THE CENTRAL BINARY AND SURROUNDING NEBULA OF THE SYMBIOTIC STAR V1016 CYGNI

摘要

We present Hubble Space Telescope (HST) Wide Field Planetary Camera 2 images of the symbiotic star V1016 Cygni that, for the first time, directly explore the inner regions of the nebula to AU scales at optical wavelengths. They also suggest that the [O Ⅲ] λλ4959, 5007 emission takes place in a bipolar outflow. We use these images to determine the position of the two stars and hence a projected binary separation of 84 +- 2 AU (assuming a distance of 2 kpc) and a position angle of 143.5° +- 10°. Furthermore, we combine our images with Very Large Array radio imaging, which enables diagnostic tests to be applied and properties of the circum-stellar nebula to be determined. Finally, we have obtained archive HST Space Telescope Imaging Spectro-graph spectra of V1016 Cygni, with which we were able to spatially resolve the source at various positions in the nebula. This enabled discovery of the ultraviolet counterpart to the ～25″ extended emission found by Bang and coworkers.