Step 1 - Create a dark background, and if it's not black, use a really dark colour that compliments the colour of the star.

Step 2 - Create a circle using blend mode 'Add' with whatever colour that contrasts with the colour of the sun, ignoring the Brightness value, and by setting Alpha/opacity to 20 or lower.

Step 3 - Using dot tool, make lots of small dots all over the circle, using the same blend mode and brush settings, and also the same colour as step 2.

Step 4 - Set blur to around 30 - 50, and make sure that alpha is still low. Switch to a colour that is the "weaker" colour of what you chose to do the star. So for purple, choose blue, for pink, choose purple, etc. Click multiple times, depending on your alpha, to get a beautiful glow coming from the star.

Step 5(optional) - This step is only for if you used a coloured dark background instead of black, but switch the blend mode to 'Subtract', decrease the blur to around 7 - 17, and colour around the star. It should enhance the glow.