HST Snapshot Survey of Post-AGB Objects

TL;DR

This study uses HST imaging to classify post-AGB objects into nebulous and stellar types, revealing a link between nebula morphology, dust optical thickness, and progenitor star mass, enhancing understanding of stellar evolution.

Contribution

It provides new high-resolution images and measurements of post-AGB objects, confirming the morphological bifurcation into DUPLEX and SOLE types and exploring their physical origins.

Findings

Nebulosities detected in 15 of 33 sources.

Dichotomy between DUPLEX and SOLE linked to dust optical thickness.

High-mass progenitors tend to form DUPLEX objects.

Abstract

The results from a Hubble Space Telescope (HST) snapshot survey of post-AGB objects are shown. The aim of the survey is to complement existing HST images of PPN and to connect various types of nebulosities with physical and chemical properties of their central stars. Nebulosities are detected in 15 of 33 sources. Images and photometric and geometric measurements are presented. For sources with nebulosities we see a morphological bifurcation into two groups, DUPLEX and SOLE, as previous studies have found. We find further support to the previous results suggesting that this dichotomy is caused by a difference in optical thickness of the dust shell. The remaining 18 sources are classified as stellar post-AGB objects, because our observations indicate a lack of nebulosity. We show that some stellar sources may in fact be DUPLEX or SOLE based on their infrared colors. The cause of the differences among the groups are investigated. We discuss some evidence suggesting that high progenitor-mass AGB stars tend to become DUPLEX post-AGB objects. Intermediate progenitor-mass AGB stars tend to be SOLE post-AGB objects. Most of the stellar sources probably have low mass progenitors and do not seem to develop nebulosities during the post-AGB phase and therefore do not become planetary nebulae.