Debris disk: Ring around star

Hi,
with this post I am answering to one comment posted about three weeks ago on Roche limit.

Could there be rings around sun?

Yes they are called Debris disks. Debris disk is created from nebula which is surrounding young star. This nebula is full of gas and dust. Either all this stuff is pushed away by radiation or planetesimals are created.

Planetesimals are huge rocks, (more than one kilometer across). They do not need Brownian motion anymore to grow because they have enough strong gravity to pull other rocks, and at some point they can be enough large to be planets.

When those planetesimals collide they left dust and rock behind them. This is what isHeic0821f.jpg called debris disk. It is not created by Roche limit as normal planetary ring is and I did not find anything about rings around star that are made by Roche but if I do I will definitely post it here.

This dust in debris disk is usually very small: 1-100 micrometers.
Our sun has this debris disk and you have probably heard about it, it is the Kuiper belt.

There is other example of debris disk and it is around very bright star called Fomalhaut. Ring Around a StarYou can see it on the right top. This star has debris disk which is moved by 1.4 billion miles (roughly 2.24 billion kilometers) to left. It is probably because of huge planet. The dark spot around star (pic. on the left and bot.) is just effect of blocking the light from Fomalhaut so we can see all the debris reflecting photons. This false-color composite image reveals the orbital motion of the planet Fomalhaut b.
Fomalhaut has at least one planet and this one is called Fomalhaut B. On wiki, I am pretty sure there is mistake in one sentence since they are saying that it is star.
You can easily find Fomalhaut on Celestia, I will write about that program probably next time.

Dragallur
PS: I lost.

Civilizations: Dyson´s sphere

Hi,
Again I will write about civilizations but this time only about Dyson´s spheres which I mentioned before as a thing which would be used by civilization of type II and type III.

View larger. | Artist's concept of a Dyson sphere via SentientDevelopments.comBecause there is high probability of all civilizations using energy, we assume that all “worlds” will need more and more energy as their population grows.
At one point there wont be enough energy on its home planet. They/we will need some source of energy which would be kind of permanent. Here comes this Dyson´s sphere because it is a sphere which surrounds home star and collects its energy.https://i2.wp.com/upload.wikimedia.org/wikipedia/commons/f/f7/Dyson_Ring.PNG

First there are smaller types of Dyson´s sphere like a Dyson´s ring. It is ring of objects sharing the same orbit and collecting energy of star. They would transfer the energy by wireless power transfer.
Expansion to ring is swarm which is lot of rings around star. BUT those ring´s orbit would intercept each other so it would be really difficult to avoid some crush.
To solve this you would have to have statellites instead of satellites. Those would be objects which would be stationary and they would not orbit the star. Those things would fight with gravity by large sail which would be pushed away from the star by solar wind. BUT this sail would have to be extremely light.. when I say extremely I mean very extremely because paper has 80g for squared meter and this sail would have to be about 0.7g for m^2. This would require ultra light nanotubes.
Last type is sphere which would collect almost all energy made by star. It would be extremely difficult to stabilize it and collect all the material.

https://i1.wp.com/i.qkme.me/3s64lw.jpgDragallur