Orbital Evidence for the Formation of GQ Lup B through Cloud Fragmentation

The GQ Lup system is comprised of three objects which include two confirmed stars, GQ Lup A and C, and a sub-stellar object, GQ Lup B. The sub-stellar object has become a subject of interest since its discovery. A large orbital period of ~1000 years has made it challenging to study certain aspects of GQ Lup B such as its formation history and object type. Currently, it is understood that GQ Lup B formed in situ either from cloud fragmentation or disk fragmentation. If one of these theories is correct, GQ Lup B would have either formed within or outside of GQ Lup A's disk. To further understand the formation history of GQ Lup B, its orbit must be observed. GQ Lup B's large distance from its host star and its face-on orbit allowed it to be directly imaged utilizing optical interferometry. The small portion of GQ Lup B's orbit that was observed could then support a best-fit orbit model created with the program orbitize! using Markov chain Monte Carlo (MCMC). Posteriors are created of GQ Lup B's orbital parameters position angle (Ω) and inclination (i). GQ Lup B's orbital parameters were then compared to GQ Lup A's disk and rotation axis. Finding a correlation between these orbital parameters would then signify that there was possibly coplanarity. No coplanarity was detected between GQ Lup A and B, which signifies that GQ Lup B possibly formed in situ via cloud fragmentation. Future work will go towards refining these results and how consistent they are with the cloud fragmentation theory.