Unveiling the birth and evolution of the H ii region Sh2-173
Based on a multiwavelength study, the interstellar medium around the H ii region Sh2-173 has been analysed. The ionized region is clearly detected in the optical and the radio continuum images. The analysis of the H i data shows a region of low emissivity that has an excellent morphological correlat...
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todo:paper_00358711_v394_n2_p900_Cichowolski2023-10-03T14:46:52Z Unveiling the birth and evolution of the H ii region Sh2-173 Cichowolski, S. Romero, G.A. Ortega, M.E. Cappa, C.E. Vasquez, J. H ii regions ISM: individual: Sh2-173 ISM: kinematics and dynamics Stars: formation Based on a multiwavelength study, the interstellar medium around the H ii region Sh2-173 has been analysed. The ionized region is clearly detected in the optical and the radio continuum images. The analysis of the H i data shows a region of low emissivity that has an excellent morphological correlation with the radio continuum emission. The H ii region is partially bordered by a photodissociation region, which, in turn, is encircled by a molecular structure. The H i and CO structures related to Sh2-173 are observed in the velocity ranges from -25 to -31 km s -1 and from -27 to -39 km s -1, respectively. Taking into account the presence of non-circular motions in the Perseus spiral arm, together with previous distance estimates for the region, we adopt a distance of 2.5 ± 0.5 kpc for Sh2-173. Seven hot stars were identified in the field of Sh2-173, being only one O-type star. The amount of energetic photons emitted by this star is enough to keep the region ionized and heat the dust. Given that an expanding H ii region may trigger star formation, a search for young stellar object (YSO) candidates was made using different infrared point source catalogues. A population of 46 YSO candidates was identified, projected on to the molecular clouds. On the other hand, Sh2-173 is located in a dense edge of a large (∼5°) H i shell, GSH 117.8+1.5-35. The possibility of Sh2-173 being part of a hierarchical system of three generations is suggested. In this scenario, the large H i shell, which probably originated due to the action of Cas OB5, would have triggered the formation of Sh2-173, which, in turn, is triggering new stars in its surrounding molecular cloud. To test this hypothesis, the ages of both the H ii region and the large shell were estimated and compared. We concluded that Sh2-173 is a young H ii region of about 0.6-1.0 Myr old. As for the large shell, we obtained a dynamical age of 5 ± 1 Myr. These age estimates, together with the relative location of the different structures, support the hypothesis that Sh2-173 is part of a hierarchical system. © 2009 RAS. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00358711_v394_n2_p900_Cichowolski |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
H ii regions ISM: individual: Sh2-173 ISM: kinematics and dynamics Stars: formation |
| spellingShingle |
H ii regions ISM: individual: Sh2-173 ISM: kinematics and dynamics Stars: formation Cichowolski, S. Romero, G.A. Ortega, M.E. Cappa, C.E. Vasquez, J. Unveiling the birth and evolution of the H ii region Sh2-173 |
| topic_facet |
H ii regions ISM: individual: Sh2-173 ISM: kinematics and dynamics Stars: formation |
| description |
Based on a multiwavelength study, the interstellar medium around the H ii region Sh2-173 has been analysed. The ionized region is clearly detected in the optical and the radio continuum images. The analysis of the H i data shows a region of low emissivity that has an excellent morphological correlation with the radio continuum emission. The H ii region is partially bordered by a photodissociation region, which, in turn, is encircled by a molecular structure. The H i and CO structures related to Sh2-173 are observed in the velocity ranges from -25 to -31 km s -1 and from -27 to -39 km s -1, respectively. Taking into account the presence of non-circular motions in the Perseus spiral arm, together with previous distance estimates for the region, we adopt a distance of 2.5 ± 0.5 kpc for Sh2-173. Seven hot stars were identified in the field of Sh2-173, being only one O-type star. The amount of energetic photons emitted by this star is enough to keep the region ionized and heat the dust. Given that an expanding H ii region may trigger star formation, a search for young stellar object (YSO) candidates was made using different infrared point source catalogues. A population of 46 YSO candidates was identified, projected on to the molecular clouds. On the other hand, Sh2-173 is located in a dense edge of a large (∼5°) H i shell, GSH 117.8+1.5-35. The possibility of Sh2-173 being part of a hierarchical system of three generations is suggested. In this scenario, the large H i shell, which probably originated due to the action of Cas OB5, would have triggered the formation of Sh2-173, which, in turn, is triggering new stars in its surrounding molecular cloud. To test this hypothesis, the ages of both the H ii region and the large shell were estimated and compared. We concluded that Sh2-173 is a young H ii region of about 0.6-1.0 Myr old. As for the large shell, we obtained a dynamical age of 5 ± 1 Myr. These age estimates, together with the relative location of the different structures, support the hypothesis that Sh2-173 is part of a hierarchical system. © 2009 RAS. |
| format |
JOUR |
| author |
Cichowolski, S. Romero, G.A. Ortega, M.E. Cappa, C.E. Vasquez, J. |
| author_facet |
Cichowolski, S. Romero, G.A. Ortega, M.E. Cappa, C.E. Vasquez, J. |
| author_sort |
Cichowolski, S. |
| title |
Unveiling the birth and evolution of the H ii region Sh2-173 |
| title_short |
Unveiling the birth and evolution of the H ii region Sh2-173 |
| title_full |
Unveiling the birth and evolution of the H ii region Sh2-173 |
| title_fullStr |
Unveiling the birth and evolution of the H ii region Sh2-173 |
| title_full_unstemmed |
Unveiling the birth and evolution of the H ii region Sh2-173 |
| title_sort |
unveiling the birth and evolution of the h ii region sh2-173 |
| url |
http://hdl.handle.net/20.500.12110/paper_00358711_v394_n2_p900_Cichowolski |
| work_keys_str_mv |
AT cichowolskis unveilingthebirthandevolutionofthehiiregionsh2173 AT romeroga unveilingthebirthandevolutionofthehiiregionsh2173 AT ortegame unveilingthebirthandevolutionofthehiiregionsh2173 AT cappace unveilingthebirthandevolutionofthehiiregionsh2173 AT vasquezj unveilingthebirthandevolutionofthehiiregionsh2173 |
| _version_ |
1782026787540172800 |