HD 147681

A multiplicity survey of the ρ Ophiuchi molecular clouds We present a volume-limited multiplicity survey with magnitude cutoff({m}K≤ 10.5 mag) of 158 young stellar objects locatedwithin or in the vicinity of the ρ Ophiuchi Dark Cloud. Withexception of eleven already well observed objects, all sources have beenobserved by us in the K-band with 3.5 m telescopes by using speckletechniques. The separation range covered by our survey is0.13''≤θ≤ 6.4'', where the lower limit is given by thediffraction limit of the telescopes and the upper limit by confusionwith background stars. The multiplicity survey is complete for fluxratios ≥ 0.1 (Δ{m}K≤ 2.5) at the diffractionlimit. After taking the background density into account the degree ofmultiplicity is 29.1%± 4.3% and thus only marginally higher thanthe value 23.5%± 4.8 % derived for the given separation range forthe main-sequence solar-like stars in the solar neighbourhood (Duquennoy& Mayor 1991). We discuss the implications of these findings.
A Multiplicity Survey of the ρ Oph Dark Cloud Not Available
Walraven photometry of nearby southern OB associations Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
On the Distance of the Scorpio / Centaurus Dark Cloud Not Available

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