Far-infrared imaging of post-AGB stars and (proto)-planetary nebulae with the AKARI Far-Infrared Surveyor

TL;DR

This study used AKARI's far-infrared imaging to investigate cool dust distribution around post-AGB stars and (proto)-planetary nebulae, finding no significant extended emission and highlighting the need for more sensitive observations.

Contribution

First far-infrared maps of selected post-AGB stars and (P)PNe with AKARI FIS, providing constraints on their dust envelopes and mass loss history.

Findings

No significant extended emission detected in the sample.

Envelope masses likely too large to be detected with AKARI FIS.

Higher sensitivity and resolution needed for future studies.

Abstract

By tracing the distribution of cool dust in the extended envelopes of post-AGB stars and (proto)-planetary nebulae ((P)PNe) we aim to recover, or constrain, the mass loss history experienced by these stars in their recent past. The Far-Infrared Surveyor (FIS) instrument on board the AKARI satellite was used to obtain far-infrared maps for a selected sample of post-AGB stars and (P)PNe. We derived flux densities (aperture photometry) for 13 post-AGB stars and (P)PNe at four far-infrared wavelengths (60, 90, 140, and 160 um). Radial (azimuthally averaged) profiles are used to investigate the presence of extended emission from cool dust. No (detached) extended emission is detected for any target in our sample at levels significant with respect to background and cirrus emission. Only IRAS 21046+4739 reveals tentative excess emission between 30 and 130". Estimates of the total dust and gas mass from the obtained maps indicate that the envelope masses of these stars should be large in order to be detected with the AKARI FIS. Imaging with higher sensitivity and higher spatial resolution is needed to detect and resolve, if present, any cool compact or extended emission associated with these evolved stars.