Webb telescope reveals a luminous stellar crime scene
2,500 years ago, one of the most beautiful features of space emerged: the Southern Ring Nebula. The nebula was vividly imaged earlier this year by the Webb Space Telescope, and astronomers now think they know exactly how a star’s violent outburst occurred and left the elegant nebula in its wake.
The star that bore the nebula was about three times the size of the Sun and 500 million years old. That’s pretty young, in stellar terms; our sun is about 4.6 billion years old and should live for another 5 billion.
About 2500 years ago, Confucius and the Buddha were still alive. The Peloponnesian Wars were about to begin. And sometime in those intervening years, a star 2,000 light-years away died, spewing gas out from a newly formed white dwarf.
The star of the Southern Ring Nebula is not yet dead, but the expulsion of gas is a major turning point in the star’s lifespan. White dwarfs are the stellar endgame; they form when stars have exhausted their nuclear energy and begin their slow cooling.
Thanks to images from the Webb Space Telescope and smart calculations and mathematical modelling by the research teamcan now the moments leading up to the stellar light show of the Southern Ring Nebula be examined in detail.
Different Webb filters mark different ones aspects of one light source, that’s why some parts of the nebula may look like pearly or translucent red, while others appear blue or orange, depending on the imageage. The Web image processors choose it highlight different aspects of objects in order to show different elements: hot gas, for exampleor star factories within larger systems.
A team of 70 astronomers worked together to determine that as many as five stars (only two of which are now visible) may have been involved in the star’s demise. Their investigation into the star’s death is published today in Natural Astronomy.
“We were surprised to find evidence of two or three companion stars that likely hastened his death, as well as another ‘innocent bystander’ star that got caught up in the interaction,” said Orsola De Marco, an astronomer at Macquarie University. and the study leader. lead author, at a university release.
The nebula origin team’s play-by-play was possible thanks to very precise measurements of the most brilliant star (the star among stars, if you will) in the Webb imagician. Webb data allowed the researchers to accurately measure the mass and how far along in its own life it iswhich in turn allowed them to deduce the mass of the central faint star before it ejected its material and created the colorful shape mist.
Webb imaged the Southern Ring with two instruments, NIRcam and MIRI. The Webb images were supplemented by data from the European Southern Observatory’s Very Large Telescope, the San Pedro de Mártir telescope, and NASA’s Gaia and Hubble space telescopes.
Only two of the stars believed to be involved in this cosmic rager are visible in Webbs representative color photograph of the nebula, taken with NIRcam. The bright star at the center of the nebula is a partner of the one that spewed out so much material that it became a white dwarf. That shriveled (and exhausted) star sits faintly along the 8-hour diffraction peak of the bright central star in the image above.
The astronomers believe that at least one star interacted with the fainter star (star 1 in the illustrated timeline below) as the latter swelled and prepared to expel its gas and become a white dwarf.
According to the team, that mysterious star (Star 3) spewed out jets of material as it interacted with the dying star, covering the faint star in dust before merging with the dwarf. Star 2 in the image is now the bright spot at the center of the nebula – a relatively steadfast character given the lack of explosive activity or gaseous emissions.
Another star (or “party-goer,” in the The analogy of the Space Telescope Science Institute of an out-of-control astrophysical party) kicked up the gas and dust released by its predecessor, creating undulating ripples in the material. Then another star (star 5 in the panels above) circled the light show, producing the ring system that circled the nebula.
Think of the white dwarf near the nebula’s core as the party host who went on a rampage and passed out long before the party ended, the researchers say. But the star gave everyone a great time while it was ready, and the party lived on thanks to him.
“We think all that gas and dust that we see floating around must have come from that one star, but it was thrown in very specific directions by the companion stars,” said Joel Kastner, an astrophysicist at the Rochester Institute of Technology. in a StScI release.
The researchers believe the same methods that revealed the specifics of the birth of the Southern Ring Nebula could help unravel the births of other nebulae, as well as the astrophysical forces at work in the interactions of stars.
The images revealing this interstellar scene were published in June; only now have researchers had time to sift through the data and present their interpretation of it.
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