A tidally interacting disk in the young triple system WL 20.
BARSONY M., GREENE T.P. and BLAKE G.A.
Abstract (from CDS):
We present high-resolution λ=2.7 mm imaging of the close triple pre-main-sequence system WL 20. Compact dust emission with integrated flux density of 12.9±1.3 mJy is associated with two components of the triple system, WL 20W and WL 20S. No emission above a 3 σ level of 3.9 mJy is detected toward the third component, WL 20E, which lies 3".17 (400 AU) due east in projection from its neighbors. A possibly warped structure of ∼0.1 M☉ and ≤3".2 extent encompasses WL 20W and WL 20S, which have a projected separation of 2".25 (∼280 AU) along a north-south axis. This structure is most likely a tidally disrupted disk surrounding WL 20S. New near-infrared spectra of the individual components show a remarkable similarity between the two T Tauri stars of the system: WL 20E has a K7 spectral type (Teff=4040 K) with rK=0.2, and WL 20W has an M0 spectral type (Teff=3800 K) with rK=0.2. The spectrum of WL 20S is consistent with that of a source intrinsically similar to WL 20W, with rK<0.9, but seen through an AV=25 in addition to the AV=16.3 to the system as a whole. Taken together, these millimeter and infrared data help explain the peculiar nature of the infrared companion, WL 20S, as resulting from a large enhancement in its dusty, circumstellar environment in relation to its companions.