Title  Search for CI in circumstellar disks around young stars	
Pi     A. Dutrey
Time   0.33 hrs
TEMPLATE 3:
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1. Name of program and authors
	Search for CI in circumstellar disks around young stars	
	Dutrey, Guilloteau et al., 


2. One short paragraph with science goal(s)

	This project proposes the detection and mapping of CI in
circumstellar disks around A stars since CI can be a good tracer of
gas in disks of moderate dust opacity such as transition disks (eg
HD141569). In such objects, the opacity at 1mum is likely < 1 but the
gas-to-dust ratio is still expected to be around ~100. Sensitivity
estimates are given for a (gas+dust) disk mass ~ 80 M_earth and a
spectral type B9.5. The assumed disk size 10'' at 100 pc (or 1000 AU).

The angular resolution expected is 1'', spectral resolution is 0.1 km/s 
 
note: calculations are adapted from the modelling of 
HD141569 by Jonkheid et al., 2006

3. Number of sources 
   
   We focus here on a single object, as example.  
 
4. Coordinates:

4.1. Rough RA and DEC
     
4.2. Moving target: no 

4.3. Time critical: no 
5. Spatial scales:

5.1. Angular resolution (arcsec): ~ 1'' 

5.2. Range of spatial scales/FOV (arcsec): single-field

5.3. Required pointing accuracy: (arcsec) standard

6. Observational setup

6.1. Single dish total power data: no

6.2. Stand-alone ACA: no

6.3. Cross-correlation of 7m ACA and 12m baseline-ALMA antennas: 
     no

6.4. Subarrays of 12m baseline-ALMA antennas: no


7. Frequencies:

7.1. Receiver band: Band 3, 4, 5, 6, 7, 8, or 9

	Bands 8  

7.2. Lines and Frequencies (GHz): 

	Band 8: CI 3P1-3P0 at 492.2 GHz

7.3. Spectral resolution (km/s): 0.1 km/s

7.4. Bandwidth or spectral coverage (km/s or GHz): 10 km/s

8. Continuum flux density: <= 10 mJy at 1.3mm

8.1. Typical value (Jy):

	Band 8: ~ 30 mJy ?

9. Line intensity:

	CI ~ 2 K per channel (Fig.9) for a source size of 10''
(conservative value because it is taken at the systemic velocity).

9.1. Typical value (K or Jy):
	
     Since only 20% of the disk is emitting at a given velocity  
(see Guilloteau et al., 2006), the expected brightness is ~ 10K. 

9.2. Required rms per channel (K or Jy): 

A 10 sigma detection per channel, requires an rms 

	CI: ~ 1 K        

9.3. Spectral dynamic range: standard

9.4. Calibration requirements: absolute      ( 10%)
                               repeatability ( 5%)
                               relative      ( 5%)

10. Polarization: no

11. Integration time for each observing mode/receiver setting (hr):
	(channel = 0.1 km/s)

10 sigma: 
	CI ~ 2 minutes  

	
12. Total integration time for program (hr): 

	For a survey of 10 sources;

10 sigma: 
	CI ~ 20 minutes or 0.33hrs 


13. Comments on observing strategy : standard mode 
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Review v2.0:
 
	Search for CI in circumstellar disks around young stars	
	Dutrey, Guilloteau et al., 


Reviewer: John Bally

Why not also observe the 810 GHz line?  The combination of 492 & 810
GHz will provide excitation constraints.  Also, can the isotopic 13CI
line be separated from the 12CI?

If the lines are bright, it would be very useful to obtain 0.1"
resolution maps in CI (both lines) to search for excitation gradients
and disk structure. Complimentary dust continuum and 13CO line
observations should also be obtained to constrain the relative
abundances of atoms, molecules, and dust and to search for localized
variations.