Wobbly Jellyfish

Credit: NASA and The Hub­ble Her­itage Team (STScI/AURA)

Some­times plan­e­tary neb­ula expand in what look like smooth bub­bles. But oth­ers take on a wob­bly appear­ance which in some cases are oddly sym­met­ri­cal. In this NASA Hub­ble Space Tele­scope image of NGC 5307, each blob of gas seems to have a coun­ter­part on the oppo­site side of the neb­ula. Astronomers call these spi­ral plan­e­tary neb­ula. It is thought that the bright cen­tral white dwarf star spews out wob­bling jet of rapidly mov­ing gas from both ends of the star, spin­ning around like a top that is about to top­ple over.

Plan­e­tary neb­ula have noth­ing to do with plan­ets except that to early astronomers these round, bub­bles of gas looked like the plan­ets Uranus and Nep­tune. Plan­e­tary neb­ula are the last stage of life for stars like our Sun. After bil­lions of years, stars reach a point where there is lit­tle hydro­gen gas to burn. To help con­vert their stel­lar fur­naces to burn other ele­ments such as helium, the star bal­loons in size to become a red giant. Even­tu­ally, how­ever, the star col­lapses back on itself. This increases the tem­per­a­ture at its core and most of the star’s mate­r­ial is cat­a­pulted into space, form­ing a bub­ble around the star. This doesn’t hap­pen all at once but in stages.

Light from NGC 5307 takes about 7,900 years to reach us here on Earth and is found in the con­stel­la­tion Hercules.