Trigonometric Parallax of the Protoplanetary Nebula OH 231.8+4.2

Abstract

AbstractWe report a trigonometric parallax measurement for the H2O masers around the protoplanetary nebula OH 231.8+4.2 carried out with the Very Long Baseline Array (VLBA). Based on astrometric monitoring for 1 year, we measured a parallax of 0.65 ± 0.01 mas, corresponding to a distance of 1.54 +0.02−0.01 kpc. The spatial distribution of H2O masers is consistent with that found in the previous studies. After removing the average proper motion of 1.4 mas yr−1, corresponding to 10 km s−1, the internal motions of the H2O maser spots indicate a bipolar outflow.