At https://phys.org/news/2023-08-outskirts-supermassive-black-hole-accretion.html … the centre of galaxies are a turbulent environment. It is thought this is because they harbour an actively feeding supermassive black hole. In addition, orbiting these incomprehensibly dense objects are swirling accretion disks of gas and dust. These feed the invisible black hole, it is thought. Or so the theory goes. As such, they emit copious amounts of energy in the electro-magnetic spectrum. This includes gamma rays – and X-rays.
Most accretion disks are impossible to directly image. Instead, astronomers and cosmologists, use the spectra of light emitted from within the disk to characterise size and behaviour. In other words – a lot of assumptions are involved. Indeed, the links begins with an ‘artists impression’ of a black hole and its accretion disk. Never the less, an interesting read. Well worth taking a look.
At https://tallbloke.wordpress.com/2023/08/18/the-clouds-on-neptune-perform-a-surprise-disappearing-act-linked-to-the-solar-cycle/ … a study claims clouds disappear on Neptune in a process linked to the solar cycle. The planet is a long way out but is firmly within the solar system and therefore subject to the solar wind, energy produced by the Sun. A Uniersity of California [Berkeley] team discovered the absence of clouds normally seen at Neptune’s mid latitudes. They started to fade back in 2019. Cloud activity dropped within a few months. Images taken in 2023 show the clouds have not returned to their previous level. Data has revealed an intriguing pattern between Neptune’s cloud cover and the solar cycle. The 11 year cycle. It may be linked to the flip of the Sun’s magnetic field at mid point in the solar cycle. This causes flucuations in dolar radiation levels. When the Sun emits more intense ultra violet light more clouds appear on Neptune – around 2 years afterwards.
See also https://arxiv.org/pdf/2307.08157.pdf … arXiv is a pre-print server and it may be hat alterations are found on publicaion. Presumably leaving the main point intact. It takes 2 years they say, for Neptune’s clouds to fully form once the solar cycle reaches its peak, The present solar cycle will peak in 2024 – s we should see another 2 years befoe Neptune’s mid latitudes are once again cloudy. Assuming the research paper is correct.