The Pillars of Creation revisited with MUSE: gas kinematics and high-mass stellar feedback traced by optical spectroscopy

TL;DR

This study uses optical spectroscopy with MUSE to analyze the gas kinematics, ionisation structure, and feedback processes in the Pillars of Creation, revealing new outflows and estimating their physical properties and lifetimes.

Contribution

It provides a detailed 3D kinematic and ionisation analysis of the Pillars of Creation using IFU data, including the discovery of a new bipolar outflow and a candidate outflow.

Findings

Detection of a previously unknown bipolar outflow at the middle pillar tip.

Estimation of the photo-evaporative mass loss rate as 70 M$_{ ext{sun}}$ per million years.

The pillars' lifetime is estimated to be around 3 million years.

Abstract

Integral field unit (IFU) data of the iconic Pillars of Creation in M16 are presented. The ionisation structure of the pillars was studied in great detail over almost the entire visible wavelength range, and maps of the relevant physical parameters, e.g. extinction, electron density, electron temperature, line-of-sight velocity of the ionised and neutral gas are shown. In agreement with previous authors, we find that the pillar tips are being ionised and photo-evaporated by the massive members of the nearby cluster NGC 6611. They display a stratified ionisation structure where the emission lines peak in a descending order according to their ionisation energies. The IFU data allowed us to analyse the kinematics of the photo-evaporative flow in terms of the stratified ionisation structure, and we find that, in agreement with simulations, the photo-evaporative flow is traced by a blueshift in the position-velocity profile. The gas kinematics and ionisation structure have allowed us to produce a sketch of the 3D geometry of the Pillars, positioning the pillars with respect to the ionising cluster stars. We use a novel method to detect a previously unknown bipolar outflow at the tip of the middle pillar and suggest that it has an embedded protostar as its driving source. Furthermore we identify a candidate outflow in the leftmost pillar. With the derived physical parameters and ionic abundances, we estimate a mass loss rate due to the photo-evaporative flow of 70 M$_{\odot}$ Myr$^{-1}$ which yields an expected lifetime of approximately 3 Myr.