From the United Airline web site:

Star Alliance lounges
When traveling internationally on any Star Alliance member,
simply present your same-day international ticket and your
Premier Executive card, and you may relax in the following
lounges:

United's Red Carpet Clubrooms
Air Canada's Maple Leaf Lounges
Air New Zealand's Koru Club Lounges
Ansett Australia's Golden Wing Club Lounges
Lufthansa's Frequent Traveller or Business Lounges
SAS' Business Class Lounges
THAI's Royal Orchid Lounges
VARIG's Business Class Lounges

Look for the "Star Gold" sign outside eligible lounges.