The Molecular Outflow from R Mon*

Abstract

Abstract We have mapped the young Herbig Be star R Mon in CO(3–2) and 13CO(3–2) with Atacama Pathfinder EXperiment in Chile and analyzed unpublished Herschel images. We find that R Mon is embedded in a small cloud with a gas temperature of ∼20 K and a total mass of ∼70 . We confirm that R Mon drives a bipolar molecular outflow, which is blueshifted north of R Mon. The blueshifted outflow has excavated the molecular cloud north of R Mon, creating the reflection nebula NGC 2261 and filling it with high-velocity gas. At “high” velocities the orientation of the outflow is approximately n–s, which agrees with the optical jet, suggesting that the accretion disk is e–w. The outflow velocities are modest, ±9 km s−1. The outflow is rather massive, ∼0.56 in the blueshifted outflow lobe. The outflow is completely optically thick in CO(3–2) toward R Mon, indicating that its envelope is ≲2000 au. The mass of the accretion disk and surrounding envelope determined from an isothermal graybody fit is ∼0.34 . We estimate a mass-loss rate of ∼(1–3) × 10−5 yr−1, corresponding to an accretion rate of (1–9) × 10−6 yr−1. We find that R Mon has bolometric luminosity of <1000 . R Mon is still in an active accretion phase, contributing to the observed luminosity. Hence, R Mon cannot be a B0 star; it must be a late B star or even an early A star.