Pentarus II was the M-class second planet in the Pentarus system.

Pentarus II was searched by miners as a possible crash site when the shuttle Nenebek, carrying Jean-Luc Picard and Wesley Crusher, was lost in 2367. (TNG: "Final Mission")

This planet was only mentioned in dialogue.
"pen-TAR-us" was the pronunciation for Pentarus from the script pronunciation guide. [1]
According to Star Trek: Star Charts ("United Federation of Planets I"), in 2378, Pentarus II was listed as a Federation member.