That looks like a deciduous shrub not a tree. It appears to have been pruned then the new growth sprouted out like stars to give it an unusual shape. If you send an image of the plant with foliage I would be better to confirm my guess but right now without leaves it looks like it could be a deciduous Exbury Azalea. This means it is the type of azalea that drops all of it's foliage during winter. If so you will soon see fragrant star like blooms on the woody frame of your shrub. Mystery plants are one of the gifts of the garden. Let us know how it blooms out. Keep growing, Marianne Binetti