The Butterfly Nebula, located just under 4,000 light-years from Earth in the constellation Scorpius, is a striking example of a planetary nebula, the end stage in the evolution of a small- to medium-sized star. The butterfly’s diaphanous “wings” consist of gas and dust that have been expelled from the dying star and illuminated from within by the star’s remaining core. The nebula’s symmetrical, double-lobed shape is a telltale sign that a companion star helped shape the outflowing gases. Both the primary star and its companion are hidden by the shroud of dust in the nebula’s center.
Enlarge / The Butterfly Nebula, situated just below 4,000 light-years from Earth within the constellation Scorpius, is a placing instance of a planetary nebula, the tip stage within the evolution of a small- to medium-sized star. The butterfly’s diaphanous “wings” encompass fuel and dirt which were expelled from the dying star and illuminated from inside by the star’s remaining core. The nebula’s symmetrical, double-lobed form is a telltale signal {that a} companion star helped form the outflowing gases. Each the first star and its companion are hidden by the shroud of mud within the nebula’s heart.

Billions of years from now, as our Solar approaches the tip of its life and helium nuclei start to fuse in its core, it’s going to bloat dramatically and switch into what’s often known as a pink big star. After swallowing Mercury, Venus, and Earth with hardly a burp, it’s going to develop so massive that it could actually not maintain onto its outermost layers of fuel and dirt.

In a wonderful denouement, it’s going to eject these layers into house to kind a fantastic veil of sunshine, which can glow like a neon signal for hundreds of years earlier than fading.

The galaxy is studded with hundreds of those jewel-like memorials, often known as planetary nebulae. They’re the conventional finish stage for stars that vary from half the Solar’s mass as much as eight instances its mass. (Extra huge stars have a way more violent finish, an explosion referred to as a supernova.) Planetary nebulae are available a surprising number of shapes, as recommended by names just like the Southern Crab, the Cat’s Eye, and the Butterfly. However as lovely as they’re, they’ve additionally been a riddle to astronomers. How does a cosmic butterfly emerge from the seemingly featureless, spherical cocoon of a pink big star?

Observations and pc fashions at the moment are pointing to an evidence that might have appeared outlandish 30 years in the past: Most pink giants have a a lot smaller companion star hiding of their gravitational embrace. This second star shapes the transformation right into a planetary nebula, a lot as a potter shapes a vessel on a potter’s wheel.

NASA’s new James Webb Space Telescope has revealed extraordinary details in the Southern Ring Nebula, a planetary nebula that lies around 2,500-light-years away in the constellation Vela. On the left, a near-infrared image shows spectacular concentric shells of gas, which chronicle the history of the dying star’s outbursts. On the right, a mid-infrared image easily distinguishes the dying star at the nebula’s center (red) from its companion star (blue). All of the gas and dust in the nebula was expelled by the red star.
Enlarge / NASA’s new James Webb Area Telescope has revealed extraordinary particulars within the Southern Ring Nebula, a planetary nebula that lies round 2,500-light-years away within the constellation Vela. On the left, a near-infrared picture reveals spectacular concentric shells of fuel, which chronicle the historical past of the dying star’s outbursts. On the correct, a mid-infrared picture simply distinguishes the dying star on the nebula’s heart (pink) from its companion star (blue). The entire fuel and dirt within the nebula was expelled by the pink star.

The dominant principle of planetary nebula formation beforehand concerned solely a single star—the pink big itself. With solely a weak gravitational maintain on its outer layers, it sheds mass very quickly close to the tip of its life, shedding as a lot as 1 p.c per century. It additionally churns like a boiling pot of water beneath the floor, inflicting the outer layers to pulse out and in. Astronomers theorized that these pulsations produce shock waves that blast fuel and dirt into house, creating what’s referred to as a stellar wind. But it takes an excessive amount of power to expel this materials fully with out having it fall again into the star. It can’t be any mild zephyr, this wind; it must have the power of a rocket blast.

After the star’s outer layer has escaped, the a lot smaller internal layer collapses right into a white dwarf. This star, which is hotter and brighter than the pink big it got here from, illuminates and warms the escaped fuel, till the fuel begins glowing by itself—and we see a planetary nebula. The entire course of could be very quick by astronomical requirements however gradual by human requirements, usually taking centuries to millennia.

Till the Hubble Area Telescope launched in 1990, “we have been fairly certain we have been heading in the right direction” towards understanding the method, says Bruce Balick, an astronomer on the College of Washington. Then he and his colleague Adam Frank, of the College of Rochester in New York, have been at a convention in Austria and noticed Hubble’s first images of planetary nebulae. “We went out to get espresso, noticed the photographs, and we knew that the sport had modified,” Balick says.

Astronomers had assumed that pink giants have been spherically symmetrical, and a spherical star ought to produce a spherical planetary nebula. However that’s not what Hubble noticed—not even shut. “It grew to become apparent that many planetary nebulae have unique axisymmetric constructions,” says Joel Kastner, an astronomer on the Rochester Institute of Expertise. Hubble revealed incredible lobes, wings, and different constructions that weren’t spherical however have been symmetric across the nebula’s essential axis, as if turned on that potter’s wheel.

In early photos from ground-based observatories, the Southern Crab Nebula appeared to have four curved “legs” like a crab. But detailed images from the Hubble Space Telescope show that these legs are the sides of two bubbles that roughly form an hourglass shape. In the center of the bubbles are two jets of gas, with “knots” that may light up when they encounter the gas between the stars. The Southern Crab, located several thousand light-years from Earth in the constellation Centaurus, appears to have had two gas-releasing events. One around 5,500 years ago created the outer “hourglass,” and a similar event 2,300 years ago created the inner, much smaller one.

In early images from ground-based observatories, the Southern Crab Nebula appeared to have 4 curved “legs” like a crab. However detailed photographs from the Hubble Area Telescope present that these legs are the perimeters of two bubbles that roughly kind an hourglass form. Within the heart of the bubbles are two jets of fuel, with “knots” which will gentle up after they encounter the fuel between the celebs. The Southern Crab, situated a number of thousand light-years from Earth within the constellation Centaurus, seems to have had two gas-releasing occasions. One round 5,500 years in the past created the outer “hourglass,” and an identical occasion 2,300 years in the past created the internal, a lot smaller one.

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