that there will be large proposal pressure to
do this type of program, so it is OK to keep in a large time request.
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Review v2.0:
 

 Structure of Debris disks  & Vega-type objects.
=================================================

  Authors: A.Dutrey, S.Guilloteau

Reviewer John Bally:

The nearby debris disk, AU Mic (D= 12 pc) is a must.  This provides
the very best change for ALMA to observe dust structure on sub-AU
scales.

I would break this into a two-phase program: First, observe all
targets in spectral line mode with a compact ALMA configuration that
delivers a roughly 1" beam to search the spectrum for gas-phase
tracers.  It is unclear what species will be most easy to detect.
Second, follow-up with line and continuum imaging at higher resolution
in a configuration chosen on the basis of signal level found in the
first phase of these observations.


Reply: YES! note that even with 1'' resolution, you need to make mosaicing.