Is my play optimal on the turn.. why or why not? Villains unknown, but are aggressive and like to make moves.

Party Poker No-Limit Hold'em, $ Hero (6 max, 5 handed) FTR converter on zerodivide.cx

Hero ($194)
UTG ($859.70)
MP ($342.99)
Button ($192.25)
SB ($444.50)

Preflop: Hero is BB with 5, J. SB posts a blind of $2.
UTG calls $4, MP calls $4, 1 fold, SB (poster) completes, Hero checks.

Flop: ($16) 9, J, 2 (4 players)
SB checks, Hero bets $13, UTG calls $13, MP calls $13, SB folds.

Turn: ($55) 2 (3 players)
Hero bets $40, UTG folds, MP folds.

Final Pot: $95

Results in white below:
No showdown. Hero wins $95.