HFG1 (PK 136+05), Abell 6 (PK 136+04.1); Cassiopeia
KAF-16803 FLI Proline
Total Exposure Time: 9.3 hours H:O:O:R:G:B 260:300:300:18:18:18 minutes; HOO binned x 2; unbinned RGB used for star color
July-August 2013; Inkom, ID
Comments: HFG1 is a planetary nebula in the constellation of Cassiopeia. It was produced by a binary star system (V664 Cas) that is moving rapidly through our Galaxy. The star is moving towards the upper-right of the image. As HFG1 plows through the interstellar medium, a bluish bowshock is produced; and a red trail of gas is left behind in its wake (ref). A deep wide-field image in the light of the Halpha+[N II] emission lines, of the planetary nebula HFG1 which surrounds the precataclysmic binary system V664 Cas, has revealed a tail of emission at least 20' long, at a position angle of 316deg. This is an ~10^5 y old trail of shocked material, left behind V664 Cas as it ejects matter whilst ploughing through its local interstellar media at anywhere between 29 and 59 km/s depending on its distance from the Sun (ref).
Abell 6 or PK 136+04.1: George Abell's examination of the Palomar Observatory Sky Survey in the mid 1960's yielded 86 planetary nebulae which have proven to be an observer's dream challenge, for many of these celestial objects are not only very faint in magnitude even under very dark skies but are also relatively large with dimensions often measured in minutes in lieu of seconds. Later analysis of Abell's catalog revealed that at least four of these objects, namely Abell 11, 32, 76 and 85, are not planetary nebulae at all. For the avid observer, an O-III filter is highly recommended in order to have any hope of visually detecting these elusive wonders (ref).
All of the objects in this image are very faint and require long exposures. More data may be added, and the image updated, as sky conditions permit. The background of this image has been lightened to enhance the faint nebulosity. The inverted H-alpha image may be seen below.