Ana M. Perez Garcia

Revealing the MID-infrared emission structure of iras 16594-4656 and iras 07027-7934

TIMMI2 diffraction-limited mid-infrared images of a multipolar proto-planetary nebula IRAS 16594-4656 and a young [WC] elliptical planetary nebula IRAS 07027-7934 are presented. Their dust shells are for the first time resolved (only marginally in the case of IRAS 07027-7934) by applying the Lucy-Richardson deconvolution algorithm to the data, taken under exceptionally good seeing conditions (≤05). IRAS 16594-4656 exhibits a two-peaked morphology at 8.6, 11.5, and 11.7 μm, which is mainly attributed to emission from PAHs. Our observations suggest that the central star is surrounded by a toroidal structure, observed edge-on, with a radius of 04 (~640 AU at an assumed distance of 1.6 kpc) and with its polar axis at P.A. ~ 80°, coincident with the orientation defined by only one of the bipolar outflows identified in the HST optical images. We suggest that the material expelled from the central source is currently being collimated in this direction and that the multiple outflow formation has not been coeval. IRAS 07027-7934 shows a bright, marginally extended emission (FWHM = 03) in the mid-infrared with a slightly elongated shape along the north-south direction, consistent with the morphology detected by HST in the near-infrared. The mid-infrared emission is interpreted as the result of the combined contribution of small, highly ionized PAHs and relatively hot dust continuum. We propose that IRAS 07027-7934 may have recently experienced a thermal pulse (likely at the end of the AGB) which has produced a radical change in the chemistry of its central star.

Anisotropy in the Mid-IR Emission of Seyfert Galaxies

Based on Mid and far-IR data of a complete set of Seyfert galaxies we analyse the Spectral Energy Distributions (SED) of these objects. These SEDs can be separated into three thermal emission components. This separation can be used to introduce some sort of spatial resolution in the inherently low resolution ISO data. It can also be applied as a method for detecting galactic disc components in high-z objects. The separation into emission components allows the study of these independently. In particular differences in the emission of the type 1 and 2 Seyferts can be seen in the warm emission component supposedly originated in dust heated by the nuclear source. The colder components tell us about the extended host galaxies.

Seyfert Galaxies in the Far IR

We show the results of a mid and far IR study of ISO data of the CfA Seyfert sample. These data allow a detailed study of the far IR Spectral Energy Distribution (SED) of these galaxies. We.nd that the mid and far IR SED of Seyfert galaxies can be explained solely through thermal reradiation of high energy photons by dust, and, that this thermalemission is made up of two or three di.erent independent components, a warm, a cold and a very cold dust component. These thermal components have been explained as produced respectively by warm dust heated by either the active nucleus or by circumnuclear starburts, cold dust heated by star forming region in the galaxy disk, and very cold dust heated by the general interstellar radiation field.

ISO Observations of Seyfert Galaxies

We present ISOPHOT observations of several objects from the CfA sample of Seyfert galaxies. Data for over 50% of the objects in the sample have been acquired so far. In all instances the far IR emission can be accounted for by assuming two different emission components.