The parallax and 3D kinematics of water masers in the massive star-forming region G034.43+0.24
Xiaofeng Mai, Bo Zhang, M. J. Reid, L. Moscadelli, Shuangjing Xu, Yan Sun, Jingdong Zhang, Wen Chen, Shiming Wen, Qiuyi Luo, Karl M. Menten, Xingwu Zheng, Andre… 展开作者
Xiaofeng Mai, Bo Zhang, M. J. Reid, L. Moscadelli, Shuangjing Xu, Yan Sun, Jingdong Zhang, Wen Chen, Shiming Wen, Qiuyi Luo, Karl M. Menten, Xingwu Zheng, Andreas Brunthaler, Ye Xu, Guangli Wang
We report a trigonometric parallax measurement of 22 GHz water masers in the massive star-forming region G034.43+0.24 as part of the Bar and Spiral Structure Legacy (BeSSeL) Survey using the Very Long Baseline Array. The parallax is 0.330$\pm$50.018 mas, corresponding to a distance of $3.03^{+0.17}_{-0.16}$ kpc. This locates G034.43+0.24 near the inner edge of the Sagittarius spiral arm and at one end of a linear distribution of massive young stars which cross nearly the full width of the arm. The measured 3-dimensional motion of G034.43+0.24 indicates a near-circular Galactic orbit. The water masers display arc-like distributions, possibly bow shocks, associated with winds from one or more massive young stars.
We report results of astrometric VLBI observations toward a Mira variable star BX~Cam using the VLBI array "VERA". The observations were performed from February 2012 to November 2014. Obtained parallax is 1.73$\pm$0.03 mas corresponding to a distance of 0.58$\pm$0.01 kpc. Parallax of this source was also reported in Gaia DR2 as 4.13$\pm$0.25 mas, and there is a 240 \% difference between these two measurements. Astrometric results from our VLBI observations show that we exactly traced angular motions of the seven maser spots in BX~Cam. We calculated stellar luminosities using both parallaxes, a…
We have studied the kinematics of Galactic masers and radio stars with measured VLBI trigonometric parallaxes and proper motions. We have considered masers with relative trigonometric parallax errors less than 10\% and determined the Galactic rotation parameters from them. In particular, the linear rotation velocity of the Galaxy at the solar distance $R_0$ has been found to be $244.4\pm4.3$ km s$^{-1}$ (for the adopted $R_0=8.1\pm0.1$ kpc). We have performed a joint and separate spectral analysis of the radial, residual tangential, and vertical maser velocities. For example, from the vertical…
Trigonometric Parallaxes of Maser Sources toward the Far Side of the Milky Way
Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；State Key Laboratory of Radio Astronomy and Technology, Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台射电天文与技术重点实验室）；University of Science and Technology of China（中国科学技术大学）；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）
We report VLBI monitoring observations of the 22 GHz water (H$_{2}$O) masers around the Mira variable BX Cam, which were carried out as a part of the EAVN Synthesis of Stellar Maser Animations (ESTEMA) project. Data of 37 epochs in total were obtained from 2018 May to 2021 June with a time interval of 3-4 weeks, spanning approximately three stellar pulsation periods ($P= \sim$440 d). In particular, the dual-beam system equipped on the VERA stations was used to measure the kinematics and parallaxes of the H$_{2}$O maser features. The measured parallax, $π=1.79\pm 0.08$ mas, is consistent with $…
We present multi-epoch observations with the VLBA of SiO maser emission in the v=1, J=1-0 transition at 43 GHz from the remnant of the red nova V838 Mon. We model the positions of maser spots to derive a parallax of 0.166+/-0.060 mas. Combining this parallax with other distance information results in a distance of 5.6+/-0.5 kpc, which agrees with an independent geometric distance of 6.1+/-0.6 kpc from modeling polarimetry images of V838 Mon's light echo. Combining these results, and including a weakly constraining Gaia DR2 parallax, yields a best estimate of distance of 5.9+/-0.4 kpc. The mase…
Based on the long-term monitoring data of the water maser since 2019.0 to 2021.0 allowed us detecting in IRAS 16293-2422 two powerful phenomena lasted about year at radial velocities near 6 and 8 km s$^{-1}$. In both cases, powerful short flares were located on the tops of less powerful, but more prolonged ones (2.5 and 0.5 kJy), radiation of which initiated the emission of more powerful flares. For the first time, configurations of several emitting maser spots located at the line of sight to the observer were discovered experimentally. This made it possible to confirm the hypothesis of activa…
The extraordinary outburst in the massive protostellar system NGC6334I-MM1: Flaring of the water masers in a north-south bipolar outflow driven by MM1B
We report VLBA observations of 22 GHz H$_{2}$O and 43 GHz SiO masers toward the Mira variable RR Aql. By fitting the SiO maser emission to a circular ring, we estimate the absolute stellar position of RR Aql and find agreement with Gaia astrometry to within the joint uncertainty of $\approx1$ mas. Using the maser astrometry we measure a stellar parallax of 2.44 $\pm$ 0.07 mas, corresponding to a distance of 410$^{+12}_{-11}$ pc. The maser parallax deviates significantly from the Gaia EDR3 parallax of 1.95 $\pm$ 0.11 mas, indicating a $3.8σ$ tension between radio and optical measurements. This …
Estimating the distances to asymptotic giant branch (AGB) stars using optical measurements of their parallaxes is not straightforward because of the large uncertainties introduced by their dusty envelopes, their large angular sizes, and their surface brightness variability. We compared the parallaxes from Gaia DR3 with parallaxes measured with maser observations with very long baseline interferometry (VLBI) to determine a statistical correction factor for the DR3 parallaxes using a sub-sample of 33 maser-emitting oxygen-rich nearby AGB stars. We found that the nominal errors on the Gaia DR3 pa…
The massive young stellar object (MYSO) G358.93-0.03-MM1 showed an extraordinary near-infrared- to (sub-)millimetre-dark and far-infrared-loud accretion burst, which is closely associated with flares of several class II methanol maser transitions, and, later, a 22 GHz water maser flare. Water maser flares provide an invaluable insight into ejection events associated with accretion bursts. Although the short timescale of the 22 GHz water maser flare made it impossible to carry out a very long baseline interferometry observation, we could track it with the Karl G. Jansky Very Large Array (VLA). …
Here we aim to characterise submillimetre water masers at 437, 439, 471, and 474 GHz towards a sample of evolved stars. We used the Atacama Pathfinder Experiment (APEX) to observe submillimetre water transitions and the CO (4-3) line towards 11 evolved stars. The sample included semi-regular and Mira variables, plus a red supergiant star. We performed radiative transfer modelling for the water masers. We also used the CO observations to determine mass loss rates for the stars. From the sample of 11 evolved stars, 7 display one or more of the masers at 437, 439, 471, and 474 GHz. We therefore f…
This paper reports observations of a 22 GHz water maser `superburst' in the G25.65+1.05 massive star forming region, conducted in response to an alert from the Maser Monitoring Organisation (M2O). Very long baseline interferometry (VLBI) observations using the European VLBI Network (EVN) recorded a maser flux density of $1.2 \times 10^{4}$ Jy. The superburst was investigated in the spectral, structural and temporal domains and its cause was determined to be an increase in maser path length generated by the superposition of multiple maser emitting regions aligning in the line of sight to the ob…
We investigate the kinematics of high mass protostellar objects within the high mass star forming region IRAS 19410+2336. We performed high angular resolution observations of 6.7-GHz methanol and 22 GHz water masers using the MERLIN (Multi-Element Radio Linked Interferometer Network) and e-MERLIN interferometers. The 6.7-GHz methanol maser emission line was detected within the $\sim$ 16--27 km s$^{-1}$ velocity range with a peak flux density $\sim$50 Jy. The maser spots are spread over $\sim$1.3 arcsec on the sky, corresponding to $\sim$2800 au at a distance of 2.16 kpc. These are the first as…
Following an eruptive accretion event in NGC6334I-MM1, flares in the various maser species, including water masers, were triggered. We report the observed relative proper motion of the highly variable water masers associated with the massive star-forming region, NGC6334I. High velocity H$_2$O maser proper motions were detected in 5 maser clusters, CM2-W2 (bow-shock structure), MM1-W1, MM1-W3, UCHII-W1 and UCHII-W3. The overall average of the derived relative proper motion is 85 km s$^{-1}$. This mean proper motion is in agreement with the previous results from VLA multi-epoch observations. Our…
Sharpless 269 (S269) is one of a few HII regions in the outer spiral arm of the Milky Way with strong water maser emission. Based on data from the Very Long Baseline Interferometry (VLBI) Exploration of Radio Astrometry (VERA) array, two parallax measurements have been published, which differ by nearly $2σ$. Each distance estimate supports a different structure for the outer arm. Moreover, given its large Galactocentric radii, S269 has special relevance as its proper motion and parallax have been used to constrain the Galactic rotation curve at large radii. Using recent Very Long Baseline Arra…
An updated model for the Perseus Spiral Arm from Trigonometric Parallax and 3-dimensional kinematic distances of distant massive stars
University of Tasmania（塔斯马尼亚大学）；International Centre for Radio Astronomy Research, The University of Western Australia（西澳大利亚大学国际射电天文研究中心）；Nanjing University（南京大学）
We wish to perform a statistical study of the location and motion of individual 22 GHz water maser cloudlets, characterized by sizes that are within a few au, with respect to the radio thermal emission from young stellar objects (YSO). For this purpose, we have been carrying out the Protostellar Outflows at the EarliesT Stages (POETS) survey of a sample (38) of high-mass YSOs. The water maser positions and three-dimensional (3D) velocities were determined through Very Long Baseline Array observations with accuracies of a few milliarcsec (mas) and a few km/s, respectively. The position of the i…
Using the Karl G. Jansky Very Large Array (VLA), we have conducted a survey for 22 GHz, 6_{1,6}-5_{2,3} H2O masers toward the Serpens South region. The masers were also observed with the Very Long Baseline Array (VLBA) following the VLA detections. We detect for the first time H2O masers in the Serpens South region that are found to be associated to three Class 0-Class I objects, including the two brightest protostars in the Serpens South cluster, known as CARMA-6 and CARMA-7. We also detect H2O masers associated to a source with no outflow or jet features. We suggest that this source is most …
Measuring Magnetic Fields from Water Masers in the Synchrotron Protostellar Jet in W3(H$_2$O)
我们报告了对W3（OH）大质量恒星形成复合体中Turner-Welch天体水脉泽的全偏振VLBA观测。这个对象驱动的同步加速器喷流，这是非常特殊的高质量的原恒星，并与强极化水脉泽源，W3（H $_2$ O），使其成为最佳的目标，调查的作用磁场的原恒星磁盘喷流系统的最内层尺度。水脉泽的线偏振辐射提供了局部磁场方向的线索，而圆偏振的塞曼分裂的测量提供了它的强度。水脉泽追踪同步加速器喷流中心的双极、双锥形外流。虽然在几千天文单位的尺度上，从脉泽推断出的磁场平均沿流轴取向，但在更小的尺度上（10秒到100秒天文单位），我们揭示了磁场和速度矢量之间的不对准，这是由于场分量沿激波阵面的压缩引起的。我们的测量结果支持这样一种情况，即磁场将从具有平行于冲击前气体流出速度的主导分量演变而来，其场强为几十mG（密度为$10^7$ cm $^{-3}$），主要由水脉泽激发处的激波后气体中几百mG量级的垂直分量所支配（密度为$10^9$ cm $^{-3}$）。一般的含义是，在未受干扰的（即未受冲击的）拱星气体中，流速将紧密地跟随磁场线，而在受prostostellar喷流冲击的气体中，磁场将重新配置为平行于冲击波阵面。
Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic masers associated with massive protostars and stars in active star-forming regions. It also includes young low-mass stars from the Gould Belt region whose radio observations were performed in continuum. Based on this, most complete sample of sources to date, we have estimated the velocities $(U,V,W)_\odot$ and the parameters of the angular velocity of Galactic rotation $Ω_0, Ω^{(1)}_0, ... , Ω^{(4)}_0$ and obtained a new …
Context. The astrometric satellite Gaia is expected to significantly increase our knowledge as to the properties of the Milky Way. The Gaia Early Data Release 3 (Gaia EDR3) provides the most precise parallaxes for many OB stars, which can be used to delineate the Galactic spiral structure. Aims. We investigate the local spiral structure with the largest sample of spectroscopically confirmed young OB stars available to date, and we compare it with what was traced by the parallax measurements of masers. Methods. A sample consisting of three different groups of massive young stars, including O-B2…
