Effects of an Embedded B-star Wind on the Properties of the Near-by Cloud: Ophiuchus

Abstract

Abstract. \(\rho\) Ophiuchii is a group of five B-stars, embedded in a nearby molecular cloud: Ophiuchus, at a distance of \(\sim\) 119 pc. A “bubble”-like structure is found in dust thermal emission around \(\rho\) Oph. The circular structure on the H\(\alpha\) map further indicates that this bubble is physically connected to the source at the center. The goal of this paper is to estimate the impact of feedback from these embedded B-stars on the molecular cloud, by comparing the energy associated with the material entrained in the bubble to the total turbulent energy of the cloud. In this paper, we combine data from the COMPLETE Survey, which includes \(^{12}\)CO (1-0) and \(^{13}\)CO (1-0) molecular line emission from FCRAO, an extinction map derived from 2MASS near-infrared data using the NICER algorithm, and far-infrared data from IRIS (60/100 \(\mu\)m) with data from the Herschel Science Archive (PACS 100/160 \(\mu\)m and SPIRE 250/350/500 \(\mu\)m). With the wealth of data tracing different components of the cloud, we try to determine the best strategy to derive physical properties and to estimate the energy budget in the shell and in the cloud. We also experiment with the hierarchical Bayesian-fitting technique introduced by Kelly et al. (2012) in an effort to eliminate the bias in the derived column densities and/or temperatures induced by noise in the far-IR data. We find that the energy entrained in the bubble is \(\sim\) 12 % of the total turbulent energy of the Ophiuchus molecular cloud. This fraction is similar to the numberArce et al. (2011) give for the Perseus molecular cloud, and it suggests the non-negligible role of B-stars in driving the turbulence in clouds. We expect that a complete survey of “bubbles” in the Ophiuchus cloud will reveal the importance of B-star winds in molecular clouds.