1. Luciano Cerrigone 1,2, Joseph L. Hora 2, Grazia Umana 1, Corrado Trigilio 1 1 INAF, Catania Astrophysical Observatory, Italy 2 Harvard-Smithsonian Center for Astrophysics, USA Asymmetrical Planetary Nebulae IV, La Palma, June 17-22 2007 Radio and Infrared observations of Transition Objects

2. Spectral type Luminosity O B A F G K M 10 6 L  10 4 L  10 2 L  1 L  10 -2 L  10 -4 L  pre-Planetary Nebulae in the HR diagram L. CerrigoneAPN IV, La PalmaJune 17-22, 2007 Proto-PN spectra range from G to A types. The evolution continues towards hotter temperatures, then pre-PN are found as B spectral type sources. We selected a sample of post-AGB objects, then having far-infrared excess, optically classified as B stars.

3. Radio continuum Infrared Ionized gas Dust and molecular gas Goal: contributing to explain the origin of non-spherical symmetry in PN and in general to understand the post-AGB to PN transition Method: inspecting envelope properties in a sample of transition objects and in particular: L. Cerrigone APN IV, La Palma June 17-22, 2007 Our project systematic differences between ionized and non ionized objects; relation between ionized gas and molecular gas or dust;

4. Very Large Array, array A Frequency: 8.4 GHz Resolution: 0.3’’ L. Cerrigone APN IV, La Palma June 17-22, 2007 VLA: High resolution radio maps

5. Spitzer: IRAC imaging L. Cerrigone APN IV, La Palma June 17-22, 2007 ~20’’ IRAC observations give us an upper limit on sizes: ~5’’ Extended structures have been detected in two targets IRAS 18070-2346IRAS 19590-1249 8.0  m3.6  m

6. Spitzer: IRS spectra L. Cerrigone APN IV, La Palma June 17-22, 2007 IRAS 22495+5134 [ArII] [NeII] PAH Silicates Radio detected targets IRAS 20462+3416 [NeII] PAH Silicates PAH Silicates

7. Spitzer: IRS spectra L. Cerrigone APN IV, La Palma June 17-22, 2007 IRAS 20572+4919 IRAS 21289+5815 PAH Silicates Non radio detected targets

8. Target6.2[ArII]7.78.510[NeII]Radio 17364xx 18379xxxx 19306xxx 21289xxx 18062xxx 19336xxxxxx 19590xxxxxx 20462xxxxxx 22023xxxxxxx 22495xxxxxx 17203x 19157x 20572x 17460xx 17381xxxx 17542xx 18435x 19200xxx 01005xxxx 06556xxxx 6.2, 7.7, 8.5  m => PAH 10  m => silicates [ArII] => 7.0  m; [NeII] => 12.8  m Summary of spectral detections L. Cerrigone APN IV, La Palma June 17-22, 2007 Silicates and radio Silicates, PAH and radio PAH, no radio Silicates, PAH, no radio Silicates, no radio PAH and radio

9. IRAS 17423-1755 SEDs L. Cerrigone APN IV, La Palma June 17-22, 2007 DUSTY parameters T star = 20000 K Chemistry: amorphous C T dust 1 = 950 K;  1 (0.55  m)= 0.14 T dust 2 = 110 K;  2 (0.55  m)= 0.18 The combination of IR and radio (cm and mm) data provides us with a strong consraint on the sub-mm SED

10. IRAS 19590-1249 SEDs L. Cerrigone APN IV, La Palma June 17-22, 2007 DUSTY parameters T star = 24000 K Chemistry: silicates T dust = 130 K  (0.55  m)= 0.115 IRS spectrum overplotted in red

11. Mid-IR imaging L. Cerrigone APN IV, La Palma June 17-22, 2007 We have performed mid-IR observations with MIRAC at the MMT Observatory. The Natural Star Adaptive Optics system allows nearly diffraction limited resolution in the 4 to 13  m range (~0.5’’). The shown images are scaled to the same resolution. MIRAC 11.7  m VLA 3.6 cm IRAS 22023+5249

12. Summary L. Cerrigone APN IV, La Palma June 17-22, 2007 Radio and Infrared observations will allow us to: build SEDs and detect the presence of different dust components; inspect the chemistry of the sample and check for an evolutionary path within this phase. We are characterizing a sample of Transition Objects selected on the basis of their Far-Infrared and Optical properties (B spectral type with IR excess).