Mapping the circumstellar SiO maser emission in R Leo

Abstract

The study of the innermost circumstellar layers around AGB stars is crucial to understand how these envelopes are formed and evolve. The SiO maser emission occurs at a few stellar radii from the central star, providing direct information on the stellar pulsation and on the chemical and physical properties of these regions. Our data also shed light on several aspects of the SiO maser pumping theory that are not well understood yet. We aim to determine} the relative spatial distribution of the 43 GHz and 86 GHz SiO maser lines in the oxygen-rich evolved star R Leo. We have imaged with milliarcsecond resolution, by means of Very Long Baseline Interferometry, the 43 GHz (28SiO v=1, 2 J=1-0 and 29SiO v=0 J=1-0) and 86 GHz (28SiO v=1 J=2-1 and 29SiO v=0 J=2-1) masing regions. We confirm previous results obtained in other oxygen-rich envelopes. In particular, when comparing the 43 GHz emitting regions, the 28SiO v=2 transition is produced in an inner layer, closer to the central star. On the other hand, the 86 GHz line arises in a clearly farther shell. We have also mapped for the first time the 29SiO v=0 J=1-0 emission in R Leo. The already reported discrepancy between the observed distributions of the different maser lines and the theoretical predictions is also found in R Leo.

accepted for publication in A&A

References in corpus (3)

• Numerical simulations of stellar SiO maser variability. Investigation of the effect of shocks
• High resolution observations of SiO masers: comparing the spatial distribution at 43 and 86 GHz
• First VLBI mapping of circumstellar 29SiO maser emission

Cited by in corpus (19)

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• Simultaneous VLBI Astrometry of H2O and SiO Masers toward the Semiregular Variable R Crateris
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• Relative astrometry of the J=1-0, v=1 and v=2 SiO masers towards R Leonis Minoris using VERA
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• The modulation of SiO maser polarization by Jovian planets
• Evidence for episodic and patchy mass ejection in the circumstellar envelope of AGB star R Leonis
• A Comparison of the Velocity Parameters of SiO v=1, J=1-0 and J=2-1 Maser Emission in Long Period Variables
• Probing the fast outflow in IRAS 15452-5459 with ATCA observations of OH, H2O, and SiO masers
• A Phase Dependent Comparison of the Velocity Parameters of SiO v=1, J=1-0 and J=2-1 Maser Emission in Long Period Variables
• Long-term Simultaneous Monitoring Observations of SiO and H2O Masers toward the Mira Variable WX Serpentis