NGTS clusters survey – VII. An enigmatic short-period circumsecondary disc candidate in Orion

Young stellar systems provide key insights into the processes governing star/planet formation, often exhibiting complex and evolving photometric variability. In this paper, we present an analysis of the object around NOI 105872, observed by the Next Generation Transit Survey (NGTS) to eclipse a young ($4.1\pm 0.4$ Myr) M-type star in the Orion Nebula Cluster. The system displays deep, asymmetric eclipses with a period of $\sim 0.69$ d, alongside variability in morphology. We combine photometric observations spanning approximately a decade from multiple ground- and space-based facilities to investigate the nature of this system. We explore a range of physical scenarios to reproduce the eclipse profiles and their evolution. After analysis, our preferred explanation is a circumsecondary disc surrounding a companion in orbit around the M-type primary. We adopt a six-parameter disc model and fit the eclipse profiles independently to each data set. The best-fitting solution yields a disc radius of $\sim 0.005\, \mathrm{au}$ or $0.98\, R_{*}$, with broadly consistent orientations across epochs, but with variations that may be attributed to disc precession or intrinsic stellar variability. Constraints from the Hill radius imply a companion mass consistent with a very low-mass stellar companion. These results establish NOI 105872 as a candidate for a circumsecondary disc system in a young stellar environment. Continued photometric monitoring and spectroscopic follow-up will be essential to confirm this interpretation. If confirmed, systems such as NOI 105872 provide valuable benchmarks for understanding disc dynamics, companion formation, and the origin of complex eclipse phenomena in young stars.