50% of stars are in Sun-like ‘singlet’ systems. The planetary nebulae we see just don’t line up.
Around 7 billion years from now, our Sun’s life will end.
Becoming a red giant, it eventually exhausts its core fuel.
Gravitation overcomes the decreased radiation, expelling the tenuous outer layers.
The hot, contracting interior — forming a white dwarf — ionizes and illuminates the ejecta.
These short-lived planetary nebulae shine for only tens of thousands of years before fading away.
All stars born with 40%-to-800% the Sun’s mass experience similar fates.
Only ~3000 planetary nebulae exist among the Milky Way’s ~400 billion stars.
And yet, there’s a tremendous mystery surrounding them.
Somehow, 80% of them show evidence of directionality.
Many are bipolar nebulae, with two opposing lobes of ejecta.
Others display spiral structures within them.
Still others are sculpted with odd, irregular shapes.
Merely 20% of planetary nebulae appear spherically symmetric: expected for singlet, Sun-like stars.
This is puzzling: 50% of all stars are singlets like our Sun.
Why, then, are only 20% of planetary nebulae spherically symmetric?
Perhaps large planets also carve irregular shapes.
Perhaps magnetic fields cause asymmetrical nebulae around singlet stars.
Or perhaps the more massive stars, shorter-lived and rapidly spinning, bias our statistics.
Despite our knowledge, we still cannot predict the Sun’s eventual nebular structure.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.
Starts With A Bang is written by Ethan Siegel, Ph.D., author of Beyond The Galaxy, and Treknology: The Science of Star Trek from Tricorders to Warp Drive.