ﻻ يوجد ملخص باللغة العربية
We present first preliminary results from AKARI/FIS pointed observations of post-AGB stars and planetary nebulae (PNe). A first analysis of the radial (azimuthally averaged) profile of the observed sources shows no evidence for excess emission due to the presence of circumstellar dust. No (detached) circumstellar faint dust-shells are seen in the image maps. Also, we present here first results of aperture flux photometry at wavelengths of 65, 90, 140 and 160 micron. Results are compared with IRAS flux densities as well as the beta release of the FIS Bright Source Catalog. Finally, spectral energy distributions are given, by way of an example, for two individual targets in our sample.
During the last years, many observational studies have revealed that binaries play an active role in the shaping of non spherical planetary nebulae. We review the different works that lead to the direct or indirect evidence for the presence of binary
Obscured by their circumstellar dusty envelopes post-AGB stars emit a large fraction of their energy in the infrared and thus, infrared sky surveys like IRAS were essential for discoveries of post-AGBs in the past. Now, with the AKARI infrared sky su
Context. There are more than 3000 known Galactic planetary nebulae (PNe), but only 492 central stars of Galactic planetary nebulae (CSPN) have known spectral types. It is vital to increase this number in order to have reliable statistics, which will
We intended to study the incidence and characteristics of water masers in the envelopes of stars in the post-AGB and PN evolutionary stages. We have used the 64-m antenna in Parkes (Australia) to search for water maser emission at 22 GHz, towards a
Accurate emission line fluxes from planetary nebulae (PNe) provide important constraints on the nature of the final phases of stellar evolution. Large, evolved PNe may trace the latest stages of PN evolution, where material from the AGB wind is retur