HFG1 was created by V664 Cas, a star with a magnitude of 14.5. But this is not a ordinary star but a binary star system consisting of a white dwarf and a sun alike star rotating around each other every 14 hours in a distance of only a few million kilometre. The binary system is making it's way through our Milky way very fast.
When HFG1 is moving that fast throug the interstellar material a shock front is generated. A long, red track of 10,000 year old gas is left behind at any place, between 29 and 59 km per second, depending o the distance to the sun.
This picture clearly shows the interesting structure of HFG1.It is defined as a planetary nebula of type F, it seems to be filled evenly. The narrow blueish shock front surrounds the central area with a small gap. The front is much brighter in the south which points to some interaction between the front and the interstellar matter. The fron is incomplete and invisible in the north.
Lifetime of planetary nebulae is about 10,000 years which is very short compared to the lifetime of about 10 billion years of the sun alike star. HFG1 is quite old and will disperse soon while the white dwarf is cooling down more and more and paled for billions of years. This is the destiny our sun is facing in about 5 billion years.
The picture shows another planetary nebula: Abell 6. This nebula also is emitting light in the OII band while it's intensity in the range of hydrogen is low. Abell 6 appears to be circular with a diameter of almost 3 arc minutes. It's edge is partly brightened terminated sharply. The central star is very faint and can barely be seen.