2006/04/24 by Hugo E. Schwarz, Hektor Monteiro, H. Monteiro · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/505904
published as Astrophys.J.648:430-434,2006 · 16 pp, 6 figues, 2 tables, submitted to the ApJ
arxiv created 2006/04/24 · openalex publication_date 2006/08/31 · arxiv updated 2009/12/01 · openalex created_date 2020/12/21 · openalex updated_date 2026/07/31
Continuing our series of papers on the three-dimensional (3D) structures of and accurate distances to planetary nebulae (PNe), we present our study of the planetary nebula NGC 6781. For this object, we construct a 3D photoionization model and, using the constraints provided by observational data from the literature, we determine the detailed 3D structure of the nebula, the physical parameters of the ionizing source, and the first precise distance. The procedure consists of simultaneously fitting all the observed emission-line morphologies, integrated intensities, and the two-dimensional (2D) density map from the [S II] line ratios to the parameters generated by the model, and in an iterative way obtaining the best fit for the central star parameters and the distance to NGC 6781, obtaining values of 950 ± 143 pc and 385 L ☉ for the distance and luminosity of the central star, respectively. Using theoretical evolutionary tracks of intermediate and low-mass stars, we derive the mass of the central star of NGC 6781 and its progenitor to be 0.60 ± 0.03 M ☉ and 1.5 ± 0.5 M ☉ , respectively.