[ad_1]
A team of scientists including Princeton’s Guðmundur Stefánsson have studied the mysterious Blue Ring Nebula, which is made up of expanding (blue) hydrogen gas expanding from a central star, which is the remnant core of a stellar fusion. The red filaments are shock wave filaments from the fusion event. Credit: NASA / JPL-Caltech / M. Seibert (Carnegie Institution for Science) / K. Hoadley (Caltech) / GALEX Team
Scientists have discovered a rare object called the Blue Ring Nebula, a hydrogen gas ring with a star in the center. The properties of this system suggest that it is the remnant of two stars meeting their ultimate end: an inward orbital dance that led to the merger of the two stars. The result offers a new window into the fate of many closely orbiting binary star systems.
In 2004, scientists with NASAGalaxy Evolution Explorer spotted an object different from all the ones they had seen in ours Milky Way Galaxy: A large, faint drop of gas that appeared to have a star in the center. In the ultraviolet wavelengths used by the satellite, the blob appeared blue – although it doesn’t actually emit light visible to the human eye – and careful observations identified two thick rings inside it, so the team dubbed it the Blue Ring Nebula. Over the next 16 years, they studied it with more ground-based and space-based telescopes, but the more they learned, the more mysterious it seemed.
A team of scientists included Princeton UniversityGuðmundur Stefánsson, Henry Norris Russell Postdoctoral Fellow in Astrophysical Sciences, combined terrestrial observations with detailed theoretical models to investigate the properties of the object. The paper describing their findings appears in the November 19, 2020 issue of Nature.
“We were in the middle of observing one night, with a new spectrograph we had recently built, when we received a message from our colleagues about a particular object made up of a hazy gas rapidly expanding away from a central star,” he said. said Stefánsson. “How was it formed? What are the properties of the central star? We were immediately thrilled to help solve the mystery! “
Most of the stars in the Milky Way are found in binary systems – pairs of stars orbiting one another. If they are close enough to each other, such systems can meet their end in a stellar merger event: as the stars evolve, they expand, and if they are close enough to each other, one of the stars can engulf its orbiting companion, causing the stars to spiral. of the companion until the two stars collide. When the companion loses its orbital energy, it can eject material at high speed.
Could this explain the mysterious Blue Ring Nebula?
Further evidence to support this hypothesis came from observations with two different spectrographs on large ground-based telescopes: the HIRES optical spectrograph on the 10-meter Keck telescope atop Maunakea in Hawaii, and the near-infrared habitable zone Planet Finder on the 10-meter Hobby-Eberly telescope at the McDonald Observatory in Texas, a new near-infrared spectrograph that Stefánsson helped design, build and commission to detect planets around nearby stars.
The Blue Ring Nebula is made up of two expanding debris cones. The base of a cone is moving towards the Earth. Both bases are outlined in magenta, revealing the shockwaves created as debris runs through space. The blue represents the material behind the shock wave and is only visible where the cones overlap. Credit: NASA /JPL-Caltech / R. Male
“The spectroscopic observations were instrumental in allowing us to further understand the object, from which we see that the central star is inflated, and we see signs of accretion probably from a surrounding debris disk,” said Stefánsson.
Indeed, the spectroscopic data coupled with theoretical modeling shows that the Blue Ring Nebula is consistent with the image of a merging binary star system, suggesting that the inward spiraling companion was likely a low-mass star. “said Keri Hoadley, a postdoctoral fellow at Caltech and lead author of the paper.
Although the relics of some of these binary fusion events have been observed previously, all of these objects have been enveloped in opaque dust and clouds, obstructing the view of the properties of the central stellar remnant. The Blue Ring Nebula is the only object that allows an unobstructed view of the central stellar remnant, offering a clear window into its properties and providing clues to the merging process.
“The Blue Ring Nebula is rare,” Hoadley said. “As such, it’s really exciting that we were able to find it and we’re excited about the possibility of finding more similar items in the future. If so, this would allow us to gain more insight into the remains of stellar mergers and the processes that govern them. “
Read Baffling 16-Year Cosmic Mystery Solved, Revealing the Missing Stellar Link for more information on this study.
Reference: “A blue ring nebula from a stellar merger several thousand years ago” by Keri Hoadley, D. Christopher Martin, Brian D. Metzger, Mark Seibert, Andrew McWilliam, Ken J. Shen, James D. Neill, Gudmundur Stefansson , Andrew Monson and Bradley E. Schaefer, November 18, 2020, Nature.
DOI: 10.1038 / s41586-020-2893-5
[ad_2]
Source link
