One of the not-often-discussed justifications for building the Hubble Space Telescope was its ability to resolve the structure of planetary nebulae. These often geometric structures surround dead and dying stars and are formed when those stars puff off the outer layers of their atmosphere. Most of the planetary nebulae we study are fairly old and unchanging as they glow faintly around a white dwarf in their core.

But most is not all. There is one notable exception: The Stingray Nebula, or more officially Hen 3-1357. In 1996, the central star underwent what is now thought to have been a short-lived Helium flash as it changed evolutionary stages, and with that flash, created a dramatic looking planetary nebula. When re-examined in 2016, Hubble found the system dramatically fainter and structurally changed. Where the shells of gas in nebulae are often seen to expand away from their origin, in this case, inner shells were seen to fall back toward the center. According to research team member Martin Guerrero: 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.

This work is detailed in a new paper in The Astrophysical Journal with first author Bruce Balick, who points out: In most studies, the nebula usually gets bigger. Here, it’s fundamentally changing its shape and getting fainter, and doing so on an unprecedented time scale. Moreover, to our surprise, it’s not growing any larger. Indeed, the once-bright inner elliptical ring seems to be shrinking as it fades.

This set of observations has captured a short-lived phenomenon driven by changes in the central star. What is amazing about this is Hubble caught the earliest moments of a planetary nebula, and now, for generations, humanity will get to watch as the star dies and the nebula is born.

More Information

HEIC press release 

NASA Hubblesite press release 

“The Fall of the Youngest Planetary Nebula, Hen 3-1357,” Bruce Balick, Martín A. Guerrero & Gerardo Ramos-Larios, 2020, to appear in the Astrophysical Journal (preprint on arxiv.org)