Why is there a star next to an email

There is a star icon next to email and number and I do not know why. It is not always there either. It disappears from time to time. I do have a couple of iCloud acccpubts syncing. That really should not matter however. I own an Apple iPhone 6s. My email is an original @me.com and a @icloud.com account that are merging in the cloud. The contact is in both the @me.com and the @icloud.com with the same information however I do have additional information in one email account (the @icloud account) however that addition information is NOT the one that is showing up with stars next to it from time to time. I find it quite odd. Any one out there seen this?