Setting the Stage

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Setting the Stage

A star system that flares up every couple of decades may be headed for an even brighter outburst by the end of the century.

MWC 560 is a binary system — two stars bound by their mutual gravity. One of them is a white dwarf — the hot, dead core of a once-normal star. Its companion is a red giant — an old, bloated star that’s on track to become a white dwarf itself.

The white dwarf “steals” gas from the companion. That forms a wide, hot disk around the white dwarf. Magnetic fields grab some of the gas and shoot it out into space in high-speed jets. One of those jets aims directly at Earth, giving astronomers a good look at what’s going on.

The system has flared up several times since it was discovered, most recently in 2016. The outbursts are powered by eruptions from the disk. The flow of gas from the red giant gets too thick for the disk to handle, so it erupts, spewing particles and energy into space.

After each outburst, the system stays a little brighter than it was after the previous one. That could mean that the disk is getting a little heavier. That’s led astronomers to speculate that the system could stage an even bigger eruption in a few decades. It might blast away the entire disk. That would form a nova — making the system shine tens of thousands of times brighter.

MWC 560 is in Monoceros, the unicorn. The constellation is in the south and southwest at nightfall, to the upper left of Orion’s Belt.

Script by Damond Benningfield

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