Despite the name, a “planetary nebula” has nothing to do with planets. They were given the confusing name 300 years ago by William Herschel because they looked like planets in their early, rudimentary telescopes. They’re really the glowing shells of gas and dust puffed out by stars nearing the end of their lives. But wait, planets might be responsible after all.
And as a special bonus for actually reading this article, I’ll treat you to a gallery of beautiful planetary nebulae.
Astronomers at the University of Rochester have announced that low-mass stars, and maybe even super-Jupiter-sized planets might actually be responsible for the beautiful puffy nebulae. Their research appears in the latest editions of the Astrophysical Journal Letters and Monthly Notices of the Royal Astronomical Society.
Most medium-sized stars, like our own Sun, will end their lives as planetary nebulae. Even though the star has lived for billions of years, this stage just lasts several tens of thousands of years. The star runs out of fuel, its core contracts, and it ejects the outermost layers of its atmosphere into space. The expanding shell can be spherical in shape, but its often twisted and elongated.
Astronomers used to think that powerful magnetic forces shape the nebula. But maybe the low-mass companion star or super-Jupiter planet might be providing the gravity that warps and distorts the shape of the nebula.
The Rochester team studied the interplay between a companion star or planet and the expanding envelope of material given off by a dying star. When the star or planet is in a very wide orbit, its gravity drags some of the envelope material around on its orbit. This creates spiral waves of nebula material that expand out from the star, bunched up by interactions with the star or planet.
There could be an entirely different effect when the companion orbits within the envelope of the dying star. It could spin up material more quickly, ejecting it into a large disk around the star. It might also work with the star’s magnetic field to force material into jets out the poles.
Of course, a companion orbiting too close to the parent star might get shredded into a debris disk orbiting the dying star. And this disk could interfere with the nice smooth expansion of stellar material.
Original Source: University of Rochester News Release