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

Abstract

Integral field unit (IFU) data of the iconic Pillars of Creation in M16 are presented. The ionization 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 ionized and neutral gas are shown. In agreement with previous authors, we find that the pillar tips are being ionized and photoevaporated by the massive members of the nearby cluster NGC 6611. They display a stratified ionization structure where the emission lines peak in a descending order according to their ionization energies. The IFU data allowed us to analyse the kinematics of the photoevaporative flow in terms of the stratified ionization structure, and we find that, in agreement with simulations, the photoevaporative flow is traced by a blueshift in the position-velocity profile. The gas kinematics and ionization structure have allowed us to produce a sketch of the 3D geometry of the Pillars, positioning the pillars with respect to the ionizing 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 photoevaporative flow of 70 M⊙ Myr−1 which yields an expected lifetime of approximately 3 Myr.