Gas Vents periodically emit gas from the planet or moon. They appear quite similar to geysers, but the gas emissions are more like a cloud rather than a geyser eruption.
The Codex has one category for gas vents.
These are some known locations of gas vents.
|HIP 41191||2C||Long: 71.2442 / Lat: 78.6442|
|Frey||4 B||Long: -70.9406 / Lat: 154.4929|