Located in the direction of the southern constellation Ara, labelled as the youngest planetary Nebula, the Stingray Nebula which is also known as Hen 3-1357 made an unexpected entry in the 1980s and was first imaged by the scientists in the 1990’s using NASA’s Hubble Space Telescope. In the centre of the nebula, we can see the fast-evolving star SAO 244567.
A team of researchers has recently found a peculiar behaviour in this young Nebula. But what is the peculiar behaviour that the researchers had found??
Well, we all know that a star can live up to billions of years and can take millions of years for its transitions between the different stages of its life. But it looks as if this little one is in a bit of a hurry to take a leave!!!
A recent image of the Nebula taken by the Hubble Telescope in 2016, shows that it has faded significantly and has changed its shape in just 20 years. If this dimming continues at the same pace, the Nebula is more likely to fade away in the next twenty or thirty years. The astronomers have also noticed that the bright inner structure of the Nebula has contracted rather than expanding as the Nebula fades.
Planetary Nebulae are formed after most of the stars swell into red giants which are formed when the hydrogen fuel is exhausted. At the end of this phase, the star expels a large amount of its outer material and over the course of a million years, this transforms into a small, compact white dwarf. The sloughed-off material expands outward for several thousand years while the star heats the material, which eventually becomes ionized and glows. The researchers compared the two images taken in 1996 and 2016.
The team analyzed light spectra from Hen 3-1357 emitted by chemical elements in the Nebula and has found that the emission levels of hydrogen, oxygen and Sulphur dropped in these years, particularly oxygen, which dropped by a factor of 900. Astronomers are still questioning why and what made the SAO 244567 light up and then fade almost as quickly.
One theory proposed by a team led by Nicole Reindl at the University of Potsdam is that the star underwent a brief burst of fresh helium fusion around its core, which stirred up its outer layers and caused its surface to both shrink and heat. If so, the star may return to a more typical transition from a red giant to the white dwarf as it’s outer layers settle back down.
But what’s more unfortunate is that the tool best used to track down the changes is itself nearing its end, Yes!!! The Hubble Space Telescope is at the final stage of its lifetime. “We can hope, but the odds aren’t good for Hubble’s survival as its three remaining gyroscopes start to fail. It’s a good race to the finish.”, says Balick.
Reference: IoPScience
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