Hi.
Your star can be a Graphic or MovieClip in which you have a timeline animation with keyframes at the following times:
0s -> star alpha is 100%;
1s -> star alpha is 0%;
2s -> star alpha is 0%;
3s -> star alpha is 100%;
4s -> star alpha is 100%;
Then you right-click between the keyframes and choose a tween type of your choice.
After setting the star animation, you go to the main timeline, create as many stars as you want, randomizing their size, position, and alpha.
Finally you distribute them to different layers and set each one to start and end at different keyframes.
Hopefully it will give you the desired effect.
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