Measurement of the Distance and Proper Motions of the H2O Masers in the Young Planetary Nebula K 3-35

TL;DR

This study used VLBI observations to measure the distance and motions of water masers in the young planetary nebula K 3-35, providing the first parallax measurement for such an object and insights into its kinematic structure.

Contribution

First parallax measurement of a planetary nebula via maser observations, enabling precise distance and motion determination.

Findings

Distance to K 3-35 is 3.9+0.7/-0.5 kpc.

Proper motion of K 3-35 is -3.34+/-0.10 mas/yr in RA and -5.93+/-0.07 mas/yr in Dec.

Detected relative proper motions suggest the destruction of the toroidal maser structure within a few years.

Abstract

In this paper we present the results of very long baseline interferometry (VLBI) ob- servations carried out with the VLBI Exploration of Radio Astrometry (VERA) array and the Very Long Baseline Array (VLBA) toward H2O masers in a young planetary nebula K 3-35. From the VERA observations we measured the annual parallax and proper mo- tion of a bright water maser spot in K 3-35. The resulting distance is D = 3.9+0.7 kpc. -0.5 This is the first time that the parallax of a planetary nebula is obtained by observations of its maser emission. On the other hand, the proper motion of K 3-35 as a whole was esti- mated to be {\mu}{\alpha} = -3.34+/-0.10 mas yr-1, {\mu}{\delta} = -5.93+/-0.07 mas yr-1. From these results we determined the position and velocity of K 3-35 in Galactic cylindrical coordinates: (R,{\theta},z) = (7.11+0.08-0.06 kpc, 27+/-5{\circ}, 140+25-18 pc) and (VR, V{\theta}, Vz) = (33+/-16, 233+/-11, 11+/-2) km s-1, respectively. Additionally, from our VLBA observations we measured the relative proper motions among the water maser spots located in the central region of the nebula, which have been proposed to be tracing a toroidal structure. The distribution and relative proper motions of the masers, compared with previous reported observed epochs, suggest that such structure could be totally destroyed within a few years, due to the action of high velocity winds and the expansion of the ionization front in the nebula.