Evolution And Photoevaporation Of Protoplanetary Disks In Clusters With Hot Background Temperatures

In this work,we explore the formation and evolution of photoevaporating disks in clusters with hot background temperatures.The model starts from the pre-stellar cloud core collapse.Theoretical studies suggest that the external photoevaporation becomes important when the disk can expand to a few tens of AU.Since the initial angular momentum of the molecular cloud core determines the disk size during the disk formation,the core properties should be considered when investigating the evolution of a photoevaporating disk.We show that external photoevaporation is suppressed in the hot temperature environments and the disk properties are determined by the core properties,such as Tcd and?.In the warm region of clusters with Tcd = 40K,external FUV photoevaporation is still ineffective even if ? is very high(?=13×10-14 s-1).The initial angular momentum is relatively low for this warm core.Most of core mass collapses onto the disk close to the central star and then is accreted.The gravitational potential well of the disk is deep.The disk become gravitational stable after the core collapse ending.The properties of the disk evolution in this case are quite different from that shown in Xiao&Chang(2018)with the same? but low Tcd(Tcd = 10 K),where most of core mass falls on the disk far from the central star and the disk is evaporated efficiently by the external FUV photoevaporation.As ? decreases,the angular momentum of the core becomes low enough that almost all the core mass collapses directly onto the central star.The disk mass is very low(<0.02M(?))and it size is also very small(<20 AU).Therefore,the disk lifetime is short?106 years.In the vicinity of massive stars,the temperatures of molecular clouds may be as high as Tcd?100K.In this case,almost all the core mass are captured by the central star regardless whether ? is high or low.The disk properties are determined by its progenitor core properties rather than the radiative intensity of external FUV fields.The disk lifetime is very short<106 years.We consider that the diversity of photoevaporating disks in clusters is not only the results of the diversity of G0 and ?,but also the results of the diversity of progenitor cloud core properties.When J of the core is low,the external photoevaporation is severely suppressed.As J increases,the external photoevaporation becomes important in truncating and dissipating the disk from the outside in when the disk approaches to its lifetime.When J is very high,the external photoevaporation is very strong and Mdisk is severely evaporated.We suggest that low-mass disks(0.002-0.004M(?))in NGC 1333 with 1-2×106 years are likely to form from the warm pre-stellar cores(>40 K)with low ?(<2×10-14 s-1).