Country Star Jason Aldean -- Hot and Heavy With 'A.I.' Chick ... Who's NOT His Wife

Country music superstar Jason Aldean got up close and personal with a former "A.I" contestant ... right in the open at a very public bar on the Sunset Strip. There's just one problem ... he's married to another woman.

TMZ obtained photos of Jason and Season 11 "A.I" contender Brittany Kerr taken on the crowded bar patio area at The Den on Wednesday night -- frequented by locals and tourists always on the hunt for celebrities.

In the photos Aldean and Kerr get very flirty ... hugging, touching each other and at one point it appears Aldean goes in for a kiss.

Aldean --- who performed this weekend in So Cal -- eventually left the bar in a cab without Brittany.

Here's the rub, Aldean is married to his high school sweetheart, Jessica Ussery, who he tied the knot with back in 2001 and they have 2 kids together.