Gaia: mapping the dynamics and morphologies of Galactic Planetary Nebulae: First Results from Gaia Data Release 2
Abstract
Planetary Nebulae (PN) are a brief evolutionary stage through which low and intermediate mass stars pass towards the end of their evolution, between red giant and white dwarf. They can probe the kinematical structure of the Milky Way, and provide an indication of the chemical evolution history of the Galaxy. Understanding the nature of the PN itself provides vital insights into the evolutionary pathways of the stars forming the PN. The ESA Gaia satellite is optimised for the detection of point sources, and in general is not sensitive to extended objects (with sizes >0.5 arcsec). However, Gaia is able to resolve local point like maxima within extended objects. This is demonstrated by early observations of the large PN NGC 6543, where the complex nebula is decomposed by Gaia into thousands of individual mapping points. With nominal lifetime Gaia astrometry, it will be possible to accurately map the evolution of the plane of sky expansion of NGC 6543 and from line of sight velocities, the complex dynamical structure of the expanding nebula. We discuss the first results from the Gaia Data Release 2 in mapping the complex dynamics of a number of extended Galactic PN in the plane of the Milky Way. This allows precise limits to be set on the expansion rates (and thus lifetimes) of a representative sample of PN. Extending the analysis to larger samples of PN enables statistical inferences concerning PN type, shape, environment, likelihood of multiple central star systems to be found. These first results demonstrate how Gaia (with its parallax and proper motion uncertainties below 50 micro-arcsec for G=15 objects) can map extended structure. We describe the combination of Gaia data with optical narrow and broad band imaging data, essential in allowing positive nebular Gaia detection cross matches and rejection of stars in the field. We discuss the use of novel image segmentation techniques, developed for the analysis of histopathology data, applied to the optical image data to create the catalogues of nebula features required when matching with the Gaia sources.
- Publication:
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American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23333507W