Rising Stars are recognized for providing high-quality answers to other users. Rising Stars receive a certificate of achievement and are on the path to becoming Community Leaders.
Atlassian Answers is based on OSQA (http://www.osqa.net/). It is not based on Jira.
The customized OSQA used in Answers is released by Atlassian, check the post here. https://answers.atlassian.com/questions/35106/is-atlassian-answers-available-for-my-company-i-d-like-to-use-it-as-a-knowledge-base