scholarly journals Annual parallax measurement of the Mira variable star BX Camelopardalis with VERA

2020 ◽  
Vol 72 (4) ◽  
Author(s):  
Masako Matsuno ◽  
Akiharu Nakagawa ◽  
Atsushi Morita ◽  
Tomoharu Kurayama ◽  
Toshihiro Omodaka ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Variable Star ◽  
Three Dimensional ◽  
Maximum Flux ◽  
V Band ◽  
The North ◽  
Mira Variable ◽  
Vlbi Observations ◽  
Time Variations ◽  
Gaia Dr2

Abstract We report the results of astrometric VLBI observations toward the Mira variable star BX Cam using the VERA VLBI array. The observation was performed from 2012 February to 2014 November. The parallax obtained is 1.73 ± 0.03 mas corresponding to a distance of 0.58 ± 0.01 kpc. The parallax of this source was reported in Gaia DR2 as 4.13 ± 0.25 mas, and there is a 240% difference between these two measurements. Astrometric results from our VLBI observations show that we exactly traced the angular motions of the seven maser spots in BX Cam. We calculated the stellar luminosities using both parallaxes, and obtained luminosities of $L_{\ast }^{\mathrm{VERA}} = 4950\pm 170\, L_{\odot }$ and $L_{\ast }^{\mathrm{Gaia}} = 870\pm 110\, L_{\odot }$. These deduced luminosities also support the validity of the parallax that we determined with VERA. Evaluating the two parallaxes, we conclude that the parallax of 1.73 ± 0.03 mas from the VERA observations is correct for BX Cam. We obtained the systemic motion of BX Cam as (μαcos δsys, ${\mu }_{\delta }^{\mathrm{sys}}$) = (13.48 ± 0.14, −34.30 ± 0.18) mas yr−1. The total of 73 H2O maser spots detected from our VLBI observations shows a spatial distribution of 30 au × 80 au, with a strong elongation along the north–south direction. They show outflows with a three-dimensional velocity of 14.79 ± 1.40 km s−1. From a comparison between the time variations of the V-band magnitudes and the H2O masers, we found that the variation of the H2O masers is relevant to that seen in the V band even though the H2O masers do not recover their maximum flux in each cycle.

3D asymmetrical kinematics of mono-age populations from LAMOST and Gaia common red clump stars

2019 ◽  
Vol 14 (S353) ◽  
pp. 19-21
Author(s):  
H.-F. Wang ◽  
Martn López-Corredoira ◽  
Y. Huang ◽  
Jeffrey L. Carlin
Keyword(s):  
Three Dimensional ◽  
Azimuthal Velocity ◽  
Giant Stars ◽  
The North ◽  
North Side ◽  
Outer Disk ◽  
Bending Mode ◽  
Red Clump ◽  
Gaia Dr2 ◽  
South Asymmetry

AbstractWith the LAMOST DR4 and Gaia DR2 common red clump giant stars, we investigate the three-dimensional kinematics of Milky Way disk stars in mono-age populations between Galactocentric distances of R = 6 and 15 kpc. We confirm the 3D asymmetrical motions of recent works, and provide time tagging of the Galactic outer disk asymmetrical motions. Radial motions present a north-south asymmetry in the region corresponding to recent density and velocity substructures that were sensitive to the perturbations in the early 6 Gyr. What’s more, we discover a new velocity substructure in the north side corresponding to density dip found recently (“south-middle opposite”) in the radial and azimuthal velocity. Meanwhile, the vertical velocity with clear vertical bulk motions or bending mode motions has no clear asymmetry corresponding to the in-plane asymmetrical features.

scholarly journals Spatial Distribution of Lichens in Metrosideros excelsa in Northern New Zealand Urban Forests

Diversity ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 170
Author(s):  
Gladys N. Benitez ◽  
Glenn D. Aguilar ◽  
Dan Blanchon
Keyword(s):  
Spatial Distribution ◽  
Species Richness ◽  
New Zealand ◽  
Lichen Species ◽  
Positive Correlation ◽  
Breast Height ◽  
Lichen Community ◽  
The North ◽  
The City ◽  
Lichen Flora

The spatial distribution of corticolous lichens on the iconic New Zealand pōhutukawa (Metrosideros excelsa) tree was investigated from a survey of urban parks and forests across the city of Auckland in the North Island of New Zealand. Lichens were identified from ten randomly selected trees at 20 sampling sites, with 10 sites classified as coastal and another 10 as inland sites. Lichen data were correlated with distance from sea, distance from major roads, distance from native forests, mean tree DBH (diameter at breast height) and the seven-year average of measured NO2 over the area. A total of 33 lichen species were found with coastal sites harboring significantly higher average lichen species per tree as well as higher site species richness. We found mild hotspots in two sites for average lichen species per tree and another two separate sites for species richness, with all hotspots at the coast. A positive correlation between lichen species richness and DBH was found. Sites in coastal locations were more similar to each other in terms of lichen community composition than they were to adjacent inland sites and some species were only found at coastal sites. The average number of lichen species per tree was negatively correlated with distance from the coast, suggesting that the characteristic lichen flora found on pōhutukawa may be reliant on coastal microclimates. There were no correlations with distance from major roads, and a slight positive correlation between NO2 levels and average lichen species per tree.

scholarly journals Spatial Distribution and Geographical Mechanism of Natural Resources in China under the Orientation of the New Economic Demands

2021 ◽  
Vol 13 (14) ◽  
pp. 7956
Author(s):  
Xiangmin Zhang ◽  
Bin Yu ◽  
Hailong Yu ◽  
Zhuofan Li ◽  
Shen Luo ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Natural Resources ◽  
New Economy ◽  
The South ◽  
The North ◽  
Ecological Resources ◽  
Demand Structure ◽  
Administrative Units ◽  
Location Map ◽  
Resource Elements

The demand structure of resources for new economy is different from the traditional one in that its development may significantly change China’s economic location map and spatial pattern. Based on 343 administrative units of prefecture-level cities in China, this research constructs the measurement index system of terrestrial surface natural resources under the orientation of the new economic demands; this research mainly analyses the spatial distribution characteristics and geographical mechanism of natural resources by means of the spatial autocorrelation and spatial similarity calculation methods. The results show that: (1) The structure and endowment of natural resources under the orientation of the new economic demands need to be reexamined. The significance of a good environment and ecological resources has been highlighted. The coupling of resource elements better reveals the availability of natural resources. (2) The natural resources decrease from southeast to northwest, showing a pattern of “abundant in the south and east and scarce in the north and west”. Natural resources have a significant positive correlation in spatial distribution with two types of agglomeration: high-high agglomeration and low-low agglomeration, showing the local agglomeration feature of “high in the south and low in the north”. (3) Natural factors such as temperature, precipitation and altitude affect the spatial distribution of natural resources, with the temperature being the most significant. This indicates that the original natural environment and its role are the geographical mechanism for the formation and distribution of natural resources. The results could provide a reference for the development and the optimization of China’s new economy.

scholarly journals Three-dimensional deformation time series of glacier motion from multiple-aperture DInSAR observation

2019 ◽  
Vol 93 (12) ◽  
pp. 2651-2660 ◽  
Author(s):  
Sergey Samsonov
Keyword(s):  
Time Series ◽  
Surface Deformation ◽  
Ground Deformation ◽  
Three Dimensional ◽  
Data Sets ◽  
Ice Flow ◽  
The North ◽  
Glacier Ice ◽  
Deformation Component ◽  
3D Deformation

AbstractThe previously presented Multidimensional Small Baseline Subset (MSBAS-2D) technique computes two-dimensional (2D), east and vertical, ground deformation time series from two or more ascending and descending Differential Interferometric Synthetic Aperture Radar (DInSAR) data sets by assuming that the contribution of the north deformation component is negligible. DInSAR data sets can be acquired with different temporal and spatial resolutions, viewing geometries and wavelengths. The MSBAS-2D technique has previously been used for mapping deformation due to mining, urban development, carbon sequestration, permafrost aggradation and pingo growth, and volcanic activities. In the case of glacier ice flow, the north deformation component is often too large to be negligible. Historically, the surface-parallel flow (SPF) constraint was used to compute the static three-dimensional (3D) velocity field at various glaciers. A novel MSBAS-3D technique has been developed for computing 3D deformation time series where the SPF constraint is utilized. This technique is used for mapping 3D deformation at the Barnes Ice Cap, Baffin Island, Nunavut, Canada, during January–March 2015, and the MSBAS-2D and MSBAS-3D solutions are compared. The MSBAS-3D technique can be used for studying glacier ice flow at other glaciers and other surface deformation processes with large north deformation component, such as landslides. The software implementation of MSBAS-3D technique can be downloaded from http://insar.ca/.

scholarly journals Three-Dimensional Spatial Distribution of Synapses in the Neocortex: A Dual-Beam Electron Microscopy Study

2013 ◽  
Vol 24 (6) ◽  
pp. 1579-1588 ◽  
Author(s):  
Angel Merchán-Pérez ◽  
José-Rodrigo Rodríguez ◽  
Santiago González ◽  
Víctor Robles ◽  
Javier DeFelipe ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
Three Dimensional ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Beam Electron ◽  
Dual Beam

Obstacle drag in stratified flow

1990 ◽  
Vol 429 (1876) ◽  
pp. 119-140 ◽  
Keyword(s):  
Experimental Study ◽  
Linear Density ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Force Balance ◽  
Video Recordings ◽  
Lee Waves ◽  
Time Variations ◽  
Obstacle Height ◽  
Stable Linear

This paper describes an experimental study of the drag of two- and three-dimensional bluff obstacles of various cross-stream shapes when towed through a fluid having a stable, linear density gradient with Brunt-Vaisala frequency, N . Drag measurements were made directly using a force balance, and effects of obstacle blockage ( h / D , where h and D are the obstacle height and the fluid depth, respectively) and Reynolds number were effectively eliminated. It is shown that even in cases where the downstream lee waves and propagating columnar waves are of large amplitude, the variation of drag with the parameter K ( = ND /π U ) is qualitatively close to that implied by linear theories, with drag minima existing at integral values of K . Under certain conditions large, steady, periodic variations in drag occur. Simultaneous drag measurements and video recordings of the wakes show that this unsteadiness is linked directly with time-variations in the lee and columnar wave amplitudes. It is argued that there are, therefore, situations where the inviscid flow is always unsteady even for large times; the consequent implications for atmospheric motions are discussed.

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