Description
Forming planetary systems in the transition from protoplanetary to debris discs are so rare, that only one such object, HD$\,$141569, was known until now. Using ALMA Band 6 observations, we present the detection of gas and millimetre dust in another recently dispersed disc around a 2 Myr-old intermediate-mass star. We searched for continuum, $^{12}$CO, $^{13}$CO, and C$^{18}$O (all J=2-1) emission. The detected $^{12}$CO gas and dust emission result in CO gas and dust masses of the order M$_{CO}$$\,$=$\,$10$^{-4}$ M$_{\oplus}$ and M$_{dust}$$\,$=$\,$0.01 M$_{\oplus}$. From the non-detections of $^{13}$CO and C$^{18}$O we provide upper limits on the total CO gas mass of around M$_{CO}$$\,$=$\,$10$^{-2}$ M$_{\oplus}$, suggesting that the $^{12}$CO emission may be optically thick and hence implying that the CO gas mass we derive should be considered as a lower limit. The asymmetry of dust distribution around our target is a feature also seen in HD$\,$141569, and both systems exhibit gas emission arising from a region inside to the dust emission. These may represent hallmark features of the transition from gas-dominated to solid body-dominated disc physics. Moreover, our target star shows a 12$\,\mu$m fractional excess comparable to HD$\,$141569, which falls in-between the protoplanetary and debris disc stages. Studying these unique systems helps us understand the processes that drive gas dispersal and its influence on the evolution of planets and planetary systems, providing new insights into disc evolution at this transitional stage.
