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Abstract: The goal of the paper is to present new results on light echoes from youngstellar objects. Broad band CCD images were obtained over three months atone-to-two week intervals for the field of NGC 6726, using the largefield-of-view remotely-operated telescope on top of Cerro Burek. We detectedscattered light echoes around two young, low-amplitude, irregular variablestars. Observations revealed not just one, but multiple light echoes frombrightness pulses of the T Tauri star S CrA and the Herbig Ae-Be star R CrA.Analysis of S CrA-s recurring echoes suggests that the star is located 138 +-16 pc from Earth, making these the closest echoes ever detected. Theenvironment that scatters the stellar light from S CrA is compatible with anincomplete dust shell or an inclined torus some 10,000 AU in radius andcontaining $\sim$ $2 \times 10^{-3}$ $M {\sun}$ of dust. The cause of suchconcentration at $\sim$ 10,000AU from the star is unknown. It could be theremnant of the envelope from which the star formed, but the distance of thecloud is remarkably similar to the nominal distance of the Oort cloud to theSun, leading us to also speculate that the dust or ice seen around S CrAmight have the same origin as the Solar System Oort cloud.



Author: J.L. Ortiz, B.E.K. Sugerman, I. de la Cueva, P. Santos-Sanz, R. Duffard, R. Gil-Hutton, M. Melita, N. Morales

Source: https://arxiv.org/







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