Are cast-animations on stealthed allies visible to enemies?

I recently played as Sona together with Twitch on bottom lane and that question came up:

If my Twitch ally is stealthed and I cast one of my abilities which affects him, can the enemy team see where the animation goes and do I give his position away to our enemies?

Solution 1:

Yes, enemy team in range see the graphical effect of Sona heal ability, even when it affects invisible allies.

Solution 2:

As Drake has said above, the graphical effect can still be seen by the opponent if Sona cast a heal on an invisible ally.

This is mainly because when Sona heals, her animation shows a green energy going towards the ally. However some champion's heals don't have targetable animation(such as Alistars heal) and will not reveal the location of an invisible ally.