A revised estimate of the distance to the clouds in the Chamaeleon complex using the Tycho-Gaia Astrometric Solution

TL;DR

This study refines distance estimates to the Chamaeleon star-forming clouds using Gaia parallaxes, revealing new distances for Chamaeleon I, II, and III, and providing insights into their spatial arrangement.

Contribution

The paper provides the first direct distance measurements to Chamaeleon I, II, and III clouds using Gaia data, improving the accuracy over previous estimates.

Findings

Chamaeleon I is 179 pc away, 20 pc further than previous estimates.

Chamaeleon II is at 181 pc, consistent with prior data.

Chamaeleon III is newly measured at 199 pc.

Abstract

The determination of the distance to dark star-forming clouds is a key parameter to derive the properties of the cloud itself, and of its stellar content. This parameter is still loosely constrained even in nearby star-forming regions. We want to determine the distances to the clouds in the Chamaeleon-Musca complex and to explore the connection between these clouds and the large scale cloud structures in the galaxy. We use the newly estimated distances obtained from the parallaxes measured by the Gaia satellite and included in the Tycho-Gaia Astrometric Solution catalog. When known members of a region are included in this catalog we use their parallaxes to infer the distance to the cloud. Otherwise, we analyze the dependence of the color excess on the distance of the stars and look for a turn-on of this excess, which is a proxy of the position of the front-edge of the star-forming cloud. We are able to measure the distance to the three Chamaeleon clouds. The distance to Chamaeleon I is 179 pc, 20 pc further away than previously assumed. The Chamaeleon II cloud is located at the distance of 181 pc, which agrees with previous estimates. We are able to measure for the first time a distance to the Chamaeleon III cloud of 199 pc. Finally, the distance of the Musca cloud is smaller than 603 pc. These estimates do not allow us to distinguish between the possibility that the Chamaeleon clouds are part of a sheet of clouds parallel to the galactic plane, or perpendicular to it. Gaia Data Release 2 will allow us to put more stringent constraints on the distances to these clouds by giving us access to parallax measurements for a larger number of members of these regions.