The universe is like a safe to which there is a combination. But the combination is locked up in the safe.

— Peter De Vries

Astronomy

Cicadas Are Basically Safe for You—And Your Dog—to Eat. Here’s What to Know

Scientific American.com - Fri, 04/26/2024 - 7:00am

Here’s what a chef, a vet and two anthropologists have to say about eating periodical cicadas

Categories: Astronomy

The Threat of a Solar Superstorm Is Growing—And We’re Not Ready

Scientific American.com - Fri, 04/26/2024 - 6:45am

Someday an unlucky outburst from our sun could strike Earth and fry most of our electronics—and we’ve already had some too-close-for-comfort near misses

Categories: Astronomy

Black Holes Can Halt Star Formation in Massive Galaxies

Universe Today - Fri, 04/26/2024 - 6:14am

It’s difficult to actually visualise a universe that is changing. Things tend to happen at snails pace albeit with the odd exception. Take the formation of galaxies growing in the early universe. Their immense gravitational field would suck in dust and gas from the local vicinity creating vast collections of stars. In the very centre of these young galaxies, supermassive blackholes would reside turning the galaxy into powerful quasars. A recent survey by the James Webb Space Telescope (JWST) reveals that black holes can create a powerful solar wind that can remove gas from galaxies faster than they can form into stars, shutting off the creation of new stars.

To remove the confusion and mystique around black holes, they are the corpse of massive stars. When supermassive stars collapse at the end of their lives their core turns into a point source that is so incredibly dense that even light, travelling at 300,000 kilometres per second, is unable to escape. It’s believed that many galaxies have supermassive black holes at their core. 

Swift scene change to the earlier part of the life of a star. Fusion in the core generates incredible amounts of energy as new elements are synthesised. Along with new elements, heat and light, a powerful outflow of electrically charged particles rushes away and permeates the surrounding space. Here in our Solar System, charged particles rush Earthward and on arrival we experience the glorious display of the northern lights. 

Visualization of the solar wind encountering Earth’s magnetic “defenses” known as the magnetosphere. Clouds of southward-pointing plasma are able to peel back layers of the Sun-facing bubble and stack them into layers on the planet’s nightside (center, right). The layers can be squeezed tightly enough to reconnect and deliver solar electrons (yellow sparkles) directly into the upper atmosphere to create the aurora. Credit: JPL

A team of astronomers using the JWST have found that, over 90 percent of the wind that flows through a distant galaxy is made of neutral gas and to date, has been invisible. Until recently it was only possible to detect ionised gas – gas which carries an electric charge – which is warm. The neutral gas in the study revealed that neutral gas was cold but JWST was able to detect it. 

The powerful outflow of neutral gas is thought to come from the supermassive blackholes at the core of some galaxies at the edge of the Universe. The team, led by Dr Rebecca Davies from Swinburne University first identified that black hole driven outflow in a distant galaxy over 10 billion light years away. The paper published in Nature explains how ‘The outflow is removing gas faster than gas is being converted into stars, indicating that the outflow is likely to have a very significant impact on the evolution of the galaxy.’

With a lack of gas and dust, star formation will slow and eventually stop. Just like a forest that always has new trees growing to replace old, dying trees, so galaxies usually have star formation to replace dying stars. Ultimately the forest, and a galaxy will be unable to grow and develop and eventually become static and slowly die with the final stars blinking out. 

This is a JWST view of the Crab Nebula. Like other supernovae, a star exploded to create this scene.The result is a rapidly spinning neutron star (a pulsar) at its heart, surrounded by material rushing out from the site of the explosion. SN 2022jli could have either a neutron star or a black hole orbiting with a companion star.

The team found that the active galactic nuclei with supermassive black holes are the driving force behind this outflow of gas. Those with the most massive black holes can even strip the host galaxy of all the star forming gasses playing a major role in the evolution of the galaxy. 

Source : New JWST observations reveal black holes rapidly shut off star formation in massive galaxies

The post Black Holes Can Halt Star Formation in Massive Galaxies appeared first on Universe Today.

Categories: Astronomy

A Long-Awaited Climate Experiment Is Poised to Launch in the Amazon. What Will It Find?

Scientific American.com - Fri, 04/26/2024 - 6:00am

Ahead of a project to spray carbon dioxide into jungle plots, researchers contemplate what its results might signal about the forest’s future.

Categories: Astronomy

Deepfake politicians may have a big influence on India’s elections

New Scientist Space - Cosmology - Fri, 04/26/2024 - 4:00am
Political campaigns are deploying AI-generated deepfake versions of politicians to reach hundreds of millions of eligible voters in India’s 2024 election – the world’s largest ever
Categories: Astronomy

Earth from Space: Seychelles

ESO Top News - Fri, 04/26/2024 - 4:00am
Image: The Copernicus Sentinel-2 mission takes us over part of the Seychelles, an island republic in the western Indian Ocean.
Categories: Astronomy