What do you call the stick on table of Tony Stark in movie iron man 3?

You're likely referring to the arc reactor that Tony Stark wears around his chest in the Iron Man movies. In Iron Man 3, it's seen as a prototype on his desk.

However, there isn't a specific name for the stick-like object on Tony's desk in Iron Man 3. It's a prop meant to represent a prototype arc reactor that Tony is working on.

The arc reactor is a fictional energy source that powers the Iron Man suit, and it was developed by Tony Stark as a replacement for the shrapnel lodged in his chest after his near-death experience in the first Iron Man movie.