High-resolution spectroscopy of the bipolar proto-planetary nebula Hen 3-1475, the Garden Sprinkler Nebula

Abstract

A detailed analysis of high-resolution spectra in the optical and near-infrared range of the central zone of the proto-planetary nebula Hen 3-1475, obtained in 2006 and 2024, is conducted. The spectrum primarily revealed stellar emission of H Balmer and Paschen series, lines of iron (Fe I, Fe II, and [Fe II]), and other significant lines of He I, Ca II, [Ca II], and O I. Several multiplets of Fe II, the H Balmer series, Ca II H and K, Na I D and He I lines exhibit P-Cygni profiles and bump-like features, which are clear indicators of strong stellar winds. The terminal velocity of the winds was calculated, reaching values up to 800 km s^-1. [Fe II] and Fe I lines  were used as gas density indicators. In these observations, no photoionized nebular lines of planetary nebulae were identified, suggesting that the central star has not reached the temperature required to photoionize the nebula. A comparison between the observations from 2006 and 2024 reveals some few significant differences, being the most important the probably ejection of a new jet emerging from the central zone and the detection of a broad component adjacent to Hα, probably originating from emission associated with a jet at 700 km s^-1. High-spectral resolution observations of the knot NW1 obtained on August 2024, are also presented. This knot shows a typical spectrum of shocked gas. The emission of this knot has changed, presently not showing [O III] 5007 and other ionized lines that were  reported in 2006.