Planetary Nebulae with UVIT: A Progress Report

TL;DR

This paper reports on UVIT observations of planetary nebulae, revealing new cold molecular hydrogen gas and comparing UV and X-ray morphologies to understand nebula evolution and address the missing mass problem.

Contribution

It provides new UV imaging data of planetary nebulae, including the first detection of cold molecular hydrogen gas, and compares UV and X-ray morphologies to study nebula evolution.

Findings

Detection of previously unseen cold molecular hydrogen gas.

UV and X-ray morphology comparisons reveal structural insights.

UVIT observations help address the missing mass problem.

Abstract

The spectral region between 1250 Angstroms - 3000 Angstroms contains important spectral lines to understand the morphological structures and evolution of planetary nebulae. This is the region sampled by UVIT through various filter bands both in the continuum and in emission lines (e.g. C IV, He I, Mg II etc.). We have mapped several planetary nebulae with different characteristics, ranging in morphology from bipolar to wide and diffuse, and in various states of ionization, comparing the UV with the x-ray morphologies wherever the x-ray images were also available. The major unanticipated discovery with UVIT has been the detection of previously undetected, cold, fluorescent, molecular hydrogen gas surrounding some planetary nebulae. This may be a possible solution to the missing mass problem. Here we present a review of our studies so far done (both published and on going) with UVIT.