scholarly journals Ram pressure effects in the galactic plane and galactic dynamos in the no-zapproximation

2012 ◽  
Vol 544 ◽  
pp. A5 ◽  
Author(s):  
D. Moss ◽  
D. Sokoloff ◽  
R. Beck
Keyword(s):  
Galactic Plane ◽  
Pressure Effects ◽  
Ram Pressure ◽  
Galactic Dynamos

Diving deeper into jellyfish: The rich population of jellyfish galaxies in Abell 901/2

2019 ◽  
Vol 15 (S359) ◽  
pp. 147-152
Author(s):  
Fernanda Roman de Oliveira ◽  
Ana Chies Santos ◽  
Fabrício Ferrari ◽  
Geferson Lucatelli
Keyword(s):  
Surface Brightness ◽  
Structural Evolution ◽  
Pressure Effects ◽  
Single System ◽  
Hydrodynamic Friction ◽  
Star Forming ◽  
Ram Pressure ◽  
The Rich ◽  
Emission Line Galaxies ◽  
Very High

AbstractJellyfish galaxies are the most striking examples of galaxies undergoing ram pressure stripping – the removal of gas as a result of a hydrodynamic friction in dense environments. As part of the OMEGA (OSIRIS Mapping of Emission-line Galaxies in Abell 901/2) survey, we have identified the largest sample of jellyfish galaxies in a single system to this date, located in the Abell 901/2 multi-cluster system at z ˜ 0.165. We present our results with a detailed description of this sample regarding their very high star formation rates and their unique spatial distribution pattern that can be explained as a result of the merging system triggering ram pressure stripping events. Furthermore, we also show the results of our most recent morphometric studies where we use Morfometryka as a tool to characterise the morphologies and structural evolution of jellyfish galaxies. Our morphometric analysis shows that jellyfish galaxy candidates have peculiar concave regions in their surface brightness profiles. Therefore, these profiles are less concentrated (lower Sérsic indices) than other star forming galaxies that are not experiencing such extreme ram pressure effects.

scholarly journals Stripping of a Planetary Nebula from the Globular Cluster M22

1993 ◽  
Vol 155 ◽  
pp. 383-383
Author(s):  
K.J. Borkowski ◽  
J.P. Harrington ◽  
Z. Tsvetanov
Keyword(s):  
Globular Cluster ◽  
Planetary Nebula ◽  
Globular Clusters ◽  
Galactic Plane ◽  
Thick Layer ◽  
Neutral Gas ◽  
Ram Pressure ◽  
Resolution Imaging ◽  
Rayleigh Taylor Instability ◽  
High Spatial Resolution Imaging

High-spatial resolution imaging in the [O III] λ5007 line of a planetary nebula (PN) in the globular cluster M22 reveals a strongly asymmetric (a half-moon shaped) nebular morphology. We confirm that this peculiar morphology is caused by the distortion of stellar ejecta by the ram pressure of the ambient interstellar medium (ISM) through which the cluster is moving with a high velocity of 200 km s−1. Bright emission knots visible in the leading (upstream) nebular section confirm theoretical expectations that the shell should have been fragmented by the Rayleigh-Taylor instability. Stripping of the PN from M22 by the ambient ISM is the first direct evidence for removal of gas from globular clusters. M22 is located at a favourable location for the ram-pressure stripping to be effective, only 400 pc below the Galactic plane, well within a 2 kpc thick layer of ionized gas enveloping the plane. Ionized (possibly neutral) gas in this layer, with a hydrogen density of ∼ 0.1 cm−3, is responsible for the observed interaction.

scholarly journals Ram Pressure Effects on the Magnetic Field of NGC 2442

2004 ◽  
Vol 217 ◽  
pp. 382-383
Author(s):  
A. Fletcher ◽  
R. Beck ◽  
J. Harnett ◽  
M. Ehle ◽  
S. Ryder
Keyword(s):  
Magnetic Field ◽  
Intergalactic Medium ◽  
Pressure Effects ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Ram Pressure ◽  
The Galaxy ◽  
The Magnetic Field

The λ6 cm radio continuum emission from the barred galaxy NGC 2442 displays several unusual features that are probably due to the interaction of the galaxy with the intergalactic medium.

scholarly journals Environmental Effects on Galaxy Evolution: Multifrequency study of nearby clusters

2015 ◽  
Vol 11 (S319) ◽  
pp. 112-112
Author(s):  
H. Bravo-Alfaro ◽  
Y. Venkatapathy ◽  
F. Durret ◽  
C. A. Caretta ◽  
V. Gamez
Keyword(s):  
Galaxy Evolution ◽  
Environmental Effects ◽  
Pressure Effects ◽  
X Ray ◽  
Cluster Galaxies ◽  
Abell Clusters ◽  
Ram Pressure ◽  
First Results

AbstractWe show first results of a multifrequency survey focused on the mechanisms driving the transformation of cluster galaxies, from late to earlier S0-types. We compare the ram-pressure effects seen on 21cm-HI images with those mechanisms affecting the old stellar disks seen on deep optical and NIR images. Our targets are the Abell clusters A85, A496, A2670, which span different relaxation degrees, masses and X-ray luminosities.

On the Mechanism of Fluid Transport Across the Grinding Zone

1996 ◽  
Vol 118 (3) ◽  
pp. 332-338 ◽  
Author(s):  
C. C. Chang ◽  
S. H. Wang ◽  
A. Z. Szeri
Keyword(s):  
Flow Rate ◽  
Fluid Transport ◽  
Tangential Velocity ◽  
Hydrodynamic Pressure ◽  
Pressure Effects ◽  
Depth Of Penetration ◽  
Continuity Equations ◽  
Creep Feed ◽  
Ram Pressure ◽  
Flow Through

By considering both hydrodynamic pressure and ram pressure effects on flow through a porous wheel, we construct here a predictive model for calculating the flow-rate of the cooling fluid through the grinding zone. The hydrodynamic pressure is computed by means of a modified Reynolds equation, with upstream boundary conditions supplied by the ram pressure. To find the tangential velocity, the radial velocity, the depth of penetration of the fluid into the wheel, and the flow rate through the grinding zone, we solve momentum and continuity equations for flow through porous media. An empirical correlation for permeability, containing two dimensionless parameters, is employed to provide correction for wheel surface roughness, yielding theoretical results that show good agreement with experimental data for both conventional and creep feed grinding.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

Southern Hemisphere Seti Survey: Five Years of Project Meta II

1997 ◽  
Vol 161 ◽  
pp. 611-621
Author(s):  
Guillermo A. Lemarchand ◽  
Fernando R. Colomb ◽  
E. Eduardo Hurrell ◽  
Juan Carlos Olalde
Keyword(s):  
Southern Hemisphere ◽  
Scattering Theory ◽  
Galactic Plane ◽  
Narrow Band ◽  
Neutral Hydrogen ◽  
Sky Survey ◽  
Inertial Frames ◽  
Interstellar Scattering ◽  
Extraterrestrial Origin ◽  
Spectral Channels

AbstractProject META II, a full sky survey for artificial narrow-band signals, has been conducted from one of the two 30-m radiotelescopes of the Instituto Argentino de Radioastronomía (IAR). The search was performed near the 1420 Mhz line of neutral hydrogen, using a 8.4 million channels Fourier spectrometer of 0.05 Hz resolution and 400 kHz instantaneous bandwidth. The observing frequency was corrected both for motions with respect to three astronomical inertial frames, and for the effect of Earths rotation, which provides a characteristic changing signature for narrow-band signals of extraterrestrial origin. Among the 2 × 1013spectral channels analyzed, 29 extra-statistical narrow-band events were found, exceeding the average threshold of 1.7 × 10−23Wm−2. The strongest signals that survive culling for terrestrial interference lie in or near the galactic plane. A description of the project META II observing scheme and results is made as well as the possible interpretation of the results using the Cordes-Lazio-Sagan model based in interstellar scattering theory.

Reduction in Pain Sensitivity from Pharmacological Elevation of Blood Pressure in Persons with Chronically Low Blood Pressure

2009 ◽  
Vol 23 (3) ◽  
pp. 104-112 ◽  
Author(s):  
Stefan Duschek ◽  
Heike Heiss ◽  
Boriana Buechner ◽  
Rainer Schandry
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pain Sensitivity ◽  
Pain Threshold ◽  
Pain Perception ◽  
Drug Effects ◽  
Pressure Effects ◽  
Double Blind ◽  
Low Blood Pressure ◽  
Present Trial

Recent studies have revealed evidence for increased pain sensitivity in individuals with chronically low blood pressure. The present trial explored whether pain sensitivity can be reduced by pharmacological elevation of blood pressure. Effects of the sympathomimetic midodrine on threshold and tolerance to heat pain were examined in 52 hypotensive persons (mean blood pressure 96/61 mmHg) based on a randomized, placebo-controlled, double-blind design. Heat stimuli were applied to the forearm via a contact thermode. Confounding of drug effects on pain perception with changes in skin temperature, temperature sensitivity, and mood were statistically controlled for. Compared to placebo, higher pain threshold and tolerance, increased blood pressure, as well as reduced heart rate were observed under the sympathomimetic condition. Increases in systolic blood pressure between points of measurement correlated positively with increases in pain threshold and tolerance, and decreases in heart rate were associated with increases in pain threshold. The findings underline the causal role of hypotension in the augmented pain sensitivity related to this condition. Pain reduction as a function of heart rate decrease suggests involvement of a baroreceptor-related mechanism in the pain attrition. The increased proneness of persons with chronic hypotension toward clinical pain is discussed.

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