“The Ghostly Final Breath of a Sun-Like Star” 

Abell 36 (PK 318+41.1, PN G318.4+41.4) [1] is a striking cosmic shroud about 800 light-years away in the constellation Virgo. Discovered in 1955 by American astronomer George Ogden Abell, this planetary nebula marks the hauntingly beautiful final stage of a dying Sun-like star. Despite its name, it is unrelated to planets; instead, it is an expanding shell of gas and plasma released as an aging star sheds its outer layers.

 At the center of this celestial tapestry, a contracting star is evolving into a white dwarf. Though rapidly shrinking, the stellar remnant remains intensely hot, with a surface temperature above 73,000 Kelvin. It emits powerful ultraviolet radiation that ionizes the surrounding expelled gases, making them glow like a vast neon sign in the cosmic darkness.

 Spanning roughly 1.5 light-years, the nebula displays striking symmetry and complexity. Its inner core forms an intricate bipolar, figure-eight pattern, with columns of gas sculpted by magnetic fields and stellar winds.

 For astrophotographers, it reveals its true majesty when mapped to the SHO—or Hubble—palette uses narrowband filters to capture emissions from ionized sulfur, hydrogen-alpha, and doubly ionized oxygen, assigning them too red, green, and blue, respectively. The glowing structure is surrounded by a vast, extremely faint halo of ancient material.

 Like all planetary nebulae, Abell 36 is beautiful but short-lived and is estimated to have formed about 10,000 years ago. As its gas expands into the interstellar medium, it will become too thin and cold to glow, fading into the surrounding universe within another 10,000 years. Studying this fleeting phenomenon offers a sobering glimpse of our own future because it reflects the fate awaiting the Sun in about 5 billion years.

 Besides the main body of Abell 36 planetary nebula (PN) the image shows many background galaxies the brightest of which are identified in the annotated version of the image shown in Fig. 1. Some of these galaxies also show details of the spiral arms and even tidal bridges for two pair of physically interacting galaxies in the FOV marked as GP1 and GF2 in the annotated inverted image shown in Fig. 2.

 Another remarkable feature here is the OIII bright diffuse arc located 8 arc. min West of the center of Abell 36 (marked as S2 in Fig 1, 2) which is independently confirmed by a recently published image by @Wolfgang Promper [2]. Most of the images of this PN taken by large aperture systems, such as VLT [3, 4] are typically covering only the main body of the PN up to 4 arc.min distance from the central star and thus missing this peripheral feature. Since the H-alpha halo (“ambient interstellar gas ionized by the central star”) of Abell 36 extend up to 2.5 deg. from its central star [5, 6] and since [7, 8] concludes that

“the formation of Abell 36 … requires multiple ejection events, changes in the orientation of main ejection axis between events, and a different collimation degree of the ejections”

the observed OIII feature might actually be physically related to Abell 36 as an older and larger radius outflow (scenario A). This scenario might also explain longitudinal fragmentation of this feature resembling the structure of the much brighter compact “arms” forming the main body of Abell 36.

 An alternative explanation for this feature could be given within the “Shocked Ghost Planetary Nebula” scenario described in [9, 10] (scenario B), however there are no indications of the existence of the counter-arc East of the main body of the PN, or H-alpha trail in its vicinity. Furthermore, the vector of the proper motion for the central star of Abell 36 is pointing Eastward - away from the OIII feature - according to Gaia DR3 measurements [1]. The third scenario is that it may be simply an overlapping feature (scenario C) physically unrelated to Abell 36. Further observations of the immediate vicinity of this PN up to 30 arc. min of angular radius are needed to distinguish between these scenarios.

Fig. 1. Annotated version of the original image.By AlexanderZaytsev

Fig. 2. Annotated inverted cropped version of the original image for better visibility of the faint
diffuse arc (S2) West of the main body of the Abell 36 (S1). By AlexanderZaytsev