Stingray Nebula

The Stingray Nebula (Hen 3-1357) is the youngest known planetary nebula. The Stingray is located in the direction of the southern constellation Ara (the Altar), and is located 18,000light-years away. Although it is some 130 times the size of the Solar System, the Stingray Nebula is only about 1/10 the size of most other known planetary nebulae. The central star of the nebula is the fast-evolving star SAO 244567. Until approximately forty years ago, it was observed on Earth as a preplanetary nebula in which the gas had not yet become hot and ionized.
The image of the nebula shows how the outer shells of gas are collimating the continuing outflow of gas from the central star—an important observation, as the process of how these outflows become collimated has not been well understood.
History.
Prior to the discovery of the nebula, its central star was known as He 3-1357, which Karl Gordon Henize classified as an A or B type Hα emission line star in 1967. It was observed in 1971 to be a preplanetary nebula when it seemed to be an asymptotic giant branch B1 supergiant. Planetary nebula emission lines were identified in this star in 1989 by the International Ultraviolet Explorer. As the nebula would be newly formed and very small, ground-based observations were not able to resolve it; so Bobrowsky observed it with the Hubble Space Telescope, discovering the nebula, which he named the "Stingray Nebula".
In 1995 the central planetary nebula nucleus was observed as a DA white dwarf, having seemingly faded by a factor of three between 1987 and 1995. The white dwarf has an estimated mass of and luminosity of and has an observed companion star separated by 0.3arcsec. Nebula mass is estimated as .
In 1998 Bobrowsky et al. described how the Hubble Space Telescope observations revealed a 17th-magnitude companion to the Stingray's 15th-magnitude central star.
The central star is unusual in that it has brightened and faded over a period of 20years. Its temperature went up by 40,000°C. An explanation for this is that it has undergone a helium flash.
In January 2021 NASA discovered that the nebula is fading. In a NASA statement a team member, Martín A. Guerrero of the Instituto de Astrofísica de Andalucía in Granada, Spain, said: "This is very, very dramatic, and very weird. What we're witnessing is a nebula's evolution in real time. In a span of years, we see variations in the nebula. We have not seen that before with the clarity we get with this view."