Eridani D was a planet with at least seven moons.

On Michael Burnham's tenth birthday, in 2236, her foster mother Amanda Grayson traveled with her on a shuttle to this planet's system. (DIS: "Lethe")

"Eridani" generally refers to stars in the constellation Eridanus, which is also home to 40 Eridani A, the presumed location of Vulcan.
According to the revised edition of the Stellar Cartography: The Starfleet Reference Library ("History of the United Federation of Planets"), Eridani was a star system near the Vulcan system.
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