Spiders, Bubbles, and Neutrons

18 January 2022

Some interesting stories this past week. At https://phys.org/news/2022-01-light-year-wide-earth-source-nearby.html … which is indeed, a startling discovery. A 1000 light year wide void around the earth is the source of all nearby, young stars. The bubble has star formation ongoing,  a chain of events they say began 14 million years ago. That seems like a millisecond in the life of the universe. Is something missing? It seems there was as they say a powerful supernova caused the creation of what is otherwise called, a super bubble. I wonder. If supernova have an electro-magnetic origin rather than being simply the explosion and collapse of a star that has finished its life cycle, how would that reshape what they are saying. It seems a bit of modeling was involved in the hypothesis as the claims are based on a 3D simulation in space time. What was modelled? What was left out? We are told this is the first time scientists have been able to explain how all nearby stars formed in a layer. In the 3D model all young stars, and star forming regions within 500 light years of earth, sit on the surface of a giant bubble. Some 15 supernovae during millions of years have exploded in order to create the bubble. However, in their modeled calculation, the bubble is moving – at around four miles a second. Is it expanding one might ask? Of course, the research paper, and its arguments, are more complicated than that – see www.nature.com/articles/s41586-021-04286-5 

At https://phys.org/news/2022-01-cosmic-spider-source-powerful-gamma-rays.html …. what is described as a cosmic spider is found to be the source of powerful gamma rays. Astronomers have found a binary system in which they theorise one star in the process of transitioning into a white dwarf, orbiting a 'neutron' star that has evolved into a rapidly spinning pulsar. The pulsar itself is said to be the origin of the gamma rays. Such binary systems have been dubbed 'cosmic spiders'  because the pulsar is thought to 'eat' the outer parts of the companion star. No wonder school boys get excited by this sort of stuff.

At https://sciencex.com/news/2022-01-black-holes-weve-mysterious-birth.html … the curtains are being drawn back on black holes, we are assured. Astronomers have captured what they think are actual pictures of black holes – and they have measured gravitational waves [as ripples in space time]. They are proceeding on the basis they are right – and have interpreted the data correctly. Observational and theoretical thinking says most black holes form when the centre of a massive star collapses at the end of its life. This involves nuclear reactions within the star core causing it to collapse inwards, rather than outwards – under gravity. This accounts for the material condensing down to extraordinary densities, the core myth at the heart of black hole theory. Sometimes the collapse comes to a stop when the core condenses, at a phase rich in particles known as neutrons – leading to a reduced explosion of material, that destroys the star = a supernova. Left behind is a neutron star. However, in situations when the collapse does not come to a stop it simply continues to break down into an ever more solid and dense object, a gravitational singularity [or black hole]. However, the exact process is still elusive, we are told. The new study is an attempt to address the process – another theory on the formation of black holes. It involves Wolf Rayet stars rather than run of the mill supernova explosions – and something else. No glow is left behind by such star explosions, as one might suspect during the collapse of a star core [a nuclear glow one might say]. They simply disappeared from view. One might ask – did they really explode? No glow means something else was going on but the assumption in the research paper is they did explode. For further info see https://doi.org/10.1038/s41586-021-04155-1 for a fascinating read.

Meanwhile, at https://phys.org/news/2022-01-astronomers-massive-black-hole-heart.html … astronomers confront a massive black hole at the heart of the Milky Way, Sagittarius A [aims rather than discoveries].

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