Astro Blog

By Science Advisor, AAAS.  Excerpt: ...The rate of cosmic expansion, known as the Hubble constant, is so important for cosmologists that the disagreement among researchers over its value has its own name: the Hubble tension. Astronomers measure it one way, using stars or supernovae with predictable brightness. Cosmologists have another way, studying ripples in the echo of the Big Bang and winding the clock forward to today. The two techniques have become increasingly precise, but they steadfastly disagree with each other. A third method is needed to  break the deadlock  . That may come through the magic of gravitational lensing, which can cause a supernova—a star exploding at the end of its life—to appear to explode again and again. If a supernova is situated behind a large mass, such as a galaxy or cluster of galaxies, then as its light passes by the mass, its gravity bends the light along different paths, producing multiple images that show the explosion at different ti...

By Daniel Clery , Science.  Excerpt: It’s as if the baby universe had caught a case of measles. Since NASA’s JWST observatory began peering into the distant universe in 2022, it has discovered a rash of “little red dots”—hundreds of them, shining within the first billion years of the 13.8-billion-year-old universe, so small and red that they defied conventional explanation. Only in the past few months has a picture begun to emerge. The little red dots, astronomers say, may be an entirely new type of object: a colossal ball of bright, hot gas, larger than the Solar System, powered not by nuclear fusion, but by a black hole. ...JWST couldn’t resolve the dots into a recognizable shape, which meant they must have been tiny—less than 2% of the diameter of the Milky Way....  Full article at https://www.science.org/content/article/early-universe-s-little-red-dots-may-be-black-hole-stars . 

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...