scholarly journals On The Radio Emission From Some Peculiar Galaxies

1966 ◽  
Vol 19 (4) ◽  
pp. 565 ◽  
Keyword(s):  
Radio Emission ◽  
Optical Spectra ◽  
Emission Lines ◽  
Relativistic Electrons ◽  
Radio Observations ◽  
Central Regions ◽  
The University ◽  
East West ◽  
Peculiar Galaxies

Radio observations have been made of 18 galaxies whose spectra and colours in their central regions are abnormal for their morphological types (Markarian 1963). Observations at 1410 and 2650 Mcls were made with the CSIRO 210 ft steerab1e telescope at Parkes, and at 408 Mcls with the east-west arm of the Mills Cross at the Molonglo Observatory of the University of Sydney. Radio emission was detected from the central regions of 13 of these galaxies. For these 13 the radio index (mr-mpg) is about 1�2 and differs by IiLbout two magnitudes from that of normal spirals. Absolute radio magnitudes of the galaxies are about -21�0. In most cases the presence of radio emission is accompanied by emission lines in the optical spectra. It is concluded that the enhanced radio emission of the galaxies investigated is due to the production of relativistic electrons in their active nuclei.

scholarly journals Radio Emission of 158 Galaxies

1968 ◽  
Vol 21 (2) ◽  
pp. 193 ◽  
Author(s):  
HM Tovmassian
Keyword(s):  
Radio Emission ◽  
Radio Telescope ◽  
Spiral Galaxies ◽  
Radio Observations ◽  
Central Regions ◽  
The University ◽  
East West

Radio observations of Hi8 mainly spiral galaxies have been made at 21 em and additional observations have been made for some at 11 and 75 em. The observations at 11 and 21 cm were made with the CSIR<z 210 ft radio telescope at Parkes and those at 75 cm with the east-west arm of the Mills Cross at the Molonglo Observatory of the University of Sydney. Radio emission was detected from central regions of 20 of the galaxies.

Discovery of five new Galactic symbiotic stars in the VPHAS+ survey

2021 ◽  
Vol 502 (2) ◽  
pp. 2513-2517
Author(s):  
Stavros Akras ◽  
Denise R Gonçalves ◽  
Alvaro Alvarez-Candal ◽  
Claudio B Pereira
Keyword(s):  
Spectroscopic Data ◽  
Selection Criterion ◽  
Optical Spectra ◽  
Emission Lines ◽  
High Rate ◽  
Symbiotic Stars ◽  
Selection Of

ABSTRACT We report the validation of a recently proposed infrared (IR) selection criterion for symbiotic stars (SySts). Spectroscopic data were obtained for seven candidates, selected from the SySt candidates of Akras et al. by employing the new supplementary IR selection criterion for SySts in the VST/OmegaCAM Photometric H-Alpha Survey. Five of them turned out to be genuine SySts after the detection of H α, He ii, and [O iii] emission lines as well as TiO molecular bands. The characteristic O vi Raman-scattered line is also detected in one of these SySts. According to their IR colours and optical spectra, all five newly discovered SySts are classified as S-type. The high rate of true SySts detections of this work demonstrates that the combination of the H α emission and the new IR criterion improves the selection of target lists for follow-up observations by minimizing the number of contaminants and optimizing the observing time.

scholarly journals High-sensitivity radio study of the non-thermal stellar bow shock EB27

2021 ◽  
Author(s):  
Paula Benaglia ◽  
Santiago del Palacio ◽  
Christopher Hales ◽  
Marcelo E Colazo
Keyword(s):  
Radio Emission ◽  
Massive Star ◽  
High Sensitivity ◽  
Bow Shock ◽  
Relativistic Electrons ◽  
Polarimetric Observation ◽  
Very Large Array ◽  
Thermal Radio Emission ◽  
The Magnetic Field ◽  
Linear Polarisation

Abstract We present a deep radio-polarimetric observation of the stellar bow shock EB27 associated to the massive star BD+43○3654. This is the only stellar bow shock confirmed to have non-thermal radio emission. We used the Jansky Very Large Array in S band (2–4 GHz) to test whether this synchrotron emission is polarised. The unprecedented sensitivity achieved allowed us to map even the fainter regions of the bow shock, revealing that the more diffuse emission is steeper and the bow shock brighter than previously reported. No linear polarisation is detected in the bow shock above 0.5%, although we detected polarised emission from two southern sources, probably extragalactic in nature. We modeled the intensity and morphology of the radio emission to better constrain the magnetic field and injected power in relativistic electrons. Finally, we derived a set of more precise parameters for the system EB27–BD+43○3654 using Gaia Early Data Release 3, including the spatial velocity. The new trajectory, back in time, intersects the core of the Cyg OB2 association.

scholarly journals Kinematics of Nuclei of Sc Galaxies

1980 ◽  
Vol 5 ◽  
pp. 191-191
Author(s):  
V. C. Rubin
Keyword(s):  
High Velocity ◽  
Stellar Population ◽  
Hii Regions ◽  
Emission Lines ◽  
High Luminosity ◽  
Rotation Curves ◽  
Velocity Gradients ◽  
Wide Range ◽  
Central Regions ◽  
Velocity Dispersions

For a sample of 21 Sc galaxies with a wide range of luminosities, of radii, and of masses, W. K. Ford and I have obtained spectra and determined rotation curves. By their kinematical behavior in their central regions, the Sc’s can be separated into two groups. Some galaxies, generally small and of low luminosity, have shallow central velocity gradients, reflecting their low central masses and densities. Other galaxies, most often large ones of high luminosity, have steep central velocity gradients. One reason this separation by central velocity gradients is of interest is because these galaxies exhibit other significant spectral differences which go hand-in-hand with the kinematical differences.The small, low luminosity galaxies show emission lines of Hα and [NII], with nuclear Ha sharp and stronger than [NII], and little or no stellar nuclear continuum, just as conventional HII regions. In contrast, the high luminosity galaxies show broad nuclear emission, with [NII] stronger than Ha. These galaxies have a strong red stellar continuum, arising from a red stellar population. The cause of the Hα[NII] intensity reversal in the nuclei of some galaxies remains unknown. However, the strong [NII] emission in generally high luminosity galaxies with massive nuclei, nuclei which show strong red continua, suggests that [Nil] intensity correlates with nuclear luminosity, and in turn with the density and velocity properties of the nuclear populations. We would expect high velocity dispersions and high bulge luminosities for galaxies with strong nuclear [NII] and steep central velocity gradients.

Conditions needed for generation of type II radio emission in the interplanetary space

2021 ◽  
Author(s):  
Immanuel Christopher Jebaraj ◽  
Athanasios Kouloumvakos ◽  
Jasmina Magdalenic ◽  
Alexis Rouillard ◽  
Vratislav Krupar ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Radio Emission ◽  
Interplanetary Space ◽  
Region Of Interest ◽  
Type Ii ◽  
Radio Observations ◽  
Wave Parameters ◽  
First Results ◽  
Radio Signature

&lt;p&gt;Eruptive events such as Coronal mass ejections (CMEs) and flares cangenerate shock waves. Tracking shock waves and predicting their arrival at Earth is a subject of numerous space weather studies. Ground-based radio observations allow us to locate shock waves in the low corona while space-based radio observations provide us opportunity to track shock waves in the inner heliosphere. We present a case study of CME/flare event, associated shock wave and its radio signature, i.e. type II radio burst.&lt;/p&gt;&lt;p&gt;In order to analyze the shock wave parameters, we employed a robust paradigm. We reconstructed the shock wave in 3D using multi-viewpoint observations and modelled the evolution of its parameters using a 3D MHD background coronal model produced by the MAS (Magnetohydrodynamics Around a Sphere).&lt;/p&gt;&lt;p&gt;To map regions on the shock wave surface, possibly associated with the electron acceleration, we combined 3D shock modelling results with the 3D source positions of the type II burst obtained using the radio triangulation technique. We localize the region of interest on the shock surface and examine the shock wave parameters to understand the relationship between the shock wave and the radio event. We analyzed the evolution of the upstream plasma characteristics and shock wave parameters during the full duration of the type II radio emission. First results indicate that shock wave geometry and its relationship with shock strength play an important role in the acceleration of electrons responsible for the generation of type II radio bursts.&lt;/p&gt;

Strengthening of a City Center Tunnel with Concrete Screw Anchors under Special Boundary Conditions

2019 ◽  
Author(s):  
Johannes Lechner ◽  
Jürgen Feix ◽  
Robert Hertle
Keyword(s):  
Ductile Failure ◽  
High Strength ◽  
Shear Capacity ◽  
City Center ◽  
Cracked Concrete ◽  
Concrete Girders ◽  
Effective Depth ◽  
The University ◽  
The City ◽  
East West

<p>The Altstadtring-Tunnel is one of the essential east-west traffic routes in the city center of Munich and was constructed in the late 1960s. Segment 34 of the tunnel was built directly underneath the existing Prince-Carl- Palais, a historic building from 1804. Therefore 15 pre-stressed concrete girders with an effective depth of</p><p>3.5 m and a maximum span of up to 30 m were built which now form the tunnel roof slab. These girders were pre-stressed with steel nowadays well known for stress corrosion cracking. A recalculation of the slab showed that no ductile failure can be guaranteed in case of a progressive rupture of the tendons. Therefore, a concept for strengthening the slab was developed using concrete screw anchors as post installed bending and shear reinforcement. The concrete screw anchors are normally installed as anchoring elements in cracked and non- cracked concrete and are available with diameters up to 22 mm. Developing this concept further, it is straight forward to use these anchoring elements as post-installed reinforcement in existing concrete structures. This new strengthening system was developed at the University of Innsbruck in the last few years and can fulfill the special requirements of this project, such as installation of the strengthening system from underneath the tunnel slab during ongoing use of the structure. High strength steel with diameters of up to 63.5 mm will be used as post-installed bending reinforcement covered with a new shotcrete layer on the underside of the tunnel slab. In total 59.3 tons of new flexural reinforcement and 7199 concrete screws for strengthening the shear capacity of the girders will be used to ensure a ductile failure of the tunnel slab. The on-site work started in March 2019 and is expected to take two years to complete.</p>

scholarly journals Problems Experienced by Adolescents with Autism Spectrum Disorder: Exploring Social, Educational and Economic Variables

2020 ◽  
Vol 8 (1) ◽  
pp. 177-186
Author(s):  
Saeb K. El Lala ◽  
Ola M. Abusukkar
Keyword(s):  
Autism Spectrum Disorder ◽  
Family Members ◽  
Autism Spectrum ◽  
Residential Area ◽  
Spectrum Disorder ◽  
Kingdom Of Saudi Arabia ◽  
Economic Problems ◽  
Adolescents With Autism ◽  
Central Regions ◽  
East West

The study investigates the problems of adolescents with Autism Spectrum Disorder (ASD) from the perspective of ASD specialists and adolescent’s families. It comprises of 228 ASD specialists and 294 families of ASD adolescents. The sample represents all areas of the Kingdom of Saudi Arabia (henceforth – KSA): north, south, east, west and centre. Variables of the study are adolescents’ gender, age, residential area, as well as the qualification of ASD specialists and family members. To accomplish the study, the researchers designed a questionnaire that includes variables regarding six significant problems: Educational, Recreational, Economic, Health, Psychological, and Social. The results reveal that families rate the economic problems higher than average, while the recreational ones – lower; specialists rate economic problems higher than average and educational ones – the lowest. As for gender variable, specialists and families note the differences in favour of females; for age variable, specialists and families note that 15-18 years old ASD adolescents have more problems. The results show that qualification of specialists as well as family members is of significant relevance in relation to ASD adolescents. Both specialists and family members are mostly from the central regions.

scholarly journals Some Observations of Shell-type Galactic Radio Sources

1967 ◽  
Vol 20 (3) ◽  
pp. 297 ◽  
Author(s):  
ER Hill
Keyword(s):  
Radio Emission ◽  
Spherical Symmetry ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Milky Way ◽  
Radio Sources ◽  
Radio Observations ◽  
Shell Type ◽  
Rosette Nebula ◽  
Galactic Radio

Radio evidence for two new supernova remnants in the Southern Milky Way is presented. Some new observations of the known supernova remnant, source 1439-62, and of the Rosette nebula, a shell source but not a supernova remnant, are also presented. The problem of finding model shells to fit the radio observations is considered and it is shown that the radio emission from 1439-62 is unlikely to originate in a shell with spherical symmetry.

scholarly journals Nebular and auroral emission lines of [Cl III] in the optical spectra of planetary nebulae

2000 ◽  
Vol 97 (9) ◽  
pp. 4551-4555 ◽  
Author(s):  
F. P. Keenan ◽  
L. H. Aller ◽  
C. A. Ramsbottom ◽  
K. L. Bell ◽  
F. L. Crawford ◽  
...  
Keyword(s):  
Planetary Nebulae ◽  
Optical Spectra ◽  
Emission Lines ◽  
Auroral Emission

scholarly journals Ultraviolet Variability of the Symbiotic Star AG PEG

1988 ◽  
Vol 103 ◽  
pp. 263-264
Author(s):  
D. Chochol ◽  
Z. Komárek ◽  
A. Vittone
Keyword(s):  
Optical Spectra ◽  
Radial Velocities ◽  
Roche Lobe ◽  
Emission Lines ◽  
High Dispersion ◽  
Symbiotic Star ◽  
Observational Material

Symbiotic star AG Peg consists of a hot subdwarf with a WN6 spectrum and a cool M3 giant, which is not filling its Roche lobe (Boyarchuk 1967, 1985). A detailed study of profiles, equivalent widths and radial velocities of emission lines in optical spectra allowed Hutchings et al. (1975) to conclude that a hot subluminous star approximately 1 M⊙ rotates rapidly and ejects material which streams towards the cool M giant with the mass 3-4 M⊙. UV observations seems to support this model.UV observations provided from the databank of the IUE satellite were obtained in 1978–81 by different observers. The observational material consists of 12 high dispersion SWP spectra and covers the region 1200 – 2100 A. The spectra were reduced at Trieste observatory using standard IUESIPS package. The radial velocities of emission lines were measured on tracings and corrected for the motion of Earth and satellite.

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