It is possible to mask a Image Texture with Emission? It is possible to mask a Image Texture with Emission on Blender, like adding soft borders or something and being able to control them, without having the need or external softwares?

As you can see, i have an image on my Render (The Sun, middle one), and i need to control the borders since are too hard and i do need a mask.
Set up the nodes as pictured below to achieve it. Just use a Gradient Texture as a mask. Set its type to Quadratic Sphere.