Some misconceptions are cleared up.
The Ring Nebula apparently has been misnamed: It’s not a ring at all, but a football-shaped jelly doughnut. A group of scientists reported this conclusion in a statement Thursday following a first-ever video reconstruction of the interstellar body based on sloughs of images from the Hubble Space Telescope and ground-based observatories.
Scientists have known of the Ring Nebula, also known as Messier 57, for centuries. French astronomer Antoine Darquier de Pellepoix first spotted it in 1779, and German nobleman Count Friedrich von Hahn made repeated observations of it over several years leading up to 1800. Von Hahn recorded seeing changes in the cloud’s middle: He saw a faint star at the center in his first sightings, but no more central star in his latter sightings.
Scientists eventually concluded that this nebula has a hollow middle and ring-shaped—hence came its present-day moniker. But the latest analysis, led by Robert O’Dell, a physics and astronomy professor at Vanderbilt University in Nashville, arrived at a wholly other conclusion. The nebula’s center is quite full, O’Dell and his team state.
However, varying patterns of motion may cause the middle to look unlike the rest of the nebula from our vantage point, and hence some of the visual illusion. The entire cloud is expanding by more than 43,000 miles an hour, but the growth is even faster at the center than it is in the outer ring. Consequently, the middle is much lower-density than the rest of the nebula.
The Hubble images that O’Dell and his team used are the highest-precision views of the nebula taken yet. While earlier observations had identified the presence of gaseous material in the center, none had gathered all of the detail of this latest Hubble presentation, such as the star that is indeed at the center—though it is now dying. The nebula measures just one light-year across, so it’s compact enough that this one star’s end-of-life expansions and contractions could stand out prominently to observers here on Earth, even if those observers were using eighteenth-century telescopes.
In fact, this dying star is probably what brought the nebula into being in the first place. Scientists designate the Ring Nebula a “planetary nebula,” which means that it forms out of the gas and dust that emanates from a star that’s fading out. While this nebula’s star will continue to shine for a fairly long while by human time, scientists say that it is definitively on its way to white-dwarf status.
Amateur astronomers can check this cloud out for themselves. With a household telescope and a good knowledge of the constellations, one can catch sight of it within the constellation Lyra.