Properties of H2O Masers and Their Associated Sources in Sagittarius B2
We present high-resolution Karl G. Jansky Very Large Array observations of the 22 GHz H<inf>2</inf>O maser line in the extended Sagittarius B2 cloud. We detect 499 H<inf>2</inf>O masers across the observed velocities between −39 and 172 km s<sup>−1</sup>. To inves...
| Authors: | , , , , , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2025 |
| Country: | España |
| Institution: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repository: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/402675 |
| Online Access: | http://hdl.handle.net/10261/402675 https://api.elsevier.com/content/abstract/scopus_id/105012433126 |
| Access Level: | Open access |
| Keyword: | Star formation Star forming regions Water masers Stellar jets Young stellar objects H II regions |
| Summary: | We present high-resolution Karl G. Jansky Very Large Array observations of the 22 GHz H<inf>2</inf>O maser line in the extended Sagittarius B2 cloud. We detect 499 H<inf>2</inf>O masers across the observed velocities between −39 and 172 km s<sup>−1</sup>. To investigate the nature of the masers, we analyze their spatial distribution and crossmatch with catalogs of H II regions and protostellar cores. 62% of masers are associated with protostellar cores and 32% with H II regions. The nature of the remaining 6% of sources was not established but is likely associated with protostellar cores. Based on the spatial extent of the groups of masers, we classify them as either outflow-associated or young stellar object (YSO)-associated. We identify 144 unique sites of maser emission: 23 are associated with H II regions and 94 with protostellar cores, of which 33 are associated with protostellar outflows and 18 with YSOs. The outflow-associated H<inf>2</inf>O maser emission is confined to within <2000 au of the central continuum source, despite shocked SiO emission extending over tens of thousands of astronomical units. The YSO-associated masers show a lack of detections at 5 < V<inf>rel</inf> < 30 km s<sup>−1</sup>, which we suggest may be due to maser self-absorption. We show how H<inf>2</inf>O masers trace the large-scale material flow in Sgr B2 North, also seen in SiO and millimeter continuum emission. Finally, we find that protostellar cores with associated H<inf>2</inf>O masers tend to have brighter 3 mm continuum emission on average, although there is no strong correlation between maser brightness and continuum flux. |
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