Create a sunlight: how to make a gradient from white to transparent?

is there a way to create a transparency on a sphere like the sunlight: very opaque at the center, and more transparent when the pixels are closer to the bounds ?

If I create a gradient with Gimp, from white to transparent, is there a way to implement it?

I need to use it in a game for Android, so I cannot really use the sun from Blender.


Anybody would know how to do this?

the black and white gradient can be used as the Fac input on a shader to give you the faded look.

Thanks, could you give me some tips to achieve this? In compositing mode, I add a mix node, and then I don’t how to go on with this?