Abstract: The Ring Nebula in Lyra. The most famous nebula, a star which has shed its outer skin while the remainder collapses to a white dwarf. In the other edge of the nebula there is a star (16.2 Magnitude). Near the star at the nebula there is a bright area (observed in 1992). Is the star located behind, inside or in the front of the Nebula? What is the influence of the star to the nebula?

Full Text of Proposal

Comments by OPC

General Comments: It is a fair proposal, to use the star to probe the nebula. Ideally, one should take a medium resolution spectrum centred on the star and including the bright nebula region, to be able to tell if the nebula is visible in the stellar spectrum as absorption lines, to be able to see whether the nebula reflects stellar radiation (in the case the star is located close to the nebula), and whether the star contributes to the excitation of that part of the nebula. It is suggested to look in the region 3800-9000 Angstrom with resolving power about 1500. For the nebula, a short CCD exposure through OIII and continuum filter should be fine. It is scientifically interesting, and may yield unexpected results on the way. Unfortunately, its feasibility depends on the availability of a suitable spectrograph.

Visibility: It is a real problem in this case; visible only very early in the night. the

Special Comments: It is not clear if a spectrograph will be available.

Expected time consumption (including overhead): About 1 hour for the spectrum, some 10 minutes for imaging.

Proposed facility: Will depend on the availability of an adequate spectrograph