The Tranome Sar system could be visually seen from Space Station KR-3. In 2311, Elias Vaughn stood in front of a viewport on the space station and tested his memory, naming all the major stars he could see in Romulan space. (ST - The Lost Era novel: Serpents Among the Ruins)
Following the weakening of the Romulan Star Empire amid the Romulan supernova in 2387, the Klingon Empire invaded Romulan space. The Klingons took control of the Tranome Sar and Nequencia systems in 2389. (STO novel: The Needs of the Many, Appendix: The Path to 2409 section)
In 2391, Praetor Taris forced a retreat of Klingon forces at the nearby Zeta Pictoris but Tranome Sar and Nequencia were not recovered. (STO novel: The Needs of the Many, Appendix: The Path to 2409 section)
The conquest of Tranome Sar and Nequencia was covered in the course "History 101: Alpha Quadrant from 2380" at Starfleet Academy, and "The Lore of the Empire" at Klingon Academy from 2409 onwards. It was recorded on datachip "The Path to 2409: Volume 10, Chapter 2". (STO - Call to Arms missions: "History 101: Alpha Quadrant from 2380", "The Lore of the Empire")
- The sources listed here do not specify if the star had any planets.