Possible Clues:

• Moon of Jupiter
• Nymph changed into Ursa Major
• Jupiter's second largest moon
• Second largest of Jupiter’s satellites
• Satellite still moving in (roughly) a circle
• Nymph who became Ursa Major
• Female reformed to bear ring - perhaps it's love
• A typical list of nymphs, including one favoured by Zeus
• She's found quickly in alphabetical list of stars
• Buzz is getting to moon