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VLBA imaging of the 3 mm SiO maser emission in the disk-wind from the massive protostellar system Orion Source I

Issaoun, S; Goddi, C; Matthews, Lynn D; Greenhill, Lincoln; Gray, M.D.; Humphreys, E. M. L.; Chandler, C. J.; Krumholz, Mark; Falcke, Heino

Description

Context. High-mass star formation remains poorly understood due to observational difficulties (e.g. high dust extinction and large distances) hindering the resolution of disk-accretion and outflow-launching regions. Aims. Orion Source I is the closest known massive young stellar object (YSO) and exceptionally powers vibrationally-excited SiO masers at radii within 100 AU, providing a unique probe of gas dynamics and energetics. We seek to observe and image these masers with Very Long...[Show more]

dc.contributor.authorIssaoun, S
dc.contributor.authorGoddi, C
dc.contributor.authorMatthews, Lynn D
dc.contributor.authorGreenhill, Lincoln
dc.contributor.authorGray, M.D.
dc.contributor.authorHumphreys, E. M. L.
dc.contributor.authorChandler, C. J.
dc.contributor.authorKrumholz, Mark
dc.contributor.authorFalcke, Heino
dc.date.accessioned2020-12-20T20:58:28Z
dc.date.available2020-12-20T20:58:28Z
dc.identifier.issn0004-6361
dc.identifier.urihttp://hdl.handle.net/1885/218603
dc.description.abstractContext. High-mass star formation remains poorly understood due to observational difficulties (e.g. high dust extinction and large distances) hindering the resolution of disk-accretion and outflow-launching regions. Aims. Orion Source I is the closest known massive young stellar object (YSO) and exceptionally powers vibrationally-excited SiO masers at radii within 100 AU, providing a unique probe of gas dynamics and energetics. We seek to observe and image these masers with Very Long Baseline Interferometry (VLBI). Methods. We present the first images of the 28SiO v = 1, J = 2−1 maser emission around Orion Source I observed at 86 GHz (λ3 mm) with the Very Long Baseline Array (VLBA). These images have high spatial (~0.3 mas) and spectral (~0.054 km s-1) resolutions. Results. We find that the λ3 mm masers lie in an X-shaped locus consisting of four arms, with blue-shifted emission in the south and east arms and red-shifted emission in the north and west arms. Comparisons with previous images of the 28SiO v = 1,2, J = 1−0 transitions at λ7 mm (observed in 2001–2002) show that the bulk of the J = 2−1 transition emission follows the streamlines of the J = 1−0 emission and exhibits an overall velocity gradient consistent with the gradient at λ7 mm. While there is spatial overlap between the λ3 mm and λ7 mm transitions, the λ3 mm emission, on average, lies at larger projected distances from Source I (~44 AU compared with ~35 AU for λ7 mm). The spatial overlap between the v = 1, J = 1−0 and J = 2−1 transitions is suggestive of a range of temperatures and densities where physical conditions are favorable for both transitions of a same vibrational state. However, the observed spatial offset between the bulk of emission at λ3 mm and λ7 mm possibly indicates different ranges of temperatures and densities for optimal excitation of the masers. We discuss different maser pumping models that may explain the observed offset. Conclusions. We interpret the λ3 mm and λ7 mm masers as being part of a single wide-angle outflow arising from the surface of an edge-on disk rotating about a northeast-southwest axis, with a continuous velocity gradient indicative of differential rotation consistent with a Keplerian profile in a high-mass proto-binary.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherSpringer
dc.sourceAstronomy and Astrophysics
dc.titleVLBA imaging of the 3 mm SiO maser emission in the disk-wind from the massive protostellar system Orion Source I
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume606
dc.date.issued2017
local.identifier.absfor020110 - Stellar Astronomy and Planetary Systems
local.identifier.ariespublicationu4351680xPUB446
local.type.statusPublished Version
local.contributor.affiliationIssaoun, S, Radboud University
local.contributor.affiliationGoddi, C, Radboud University
local.contributor.affiliationMatthews, Lynn D, MIT Haystack Observatory
local.contributor.affiliationGreenhill, Lincoln, Harvard-Smithsonian Center for Astrophysics
local.contributor.affiliationGray, M.D., University of Manchester
local.contributor.affiliationHumphreys, E. M. L., European Southern Observatory
local.contributor.affiliationChandler, C. J., National Radio Astronomy Observatory
local.contributor.affiliationKrumholz, Mark, College of Science, ANU
local.contributor.affiliationFalcke, Heino, Radboud University
local.identifier.doi10.1051/0004-6361/201731548
dc.date.updated2020-11-23T11:26:52Z
local.identifier.scopusID2-s2.0-85032378813
CollectionsANU Research Publications

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