A5041420194- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- GNSS positioning and interference
- Molecular Spectroscopy and Structure
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Superconducting and THz Device Technology
- Particle Detector Development and Performance
- Cryospheric studies and observations
- Educational Research and Pedagogy
- Spectroscopy and Laser Applications
- Identification and Quantification in Food
- Advanced SAR Imaging Techniques
- Hungarian Social, Economic and Educational Studies
- Quantum, superfluid, helium dynamics
Joint Institute for VLBI ERIC
2017-2024
University of Tasmania
2019-2023
Xinjiang Astronomical Observatory
2018-2022
Chinese Academy of Sciences
2020-2022
Kagoshima University
2016-2021
University of Szeged
2020
Netherlands Institute for Radio Astronomy
2019
Konkoly Observatory
2018
Research Centre for Astronomy and Earth Sciences
2018
Budapest University of Technology and Economics
2012-2013
Class II methanol masers are signs of massive young stellar objects (MYSOs). Recent findings show that MYSO accretion bursts cause flares these masers. Thus, maser monitoring can be used to identify such bursts. Burst-induced SED changes provide valuable information on a very intense phase high-mass star formation. In mid-January 2019, flare the G358.93-0.03 was reported. ALMA and SMA imaging resolved core forming region proved association with brightest continuum source MM1. However, no...
Context. Recent studies have shown that 6.7 GHz methanol maser flares can be a powerful tool for verifying the mechanisms of production and even specific signatures accretion rate changes in early stages high-mass star formation. Aims. We characterize spatial structure evolution water masers during flare emission at young stellar object (HMYSO) G24.33+0.14. Methods. Very Long Baseline Array (VLBA) was used to image 12.2 22.2 vapor three epochs guided by monitoring line with Torun 32m...
Wereportthefirstmulti-epochmilliarcsecondresolutionimagingofthe6.7-GHzclassIImethanolmaseremissionassociated with the high-mass protocluster system NGC6334I. The observations cover 4 epochs over a 10-year period between March 2010 and 2020. We confirm emergence of number new regions 6.7-GHz methanol maser emission in molecular gas surrounding NGC6334-MM1, which lies north previously known class II sites are associated NGC6334-MM3 -MM2. is located close to strongest (sub)millimetre source...
Context. It will soon become possible to directly link the most accurate radio reference frame with Gaia optical using many common extragalactic objects. is important know level of coincidence between and positions compact active galactic nuclei (AGN). Aims. Using best catalogues available at present, we investigate how AGN significantly large optical-radio positional offsets exist as well causes these offsets. Methods. We performed a case study by finding counterparts International...
Abstract Very Long Baseline Interferometry (VLBI) astrometry is a well established technique for achieving ±10 μ as parallax accuracies at frequencies above 10 GHz. At lower frequencies, uncompensated interferometer delays associated with the ionosphere play dominant role in limiting astrometric accuracy. Multiview novel VLBI calibration method, which uses observations of multiple quasars to accurately model and remove time-variable, directional-dependent changes delay. Here we extend by...
Abstract In 2019 September, a sudden flare of the 6.7 GHz methanol maser was observed toward high-mass young stellar object (HMYSO) G24.33+0.14. This may represent fourth detection transient mass accretion event in an HMYSO after S255IR NIRS3, NGC 6334I-MM1, and G358.93−0.03-MM1. G24.33+0.14 is unique among these sources as it clearly shows repeating with 8 yr interval. Using Atacama Large Millimeter/submillimeter Array (ALMA), we millimeter continuum molecular lines pre-flare phase 2016...
Abstract One of the major puzzles in study stellar evolution is formation process bipolar and multipolar planetary nebulae. There growing consensus that collimated jets create cavities with dense walls slowly expanding (10–20 km s −1 ) envelope ejected previous evolutionary phases, leading to observed morphologies. However, launching jet way it interacts circumstellar material such asymmetric morphologies have remained poorly known. Here we present for first time CO emission from asymptotic...
Abstract The arrival of the Square Kilometer Array (SKA) will revitalize all aspects Very Long Baseline Interferometry (VLBI) astronomy at lower frequencies. In last decade, there have been huge strides toward routinely achieving high precision VLBI astrometry frequencies dominated by tropospheric contributions, most notably 22 GHz, using advanced phase-referencing techniques. Nevertheless, to increase capability for astrometric measurements low radio (<8 GHz), an effective calibration...
This paper reports observations of a 22 GHz water maser `superburst' in the G25.65+1.05 massive star forming region, conducted response to an alert from Maser Monitoring Organisation (M2O). Very long baseline interferometry (VLBI) using European VLBI Network (EVN) recorded flux density $1.2 \times 10^{4}$ Jy. The superburst was investigated spectral, structural and temporal domains its cause determined be increase path length generated by superposition multiple emitting regions aligning line...
Abstract In this paper, we report new detections of SiO v = 1 and 2 J → 0 masers in the “water fountain” source IRAS 16552−3050, which was observed with Nobeyama 45 m telescope during 2021 March–April. Water fountains are evolved stars whose H O maser spectra trace high-velocity outflows >100 km s −1 . This is second known case a water fountain, after their prototypical source, W 43A. These should shed light on evolutionary status category stars, likely to be at end asymptotic giant...
Water fountains are evolved stars showing early stages of collimated mass loss during transition from the asymptotic giant branch, providing valuable insight into formation asymmetric planetary nebulae. We report results multi-epoch VLBI observations, which determine spatial and three-dimensional kinematic structure H2O masers associated with water fountain IRAS 18113-2503. The trace three pairs high-velocity (~150-300 km/s) bipolar bow shocks on a scale 0.18'' (~2000 au). expansion...
We present the spectral and spatial evolution of H$_2$O masers associated with water fountain source IRAS 18043$-$2116 found in observations Nobeyama 45 m telescope Australia Telescope Compact Array. have new highest velocity components (at red-shifted side $V_{\rm LSR}\simeq376~\mathrm{km~s}^{-1}$ at blue-shifted LSR}\simeq$ $-165~\mathrm{km~s}^{-1}$), resulting spread $\simeq 540~\mathrm{km~s}^{-1}$ breaks speed record fast jets/outflows this type sources. The locations those offsets from...
Abstract Does a broad-line region (BLR) wind in radio-quiet (RQ) active galactic nuclei (AGN) extend to parsec scales and produce radio emission? We explore the correlations between parsec-scale BLR sample of 19 RQ Palomar–Green quasars. The is defined based on spectral slope compactness emission at 1.5–5 GHz, by excess blue wing C iv line profile. five objects with both indicators are found high Eddington ratios, L / Edd (≥0.66), eight nine neither nor winds reside low (≤0.28). This...
In this work we aimed to describe the three-dimensional morphology and kinematics of molecular gas water-fountain nebula IRAS 16342-3814. order do this, retrieved data from ALMA archive analyse it using a simple spatio-kinematical model. We used software SHAPE construct model in By reproducing intensity distribution position-velocity diagram CO emission observations derived velocity field gas. CO(1-0) support physical interpretation A that includes high-velocity collimated outflow embedded...
Abstract We present a kinematic study of the sub-parsec-scale radio jet galaxy 3C 84/NGC 1275 with VLBI Exploration Radio Astrometry (VERA) array at 22 GHz for 80 epochs from 2007 October to 2013 December. The averaged radial velocity bright component “C3” reference core is found be 0.27 ± 0.02 c between and This constant C3 naturally explained by advancing motion head mini-radio lobe. also find non-linear in respect core. briefly discuss possible origins this motion.
Abstract Active galactic nuclei (AGN) have been observed as far redshift $z \sim 7$ . They are crucial in investigating the early Universe well growth of supermassive black holes at their centres. Radio-loud AGN with jets seen a small viewing angle called blazars and show relativistic boosting emission. Thus, apparently brighter easier to detect high-redshift Universe. DES J014132.4–542749.9 is radio-luminous but X-ray weak blazar candidate = 5$ We conducted high-resolution radio...
Abstract This paper describes an overview of the FLASHING (Finest Legacy Acquisitions SiO-/H2O-maser Ignitions by Nobeyama Generation) project promoted using 45 m telescope Radio Observatory, which aims to intensively monitor H2O (at 22 GHz) and SiO 43 masers associated with so-called “water fountain” sources. Here we show scientific results based on data taken in first five seasons FLASHING, from 2018 December 2023 April. We evolution maser spectra, discovering new spectral components that...
Abstract We discovered new high-velocity components of H2O maser emission in one the “water fountain” sources, IRAS 18286−0959, which has been monitored using Nobeyama 45 m telescope FLASHING (Finest Legacy Acquisitions SiO- and H2O-maser Ignitions by Generation) project since 2018 December. The spectra show with extremely high expansion velocities (&gt;200 km s−1 projected line sight), some are located symmetrically spectrum respect to systemic velocity. They were also mapped KaVA (KVN...
Abstract We report on the measurement of trigonometric parallaxes 1612 MHz hydroxyl masers around two asymptotic giant branch stars, WX Psc and OH 138.0+7.2, using NRAO Very Long Baseline Array with in-beam phase referencing calibration. obtain a 3 σ upper limit ≤5.3 mas parallax Psc, corresponding to lower distance estimate ≳190 pc. The obtained 138.0+7.2 is 0.52 ± 0.09 (±18%), <?CDATA ${1.9}_{-0.3}^{+0.4}\,\mathrm{kpc}$?> , making this first maser below one milliarcsecond. also introduce...
We have performed a molecular line search toward the flaring 6.7-GHz masers G24.33+0.13 and G359.62-0.24 using Australia Telescope Compact Array. present spectra of class~II methanol 22.2-GHz water these sources provide comparison with other recent events experienced. also detect fourth example 23.4-GHz class~I maser, eleventh 4.8-GHz formaldehyde maser G24.33+0.13. Alongside results, we observe previously detected ammonia (3,3) emission report upper limits on presence various cm-wavelength...
We present the first results from Southern Hemisphere Parallax Interferometric Radio Astrometry Legacy Survey (\spirals): $10\mu$as-accurate parallaxes and proper motions for two southern hemisphere 6.7 GHz methanol masers obtained using inverse MultiView calibration method. Using an array of radio telescopes in Australia New Zealand, we measured trigonometric parallax associated with star formation region G232.62+00.99 $\pi = 0.610\pm0.011$~mas, $\mu_x=-2.266\pm0.021$~mas~y$^{-1}$...
This chapter summarizes radio astrometry in relation to current very long baseline interferometry (VLBI) projects and describes its perspectives with the SKA. The scientific goals of SKA have been discussed international Japanese communities researchers, whose major issues are shown here. We demonstrated some issues, such as censuses possible targets technical feasibility frequency bands. preliminary results our case studies on also presented. In addition, synergy commensality astrometric...
We present the first results from Southern Hemisphere Parallax Interferometric Radio Astrometry Legacy Survey (\spirals): $10μ$as-accurate parallaxes and proper motions for two southern hemisphere 6.7 GHz methanol masers obtained using inverse MultiView calibration method. Using an array of radio telescopes in Australia New Zealand, we measured trigonometric parallax associated with star formation region G232.62+00.99 $π= 0.610\pm0.011$~mas, $μ_x=-2.266\pm0.021$~mas~y$^{-1}$...