Is Serpens more crowded than other nearby star-forming regions?

Simin Tong, Nienke van der Marel, Jonathan P. Williams, Alexa R. Anderson

It is widely accepted that protoplanetary disks have a lifetime of a few million years, which makes it challenging for humans to study the disk evolution. But if we could examine disks in star-forming regions with known ages and habitats, we are able to statistically investigate how disks evolve and what kind of external environments could regulate the evolution. We surveyed the Serpens star-forming region in ALMA cycle 7 with high- and low-resolution configurations to investigate whether the relatively high stellar density at Serpens, proposed by previous studies, could have more frequent dynamical interactions and lead to different dust disk mass distributions, compared to other nearby star-forming regions, such as Taurus and Lupus star-forming regions. We measured the disk sub-millimeter flux densities and converted them to dust disk masses, adopting distance information from the Gaia DR3, which gives a median distance of 462 pc to the Serpens. Analysis of the disk mass cumulative distribution and the 3D stellar density suggests that Serpens may not be as dense as we expect. We also serendipitously discovered 1) 30 young stellar object candidates, which have never been observed before; 2) two transition disks with cavities of ~94 au and ~87 au; 3) bipolar and monopolar 12CO outflows ejected from observed targets.