Space is chaotic.
The universe is a huge expanse of a (so-far) never-ending abyss, which humans have only discovered a tiny bit of. And in this tiny bit, NASA has recently observed two stars going haywire.
Most stars are static, but and nuclear fusion engines, they live placid lives for hundreds of millions to billions of years. But sometimes, towards the end of their lives they can turn into crazy whirligigs, puffing off shells and jets of hot gas.
NASA's astronomers employed Hubble's full range of imaging capabilities to dissect such crazy fireworks happening in two nearby young planetary nebulas.
The two stars are: NGC 6302, which is dubbed the Butterfly Nebula because of its wing-like appearance and NGC 7027, which resembles a jewel bug, an insect with a brilliantly colorful metallic shell.
When I looked in the Hubble archive and realized no one had observed these nebulas with Hubble's Wide Field Camera 3 across its full wavelength range, I was floored," said Joel Kastner of Rochester Institute of Technology, in a NASA blog. "These new multi-wavelength Hubble observations provide the most comprehensive view to date of both of these spectacular nebulas. As I was downloading the resulting images, I felt like a kid in a candy store."
The new Hubble images revealed in vivid detail how both nebulas are splitting themselves apart on extremely short timescales — allowing astronomers to see changes over the past couple decades. Some of this rapid change may be indirect evidence of one star merging with its companion star.
"The nebula NGC 7027 shows emission at an incredibly large number of different wavelengths, each of which highlights not only a specific chemical element in the nebula, but also the significant, ongoing changes in its structure," said Kastner.
The research team also observed the Butterfly Nebula, which is a counterpart to the "jewel bug" nebula: Both are among the dustiest planetary nebulas known and both also contain unusually large masses of gas because they are so newly formed. This makes them a very interesting pair to study in parallel, say researchers.
Researchers also felt that at the hearts of both nebulas may have been two stars circling around each other. Evidence for such a central "dynamic duo" comes from the bizarre shapes of these nebulas. Each has a pinched, dusty waist and polar lobes or outflows, as well as other, more complex symmetrical patterns.
A leading theory for the generation of such structures in planetary nebulas is that the mass-losing star is one of two stars in a binary system.
The two stars orbit one another closely enough that they eventually interact, producing a gas disk around one or both stars. The disk is the source of outflowing material directed in opposite directions from the central star.
"The hypothesis of merging stars seems the best and simplest explanation for the features seen in the most active and symmetric planetary nebulas. It's a powerful unifying concept, so far without rival," said Bruce Balick from the University of Washington in Seattle.