Astro Blog

By Steve Schulze et al, Nature.  Abstract: Stars are initially powered by the fusion of hydrogen to helium. These ashes serve as fuel in a series of stages 1 , 2 , 3 , transforming massive stars into a structure of shells. These are composed of natal hydrogen on the outside and consecutively heavier compositions inside, predicted to be dominated by He, C/O, O/Ne/Mg and O/Si/S (refs.  4 , 5 ). Silicon and sulfur are fused into iron, leading to the collapse of the core and either a supernova explosion or the formation of a black hole 6 , 7 , 8 , 9 . ...Here we report the discovery of the supernova (SN) 2021yfj resulting from a star stripped to its O/Si/S-rich layer. We directly observe a thick, massive Si/S-rich shell, expelled by the progenitor shortly before the supernova explosion.... [From ScienceAdvisor: Researchers spotted the consequential supernova, called SN 2021yfj, from California’s Zwicky Transient Facility, .... They found that the exploded star was about 60 times the ...

By Daniel Clery , Science.  Excerpt: Staring deep into space and far back in time, a team of astronomers may have spotted a galaxy full of stars made from only the primordial gas created in the Big Bang. Such “population III stars” would have formed from hydrogen and helium and nothing else, and researchers have been searching for them for decades.... If confirmed, the discovery, made with NASA’s JWST space observatory, opens a window on the starting point of the chemical enrichment of the universe, in which the heavier elements needed to make planets and life began to be forged in stellar explosions. ...The nature of population III stars remains uncertain. Most theorists think they were huge, with masses up to 1000 times that of the Sun, 10 times larger than any star around today. ...The gigantic stars that resulted would also burn hot and fast, ending in a supernova explosion after just a few million years. That brief first flash of population III stars is hard for astronomers to...

By Hannah Richter , Science.  Excerpt: “Dust is the building block of the universe,” says Melissa Shahbandeh, an astrophysicist at the Space Telescope Science Institute (STScI). Over millions of years, specks of cosmic dust and gas clump together to form large, dense clouds from which planets and stars are born. But the dust’s own origins have been mysterious. Now, in data from NASA’s JWST space observatory, Shahbandeh and her colleagues  have found a source for the dust that filled the early universe : giant stellar explosions called interacting supernovae, whose intense shockwaves can blast out dusty plumes that accumulated in the supernovae’s surroundings. These results, presented last week at the meeting of the American Astronomical Society and submitted to The Astrophysical Journal are “impressive,” says Lifan Wang, an astrophysicist at Texas A&M University who was not involved in the work. ...The findings...deepen understanding of where Earth and everything...

https://www.science.org/content/article/stars-may-form-10-times-faster-thought Ling Xin, Science Magazine.  Excerpt: Astronomers have long thought it takes millions of years for the seeds of stars like the Sun to come together. Clouds of mostly hydrogen gas coalesce under gravity into prestellar cores dense enough to collapse and spark nuclear fusion, while magnetic forces hold matter in place and slow down the process. But observations using the world’s largest radio telescope are casting doubt on this long gestational period. Researchers have zoomed in on a prestellar core in a giant gas cloud—a nursery for hundreds of baby stars—and found the tiny embryo may be forming 10 times faster than thought, thanks to weak magnetic fields. “If this is proven to be the case in other gas clouds, it will be revolutionary for the star formation community,” says Paola Caselli from the Max Planck Institute for Extraterrestrial Physics, who was not involved with the research.…