Associations of water and methanol masers at milli-arcsec angular resolution in two high-mass young stellar objects

Abstract

Most previous high-angular (<0.1 arcsec) resolution studies of molecular masers in high-mass star forming regions (SFRs) have concentrated mainly on either water or methanol masers. While high-angular resolution observations have clarified that water masers originate from shocks associated with protostellar jets, different environments have been proposed in several sources to explain the origin of methanol masers. Tha aim of the paper is to investigate the nature of the methanol maser birthplace in SFRs and the association between the water and methanol maser emission in the same young stellar object. We have conducted phase-reference Very Long Baseline Interferometry (VLBI) observations of water and methanol masers toward two high-mass SFRs, Sh 2-255 IR and AFGL 5142. In Sh 2-255 IR water masers are aligned along a direction close to the orientation of the molecular outflow observed on angular scales of 1-10 arcsec, tracing possibly the disk-wind emerging from the disk atmosphere. In AFGL 5142 water masers trace expansion at the base of a protostellar jet, whilst methanol masers are more probably tracing infalling than outflowing gas. The results for AFGL 5142 suggest that water and methanol masers trace different kinematic structures in the circumstellar gas.

arXiv comment11 pages, 3 figures, accepted for publication in Astronomy & Astrophysics

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• N2H+ depletion in the massive protostellar cluster AFGL 5142
• Star Formation Activity in the Galactic HII Complex S255-S257
• Mapping Observations of 6.7 GHz Methanol Masers with Japanese VLBI Network
• Protostellar Outflows at the EarliesT Stages (POETS). I. Radio thermal jets at high resolution nearby H${}_2$O maser sources
• ALMA View of the Infalling Envelope around a Massive Protostar in S255IR SMA1
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• EVN observations of 6.7-GHz methanol maser polarization in massive star-forming regions II. First statistical results
• Water maser variability in a high-mass YSO outburst -- VERA and ALMA observations of S255 NIRS 3
• Revealing the "missing" low-mass stars in the S254-S258 star forming region by deep X-ray imaging
• Formaldehyde and H110a observations towards 6.7 GHz methanol maser sources
• Multiple outflows in the high-mass cluster forming region, G25.82-0.17
• Sejong open cluster survey (SOS) - V. The active star forming region Sh 2-255 -- 257
• Milliarcsecond structure of water maser emission in two young high-mass stellar objects associated with methanol masers
• Spectral survey of a Hot core with an Eruptive Accretion in S255IR NIRS3 (SHEA): The discovery of class I and class II millimeter methanol maser transitions
• Imaging Molecular Outflow in Massive Star-forming Regions with HNCO Lines
• Simultaneous 22 GHz Water and 44 GHz Methanol Masers Survey of Ultracompact HII Regions