A study of the ρ Ophiuchi cloud:: Mapping the distribution and the motions of interstellar gas

Guest Investigator results from Hipparcos, combined with high-resolution optical spectra obtained with the Anglo-Australian Observatory, Kitt Peak National Observatory, and McDonald Observatory, are used to create a three-dimensional map of the stars and several interstellar gas components in the rho Oph cloud complex. Many principal gas components are interspersed among the bright stars, which can be subdivided into three main groupings on the basis of right ascension and declination. At least one of these main gas components may persist over about 10 pc laterally, and there is evidence for an overall bulk movement of the gas, as determined from the observed radial velocities. We find the diffuse portion of the cloud complex to be clumpy, scattered over a distance range of similar to 110-150 pc. We find the most likely distance to the dense molecular cloud to be 122 +/- 8 pc.