OP,
Per the Star Alliance website.
You both can use the Avianca lounges in BOG. You're Star Gold so you've got access on status with one guest.
The only issue is if you're leaving on a non Star Alliance airline. Avianca won't let you in even if you came in on a Star Alliance airline.
Last edited by ttuna3; Apr 13, 2017 at 12:31 pm
Reason: Added Reference