How to make a large light source?

I am working on a project involving space and it requires a sun. So far I used the unity particle systems to make the sun and provide all the effects but now the challenge is to make the sun as the only light source without lighting itself anymore because i already have all the effects! I tried using point lights but that makes the moon shadow on planet rough like squares and is useless. Is there any way to make the entire sun sphere as a large light source something similar to a point light?

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