Particular is probably your best bet unless you can afford to purchase a separate app like Particle Illusion. Particular can seem pretty daunting, but only because there are so many controls, many of which can be ignored in your case. Here’s a few settings that will push you in the right direction, but I don’t have AE open so some of these points are from memory:
1. Use an expression to tie the Particular emitter’s position to the position of a star layer created in AE or Illustrator, etc. Place the particular layer behind the star layer so that any emitted particles come from behind it.
2. Focus on just a few particular settings at first, such as particle type, number of particles, velocity and lifespan:
– For particle type, use star or something other than the default. Apply the glow effect to your particular layer to give them that sparkly look.
– For # of particles, try a high value at first just so you can see what you’re doing, maybe 1,000.
– For lifespan, set this to something like 1 second, again just so you can see the effect clearly and adjust it later. This setting will cause the particles to “die” 1 second after they are emitted. You will later need to adjust this to taste.
– Velocity controls how far from their origin point particles will shoot over time. Since you want the particles to leave a trail behind the star, the velocity should be set quite low so they aren’t shooting all over the place.
Once that all works out roughly to your liking, start playing with things like the color and opacity. Particular has some really cool “color over life” and “opacity over life” settings that allow you to set a color when they are born, and the color they become as they get older. To use these tools you simply draw a curve in the red box they provide that defines when the color/opacity should be changed. For opacity, a straight line from the upper left to lower right of the box will cause them to fade evenly over time. Do this with the color over life as well, which will cause them to change color over time (giving a nice rainbow cheese effect!) and fade out as they die, so they don’t just pop off of the screen.
From there, animating your star should give you a rough approximation of what you’re looking for. If any of this doesn’t make sense, or you get hung up on anything, post here and I’ll try to help further.
Good luck!