Astronomers have compared archival images of a young planetary nebula to reveal how the shroud of gas around an ageing star has faded over time. The Stingray Nebula is the youngest known planetary nebula, and Hubble Space Telescope images are providing a fascinating insight into cosmic processes at work.
Hen 3-1357 is nicknamed the Stingray Nebula due to its resemblance to the aquatic animal (one of many nebulae that look like animals).
Planetary nebulae have nothing to do with planets. In fact, they occur when smaller stars much like our own Sun begin to age and die and their outer layers shed, expanding outwards into space.
This often produces a blown-up, bulbous shape that resembles a planet: hence their name.
The Stingray Nebula is fading fast, as these Hubble Space Telescope images show. The left image was captured in 1996, and the right image was captured in 2016. The difference between the two is drastic.
Gone are the bright blue shells of gas near the nebula’s centre, and the curved outer edges have diminished to the extent that this planetary nebula no longer quite resembles the stingray shape after which it was named.
The Stingray Nebula is a shadow of its former self, no longer a luminous, well-defined object standing out against the blackness of space.
Many of these visual changes are a result of a difference in the light emitted by glowing gasses such as nitrogen, hydrogen and oxygen emanating from the central dying star, say astronomers. Oxygen emission in particular has dropped in brightness by almost 1,000 times.
Cosmic processes occur over such vast periods of time that it’s not always possible to observe the changes in action, but these newly-released Hubble images do just that.
“Because of Hubble’s optical stability, we are very, very confident that this nebula is changing in brightness,” says Martin Guerrero of the Instituto de Astrofísica de Andalucía in Granada, Spain, one of the members of the team behind the study.
“That easy to see since, unlike the nebula, all of the other stars in the Hubble image – including a distant companion star – stayed constant in brightness.”
Observatory Hubble Space Telescope
Release date 3 December 2020
Image Credit NASA, ESA, B. Balick (University of Washington), M. Guerrero (Instituto de Astrofísica de Andalucía), and G. Ramos-Larios (Universidad de Guadalajara)