HST STIS UV Spectroscopic Observations of the Protoplanetary Nebula Hen3-1475

TL;DR

This study uses HST STIS UV spectroscopy to image and analyze the complex jet structure of the protoplanetary nebula Hen3-1475, revealing detailed velocity gradients and shock features.

Contribution

First UV monochromatic imaging of a protoplanetary nebula with high spatial resolution, providing new insights into jet dynamics and shock phenomena.

Findings

Resolved the inner NW1 knot into four components in MgII emission.

Discovered a negative radial velocity gradient in NW1 from -1550 km/s to -300 km/s.

Components show minimal proper motion despite high radial velocities.

Abstract

We present UV spectra of the protoplanetary nebula (pPN) Hen3-1475 obtained with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). Our deep, low-dispersion spectroscopy enables monochromatic imaging of Hen3-1475 in UV nebular emission lines, the first of such attempt ever made for a pPN. The high spatial resolution of STIS imaging allows an unprecedentedly sharp view of the S-shaped jet, especially the inner NW1 knot, which is resolved into four components in the MgII 2800 line emission. Through critical comparison with HST optical narrowband images, we found a negative radial velocity gradient in NW1, from -1550 km/s on its innermost component to about -300 km/s on the outermost. Despite their high radial velocities, these components of NW1 mostly show no obvious (or very small) proper motions, indicating that they might be quasi-stationary shocks near the tip of the conical flow along the collimated jet of Hen3-1475.