scholarly journals Box/peanut-shaped bulges in action space

2020 ◽  
Vol 498 (3) ◽  
pp. 3334-3350
Author(s):  
Victor P Debattista ◽  
David J Liddicott ◽  
Tigran Khachaturyants ◽  
Leandro Beraldo e Silva

ABSTRACT We introduce the study of box/peanut (B/P) bulges in the action space of the initial axisymmetric system. We explore where populations with different actions end up once a bar forms and a B/P bulge develops. We find that the density bimodality due to the B/P bulge (the X-shape) is better traced by populations with low radial, ${\it J}_{R,0}$, or vertical, ${\it J}_{z,0}$, actions, or high azimuthal action, ${\it J}_{\phi ,0}$. Generally, populations separated by ${\it J}_{R,0}$ have a greater variation in bar strength and vertical heating than those separated by ${\it J}_{z,0}$. While the bar substantially weakens the initial vertical gradient of ${\it J}_{z,0}$, it also drives a strikingly monotonic vertical profile of ${\it J}_{R,0}$. We then use these results to guide us in assigning metallicity to star particles in a pure N-body model. Because stellar metallicity in unbarred galaxies depends on age as well as radial and vertical positions, the initial actions are particularly well suited for assigning metallicities. We argue that assigning metallicities based on single actions, or on positions, results in metallicity distributions inconsistent with those observed in real galaxies. We therefore use all three actions to assign metallicity to an N-body model by comparing with the actions of a star-forming, unbarred simulation. The resulting metallicity distribution is pinched on the vertical axis, has a realistic vertical gradient, and has a stronger X-shape in metal-rich populations, as found in real galaxies.

Geophysics ◽  
1971 ◽  
Vol 36 (1) ◽  
pp. 216-216
Author(s):  
Sigmund Hammer

The foregoing discussion by Dr. Thyssen‐Bornemisza calls attention to interesting extensions of the rather simplified theoretical analysis in my paper. Dr. Thyssen‐Bornemisza has published extensively on the subject of the vertical gradient of gravity and its applications in exploration. My paper was limited to a very specific topic, namely the variability of the vertical gradient along a vertical profile above an anomalous mass.


2018 ◽  
Vol 14 (A30) ◽  
pp. 263-264
Author(s):  
Jorge K. Barrera-Ballesteros ◽  
Li-hwai Lin ◽  
Bu-Ching Hsieh ◽  
Hsi-An Pan ◽  
Sebastian Sánchez ◽  
...  

AbstractInteractions and mergers have been known as key scenarios to enhance global star formation rates and to lower the metal content of galaxies. However, little is known on how interactions affect the spatial distribution of gas metallicities. Thanks to the SDSS-IV MaNGA survey we are able to statistically constrain the impact of interactions across the optical distributions of galaxies. In this study, we compare the radial distribution of the ionized gas metallicity from a sample of 329 interacting objects – covering different interaction stages – with a statistical robust control sample. Our results suggest that galaxies close to coalesce tend to have flat, lower metallicities than non-interacting star-forming galaxies.


1969 ◽  
Vol 38 (4) ◽  
pp. 833-842 ◽  
Author(s):  
D. V. Krishna ◽  
L. V. Sarma

We consider here the flow due to the oscillation of a slender oblate spheroid in a non-homogeneous, rotating fluid confined between two parallel planes which are perpendicular to the (vertical) axis of rotation. The direction of oscillation of the spheroid is perpendicular to the axis of rotation. By solving a set of dual integrals the steady-state solution is obtained in the two cases when the plates are at an infinite distance from the body and when they are at a large but finite distance. The singular or discontinuous surfaces observed in the case of homogeneous fluid are absent here. Also, the steady-state velocity is no longer independent of the distance along the axis of rotation. The velocity has now a vertical gradient, an important feature in the case of stratified fluid. It is also found that the presence of the plane boundaries increases the force on the body.


Author(s):  
H. A. Harutyunian ◽  
E. H. Nikoghosyan ◽  
N. M. Azatyan

We developed an automatic code to determine some physical parameters describing the radiation of a simple one-temperature black body model and implemented it to calculating the temperatures and masses of molecular clouds in several star formation regions, using the observed IR emission fluxes for the chosen sources. Calculations show that the used commonly simplifications need to study in more detail for estimating the accuracy of computing results.


Author(s):  
Aleksey Marchenko

Observations of drifting icebergs by the ice trackers installed at their surface show their rotation relatively vertical axis. Iceberg rotation can influence drift characteristics and potentially dangerous for the iceberg towing. In the present paper 2D motion of floating icebergs in the presence of wind drag and unsteady water flow is considered. The water flow is assumed two dimensional and with uniform vertical profile. The direction and magnitude of the current speed are varying with the time. Temporal variability of the flow is associated with semidiurnal tidal. The inertial properties of an iceberg are characterised by three components of the added mass tensor. The iceberg motion is described by the Kirchoff equations written in the frame of reference sliding with the fluid. The rotation of cylindrical icebergs with elliptic horizontal cross-sections is investigated depending on the wind and fluid flow characteristics.


1986 ◽  
Vol 61 (2) ◽  
pp. 712-718 ◽  
Author(s):  
E. Bar-Yishay ◽  
R. E. Hyatt ◽  
J. R. Rodarte

In head-up dogs the vertical gradient of transpulmonary pressure (VGTP) disappears after pneumothorax develops. Our laboratory recently confirmed that the heart moves downward and posteriorly with pneumothorax. To study the extent to which the heart is supported by the lungs, we used a linear elasticity model and finite-element analysis. The lung and heart were assumed to be symmetric along a vertical axis. Reported values of the elastic properties of lung and heart were assigned. The model was generated first without the heart, using the lung alone. The heart was then added to the model. Finally, heart weight was doubled. Adding the heart caused the VGTP to increase; doubling the heart weight further increased the VGTP. These increases were more pronounced at higher lung volumes. Lung inflation was accompanied by an upward displacement of the heart. Inclusion of the heart caused increased inhomogeneities in regional volume distribution. The effect of heart weight may in part explain why the VGTP in the head-up dog is greater than that predicted by lung density.


Author(s):  
Issa A. Ramirez ◽  
Craig P. Lusk

The kinematic equations for approximating the deflection of a three-dimensional cantilever beam were developed. The numerical equations were validated with a Finite Element Analysis program. With these equations, a pseudo-rigid-body model (PRBM) for an axisymmetric straight beam was developed. The axisymmetric PRBM consists of a spherical joint connecting two rigid links. The location of the deformed end of the beam is determined by two angles and the characteristic radius factor. The angle of the beam with respect to the vertical axis depends on the direction of the force with respect to the undeformed coordinate system. The Pearson’s correlation coefficient for the Finite Element Analysis model and the numerical integration is 0.952.


2014 ◽  
Vol 10 (S309) ◽  
pp. 362-362
Author(s):  
Etsuko Mieda ◽  
Shelley A. Wright ◽  
James E. Larkin ◽  
Lee Armus ◽  
Stephanie Juneau

AbstractWe present first results from the Intermediate Redshift OSIRIS Chemo-Kinematic Survey (IROCKS) of z ∼ 1 star forming galaxies (Mieda et al. in prep). We have targeted Hα and [NII] emission lines in J-band and have spatially resolved the galaxies at sub-kilo parsec scale. We have combined our sample with deep HST continuum images, and are able to reveal the dynamics, morphologies, metallicity distribution, emission-line diagnostics, and star formation rates of galaxies spanning this crucial z ∼ 1 epoch.


2015 ◽  
Vol 15 (20) ◽  
pp. 28217-28247 ◽  
Author(s):  
A. Weigelt ◽  
R. Ebinghaus ◽  
N. Pirrone ◽  
J. Bieser ◽  
J. Bödewadt ◽  
...  

Abstract. Measurements of the vertical distribution of atmospheric mercury (Hg) are rare, because airborne measurements are expensive and labour intensive. Consequently, only a few vertical Hg profile measurements have been reported since the 1970s. Besides the CARIBIC passenger aircraft observations, the latest vertical profile over Europe was measured in 1996. Within the Global Mercury Observation System (GMOS) project four vertical profiles were taken on board research aircraft (CASA-212) in August 2013 in background air over different locations in Slovenia and Germany. Each vertical profile consists of at least seven 5 min horizontal flight sections from 500 m above ground to 3000 m a.s.l. Gaseous elemental mercury (GEM) was measured with a Tekran 2537X analyser and a Lumex RA-915-AM. Total gaseous mercury (TGM) was measured using a Tekran 2537B analyser and gaseous oxidized mercury (GOM) was sampled onto 8 denuders for post flight analysis (one for each profile, three during the transfer flights, and two blanks). In addition to the mercury measurements, SO2, CO, O3, NO, NO2, as well as basic meteorological parameters (pressure, temperature, relative humidity) have been measured. Additional ground based speciated mercury measurements at the GMOS master site in Waldhof (Germany) were used to extend the profile to the ground. No vertical gradient was found inside the well mixed boundary layer (variation by less than 0.1 ng m-3) at different sites with GEM varying from location to location between 1.4 and 1.6 ng m-3 (STP; standard conditions: p = 1013.25 hPa, T = 273.15 K). At all locations GEM dropped to 1.3 ng m-3 (STP) when entering the free troposphere and remained constant at higher altitudes. The combination of the vertical profile, measured on 21 August 2013, over Leipzig (Germany) with the CARIBIC measurements during ascent and descent to Frankfurt airport (Germany) at approximately the same time provide a unique central European vertical profile from inside the boundary layer (550 m a.s.l.) to the upper free troposphere (10 500 m a.s.l.) and shows a fairly constant free tropospheric TGM concentration of 1.3 ng m-3 (STP). The highest GOM concentrations of up to 60 pg m-3 (STP, denuder samples) were found above the boundary layer during the transfer flights.


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