NASA’s Butterfly Nebula Shot Foreshadows Our Sun Burning Out In A Blaze Of Glory
New research indicates that something is awry within the Butterfly Nebula, also known as NGC 6302. A team of astronomers at the University of Washington found "dramatic changes in the material within the wings," after comparing two pictures captured by NASA's Hubble Space Telescope in 2009 and 2020. The team shared their findings last week at the 241st meeting of the American Astronomical Society in Seattle.
According to the research, powerful winds are driving complex alterations of material within the nebula's wings. The astronomers said they want to explore how such activity is possible from what should be a "sputtering, largely moribund star with no remaining fuel."
Yellow dwarf stars like our own Sun can become red giant stars once they burn through their stock of hydrogen and instead begin burning helium. The nebulae form when a red giant star runs out of this helium fuel and sheds its outer shell. What remains is a near Earth-sized white dwarf star at the center as the shell it shed drifts into surrounding space.
"The Butterfly Nebula is extreme for the mass, speed, and complexity of its ejections from its central star, whose temperature is more than 200 times hotter than the sun yet is just slightly larger than Earth," remarked team leader Bruce Balick, a University of Washington professor emeritus of astronomy. "I've been comparing Hubble images for years and I've never seen anything quite like it."
The team of astronomers compared two high-quality images taken by NASA's Hubble telescope captured 11 years apart in order to outline the speeds and growth patterns of features within the nebula's wings. The majority of the analysis was gathered by Lars Borchert, a graduate student at Aarhus University in Denmark who joined the study as a University of Washington undergraduate student.
Borchert's research showed that about half a dozen "jets", beginning about 2,300 years ago and ending 900 years ago, were pushing material out in a "series of asymmetrical outflows." While material closer to the central star is moving slowly, material in the outer portions of the nebula is moving at a speed around a tenth faster, or about 500 miles per second. As the paths of the jets cross one another, they form "messy" structures and growth patterns within the wing structures.
According to Balick, the nebula's multi-polar and quickly changing interior structure is not easily explained using existing models of how planetary nebula form and evolve. One of the possibilities is that the center of the nebula, which is hidden by dust and debris, may have merged with a companion star, in turn "creating complex magnetic fields and generating the jets."
"At this point, these are all just hypotheses," explained Balick. "What this shows us is that we don't fully understand the full range of shaping processes at work when planetary nebulae form. The next step is to image the nebular center using the James Webb Space Telescope, since infrared light from the star can penetrate through the dust."
The new research from the University of Washington helps to show how the materials for the star systems of tomorrow will evolve, as well as how the "building blocks of our own oasis were produced and gathered billions of years ago."
Balick added, "It's a creation story that is happening over and over again in our universe. The shaping processes provide key insight into the history and impacts of the stellar activity."