1.3 mm Dust Continuum Observations of Young X-ray Selected Stars in Ophiuchus

Abstract

We have performed 1.3 mm dust continuum observations for a sample of 18 X-ray selected pre-main sequence (PMS) stars in the Ophiuchus star forming region with the MPIfR 7-channel bolometer array mounted at the IRAM 30m Millimeter Radio Telescope (MRT). We have detected cold dust emission from 3 of the objects and have derived 3σ upper limits (∼21 mJy) for the remaining objects. These upper limits suggest that the cold dust masses are less than 5 · 10–⁵ M_⊙.

In addition, we have mapped the hierarchical triple SR24 at λ = 1.3 mm with the 7-channel bolometer array. We detected cold dust emission only from the southern component with a peak intensity of ∼ 230 m Jy and a corresponding circumstellar disk mass of ∼ 0.035 M_⊙ (gas + dust), while for the northern component we derived an upper limit of 10 % of the SR 24S peak flux density. The non-detection of 1.3 mm emission from SR 24N suggests a lack of cold circumstellar dust in the outer part of the disk, which might have been cleared by the close companion 0″.2 away from SR 24N.