Question: What do you call the dust around supermassive black holes?

Bella Boulderstone answered on 19 Jun 2019:

The dust around supermassive black holes acts as a funnel for stuff from the galaxy to get to the accretion disc (which then gets stuff into the black hole). The dust forms a shape a bit like a donut which is called a ‘torus’, except if the donut was made of dust, wasn’t that solid and went around the black hole.

The dust itself closest in to the accretion disc is made of tiny grains of graphite (just like in your pencil) before it turns from a solid directly into a gas to join the stuff in the accretion disc. Other types of dust hang out in the donut, but the closer in you get, the hotter it gets and so they turn into gasses before the graphite bits. Those types of dust are called silicates, a little bit like what sand is made up of.

Great question!