|
Description
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^+11+11^_-10-10_pc, where the quoted uncertainties are statistical and systematic uncertainties, respectively, 20 pc further away than previously assumed. The Chamaeleon II cloud is located at the distance of 181^+6+11^_-5-10_pc, which agrees with previous estimates. We are able to measure for the first time a distance to the Chamaeleon III cloud of 199^+8+12^_-7-11_pc. Finally, the distance of the Musca cloud is smaller than 603^+91+133^_-70-92_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. We have measured a larger distance to the Chamaeleon I cloud than assumed in the past, confirmed the distance to the Chamaeleon II region, and measured for the first time the distance to the Chamaleon III cloud. These values are consistent with the scenario where the three clouds are part of a single large scale structure. 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.
|
