The Gould's Belt Distances Survey (GOBELINS) III. The distance to the Serpens/Aquila Molecular Complex

TL;DR

This study uses VLBA observations to measure precise distances and proper motions of stars in the Serpens/Aquila complex, establishing a unified distance of approximately 436 parsecs and confirming the physical association of multiple regions.

Contribution

It provides new, precise distance measurements to the Serpens/Aquila complex and demonstrates that key regions are part of a single cloud structure, using multi-epoch VLBA data.

Findings

Distance to the complex is 436.0 ± 9.2 pc.

Serpens Main, W40, and Serpens South are physically connected.

Orbital parameters of the binary EC 95 were derived.

Abstract

We report on new distances and proper motions to seven stars across the Serpens/Aquila complex. The observations were obtained as part of the Gould's Belt Distances Survey (GOBELINS) project between September 2013 and April 2016 with the Very Long Baseline Array (VLBA). One of our targets is the proto-Herbig AeBe object EC 95, which is a binary system embedded in the Serpens Core. For this system, we combined the GOBELINS observations with previous VLBA data to cover a total period of ~8 years, and derive the orbital elements and an updated source distance. The individual distances to sources in the complex are fully consistent with each other, and the mean value corresponds to a distance of $436.0\pm9.2$~pc for the Serpens/W40 complex. Given this new evidence, we argue that Serpens Main, W40 and Serpens South are physically associated and form a single cloud structure.