A new planetary nebula NGC 6164-65 (Cederblad 135a, b).
Abstract
Objective-prism photographs of NGC 6164-65 taken in the light of Ha and FNII~ in the course of the Michigan-Mount Wilson Ha Survey show a markedly symmetrical distribution of gas about the central star HD 148937 (Harvard spectral class Bo). The shape of the nebula is roughly that of a figure "8" with small knots in the nebulosity showing central symmetry. These details are confirmed on direct photographs obtained with the ~8-inch Schmidt. The apparent brightness (6.89 mpg) of the central star is greater than that of any other planetary nucleus. Assuming the nucleus to be a main sequence Bo star, Cederblad derived a distance of 670 parsecs. If, as seems more likely, it is a subluminous B or 0 star comparable to other planetary nuclei, its distance is reduced to about 159 parsecs. The 370" angular diameter of the nebula is the fourth largest on record. At a distance of 670 parsecs this yields a linear diameter of 1.2 parsecs; while at 150 parsecs the derived linear diameter is 0.27 parsec. This object is clearly a planetary nebula from a morphological viewpoint, but spectroscopic observations of the nebula and central star are required to determine whether or not it fits this description from an evolutionary point of view. Whatever the result, the object is of unusual interest and deserves further investigation. Smithsonian Astrophysical Observatory, Cambridge, Mass.
- Publication:
-
The Astronomical Journal
- Pub Date:
- 1959
- DOI:
- 10.1086/108043
- Bibcode:
- 1959AJ.....64S..51H