scholarly journals Radio-continuum jets around the peculiar galaxy pair ESO 295-IG022

2010 ◽  
pp. 31-37 ◽  
Author(s):  
M.D. Filipovic ◽  
E.J. Crawford ◽  
P.A. Jones ◽  
G.L. White
Keyword(s):  
Spectral Index ◽  
Radio Continuum ◽  
Line Of Sight ◽  
Peculiar Galaxy ◽  
New Radio ◽  
High Resolution Images ◽  
Variable Flux ◽  
Jet Structure ◽  
Very High ◽  
Compact Array

We report new radio-continuum observations with the Australia Telescope Compact Array (ATCA) of the region surrounding the peculiar galaxy pair ESO 295-IG022 at the centre of the poor cluster Abell S0102. We observed this cluster at wavelengths of ?=20/13 and 6/3 cm with the ATCA 6 km array. With these configurations, we achieved a resolution of ~2'' at 3 cm which is sufficient to resolve the jet-like structure of ~3' length detected at 20 cm. From our new high resolution images at 6 and 3 cm we confirm the presence of a double jet structure, most likely originating from the northern galaxy (ESO 295-IG022-N), bent and twisted towards the south. We found the spectral index of the jet to be very steep (?=-1.32). No point source was detected that could be associated with the core of ESO 295-IG022-N. On the other hand, ESO 295-IG022-S does not show any jet structure, but does show a point radio source. This source has variable flux and spectral index, and appears to be superposed on the line-of-sight of the jets (seen at 20-cm) originating from the northern galaxy ESO 295-IG022-N. Finally, regions of very high and somewhat well ordered polarization were detected at the level of 70%.

scholarly journals Radio Continuum Observations of NGC 1961: Interaction with the Intergalactic Medium or the Remnant of a Merger?

1999 ◽  
Vol 186 ◽  
pp. 132-132
Author(s):  
U. Lisenfeld ◽  
P. Alexander ◽  
G. Pooley
Keyword(s):  
Intergalactic Medium ◽  
Radio Continuum ◽  
Sharp Edge ◽  
The South ◽  
Dynamical Mass ◽  
Peculiar Galaxy ◽  
North West ◽  
The North ◽  
New Radio ◽  
Optical Appearance

We present new radio continuum images of the supermassive, peculiar galaxy NGC 1961 at 1.5, 4.9, 8.4 and 15 GHz. NGC 1961 (Arp 184) is a very massive (dynamical mass > 1012M⊙) Sb galaxy with a peculiar and asymmetric optical appearance. Furthermore, it exhibits an unusual, asymmetric HI distribution with an extensive wing of gas extending 30 kpc to the north-west and a sharp edge to the south-east (Shostak et al. 1982).

Bipolar outflow of gas in the spiral galaxy NGC 3079

1986 ◽  
Vol 64 (4) ◽  
pp. 531-535 ◽  
Author(s):  
Nebojsa Duric ◽  
E. R. Seaquist
Keyword(s):  
Spectral Index ◽  
Spiral Galaxy ◽  
Central Region ◽  
Qualitative Description ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Bipolar Outflow ◽  
The Galaxy

Very large array, radio-continuum observations of the edge-on spiral galaxy NGC 3079 are presented. The observations reveal that the nucleus has windlike properties and that the central region of the galaxy exhibits an unusual figure-eight morphology that shows evidence of severe depolarization and a flattening spectral index away from the nucleus. A qualitative description of a model is presented to account for the observed radio properties. It is shown that a wind-driven shock propagating away from the nucleus and focused by the ambient disk gas can give rise to the observed morphology.

scholarly journals Mask R-CNN and OBIA Fusion Improves the Segmentation of Scattered Vegetation in Very High-Resolution Optical Sensors

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 320
Author(s):  
Emilio Guirado ◽  
Javier Blanco-Sacristán ◽  
Emilio Rodríguez-Caballero ◽  
Siham Tabik ◽  
Domingo Alcaraz-Segura ◽  
...  
Keyword(s):  
High Resolution ◽  
Optical Sensors ◽  
Biotic Interactions ◽  
Relevant Information ◽  
Vegetation Monitoring ◽  
Object Based Image Analysis ◽  
Object Based ◽  
Segmentation Methods ◽  
High Resolution Images ◽  
Very High

Vegetation generally appears scattered in drylands. Its structure, composition and spatial patterns are key controls of biotic interactions, water, and nutrient cycles. Applying segmentation methods to very high-resolution images for monitoring changes in vegetation cover can provide relevant information for dryland conservation ecology. For this reason, improving segmentation methods and understanding the effect of spatial resolution on segmentation results is key to improve dryland vegetation monitoring. We explored and analyzed the accuracy of Object-Based Image Analysis (OBIA) and Mask Region-based Convolutional Neural Networks (Mask R-CNN) and the fusion of both methods in the segmentation of scattered vegetation in a dryland ecosystem. As a case study, we mapped Ziziphus lotus, the dominant shrub of a habitat of conservation priority in one of the driest areas of Europe. Our results show for the first time that the fusion of the results from OBIA and Mask R-CNN increases the accuracy of the segmentation of scattered shrubs up to 25% compared to both methods separately. Hence, by fusing OBIA and Mask R-CNNs on very high-resolution images, the improved segmentation accuracy of vegetation mapping would lead to more precise and sensitive monitoring of changes in biodiversity and ecosystem services in drylands.

Hands Stencils in El Castillo Cave (Puente Viesgo, Cantabria, Spain). An Interdisciplinary Study

2021 ◽  
pp. 1-21
Author(s):  
Sergio Ripoll ◽  
Vicente Bayarri ◽  
Francisco J. Muñoz ◽  
Ricardo Ortega ◽  
Elena Castillo ◽  
...  
Keyword(s):  
High Resolution ◽  
Real Data ◽  
Digital Processing ◽  
The Other ◽  
Major Step ◽  
The People ◽  
High Resolution Images ◽  
Real Picture ◽  
Interdisciplinary Study ◽  
Very High

Our Palaeolithic ancestors did not make good representations of themselves on the rocky surfaces of caves and barring certain exceptions – such as the case of La Marche (found on small slabs of stone or plaquettes) or the Cueva de Ambrosio – the few known examples can only be referred to as anthropomorphs. As such, only hand stencils give us a real picture of the people who came before us. Hand stencils and imprints provide us with a large amount of information that allows us to approach not only their physical appearance but also to infer less tangible details, such as the preferential use of one hand over the other (i.e., handedness). Both new and/or mature technologies as well as digital processing of images, computers with the ability to process very high resolution images, and a more extensive knowledge of the Palaeolithic figures all help us to analyse thoroughly the hands in El Castillo cave. The interdisciplinary study presented here contributes many novel developments based on real data, representing a major step forward in knowledge about our predecessors.

scholarly journals Radio continuum observations of massive stars in open cluster NGC 6231 and the Sco OB1 association

2003 ◽  
Vol 212 ◽  
pp. 230-231 ◽  
Author(s):  
Diah Y.A. Setia Gunawan ◽  
Jessica M. Chapman ◽  
Ian R. Stevens ◽  
Gregor Rauw ◽  
Claus Leitherer
Keyword(s):  
Massive Stars ◽  
Open Cluster ◽  
Radio Continuum ◽  
Spectral Indices ◽  
Program Show ◽  
Compact Array

We present results of the Australia Telescope Compact Array (ATCA) radio continuum observations of massive stars in the Sco OB1 association. Most stars detected in the program show spectral indices lower than value expected from thermal free-free emission.

scholarly journals Thermal radio absorption as a tracer of the interaction of SNRs with their environments

2021 ◽  
Vol 653 ◽  
pp. A62
Author(s):  
G. Castelletti ◽  
L. Supan ◽  
W. M. Peters ◽  
N. E. Kassim
Keyword(s):  
Spectral Index ◽  
Supernova Remnants ◽  
Surrounding Medium ◽  
Low Frequency ◽  
Power Laws ◽  
Line Of Sight ◽  
Pulsar Wind Nebulae ◽  
Very Large Array ◽  
Murchison Widefield Array ◽  
Thermal Absorption

We present new images and continuum spectral analysis for 14 resolved Galactic supernova remnants (SNRs) selected from the 74 MHz Very Large Array Low-Frequency Sky Survey Redux (VLSSr). We combine new integrated measurements from the VLSSr with, when available, flux densities extracted from the Galactic and Extragalactic All-Sky Murchison Widefield Array Survey and measurements from the literature to generate improved integrated continuum spectra sampled from ~15 MHz to ~217 GHz. We present the VLSSr images. When possible we combine them with publicly available images at 1.4 GHz, to analyse the resolved morphology and spectral index distribution across each SNR. We interpret the results and look for evidence of thermal absorption caused by ionised gas either proximate to the SNR itself, or along its line of sight. Three of the SNRs, G4.5+6.8 (Kepler), G28.6−0.1, and G120.1+1.4 (Tycho), have integrated spectra which can be adequately fit with simple power laws. The resolved spectral index map for Tycho confirms internal absorption which was previously detected by the Low Frequency Array, but it is insufficient to affect the fit to the integrated spectrum. Two of the SNRs are pulsar wind nebulae, G21.5−0.9 and G130.7+3.1 (3C 58). For those we identify high-frequency spectral breaks at 38 and 12 GHz, respectively. For the integrated spectra of the remaining nine SNRs, a low frequency spectral turnover is necessary to adequately fit the data. In all cases we are able to explain the turnover by extrinsic thermal absorption. For G18.8+0.3 (Kes 67), G21.8−0.6 (Kes 69), G29.7−0.3 (Kes 75), and G41.1−0.3 (3C 397), we attribute the absorption to ionised gas along the line of sight, possibly from extended H II region envelopes. For G23.3−0.3 (W41) the absorption can be attributed to H II regions located in its immediate proximity. Thermal absorption from interactions at the ionised interface between SNR forward shocks and the surrounding medium were previously identified as responsible for the low frequency turnover in SNR G31.9+0.0 (3C 391); our integrated spectrum is consistent with the previous results. We present evidence for the same phenomenon in three additional SNRs G27.4+0.0 (Kes 73), G39.2–0.3 (3C 396), and G43.3–0.2 (W49B), and derive constraints on the physical properties of the interaction. This result indicates that interactions between SNRs and their environs should be readily detectable through thermal absorption by future low frequency observations of SNRs with improved sensitivity and resolution.

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