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 Radio and Infrared observations of Transition Objects

Spectral type Luminosity O B A F G K M 10 6 L  10 4 L  10 2 L  1 L  L  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.

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;

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

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 IRAS  m3.6  m

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

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

Target6.2[ArII] [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

IRAS SEDs L. Cerrigone APN IV, La Palma June 17-22, 2007 DUSTY parameters T star = 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

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

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

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).