Title Post-AGB Stars: proto-planetary and planetary nebulae Pi P. Cox Time 238 hrs Project: Post-AGB Stars: proto-planetary and planetary nebulae ================================================================== 1. Name of program and authors Probing the physical and chemical properties of proto-planetary nebulae Authors: Pierre Cox 2. Science goal(s) The physical mechanisms which govern the evolution of proto-planetary nebulae (PPNe) are poorly documented because relatively few objects are known to be in this rapid transition between the AGB and planetary nebula phase. The role played by high-velocity winds which interact with the slowly expanding AGB envelope during the PPN phase has been recognized as essential in the shaping of the planetary nebulae. However, the details of the interaction and the precise evolution from the symmetric AGB envelope to the asymmetries which characterize planetary nebulae are still not well understood. The rapid erosion of the AGB envelope through multiple high-velocity outflows and UV photons is not only structural but is also reflected in the unusual rich chemistry observed in PPN. In the inner zones, the UV photons from the central star photodissociate the molecular species produced during the AGB phase initiating a chemistry which is radically different from the AGB photochemistry and is now dominated by ion-neutral reactions. Such reactions allow the formation of O-bearing molecules in the inner regions of carbon-rich environments, including water and OH. The effect of the UV radiation on the acetylene and methane, which are still available in the gas phase, can produce new hydrocarbons, including benzene as observed in CRL618. The main goals of the program are to observe all know PPN accessible from the sourthern skies, in order to improve our knowledge on the mechanisms responsible for the onset of high-velocity winds after the AGB phase, probe the inner dense regions of PPN, which trace the last mass-loss event of the AGB phase, and to study the unusual chemistry by obtaining line surveys of a few sources. 3. Number of sources: 16 PPN observable in the southern hemisphere (from catalogue of Bujarrabal et al. 2001) 4. Coordinates and expected fluxes (examples with measured radio data): 4.1 Rough RA and DEC Name RA Dec (J2000.0) Frosty Leo 09:39:54.0 11:58:54 He3-1475 17:45:14.1 -17:56:47 IRC+10240 19:26:48.0 11:21:17 IRAS19500-1709 19:52:52.6 -17:01:50 IRAS07134+1005 07:16:10.3 09:59:48 Hen3-401 10:19:32.5 -60:13:29 Robert22 10:21:33.8 -58:05:48 HD101584 11:40:58.8 -55:34:26 Boomerang 12:44:45.5 -54:31:12 He2-113 14:59:53.5 -54:18:08 Mz-3 16:17:13.6 -51:59:06 M2-9 17:05:37.9 10:08:32 CPD-568032 17:09:00.9 -56:54:48 IRAS17150-3224 17:18:19.7 -32:27:21 OH17.7-2.0 18:30:30.7 -14:28:57 R Sct 18:47:29.0 -05:42:19 4.2. Moving target: yes/no (e.g. comet, planet, ...) no 4.3. Time critical: yes/no (e.g. SN, GRB, ...) no 5. Spatial scales: 5.1. Angular resolution (arcsec): 0.10-0.20 5.2. Range of spatial scales/FOV (arcsec): (optional: indicate whether single-field, small mosaic, wide-field mosaic...) Most sources have sizes of about 20 arcsec. 5.3. Single dish total power data: yes/no no 5.4. ACA: yes/no no 5.5. Subarrays: yes/no no 6. Frequencies: 6.1. Receiver band: Bans 3 Band 6 Band 7 Band 9 6.2. Lines and Frequencies (GHz): multi-line: with multi (TBD) freqency settings. 6.3. Spectral resolution (km/s): 1-3 km/s 6.4. Bandwidth or spectral coverage (km/s or GHz): 100 to 500 km/s 7. Continuum flux density: 7.1. Typical value (Jy): a few 10 to 100 mJy 7.2. Required continuum rms (Jy or K): 0.01 Jy 7.3. Dynamic range within image: >100 N/A; no nearby weaker objects expected 8. Line intensity: 8.1. Typical value (K or Jy): The CO lines are normally bright in bright in PPN. The less abundant molecules will have a few K. 8.2. Required rms per channel (K or Jy): 1 K for most of the objects. 8.3. Spectral dynamic range: >100 for brightest lines 9. Polarization: yes for a few sources 10. Integration time for each observing mode/receiver setting (hr): 10 min/Bd 3, 20 min/Bd 6 30 min/Bd 7, 9 - for 0.3 arcsec resolution and 0.2-0.3 K (1 sigma) sensitivity Number of settings per Band will be 10. 11. Total integration time for program: 16 x 10 x 10m : 26 h Band 3 16 x 10 x 20m: 52 h Band 6 16 x 10 x 30m: 80 h Band 7 16 x 10 x 30m: 80 h Band 9 ------------------------------------------- 238 h total ************************************************************************** Review Peter Schilke: High scientific interest. Can certainly lead to a proposal, but isn't really one. There is only a vague idea which and how many lines should be observed, so the time estimate is very uncertain. Line surveys are mentioned in the justification, but there is no time allocated for them in this proposal. The need for the spectral/spatial resolution used isn't justified. Reply Cox: I agree with the remark by Peter re the line survey and a more detailed proposal should indeed be written. For the spectral/spatial resolution requested, the lines can be narrow (in the central regions unaffected by the outflows) so that 1-3 km/s is mandatory. For spatial resolution, sub-arcsecond resolution is needed to study the detailed morphology in poarticular in the central regions. -------------------------------------------------- Review v2.0: 3.4.1 Post-AGB stars: PPN and PN Cox 238 Band 7 and 9 are requested, which have fields of view of 20" and 10" respectively though no single dish/ACA data are required. I think that these datasets for larger sources do in fact need shorter spacings or interpretation could be quite complex. Probably, data in Bands 4, 5, 8 and 10 would be of interest also, though the project was not updated. It is hard to justify as the specifically targeted lines are not detailed although the source list is quite detailed.