New sub-millimeter heterodyne observations of CO and HCN in Titan's atmosphere with the APEX Swedish Heterodyne Facility Instrument

TL;DR

This paper demonstrates the use of the APEX Swedish Heterodyne Facility Instrument to observe CO and HCN in Titan's atmosphere, providing insights into its composition and testing the instrument's capabilities for planetary atmospheric studies.

Contribution

It introduces sub-millimeter heterodyne observations of Titan's atmosphere using APEX and SHFI, and evaluates the instrument's effectiveness in constraining atmospheric chemical profiles.

Findings

Successful detection of CO(2-1) and HCN(3-2) lines in Titan's atmosphere.

Radiative transfer calculations help constrain molecular vertical profiles.

Validated APEX-1 instrument's performance for planetary atmospheric research.

Abstract

The origin of the atmosphere of the largest moon of Saturn, Titan, is poorly understood and its chemistry is rather complicated. Ground-based millimeter/sub-millimeter heterodyne spectroscopy resolves line shapes sufficiently to determine information in Titan's atmospheric composition (on vertical profiles and isotopic ratios). We test the capabilities of the Swedish Heterodyne Facility Instrument (SHFI), Receiver APEX-1, together with the Atacama Pathfinder EXperiment APEX 12-m telescope for Titan's atmospheric observations. In particular we present sub-millimeter observations of the CO(2-1) and HCN(3-2) lines of the Titan stratosphere with APEX, and with SHFI taken during the Science Verification (SV) instrument phase on March and June 2008. With the help of appropriate radiative transfer calculations we investigate the possibility to constrain the chemical concentrations and optimize the performance of the APEX-1 instrument for inferring vertical profiles of molecular components of the atmosphere of Titan.