Title Infall velocity structure of starless cores
Pi     JP. Myers
Time   100 hrs
1. Name: Infall velocity structure of starless cores
     Authors: P. Myers, T. Bourke, C. De Vries (CfA)

  2. Science goal: Determine the spatial structure of inward motions 
in a sample of starless cores showing infall asymmetry in multiple 
lines at lower angular resolution. Select lines known to trace gas 
densities 10^4 to 10^6 cm^(-3).  Select lines with minimal abundance 
depletion due to  freeze-out onto grains (N2H+, N2D+, DCO+) to trace 
motions in the inner core, and with strong depletion (HCO+, HCN), to 
trace motions in the outer core.  Select lines with resolved 
hyperfine structure (N2H+ 1-0, N2D+ 1-0, HCN 1-0) to probe zones 
along the line of sight with differing optical depth.  Measure the 
continuum structure to obtain the density profile with radius. 
Compare the spectra, maps, and density profile with monte carlo 
radiative transfer models to constrain the velocity field with 
radius.  Test the consistency of the velocity field with models of 
gravity-driven motion, including infall onto point mass and onto 
extended mass, and including resistive forces due to gas pressure 
gradients and to magnetic fields (ambipolar diffusion).

3. Number of sources: 10

4. Coordinates:

   4.1. 10 sources distributed over sky (RA=any, DEC=any visible)
     
   4.2. Moving target: no

   4.3. Time critical: no


5.  Spatial scales:

   5.1. Angular resolution: 1"

   5.2. Range of spatial scales/FOV:

   5.3. Single dish: yes

   5.4. ACA: yes

   5.5. Subarrays: no


6. Frequencies:

   6.1. Receiver band:

   6.2. Lines:  N2H+ 1-0, 3-2
	       N2D+ 1-0, 3-2
	       DCO+ 2-1, 3-2
	       HCN 1-0, 2-1, 3-2
	       HCO+ 1-0, 2-1, 3-2

   6.3. Spectral resolution (km/s): 0.03 km/s

   6.4. Spectral coverage (km/s or GHz): 30 km/s


7. Continuum flux density:

   7.1. Typical value: O.05 Jy

   7.2. Continuum peak value: 0.1 Jy

   7.3. Required continuum rms: 0.001 Jy

   7.4. Dynamic range in image:


8. Line intensity:

   8.1. Typical value: 3 K

   8.2. Required rms per channel: 0.01 K

   8.3. Spectral dynamic range:


9. Polarization: no

10. Integration time per setting: 10 x 10 hrs

11. Total integration time for program: 100 hr

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Review John Richer: see program 2.1.1.










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Review v2.0:
 
init_8 = 2.1.8

1. Name: Infall velocity structure of starless cores
     Authors: P. Myers, T. Bourke, C. De Vries (CfA)

Unchanged w.r.t. DRSP 1.1. Do we still think that the maolecules
mentioned are the appropriate tracers. Are we really sure we
understand the chemistry and the depletion characteristics? There's
overlap witg 2.1.1 where H2D+ is proposed.