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An Elliptical Ring Nebulosity Around Serpens/SVS 20: Circumbinary Disk or Outflow?

C. Eiroa, J. Palacios
Dpto. Fisica Teorica, Universidad Autonoma de Madrid. Spain

M. M. Casali
Royal Observatory Edinburgh, UK

Serpens SVS 20 is a binary pre-main sequence star, whose components are separated by 1.5 arcsec. Although of very different brightness, both components have the same spectral energy distribution in the range 0.9 to 5 microns. Eiroa and Casali (1992) discovered that SVS 20 had a arc-shaped nebulosity, departing from the binary star towards the southwest. Recent images of better spatial resolution show that this nebulosity is in fact a nebulous ring of elliptical shape, centered in the binary star, with two nearly symmetric extensions, as spiral-like arms. Possible explanations for this structure are a circumbinary disk or an outflow.