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Context. Water vapor emission at 22 GHz from masers associated with star-forming regions is highly variable. Aims. We present a database of up to 20 years of monitoring of a sample of 43 masers within star-forming regions. The sample covers…

We report new (1995) Very Large Array observations and (1984 - 1999) Effelsberg 100m monitoring observations of the 22 GHz H2O maser spectrum of the Seyfert 2 galaxy NGC 1068. The sensitive VLA observations provide a registration of the 22…

From measuring the annual parallax of water masers over one and a half years with VERA, we present the trigonometric parallax and corresponding distance of another newly identified water maser source in the region of IRAS 20231+3440 as…

VLBA observations of water masers toward the region of NGC1333 near SVS13, the driving source for the well-known Herbig-Haro objects HH7-11, are reported. Maser emission was observed over four epochs spaced by three weeks during late 1998.…

Astrophysics · Physics 2007-05-23 Alwyn Wootten , Kevin Marvel , Mark Claussen , Bruce Wilking

We present the results of single-dish and VLBI observations for the water-vapor masers at the nucleus of the Seyfert 2, IC 2560. We monitored velocities of the maser features with the 45-m telescope of the Nobeyama Radio Observatory. Using…

Astrophysics of Galaxies · Physics 2015-06-05 Aya Yamauchi , Naomasa Nakai , Yuko Ishihara , Philip Diamond , Naoko Sato

Aims. We report the discovery of periodic maser variability of an unusual pattern in the high-mass young stellar object G26.598-0.024. Methods. A ten-year monitoring of the 6.7 GHz methanol maser was carried out with the Torun 32 m radio…

Astrophysics of Galaxies · Physics 2025-08-14 P. Wolak , M. Szymczak , A. Kobak , A. Varma , A. Bartkiewicz , J. O. Chibueze , B. Stecklum , C. J. Ugwu

Highly collimated jets found in AGB and post-AGB stars are expected to play an important role for shaping planetary nebulae. Recent VLBI observations of H2O maser sources have revealed that some of the spatio-kinematical structures of H2O…

Astrophysics · Physics 2009-11-13 Hiroshi Imai

We wish to understand the reasons for the strong variability of H2O masers in circumstellar shells of late-type stars. We monitored RX Boo and SV Peg in the 22-GHz maser line of water vapour with single-dish telescopes. The monitoring…

Astrophysics · Physics 2009-11-13 A. Winnberg , D. Engels , J. Brand , L. Baldacci , C. M. Walmsley

We observed H$_2$O (6$_{16}$ $\rightarrow$ 5$_{23}$) maser emission associated with the high-mass star-forming region IRAS 23139+5959 using the KaVA a combination of VLBI arrays between the KVN (Korea) and VERA (Japan). Through multi-epoch…

In this paper we analyze multi-epoch Very Long Baseline Interferometry (VLBI) water maser observations carried out with the Very Long Baseline Array (VLBA) toward the high-mass star-forming region AFGL 2591. We detected maser emission…

The NGC 1333 IRAS 4 region was observed in the 22 GHz H2O maser line with an angular resolution of about 0.08 arcseconds. Two groups of masers were detected, one near IRAS 4A and the other near BI. Among the eight maser spots detected near…

Astrophysics · Physics 2009-11-13 Geumsook Park , Minho Choi

We report observations of water masers around the semiregular variable RT Virginis (RT Vir), which have been made with the Very Long Baseline Array (VLBA) of the National Radio Astronomy Observatory (NRAO) at five epochs, each separated by…

The results of the study of the maser emission source IRAS 18316$-$0602 in the H$_2$O line at $\lambda =1.35$ cm are reported. The observations have been carried out at the RT-22 radio telescope of the Pushchino Radio Astronomy Observatory…

Astrophysics of Galaxies · Physics 2018-03-28 E. E. Lekht , M. I. Pashchenko , G. M. Rudnitskij , A. M. Tolmachev

H$_2$O maser emission at 22 GHz in the circumstellar envelope is one of the good tracers of detailed physics and kinematics in the mass loss process of asymptotic giant branch stars. Long-term monitoring of an H$_2$O maser spectrum with…

Solar and Stellar Astrophysics · Physics 2018-01-10 H. Sudou , M. Shiga , T. Omodaka , C. Nakai , H. Takaba

We present the results of multi-epoch VLBI observations of water masers in the AGFL 5142 massive star forming region. We measure an annual parallax of $\pi=0.467 \pm 0.010$ mas, corresponding to a source distance of…

We report on the astrometric registration of VLBI images of the SiO and water masers in OH231.8+4.2, the iconic Proto-Planetary Nebula also known as the Calabash nebula, using the KVN and Source/Frequency Phase Referencing. This, for the…

Solar and Stellar Astrophysics · Physics 2018-04-17 Richard Dodson , Maria Rioja , Valentin Bujarrabal , J. Kim , S. H. Cho , Y. K. Choi , Y. Youngjoo

We present single-dish monitoring of the spectra of 13 extragalactic water megamasers taken over a period of 9 years and a single epoch of sensitive spectra for 7 others. Our data include the first K-band science observations taken with the…

Astrophysics · Physics 2009-11-07 J. A. Braatz , A. S. Wilson , C. Henkel , R. Gough , M. Sinclair

We report on the periodic flux variations in the 6.7 GHz $\mathrm{CH_3OH}$ maser associated with the high-mass protostar G353.273+0.641, based on 13 yr of monitoring mainly by the Hitachi 32 m telescope. We identified a periodicity of 309…

Solar and Stellar Astrophysics · Physics 2026-02-04 Sohta Harajiri , Kazuhito Motogi , Ryota Nakamura , Yoshinori Yonekura , Yoshihiro Tanabe , Kenta Fujisawa

The active star-forming region W33B is a source of OH and H2O maser emission located in distinct zones around the central object. The aim was to obtain the complete Stokes pattern of polarised OH maser emission, to trace its variability and…

Astrophysics of Galaxies · Physics 2015-02-25 P. Colom , E. E. Lekht , M. I. Pashchenko , G. M. Rudnitskij

We present the first images of the 28SiO v=1, J=2-1 maser emission around the closest known massive young stellar object Orion Source I observed at 86 GHz (3mm) with the VLBA. These images have high spatial (~0.3 mas) and spectral (~0.054…

Astrophysics of Galaxies · Physics 2017-10-25 S. Issaoun , C. Goddi , L. D. Matthews , L. J. Greenhill , M. D. Gray , E. M. L. Humphreys , C. J. Chandler , M. Krumholz , H. Falcke
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