I run into this video today and I’m really curious about how to make the sun of the first 30 second.
?v=J7aXFXKmhJY
Either you use a combination between particles and material effects, or just use materials for that.
e.g just create a plane mesh with 2 different material slots (the inner and outer part)
-inner part -> use a mask to add a white and yellow colour + also add a value to the emissive slot
-outer part -> add a red colour + emissive and let a mask/alpha channel rotate/move a little bit 
Thank you, , actually I found something similar in the marketplace, but your hint is very helpful.
And I have also learned a lot from your youtube videos, BTW. Good Job!