Sh2-173 and its environs: a hierarchical system of three generations?

S. CICHOWOLSKI; G. ROMERO; M. ORTEGA; C. CAPPA; J. VÁSQUEZ

San Juan, Argentina

Congreso; 51 Reunión Anual de la Asociación Argentina de Astronomía; 2008

We present a multiwavelength study of the interstellar medium (ISM) around the HII region Sh2-173. The ionized region is detected in the optical, in the radio continuum, and in the infrared images. Sh2-173 presents a stratified structure: the ionized gas is partially bordered by a photodissociation region (PDR), which in turn, is encircled by a molecular structure. Based on different colour criteria and using the available infrared point source catalogues, we have identified 46 young stellar object (YSO) candidates located onto the molecular gas associated with Sh2-173. On the other hand, Sh2-173 is located in a dense edge of a large HI shell. Based on the age estimates of the different structures we concluded that Sh2-173 may be part of a hierarchical system of three generation.