This is a fictonal exoplanet that orbits Canopus (the link goes to the wikipedia page) Note: I do not believe that any planets have been discovered orbiting Canopus.
  It has a very high gravity because of its large mass, half the size of Canopus. It has many small frozen islands dotted around its large lava ocean. Below the surface there is an abundance of diamond, because of the heat and pressure of the planet[]. There is also a lot of quartz as it is created inside of igneous rock, such as obsidian, as magma cools[].
  It has 3 rings and 2 moons. The rings are made up of bits of ice and stone. The moons were likely formed inside the rings, as they are both made of ice and rocks.

Made up story
The planet was dicovered when Voyager 1 sent out a strange signal, so the NASA scientists turned on the cameras and saw that Voyager was orbiting an undiscovered planet. Unfortunately, because of the planet's strong gravity, the space probe quickly began to lose orbit and plummet to the surface of the planet before NASA could get much information about it.

*Map size: 550x550 (circular)
*Version:1.17