Prasanta Gorai, Kotomi Taniguchi, Jonathan C. Tan, Miguel Gómez-Garrido, Viviana Rosero, Izaskun Jiménez-Serra, Yichen Zhang, Giuliana Cosentino, Chi-Yan Law, Rubén Fedriani, Gemma Busquet, Brandt A. L. Gaches, Maryam Saberi, Ankan Das
{"title":"索非亚大质量(SOMA)恒星形成q波段追踪","authors":"Prasanta Gorai, Kotomi Taniguchi, Jonathan C. Tan, Miguel Gómez-Garrido, Viviana Rosero, Izaskun Jiménez-Serra, Yichen Zhang, Giuliana Cosentino, Chi-Yan Law, Rubén Fedriani, Gemma Busquet, Brandt A. L. Gaches, Maryam Saberi, Ankan Das","doi":"10.1051/0004-6361/202556220","DOIUrl":null,"url":null,"abstract":"<i>Context<i/>. Hydrogen recombination lines (HRLs) are valuable diagnostics of the physical conditions in ionized regions surrounding high-mass stars. Understanding these lines, including broadening mechanisms and intensity trends, can provide insights into HII region densities, temperatures, and kinematics.<i>Aims<i/>. This study aims to investigate the physical properties of ionized gas around massive protostars by analysing the HRLs (H<i>α<i/> and H<i>β<i/>) in the Q band.<i>Methods<i/>. We carried out observations using the Yebes 40m radio telescope in the Q band (30.5–50 GHz) towards six high-mass protostars selected from the SOMA Survey (G45.12+0.13, G45.47+0.05, G28.20−0.05, G35.20−0.74, G19.08−0.29, and G31.28+0.06). The observed line profiles were analysed to assess broadening mechanisms, and electron densities and temperatures were derived. The results were compared with available Q-band data from the TianMa 65-m Radio Telescope (TMRT) that have been reported in the literature, and ALMA Band 1 (35–50 GHz) Science Verification observations towards Orion KL, analysed in this study.<i>Results<i/>. A total of eight H<i>α<i/> (n = 51 to 58) and ten H<i>β<i/> (n = 64 to 73) lines were detected towards G45.12+0.13, G45.47+0.05, and G28.20−0.05; there were no detections in other sources. We derived electron densities of ~1−5 × 10<sup>6<sup/> cm<sup>−3<sup/> and temperatures of 8000–10 000 K for the sources. However, for Orion KL, we obtained an electron density one order of magnitude lower, while its temperature was found to be more similar. Interestingly, G45.12 and G28.20 show an increasing intensity trend with frequency for both H<i>α<i/> and H<i>β<i/> transitions, contrary to the decreasing trend observed in Orion KL.<i>Conclusions<i/>. The line widths of the detected HRLs indicate contributions from both thermal and dynamical broadening, suggesting the presence of high-temperature ionized gas that is likely kinematically broadened (e.g. due to turbulence, outflows, rapid rotation, or stellar winds). Pressure broadening caused by electron density may also have a minor effect. We discuss different scenarios to explain the measured line widths of the HRLs. The contrasting intensity trends between the sources may reflect variations in local physical conditions or radiative transfer effects, highlighting the need for further investigation through higher-resolution observations and detailed modelling.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"86 1","pages":""},"PeriodicalIF":5.8000,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"The SOFIA Massive (SOMA) star formation Q-band follow-up\",\"authors\":\"Prasanta Gorai, Kotomi Taniguchi, Jonathan C. Tan, Miguel Gómez-Garrido, Viviana Rosero, Izaskun Jiménez-Serra, Yichen Zhang, Giuliana Cosentino, Chi-Yan Law, Rubén Fedriani, Gemma Busquet, Brandt A. L. Gaches, Maryam Saberi, Ankan Das\",\"doi\":\"10.1051/0004-6361/202556220\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<i>Context<i/>. Hydrogen recombination lines (HRLs) are valuable diagnostics of the physical conditions in ionized regions surrounding high-mass stars. Understanding these lines, including broadening mechanisms and intensity trends, can provide insights into HII region densities, temperatures, and kinematics.<i>Aims<i/>. This study aims to investigate the physical properties of ionized gas around massive protostars by analysing the HRLs (H<i>α<i/> and H<i>β<i/>) in the Q band.<i>Methods<i/>. We carried out observations using the Yebes 40m radio telescope in the Q band (30.5–50 GHz) towards six high-mass protostars selected from the SOMA Survey (G45.12+0.13, G45.47+0.05, G28.20−0.05, G35.20−0.74, G19.08−0.29, and G31.28+0.06). The observed line profiles were analysed to assess broadening mechanisms, and electron densities and temperatures were derived. The results were compared with available Q-band data from the TianMa 65-m Radio Telescope (TMRT) that have been reported in the literature, and ALMA Band 1 (35–50 GHz) Science Verification observations towards Orion KL, analysed in this study.<i>Results<i/>. A total of eight H<i>α<i/> (n = 51 to 58) and ten H<i>β<i/> (n = 64 to 73) lines were detected towards G45.12+0.13, G45.47+0.05, and G28.20−0.05; there were no detections in other sources. We derived electron densities of ~1−5 × 10<sup>6<sup/> cm<sup>−3<sup/> and temperatures of 8000–10 000 K for the sources. However, for Orion KL, we obtained an electron density one order of magnitude lower, while its temperature was found to be more similar. Interestingly, G45.12 and G28.20 show an increasing intensity trend with frequency for both H<i>α<i/> and H<i>β<i/> transitions, contrary to the decreasing trend observed in Orion KL.<i>Conclusions<i/>. The line widths of the detected HRLs indicate contributions from both thermal and dynamical broadening, suggesting the presence of high-temperature ionized gas that is likely kinematically broadened (e.g. due to turbulence, outflows, rapid rotation, or stellar winds). Pressure broadening caused by electron density may also have a minor effect. We discuss different scenarios to explain the measured line widths of the HRLs. The contrasting intensity trends between the sources may reflect variations in local physical conditions or radiative transfer effects, highlighting the need for further investigation through higher-resolution observations and detailed modelling.\",\"PeriodicalId\":8571,\"journal\":{\"name\":\"Astronomy & Astrophysics\",\"volume\":\"86 1\",\"pages\":\"\"},\"PeriodicalIF\":5.8000,\"publicationDate\":\"2025-10-13\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Astronomy & Astrophysics\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.1051/0004-6361/202556220\",\"RegionNum\":2,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Astronomy & Astrophysics","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1051/0004-6361/202556220","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
The SOFIA Massive (SOMA) star formation Q-band follow-up
Context. Hydrogen recombination lines (HRLs) are valuable diagnostics of the physical conditions in ionized regions surrounding high-mass stars. Understanding these lines, including broadening mechanisms and intensity trends, can provide insights into HII region densities, temperatures, and kinematics.Aims. This study aims to investigate the physical properties of ionized gas around massive protostars by analysing the HRLs (Hα and Hβ) in the Q band.Methods. We carried out observations using the Yebes 40m radio telescope in the Q band (30.5–50 GHz) towards six high-mass protostars selected from the SOMA Survey (G45.12+0.13, G45.47+0.05, G28.20−0.05, G35.20−0.74, G19.08−0.29, and G31.28+0.06). The observed line profiles were analysed to assess broadening mechanisms, and electron densities and temperatures were derived. The results were compared with available Q-band data from the TianMa 65-m Radio Telescope (TMRT) that have been reported in the literature, and ALMA Band 1 (35–50 GHz) Science Verification observations towards Orion KL, analysed in this study.Results. A total of eight Hα (n = 51 to 58) and ten Hβ (n = 64 to 73) lines were detected towards G45.12+0.13, G45.47+0.05, and G28.20−0.05; there were no detections in other sources. We derived electron densities of ~1−5 × 106 cm−3 and temperatures of 8000–10 000 K for the sources. However, for Orion KL, we obtained an electron density one order of magnitude lower, while its temperature was found to be more similar. Interestingly, G45.12 and G28.20 show an increasing intensity trend with frequency for both Hα and Hβ transitions, contrary to the decreasing trend observed in Orion KL.Conclusions. The line widths of the detected HRLs indicate contributions from both thermal and dynamical broadening, suggesting the presence of high-temperature ionized gas that is likely kinematically broadened (e.g. due to turbulence, outflows, rapid rotation, or stellar winds). Pressure broadening caused by electron density may also have a minor effect. We discuss different scenarios to explain the measured line widths of the HRLs. The contrasting intensity trends between the sources may reflect variations in local physical conditions or radiative transfer effects, highlighting the need for further investigation through higher-resolution observations and detailed modelling.
期刊介绍:
Astronomy & Astrophysics is an international Journal that publishes papers on all aspects of astronomy and astrophysics (theoretical, observational, and instrumental) independently of the techniques used to obtain the results.