Variability in Proto-Planetary Nebulae: VIII. A New Sample of Southern Hemisphere Objects

TL;DR

This study analyzes light variability in nine southern proto-planetary nebulae over nine years, revealing pulsation periods, trends with temperature, and evidence of binary systems with circumbinary disks.

Contribution

It provides a new long-term observational dataset of PPNe, identifying pulsation periods and potential binary-induced variability in southern hemisphere objects.

Findings

Pulsation periods range from 24 to 73 days.

Shorter periods and smaller light variations correlate with higher temperatures.

Evidence of long-term variability suggests binary companions and circumbinary disks.

Abstract

As part of our continuing study of light variability in proto-planetary nebulae (PPNe), we present the results from a long-term study of nine southern hemisphere objects. We have monitored their light variations over a nine-year interval from 2010-2018. These were supplemented by data from the ASAS-SN and ASAS-3 surveys, leading to combined light curves from 2000 to 2020. Pulsation periods were found in seven of the objects, although the three shortest must be regarded as tentative. The periods range from 24 to 73 days. When compared with the results of previous studies of the light variations in PPNe, we find that they show the same trends of shorter period and smaller light variations with higher temperatures. Luminosities were calculated based on the spectral energy distributions, reddening, and Gaia distances, and these confirm the identification of all but one as post-AGB objects. Three of the stars possess long-period variations of 5 to 19 years. These are most likely due to the periodic obscuration of the star by a disk, suggesting the presence of a binary companion and a circumbinary disk.