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A Tidally Interacting Disk in the Young Triple System WL 20?
We present high-resolution λ=2.7 mm imaging of the close triplepre-main-sequence system WL 20. Compact dust emission with integratedflux density of 12.9+/-1.3 mJy is associated with two components of thetriple system, WL 20W and WL 20S. No emission above a 3 σ level of3.9 mJy is detected toward the third component, WL 20E, which lies 3.17"(400 AU) due east in projection from its neighbors. A possibly warpedstructure of ~0.1 Msolar and <=3.2" extent encompasses WL20W and WL 20S, which have a projected separation of 2.25" (~280 AU)along a north-south axis. This structure is most likely a tidallydisrupted disk surrounding WL 20S. New near-infrared spectra of theindividual components show a remarkable similarity between the two TTauri stars of the system: WL 20E has a K7 spectral type(Teff=4040 K) with rK=0.2, and WL 20W has an M0spectral type (Teff=3800 K) with rK=0.2. Thespectrum of WL 20S is consistent with that of a source intrinsicallysimilar to WL 20W, with rK<0.9, but seen through anAV=25 in addition to the AV=16.3 to the system asa whole. Taken together, these millimeter and infrared data help explainthe peculiar nature of the infrared companion, WL 20S, as resulting froma large enhancement in its dusty, circumstellar environment in relationto its companions.
| A homogeneous catalog of new UBV and H-beta photometry of B- and A-type stars in and around the Scorpius-Centaurus OB association
B- and A-type stars in and near the Sco-Cen OB association areinvestigated with UBV and H-beta photometry to acquire data relevant tothe luminosity function of Sco-Cen. The measurements generally consistof two 10-s integrations of U, B, V, (W, N) filters, and theobservations are corrected iteratively for atmospheric extinction andinstrumental response. The data presented give the mean V magnitude,mean B-V, mean U-B, and the estimated uncertainties for these values.The catalog provides a homogeneous catalog of data for a large fieldwith stellar objects delineating membership to the association Sco-Cenand that affect the luminosity function of the aggregate.
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