Simultaneous VLBI Astrometry of H2O and SiO Masers toward the Semiregular Variable R Crateris

Abstract

We obtained, for the first time, astrometrically registered maps of the 22.2 GHz H2O and 42.8, 43.1, and 86.2 GHz SiO maser emission toward the semiregular b-type variable (SRb) R Crateris, at three epochs (2015 May 21, and 2016 January 7 and 26) using the Korean Very-long-baseline Interferometry Network. The SiO masers show a ring-like spatial structure, while the H2O maser shows a very asymmetric one-side outflow structure, which is located at the southern part of the ring-like SiO maser feature. We also found that the 86.2 GHz SiO maser spots are distributed in an inner region, compared to those of the 43.1 GHz SiO maser, which is different from all previously known distributions of the 86.2 GHz SiO masers in variable stars. The different distribution of the 86.2 GHz SiO maser seems to be related to the complex dynamics caused by the overtone pulsation mode of the SRb R Crateris. Furthermore, we estimated the position of the central star based on the ring fitting of the SiO masers, which is essential for interpreting the morphology and kinematics of a circumstellar envelope. The estimated stellar coordinate corresponds well to the position measured by Gaia.

References in corpus (17)

• Multiple Molecular Winds in Evolved Stars I. A Survey of CO(2-1) and CO(3-2) Emission from 45 Nearby AGB Stars
• Mass loss rates of a sample of irregular and semiregular M-type AGB-variables
• Astrometric accuracy of phase-referenced observations with the VLBA and EVN
• An Improved Model of SiO Maser Emission in Miras
• A movie of a star: multi-epoch VLBA imaging of the SiO masers towards the Mira variable TX Cam
• Numerical simulations of stellar SiO maser variability. Investigation of the effect of shocks
• High Precision Astrometric Millimeter VLBI Using a New Method for Atmospheric Calibration
• Single dish performance of KVN 21-m radio telescopes:Simultaneous observations at 22 and 43 GHz
• High resolution observations of SiO masers: comparing the spatial distribution at 43 and 86 GHz
• Imaging the Radio Photospheres of Mira Variables
• The Distance and Size of the Red Hypergiant NML Cyg from VLBA and VLA Astrometry
• The 3-D kinematics of water masers around the semiregular variable RT Virginis
• SiO masers from AGB stars in the vibrationally excited v=1,v=2, and v=3 states
• Astrometrically Registered Simultaneous Observations of the 22 GHz H${}_2$O and the 43GHz SiO masers towards R Leonis Minoris using KVN and Source/Frequency Phase Referencing
• Mapping the circumstellar SiO maser emission in R Leo
• Astrometrically registered maps of H2O and SiO masers toward VX Sagittarii
• VLBI Monitoring Observations of Water Masers Around the Semi-Regular Variable Star R Crateris

Cited by in corpus (7)

• Precise radio astrometry and new developments for the next generation of instruments
• Inner dusty envelope of the AGB stars W~Hydrae, SW\,Virginis, and R~Crateris using SPHERE/ZIMPOL
• Asymmetric distributions of H2O and SiO masers towards V627 Cas
• Mapping circumstellar magnetic fields of late-type evolved stars with the Goldreich-Kylafis effect: CARMA observations at $\lambda 1.3$ mm of R Crt and R Leo
• Very fast variations of SiO maser emission in evolved stars
• Long-term Simultaneous Monitoring Observations of SiO and H2O Masers toward the Mira Variable WX Serpentis
• Water vapour masers in long-period variable stars II. The semi-regular variables R Crt and RT Vir