0000000000544652

AUTHOR

K. Hachisuka

showing 3 related works from this author

The kinematics of water masers in the stellar molecular outflow source, IRAS 19134+2131

2004

Using the Very Large Array (VLA) and the Very Long Baseline Array (VLBA), we have observed water maser emission in the proto-planetary nebula candidate IRAS 19134+2131, in which the water maser spectrum has two groups of emission features separated in radial velocity by ∼100 km s^−1. The blue-shifted and red-shifted clusters of maser features are clearly separated spatially by ∼150 mas, indicative of a fast collimated flow. However, not all of the maser features are aligned along the axis of the flow, as is seen in the similar high-velocity water maser source, W43A. Comparing the VLA and VLBA maps of the water maser source, we find 4 maser features that were active for 2 years. Using only V…

Stellar kinematicsAstrophysics::High Energy Astrophysical PhenomenaOutflowsAstrophysics::Cosmology and Extragalactic AstrophysicsAstrophysicsUNESCO::ASTRONOMÍA Y ASTROFÍSICAAGB and post-AGBlaw.inventionlawIndividual starsAstrophysics::Solar and Stellar AstrophysicsAsymptotic giant branchOH/IR starMaserMasers stars ; AGB and post-AGB ; Distances ; Kinematics Winds ; Outflows ; Individual stars ; IRAS 19134+2131Astrophysics::Galaxy AstrophysicsVery Long Baseline ArrayPhysicsNebulaKinematics WindsAstronomyIRAS 19134+2131Astronomy and AstrophysicsGalactic plane:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia [UNESCO]Masers starsDistancesRadial velocitySpace and Planetary ScienceUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia:ASTRONOMÍA Y ASTROFÍSICA [UNESCO]Astronomy & Astrophysics
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Water Maser Motions in W3(OH) and a Determination of Its Distance

2006

We report phase-referencing VLBA observations of H2O masers near the star-forming region W3(OH) to measure their parallax and absolute proper motions. The measured annual parallax is 0.489 +/- 0.017 milli-arcseconds (2.04 +/- 0.07 kpc), where the error is dominated by a systematic atmospheric contribution. This distance is consistent with photometric distances from previous observations and with the distance determined from CH3OH maser astrometry presented in a related paper. We also find that the source driving the H2O outflow, the ``TW-object'', moves with a 3-dimensional velocity of > 7 km/s relative to the ultracompact HII region W3(OH).

PhysicsAstrophysics (astro-ph)Measure (physics)FOS: Physical sciencesAstronomy and AstrophysicsAstrometryAstrophysicsAstrophysicslaw.inventionSpace and Planetary SciencelawOutflowMaserParallaxThe Astrophysical Journal
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Towards an Understanding of the Dynamics of the Milky Way

2005

Determination of outer rotation curve using Galactic masers The rotation curve of the Galaxy is poorly determined outside the solar circle (e.g. Honma & Sofue 1997). The situation makes difficult to derive the dynamical mass of the Galaxy, which is essential for inferring the amount of Galactic dark gravitating matter. We selected Galactic masers in this study since they distributed over the whole Galaxy. Moreover, they can observed with VLBI at extremely high angular resolution, allowing a measurement of the annual parallax, and thus the source’s distance, and its proper motion due to Galactic rotation with phase referencing VLBI astrometric observation. We have already performed phase-ref…

PhysicsProper motionAstrophysics::High Energy Astrophysical PhenomenaMilky WayAstrophysics::Instrumentation and Methods for AstrophysicsPerseus ArmAstronomyAstrophysics::Cosmology and Extragalactic AstrophysicsGalaxylaw.inventionlawVery-long-baseline interferometryAstrophysics::Solar and Stellar AstrophysicsMaserParallaxAstrophysics::Galaxy AstrophysicsGalaxy rotation curve
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