Description
Binary hardening is more efficient in gas-rich environments, leading to an enhanced number of close-separation binaries.
While the exact criteria for common envelope (CE) formation are still uncertain, it is generally suggested that the binary pericenter should be small to initiate an unstable mass transfer. Hence, CE formation is expected to be more prevalent in gas-rich environments, including clusters hosting multiple populations, which are expected to be the majority of globular clusters.
In these clusters, the existence of a second (or further) population of stars suggests a significant secondary epoch of gas, to support the formation of the second population of stars.
Here we explore the available parameter space for CE formation in gas-rich clusters.
We find that the fraction of binaries within the region in the parameter space that could go through CE increases by an order of magnitude.
The implications of the increased fraction of CEs in these clusters could play a significant role in various astrophysical processes and phenomena, such as the formation of hard binaries, supernovae, Thorne Zytkow objects, gravitational waves and others.
