Spatially resolved HCN J=4--3 and CS J=7--6 emission from the disk around HD 142527

TL;DR

This study presents the first spatially resolved detections of HCN J=4-3 and CS J=7-6 lines in the disk around HD 142527, revealing azimuthal asymmetries and the influence of dust concentration on molecular emission.

Contribution

First detection of CS J=7-6 emission in a protoplanetary disk with spatial resolution, providing new insights into disk chemistry and structure.

Findings

Both emission lines are azimuthally asymmetric.

Line emission is suppressed under the dust continuum peak.

Dust concentration affects molecular line emission through opacity and temperature effects.

Abstract

The disk around HD 142527 attracts a lot of attention, amongst others because of its resolved (sub) mm dust continuum that is concentrated into a horseshoe-shape towards the north of the star. In this manuscript we present spatially resolved ALMA detections of the HCN J=4-3 and CS J=7-6 emission lines. These lines give us a view deeper into the disk compared to the (optically thicker) CO isotopes. This is the first detection of CS J=7-6 coming from a protoplanetary disk. Both emission lines are azimuthally asymmetric and are suppressed under the horseshoe-shaped continuum emission peak. A possible mechanism to explain the decrease under the horseshoe-shaped continuum is the increased opacity coming from the higher dust concentration at the continuum peak. Lower {\gr dust and/or gas} temperatures and an optically thick radio-continuum reduce line emission by freeze-out and shielding of emission from the far side of the disk.