Object name: PNABELL79

Designation(s): PNABELL79,

The possible planetary nebula Abell 79 is located in Lacerta. I found three different distance estimates for it, 5800, 4200 and 3250+/-500 light-years. This shows how difficult determining the distances to these objects is. Even more confusing is that this page about the Keck telescope considers it a "Planetary Super Nova Remnant" (scroll down half the page). Except for that reference all others I found call it a true planetary nebula which is the outer shell thrown off as a dying star turns into a dead white dwarf. A supernova remnant would create a neutron star or black hole (if it doesn't destroy the star entirely) which is a much denser and smaller object. So I decided to see if I could find anything on its central star and came up with this paper: It lists the central star as spectral type F0V. That means it is a main sequence star like our sun just somewhat more massive and therefore hotter and bluer but certainly not a white dwarf or neutron star. That means it isn't the star that created the nebula but could be a less massive companion that hasn't yet lived out its life. Its light is masking the true central star if it is there and therefore a true planetary nebula. Finding only one reference calling it a planetary SNR I'll go with true planetary though it does appear rather strange for one. The companion may have influenced its appearance, however. F stars normally wouldn't have the needed UV light needed to cause the nebula to glow so I doubt it is the source of the nebula's emissions assuming the F0V classification is correct. That normally requires an O or B star. So it is either ionized by a hidden small but very hot object (white dwarf or neutron star) or is energized by the shock wave created when the expanding shell hits the interstellar medium as is seen in the Veil and similar SNRs.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

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