Imaging the Jet of MWC 349A with Resolved Radio Recombination Line Emission from ALMA

Jets and disk winds arise from materials with excess angular momentum ejected from the accretion disks in forming stars. How these structures are launched and how they impact the gas within the innermost regions of these objects remains poorly understood. MWC349A is a massive star that has a circums...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2024-08, Vol.971 (1), p.L7
Main Authors: Martínez-Henares, Antonio, Zhang, Qizhou, Jiménez-Serra, Izaskun, Martín-Pintado, Jesús, Huélamo, Nuria, Prasad, Sirina, Moran, James, Báez-Rubio, Alejandro
Format: Article
Language:English
Subjects:
Accretion disks
Angular momentum
Angular resolution
Angular velocity
Circumstellar masers
Continuum radiation
Cubes
Emissions
H II regions
Hydrogen
Kepler laws
Kinematics
Legal issues
Masers
Massive stars
Radiative transfer
Radio telescopes
Star formation
Stellar accretion disks
Stellar jets
Stellar winds
Wind
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Summary:Jets and disk winds arise from materials with excess angular momentum ejected from the accretion disks in forming stars. How these structures are launched and how they impact the gas within the innermost regions of these objects remains poorly understood. MWC349A is a massive star that has a circumstellar disk that rotates in accord with Kepler’s Law, with an ionized wind and a high-velocity jet launched from the disk surface. The strongly maser-amplified emission of hydrogen radio recombination lines (RRLs) observed toward this system provides a comprehensive picture of its ionized environment with exquisite detail. In this Letter, we present Atacama Large Millimeter/submillimeter Array observations of the H26 α RRL and continuum emission obtained with the highest angular resolution ever used toward this source (beam of ∼0.″02). The maser RRL emission is resolved for the first time and clearly delineates the ionized disk, wind, and jet. We analyzed the RRL data cubes with the 3D non-LTE radiative transfer model MORELI, confirming that the jet is poorly collimated. We found that the jet orientation is closer to the rotation axis of the system than derived from spatially unresolved data. This study confirms that hydrogen RRL masers are powerful probes of the physical structure and kinematics of the innermost ionized material around massive stars.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/ad638d