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Sample records for bulges thermodynamic consequences

  1. Bulge Formation

    CERN Document Server

    Combes, F

    1999-01-01

    The currently discussed theories of bulge formation are reviewed, including the primordial scenario, where bulges form rapidly and then accrete disks, the secular scenario, where bulges are formed by dynamical evolution of disks through bars and galaxy interactions, and some combinations of both, where formation of bulges and disks are more continuous and interleaved. The various scenarios make specific predictions about the relative masses, angular momenta, colours, metallicities of bulges relative to disks, and the bulge-to-disk ratio as a function of time. Dynamical processes relevant to the formation of bulges (bar instabilities, mergers) are described and tested against observed statistics. Current data suggest a dynamical feedback from gravitational instabilities in bulge and disk formation. It is very difficult to discriminate between the various scenarios from surveys at z=0 only, and observations at high redshift are presently the best hope for large progress.

  2. Are the Laws of Thermodynamics Consequences of a Fractal Properties of Universe?

    OpenAIRE

    Kobelev, L. Ya.

    2000-01-01

    Why in our Universe the laws of thermodynamics are valid? In the paper is demonstrated the reason of it: if the time and the space are multifractal and the Universe is in an equilibrium state the laws of the thermodynamics are consequences of it's multifractal structure.

  3. Lorentz Symmetry Breaking and its consequences on Thermodynamics

    International Nuclear Information System (INIS)

    Full text: In this work, we study the effects of Lorentz Symmetry Breaking on thermodynamics properties of ideal gases. We start from a dispersion relation obtained from the Carroll-Field-Jackiw model to Electrodynamics with Lorentz and CPT violation term. With this, we compute the thermodynamics quantities for a Boltzmann, Bose-Einstein and Fermi-Dirac distributions. Two regimes are analyzed: the non-relativistic and the relativistic one. In the first case we show that the topological mass induced by the Chern-Simons term behaves as a chemical potential. For the Bose-Einstein condensates with these Lorentz breaking, the critical values as particle number, and temperature, are modified. These results are the same that were obtained by Colladay et al, whose perform the non-relativistic limit directly in the Hamiltonian for a Lorentz symmetry violating theory and used this to study the Bose-Einstein condensate to obtain a bound for the background field which perform the breaking. The original contribution of these work is in the relativistic regime, where we show that a new phase transition for a Bose -Einstein gas, can be induced by the Lorentz Symmetry Breaking parameters. Some applications in cosmology and astrophysics are commented. (author)

  4. Lorentz Symmetry Breaking and its consequences on Thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Costa-Soares, T.; Sales, J.A. de; Otoya, V.J. Vasques [Instituto Federal de Educacao, Ciencia e Tecnologia do Sudeste de Minas Gerais (IF Sudeste MG), MG (Brazil)

    2011-07-01

    Full text: In this work, we study the effects of Lorentz Symmetry Breaking on thermodynamics properties of ideal gases. We start from a dispersion relation obtained from the Carroll-Field-Jackiw model to Electrodynamics with Lorentz and CPT violation term. With this, we compute the thermodynamics quantities for a Boltzmann, Bose-Einstein and Fermi-Dirac distributions. Two regimes are analyzed: the non-relativistic and the relativistic one. In the first case we show that the topological mass induced by the Chern-Simons term behaves as a chemical potential. For the Bose-Einstein condensates with these Lorentz breaking, the critical values as particle number, and temperature, are modified. These results are the same that were obtained by Colladay et al, whose perform the non-relativistic limit directly in the Hamiltonian for a Lorentz symmetry violating theory and used this to study the Bose-Einstein condensate to obtain a bound for the background field which perform the breaking. The original contribution of these work is in the relativistic regime, where we show that a new phase transition for a Bose -Einstein gas, can be induced by the Lorentz Symmetry Breaking parameters. Some applications in cosmology and astrophysics are commented. (author)

  5. Galactic bulges

    CERN Document Server

    Peletier, Reynier; Gadotti, Dimitri

    2016-01-01

    This book consists of invited reviews on Galactic Bulges written by experts in the field. A central point of the book is that, while in the standard picture of galaxy formation a significant amount of the baryonic mass is expected to reside in classical bulges, the question what is the fraction of galaxies with no classical bulges in the local Universe has remained open. The most spectacular example of a galaxy with no significant classical bulge is the Milky Way. The reviews of this book attempt to clarify the role of the various types of bulges during the mass build-up of galaxies, based on morphology, kinematics, and stellar populations, and connecting their properties at low and high redshifts. The observed properties are compared with the predictions of the theoretical models, accounting for the many physical processes leading to the central mass concentration and their destruction in galaxies. This book serves as an entry point for PhD students and non-specialists and as a reference work for researchers...

  6. Some consequences from the thermodynamics of the synthesis of solar fuels

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, C.G. [Universidad de Sevilla (Spain). Departamento de Ingenieria Energetica y Mecanica de Fluidos

    2003-08-01

    This report derives thermodynamic relations that give information on questions of interest like the sustainability of the energy system, the accounting of their external costs or the harmonization between renewable energies and fossil fuels. Three important consequences of this work are, on the one hand, the existence of objective conditioners that help to the preselection of fuel candidates to be burned or solar synthesized in a certain location; for sustainability, the best fuel to be burned is carbon, whereas the one to be solar synthesized is hydrogen. On the other hand, the processing of the cycle of fuels replaced by solar synthesis, which takes place without chemical or mechanical environmental impacts, whereas the net environmental thermal impact (avoided environmental heating) is equal to the produced net work (null in the worst of the cases). Finally, the fuel replacement by solar synthesis allows to establish objective criteria of valuation of the external costs of the fossil fuel combustion. The integrating consideration between fuels suitable for their solar synthesis or for their combustion (each one of them depending on the climatic characteristics of the location, reason why they do not have to be the same) suggests the use of the fuel more suitable for solar synthesis as a chemical contribution for the replacement of the most advisable fuel for its final consumption; this consideration supposes the establishment of a parallelism between the previous results, consequence exclusively of Thermodynamics, and the corresponding ones to the biological photosynthesis, according to Biochemistry. (author)

  7. Formation of Bulges

    CERN Document Server

    Silk, J; Silk, Joseph; Bouwens, Rychard J.

    1998-01-01

    Bulges, often identified with the spheroidal component of a galaxy, have a complex pedigree. Massive bulges are generally red and old, but lower mass bulges have broader dispersions in color that may be correlated with disk colors. This suggests different formation scenarios. I will review possible formation sequences for bulges, describe the various signatures that distinguish these scenarios, and discuss implications for the high redshift universe.

  8. Polar-bulge galaxies

    CERN Document Server

    Reshetnikov, V P; Mosenkov, A V; Sotnikova, N Ya; Bizyaev, D V

    2015-01-01

    Based on SDSS data, we have selected a sample of nine edge-on spiral galaxies with bulges whose major axes show a high inclination to the disk plane. Such objects are called polar-bulge galaxies. They are similar in their morphology to polar-ring galaxies, but the central objects in them have small size and low luminosity. We have performed a photometric analysis of the galaxies in the g and r bands and determined the main characteristics of their bulges and disks. We show that the disks of such galaxies are typical for the disks of spiral galaxies of late morphological types. The integrated characteristics of their bulges are similar to the parameters of normal bulges. The stellar disks of polar-bulge galaxies often show large-scale warps, which can be explained by their interaction with neighboring galaxies or external accretion from outside.

  9. Thermodynamics

    CERN Document Server

    Fermi, Enrico

    1956-01-01

    Indisputably, this is a modern classic of science. Based on a course of lectures delivered by the author at Columbia University, the text is elementary in treatment and remarkable for its clarity and organization. Although it is assumed that the reader is familiar with the fundamental facts of thermometry and calorimetry, no advanced mathematics beyond calculus is assumed.Partial contents: thermodynamic systems, the first law of thermodynamics (application, adiabatic transformations), the second law of thermodynamics (Carnot cycle, absolute thermodynamic temperature, thermal engines), the entr

  10. Clumpy Disc and Bulge Formation

    CERN Document Server

    Perez, J; Tissera, P; Michel-Dansac, L

    2013-01-01

    We present a set of hydrodynamical/Nbody controlled simulations of isolated gas rich galaxies that self-consistently include SN feedback and a detailed chemical evolution model, both tested in cosmological simulations. The initial conditions are motivated by the observed star forming galaxies at z ~ 2-3. We find that the presence of a multiphase interstellar media in our models promotes the growth of disc instability favouring the formation of clumps which in general, are not easily disrupted on timescales compared to the migration time. We show that stellar clumps migrate towards the central region and contribute to form a classical-like bulge with a Sersic index, n > 2. Our physically-motivated Supernova feedback has a mild influence on clump survival and evolution, partially limiting the mass growth of clumps as the energy released per Supernova event is increased, with the consequent flattening of the bulge profile. This regulation does not prevent the building of a classical-like bulge even for the most ...

  11. Lagrange equations coupled to a thermal equation: mechanics as consequence of thermodynamics

    CERN Document Server

    Gruber, C; 10.3390/e13020367

    2011-01-01

    Following the analytic approach to thermodynamics developed by Stueckelberg, we study the evolution equations of a closed thermodynamic system consisting of point particles in a fluid. We obtain a system of coupled differential equations describing the mechanical and the thermal evolution of the system. The coupling between these evolution equations is due to the action of a viscous friction term. Finally, we apply our coupled evolution equations to study the thermodynamics of an isolated system consisting of identical point particles interacting through a harmonic potential.

  12. Thermodynamic study of clathrates hydrates from hydrocarbon gas mixtures consequences for CO2 capture and flow assurance

    OpenAIRE

    Le, Quanq-Du; Le Quang, Duyen; Bouillot, Baptiste; Herri, Jean-Michel

    2014-01-01

    This work presents details on the experimental procedure to measure the composition of the hydrate that crystallizes from a hydrocarbon gas mixture. We show that the results are time dependent and tend to thermodynamic equilibrium as time tends to infinity. An immediate consequence concerns two major domains of applications, CO2 capture from power plants, as well as flow assurance in the oil and gas industry. In fact, in both the cases, the crystallization is under non equilibrium conditions,...

  13. Eyes, Bulging (Proptosis)

    Science.gov (United States)

    ... 2 Diabetes, Heart Disease a Dangerous Combo Are 'Workaholics' Prone to OCD, Anxiety? ALL NEWS > Resources First ... causing bulging also presses on the optic nerve. Causes The most common cause is Graves disease, which ...

  14. Thermodynamics

    CERN Document Server

    Solanki, Arun

    2008-01-01

    The comprehension of the laws which govern any material system is greatly facilitated by considering the energy and entropy of the system in various states of which it is capable. As in the case of simply mechanics systems, the performance of mechanical work, the function which expresses the capability of the system for this kind of action also plays the leading part in the theory of equilibrium. The present book is written to explain the basic concepts, theories and equilibrium concerning thermodynamics of fluids and stationary systems, geometrical representation of thermodynamic properties

  15. Some consequences from polylinearity of thermodynamic functions of atomization reactions of binary compounds

    International Nuclear Information System (INIS)

    Interrelation between thermodynamic functions of atomization reactions of binary halides E(Xi)n, values of the functions in an isoparametric point and interatomic distances l(E-Xi) has been revealed on the basis of literature data. An equation describing the interrelation is suggested. It has been identical to correlation ratios used in organic chemistry for characterizing electronic and steric effects of halides ions. 14 refs., 1 fig., 1 tab

  16. Chemical buffering in natural and engineered barrier systems: Thermodynamic constraints and performance assessment consequences

    International Nuclear Information System (INIS)

    Thermodynamic and kinetic constraints on the chemical buffering properties of natural and engineered-barrier systems are derived in this study from theoretical descriptions, incorporated in the reaction-path model, of reversible and irreversible mass transfer in multicomponent, multiphase systems. The buffering properties of such systems are conditional properties because they refer to a specific aqueous species in a system that is open with respect to a specific reactant. The solution to a mathematical statement of this concept requires evaluation of the dependence of the activity of the buffered species on incremental changes in the overall reaction-progress variable. This dependence can be represented by a truncated Taylor's series expansion, where the values of associated derivatives are calculated using finite-difference techniques and mass-balance, charge-balance and mass-action constraints. Kinetic constraints on buffering behavior can also be described if the relation between reactant flux and reaction rate is well defined. This relation is explicit for the important case of advective groundwater flow and water-rock interaction. We apply the theoretical basis of the chemical buffering concept to processes that could affect the performance of a deep geologic repository for nuclear waste. Specifically, we focus on the likelihood that an inverse relation must exist between the buffer intensity and the migration velocity of reaction fronts in systems involving advective or diffusive mass transport. A quantitative understanding of this relation would provide the basis for evaluating the potential role of chemical buffering in achieving the isolation and retardation functions, of the EBS and geosphere in a KBS-3 repository. Our preliminary evaluation of this role considers the effects of chemical buffering on the propagation velocity of a pH front in both the near- and far field. We use a geochemical modeling technique compatible with the reaction-path model to

  17. Chemical buffering in natural and engineered barrier systems: Thermodynamic constraints and performance assessment consequences

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, R.C.; Wei Zhou [Monitor Scientific, LLC, Denver, CO (United States)

    2000-12-01

    Thermodynamic and kinetic constraints on the chemical buffering properties of natural and engineered-barrier systems are derived in this study from theoretical descriptions, incorporated in the reaction-path model, of reversible and irreversible mass transfer in multicomponent, multiphase systems. The buffering properties of such systems are conditional properties because they refer to a specific aqueous species in a system that is open with respect to a specific reactant. The solution to a mathematical statement of this concept requires evaluation of the dependence of the activity of the buffered species on incremental changes in the overall reaction-progress variable. This dependence can be represented by a truncated Taylor's series expansion, where the values of associated derivatives are calculated using finite-difference techniques and mass-balance, charge-balance and mass-action constraints. Kinetic constraints on buffering behavior can also be described if the relation between reactant flux and reaction rate is well defined. This relation is explicit for the important case of advective groundwater flow and water-rock interaction. We apply the theoretical basis of the chemical buffering concept to processes that could affect the performance of a deep geologic repository for nuclear waste. Specifically, we focus on the likelihood that an inverse relation must exist between the buffer intensity and the migration velocity of reaction fronts in systems involving advective or diffusive mass transport. A quantitative understanding of this relation would provide the basis for evaluating the potential role of chemical buffering in achieving the isolation and retardation functions, of the EBS and geosphere in a KBS-3 repository. Our preliminary evaluation of this role considers the effects of chemical buffering on the propagation velocity of a pH front in both the near- and far field. We use a geochemical modeling technique compatible with the reaction-path model

  18. Possible Cosmological consequences of thermodynamics in a unified approach to gravitational and strong interactions

    International Nuclear Information System (INIS)

    A unified geometrical approach to strong and gravitational interactions has been recently proposed, based on the classical methods of General Relativity. According to it, hadrons can be regarded as black-hole type solutions of new field equations describing two tensorial metric-field (the ordinary gravitational field, and the strong one). In this paper, we first seize the opportunity for an improved exposition of some elements of the theory relevant to our present scope. Secondly, by extending the Bekenstein-Hawking thermodynamics to the above mentioned strong black-holes (SBH), it is shown: 1) that SBH thermodynamics seems to require a new expansion of our cosmos after its Big Crunch (i.e. that a recontraction of our cosmos has to be followed by a new creation); 2) that a collapsing star with mass M approximately in the range 3 to 5 solar masses, once reached the neutron-star density, could re-explode tending to form a (radiating) object with a diameter of the order of 1 light-day: thus failing to create a gravitational black-hole

  19. The X-shaped Bulge of the Milky Way revealed by WISE

    CERN Document Server

    Ness, Melissa

    2016-01-01

    The Milky Way bulge has a boxy/peanut morphology and an X-shaped structure. This X-shape has been revealed by the `split in the red clump' from star counts along the line of sight toward the bulge, measured from photometric surveys. This boxy, X-shaped bulge morphology is not unique to the Milky Way and such bulges are observed in other barred spiral galaxies. N-body simulations show that boxy and X-shaped bulges are formed from the disk via dynamical instabilities. It has also been proposed that the Milky Way bulge is not X-shaped, but rather, the apparent split in the red clump stars is a consequence of different stellar populations, in an old classical spheroidal bulge. We present a WISE image of the Milky Way bulge, produced by downsampling the publicly available "unWISE" coadds. The WISE image of the Milky Way bulge shows that the X-shaped nature of the Milky Way bulge is self-evident and irrefutable. The X-shape morphology of the bulge in itself and the fraction of bulge stars that comprise orbits withi...

  20. QCD ghost reconstruction of f(G) gravity and its thermodynamic consequences

    Science.gov (United States)

    Chattopadhyay, Surajit

    2016-07-01

    In the present study we have presented a reconstruction scheme for f(G) gravity, where G represents Gauss-Bonnet invariant and we have chosen the scale factor in power-law form. It should be mentioned that f(G) gravity is not ``ad hoc" but comes out from the problem of non-local gravity theories. The works of Capozziello et al. (2013, 2014) need to be mentioned in this context. Capozziello et al. (2013) studied the Gauss-Bonnet gravity with Lagrange multiplier constraints in view to recover realistic dark energy behaviors and could recover the so-called Little Rip cosmology. Capozziello et al. (2014) built several solutions for F(R) + F(G) gravity with matter, but without Lagrange multipliers. In the present work, considering a flat FRW universe, we have considered a correspondence between f(G) gravity and QCD ghost dark energy. After getting a reconstructed solution for f(G) we have plotted f(G) against G, where it is apparent that f(G)→ 0 as G→ 0, which is one of the sufficient conditions for a realistic model. We have plotted the effective equation of state parameter for n>1 and observed that w_{eff}≥ -1 i.e. it behaves like quintessence. For n≈ 2, w_{eff} is reaching -1 at late stage of the universe. However, it is not crossing the phantom boundary. Subsequently, considering dynamical apparent horizon as the enveloping horizon of the universe we have derived expression for the time derivative of total entropy dot{S}_{total} and we have observed that dot{S}_{total}>0 throughout the evolution of the universe. This indicated validity of the generalized second law of thermodynamics under this reconstruction of f(G) gravity. References: Capozziello, S., Francaviglia, M., Makarenko, A. N.: Astrophys. Space Sci., 603 (2014) Capozziello, S., Makarenko, A. N., Odintsov, S. D.: Phys. Rev. D, 87 084037 (2013)

  1. Climate Change and its Potential Consequences to the Thermodynamics of an Alpine Lake

    Science.gov (United States)

    Fink, G.

    2012-04-01

    The characteristics of mixing processes as well as duration, frequency, and stability of an alpine lake's stratification are strongly coupled to the local climate conditions. These physical processes then again define the way in which life - from bacteria to human being - develops in this environment. Hence, probably economic and cultural lake uses are affected by climate change. Studies discovered reactions of lake physics due to global warming in central Europe in measured time series. The question is: What changes in alpine lake's thermodynamic processes do we have to expect in the next decades? This question is directed at first to general lake properties like water temperature, metalimnion depth, and heat balance and their behavior in space and time. Secondly, there is a need for information about mixing processes in these monomictic lakes. Mixing is important for the distribution of e.g. nutrients and oxygen. Thus, it is necessary to know how mixing intensity changes under likely future climate conditions. For this purpose three representative lakes were selected: Lake Constance (international), Lago di Viverone (Italy), and Woerthersee (Austria). For each lake a 1dv hydrodynamic model was built up, calibrated with an evolutionary algorithm, and finally validated. The model's source code is in an experimental state and it was provided by Deltares (Netherlands). During calibration the calculated mean monthly temperatures in different depths were compared to measurements. Then, based upon measured meteorological data "what if"-scenarios of air temperature, wind speed, cloud cover and relative humidity were developed by changing the mean value or by removing the old trend and adding a new one. When driving the model with this broad range of meteorology the result is a sensitivity study. This allows the determination of the lake's sensitivity e.g. regarding mixing intensity on changing climate, in a way that is independent from rough regional climate projections

  2. The black hole mass-bulge mass correlation: bulges versus pseudo-bulges

    CERN Document Server

    Hu, Jian

    2009-01-01

    We investigate the scaling relations between the supermassive black holes mass (M_bh) and the host bulge mass in elliptical galaxies, classical bulges, and pseudo-bulges. We use two-dimensional image analysis software BUDDA to obtain the structural parameters of 57 galaxies with dynamical M_bh measurement, and determine the bulge K-band luminosities (L_bul,K), stellar masses (M_s), and dynamical masses (M_d). The updated M_bh-L_bul,K, M_bh-M_s, and M_bh-M_d correlations for elliptical galaxies and classical bulges give M_bh~0.006M_s or 0.003M_d. The most tight relationship is log(M_bh/M_sun)=a+b log(M_d/10^11 M_sun), with a=8.46+/-0.05, b=0.90+/-0.06, and intrinsic scatter 0.27 dex. The pseudo-bulges follow their own relations, they harbor an order of magnitude smaller black holes than those in the same massive classical bulges, i.e. M_bh~0.0003M_s or 0.0002M_d. Besides the M_bh-\\sigma (bulge stellar velocity dispersion) relation, these bulge type dependent M_bh-M_bul scaling relations provide information for...

  3. Composition of the Galactic bulge

    CERN Document Server

    McWilliam, A; William, Andrew Mc

    2003-01-01

    We present detailed abundance results for 9 Galactic bulge stars in Baade's Window, based on HIRES (R=45,000--60,000) spectra taken with the Keck I telescope. The alpha elements show non-uniform enhancements relative to the Solar neighborhood trends: Mg and Si are enhanced in all our bulge stars by $\\sim$0.5--0.3 dex, showing a slight decrease with increasing [Fe/H]. Oxygen is enhanced in most bulge stars, similar to the Galactic halo, but the [O/Fe] ratios suddenly decline beginning at [Fe/H]=$-$0.5 dex, with a slope consistent with no oxygen production in the bulge for [Fe/H]$\\geq

  4. Cosmological thermodynamics with Hawking temperature on the apparent horizon and Unruh temperature of the fluid: Some interesting consequences

    Science.gov (United States)

    Saha, Subhajit

    2016-06-01

    Thermodynamics on the cosmological apparent horizon of a flat Friedmann-Lemaitre-Robertson-Walker metric has been investigated with Bekenstein entropy and Hawking temperature on the horizon, and Unruh temperature for the fluid inside the horizon. This temperature is experienced by a radial comoving observer infinitesimally close to the horizon due to the pressure exerted by the fluid bounded by the horizon. An expression for the entropy of the fluid has been obtained which is found to be proportional to the volume of the thermodynamic system which implies that the Unruh temperature of the fluid is inconsistent with the holographic principle. Further, we have been able to find an expression for the effective entropy of the system. Finally, assuming a barotropic equation of state p=wρ (w constant) for the fluid, it has been shown that the generalized second law holds good for a non-phantom w, while thermodynamic equilibrium is never possible for such a scenario.

  5. Cosmological thermodynamics with Hawking temperature on the apparent horizon and Unruh temperature of the fluid: Some interesting consequences

    CERN Document Server

    Saha, Subhajit

    2016-01-01

    Thermodynamics on the cosmological apparent horizon of a flat Friedmann-Lemaitre-Robertson-Walker metric has been investigated with Bekenstein entropy and Hawking temperature on the horizon, and Unruh temperature for the fluid inside the horizon. This temperature is experienced by a radial comoving observer infinitesimally close to the horizon due to the pressure exerted by the fluid bounded by the horizon. An expression for the entropy of the fluid has been obtained which is found to be proportional to the volume of the thermodynamic system which implies that the Unruh temperature of the fluid is inconsistent with the holographic principle. Further, we have been able to find an expression for the effective entropy of the system. Finally, assuming a barotropic equation of state $p=w\\rho$ ($w$ constant) for the fluid, it has been shown that the generalized second law holds good for a non-phantom w, while thermodynamic equilibrium is never possible for such a scenario.

  6. Bulge Formation via Mergers in Cosmological Simulations

    CERN Document Server

    Brooks, Alyson M

    2015-01-01

    The latest generation of cosmological simulations are on the verge of being able to resolve the structure of bulges for the first time. Hence, we review the current state of bulge formation in cosmological simulations, and discuss open questions that can be addressed in the near future by simulators, with a particular focus on merger-driven bulge growth. Galaxy mergers have long been assumed to produce classical bulges in disk galaxies. Under this bulge-formation model, though, the high rates of mergers in Cold Dark Matter galaxy formation theory predict many more classical bulges than are observed. Furthermore, simulations of galaxy formation continue to generally produce too massive of bulges. Feedback offers a promising avenue for reducing merger-driven bulge growth by maintaining high gas fractions in galaxies and ejecting low-angular momentum gas driven to the centers of galaxies. After reviewing the results of relevant research that has been published to date, we use cosmological simulations to explore ...

  7. Thermodynamic study of clathrates hydrates from hydrocarbon gas mixtures Consequences for capture CO2 and flow assurance

    OpenAIRE

    Bouillot, Baptiste; Le, Quang-Du; Le Quang, Duyen; Herri, Jean-Michel

    2014-01-01

    This work is a contribution to the global understanding of the coupling between kinetics and thermodynamics to explain the composition of the clathrate hydrates during their crystallization from an aqueous liquid and a hydrocarbon gas phase. In this work, we face new experimental facts that open questioning after comparing the classical modeling of clathrate hydrates following the approach of [1] with our experimental data following a new procedure allowing determining the hydrate composition...

  8. Chemistry of the Galactic Bulge: New Results

    Science.gov (United States)

    Zoccali, Manuela; Hill, Vanessa; Barbuy, Beatriz; Lecureur, Aurelie; Minniti, Dante; Renzini, Alvio; Gonzalez, Oscar; Gómez, Ana; Ortolani, Sergio

    2009-06-01

    VLT-FLAMES observations provide by far the largest sample of high dispersion spectra of Bulge red giants available. Five years of work on these 900 spectra have yielded the abundances of different elements in the Milky Way Bulge, and new results on its formation. The results so far include the Bulge metallicity distribution, the Bulge metallicity gradient, the metallicity dependence on kinematics, the history of enrichment with alpha-elements, as well as the lithium abundance. The evidence collected on Milky Way Bulge chemical enrichment supports a rapid early formation scenario, and the metallicity gradient argues against formation via secular bar evolution.

  9. Discovery in the Galactic Bulge

    Science.gov (United States)

    Kohler, Susanna

    2015-11-01

    In our efforts to map our galaxys structure, one region has remained very difficult to probe: the galactic center. A new survey, however, uses infrared light to peer through the gas and dust in the galactic plane, searching for variable stars in the bulge of the galaxy. This study has discovered a population of very young stars in a thin disk in the galactic center, providing clues to the star formation history of the Milky Way over the last 100 million years.Obscured CenterThe center of the Milky Way is dominated by a region known as the galactic bulge. Efforts to better understand this region in particular, its star formation history have been hindered by the stars, gas, and dust of the galactic disk, which prevent us from viewing the galactic bulge at low latitudes in visible light.The positions of the 35 classical Cepheids discovered in VVV data, projected onto an image of the galactic plane. Click for a better look! The survey area is bounded by the blue lines, and the galactic bar is marked with a red curve. The bottom panel shows the position of the Cepheids overlaid on the VVV bulge extinction map. [Dkny et al. 2015]Infrared light, however, can be used to probe deeper through the dust than visible-light searches. A new survey called VISTA Variables in the Via Lactea (VVV) uses the VISTA telescope in Chile to search, in infrared, for variable stars in the inner part of the galaxy. The VVV survey area spans the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high.Led by Istvn Dkny, a researcher at the Millennium Institute of Astrophysics and the Pontifical Catholic University of Chile, a team has now used VVV data to specifically identify classical Cepheid variable stars in the bulge. Why? Cepheids are pulsating stars with a very useful relation between their periods and luminosities that allows them to be used as distance indicators. Moreover, classical Cepheids are indicators of young stellar populations which can

  10. The Metallicity Distribution of the Milky Way Bulge

    Science.gov (United States)

    Ness, M.; Freeman, K.

    2016-06-01

    The Galactic bulge of the Milky Way is made up of stars with a broad range of metallicity, -3.0 function decreases as a function of height z from the plane and, more weakly, with galactic radius R GC. The most metal-rich stars in the inner Galaxy are concentrated to the plane and the more metal-poor stars are found predominantly further from the plane, with an overall vertical gradient in the mean of the metallicity distribution function of about - 0.45 dex kpc-1. This vertical gradient is believed to reflect the changing contribution with height of different populations in the innermost region of the Galaxy. The more metal-rich stars of the bulge are part of the boxy/peanut structure and comprise stars in orbits which trace out the underlying X-shape. There is still a lack of consensus on the origin of the metal-poor stars ([Fe/H] function of the bulge, and identifying if there is a unique bulge population which has formed separately from the disk and halo, has important consequences for identifying the relevant processes in the formation and evolution of the Milky Way.

  11. Oxidation-reduction properties of americium, curium, berkelium, californium, einsteinium and fermium, and thermodynamic consequences for the 5f series

    International Nuclear Information System (INIS)

    The amalgamation of 5f elements from Am to Fm has been studied by using 241Am, 244Cm, 249Bk, 249Cf, 252Cf, 253Es, 254Es, 252Fm and 255Fm with two electrochemical methods, radiocoulometry and radiopolarography, perfectly adapted to investigate extremely diluted solutions when the concentration of electroactive species is as low as 10-16M. The theory of radiocoulometry has been developed in the general cases of reversible and irreversible electrode process. It has been used to interpret the experimental data on the kinetic curves of amalgamation, and to estimate the standard rate constant of the electrode process in complexing medium (citric). On the other hand the radiopolarographic method has been applied to study the mechanism of reduction at the dropping mercury electrode of cations M3+ in aqueous medium to the metal M with formation of amalgam. The results are exploited into two directions: 1- Acquisition of some data concerning the oxidation-reduction properties of elements from Am to Fm. Therefore the standard electrode E0 [M(III-0)] potentials for Bk, Cf and Es, and the standard electrode E0 [M(II-0)] potential for Fm are estimated and the relative stability of each oxidation state (from II to VII) of 5f elements is discussed; 2- Acquisition of unknown thermodynamic data on transcalifornium elements. Correlations between 4f and 5f elements are precised and some divergences appear for the second half of 4f and 5f series (i.e. for 65<=Z<=71 and 97<=Z<=103)

  12. Limit diffusion coefficients and some aqueous ions of 5f and 4f elements, thermodynamic consequences for actinides

    International Nuclear Information System (INIS)

    The diffusion of the aqueous ions of Am3+, Cm3+, Cf3+, Es3+ and for comparison, Ce3+, Eu3+, Gd3+, Tm3+, Yb3+ was investigated in aqueous LiCl-HCl solutions (pH=2.5) at 25.000C by the open-ended capillary method. The diffusion coefficients obtained in the limit of zero ionic strength are used to estimate the hydrated radius of the considered elements and, consequently, the average number h of water molecules involved. A single S-shaped curve is obtained when this number h is plotted versus the cristallographic radius of the lanthanide (III) and actinide (III) cations. A similar change is assumed, for the inner sphere hydration number, from which values can be derived for actinides. From these results ΔHsub(hyd)sup(0) values have been calculated using a general analytical expression of the hydration enthalpie developped in this work. Finally, data of the sum of ionization potentials are proposed for the transuranium elements

  13. 3-Dimensional dynamics of the galactic bulge

    NARCIS (Netherlands)

    Soto Vicencio, Mario Humberto

    2010-01-01

    This thesis is part of a project which attempts to unveil the structure of the galactic bulge of our galaxy through the study of the kinematics of stars in low foreground extinction windows.Thus, in order to effectively constraint the phase-space distribution function of the galactic bulge, we have

  14. Fluorine Abundances in the Milky Way Bulge

    CERN Document Server

    Cunha, K; Gibson, B K

    2008-01-01

    Fluorine (19F) abundances are derived in a sample of 6 bulge red giants in Baade's Window. These giants span a factor of 10 in metallicity and this is the first study to define the behavior of 19F with metallicity in the bulge. The bulge results show an increase in F/O with increasing oxygen. This trend overlaps what is found in the disk at comparable metallicities, with the most oxygen-rich bulge target extending the disk trend. The increase in F/O in the disk arises from 19F synthesis in both asymptotic giant branch (AGB) stars and metal-rich Wolf-Rayet (WR) stars through stellar winds. The lack of an s-process enhancement in the most fluorine-rich bulge giant in this study, suggests that WR stars represented a larger contribution than AGB stars to 19F production in the bulge when compared to the disk. If this result for fluorine is combined with the previously published overall decline in the O/Mg abundance ratios in metal-rich bulge stars, it suggests that WR winds played a role in shaping chemical evolut...

  15. Spectroscopic bulge-disc decomposition: a new method to study the evolution of lenticular galaxies

    CERN Document Server

    Johnston, E J; Merrifield, M R; Bedregal, A G

    2012-01-01

    A new method for spectroscopic bulge-disc decomposition is presented, in which the spatial light profile in a two-dimensional spectrum is decomposed wavelength-by-wavelength into bulge and disc components, allowing separate one-dimensional spectra for each component to be constructed. This method has been applied to observations of a sample of nine S0s in the Fornax Cluster in order to obtain clean high-quality spectra of their individual bulge and disc components. So far this decomposition has only been fully successful when applied to galaxies with clean light profiles, consequently limiting the number of galaxies that could be separated into bulge and disc components. Lick index stellar population analysis of the component spectra reveals that in those galaxies where the bulge and disc could be distinguished, the bulges have systematically higher metallicities and younger stellar populations than the discs. This correlation is consistent with a picture in which S0 formation comprises the shutting down of s...

  16. VERY METAL-POOR STARS IN THE OUTER GALACTIC BULGE FOUND BY THE APOGEE SURVEY

    International Nuclear Information System (INIS)

    Despite its importance for understanding the nature of early stellar generations and for constraining Galactic bulge formation models, at present little is known about the metal-poor stellar content of the central Milky Way. This is a consequence of the great distances involved and intervening dust obscuration, which challenge optical studies. However, the Apache Point Observatory Galactic Evolution Experiment (APOGEE), a wide-area, multifiber, high-resolution spectroscopic survey within Sloan Digital Sky Survey III, is exploring the chemistry of all Galactic stellar populations at infrared wavelengths, with particular emphasis on the disk and the bulge. An automated spectral analysis of data on 2403 giant stars in 12 fields in the bulge obtained during APOGEE commissioning yielded five stars with low metallicity ([Fe/H] ≤ –1.7), including two that are very metal-poor [Fe/H] ∼ –2.1 by bulge standards. Luminosity-based distance estimates place the 5 stars within the outer bulge, where 1246 of the other analyzed stars may reside. A manual reanalysis of the spectra verifies the low metallicities, and finds these stars to be enhanced in the α-elements O, Mg, and Si without significant α-pattern differences with other local halo or metal-weak thick-disk stars of similar metallicity, or even with other more metal-rich bulge stars. While neither the kinematics nor chemistry of these stars can yet definitively determine which, if any, are truly bulge members, rather than denizens of other populations co-located with the bulge, the newly identified stars reveal that the chemistry of metal-poor stars in the central Galaxy resembles that of metal-weak thick-disk stars at similar metallicity.

  17. Globular clusters in the Galactic bulge

    CERN Document Server

    Bica, E; Barbuy, B

    2015-01-01

    A view of the Galactic bulge by means of their globular clusters is necessary for a deep understanding of its formation and evolution. Connections between the globular cluster and field star properties in terms of kinematics, orbits, chemical abundances and ages should shed light on different stellar population components. Based on spatial distribution and metallicity, we define a probable best list of bulge clusters, containing 43 entries. Future work on newly discovered objects, mostly from the VVV survey, is suggested. These candidates might alleviate the issue of missing clusters on the far side of the bulge. We discuss the reddening law affecting the cluster distances towards the center of the Galaxy, and conclude that the most suitable total-to-selective absorption value appears to be R$_{\\rm V}$=3.2, in agreement with recent analyses. An update of elemental abundances for bulge clusters is provided.

  18. The hydraulic bulge tester in fracture studies

    International Nuclear Information System (INIS)

    In this work the behavior of different metals under biaxial hydraulic bulging was studied in terms of fracture mechanics. Three different materials, namely: SIC aluminium, mild steel and copper were examined and their fracture behavior was assessed by introducing starter cracks in the test pieces in different ways before bulging. The pressure-volume relationships were obtained and the crack growth rates were measured during bulging at different elliptical die ratios (1,1.5,2 and 3). It was found that increasing the die ratio, with everything else remaining as before, resulted in a remarkable reduction to the volume and increase in the pressure and subsequently an increase in the crack growth rates of all materials. Double Edge Notched (DEN) specimen experiments were also conducted on the three materials to measure their fracture toughness and the results compared with those obtained from bulging experiments. (author)

  19. Galaxy Bulges and Elliptical Galaxies - Lecture Notes

    CERN Document Server

    Gadotti, Dimitri A

    2012-01-01

    Our knowledge on the central components of disk galaxies has grown substantially in the past few decades, particularly so in the last. This frantic activity and the complexity of the subject promote confusion in the community. In these notes, I discuss the concept of galactic bulge and its different flavors. I also address fundamental scaling relations and the bulge-elliptical galaxy connection, their central black holes and formation models. In particular, I aim at conveying three important notions: (i): box/peanuts are just the inner parts of bars; (ii): the physical reality of two different families of bulges is evident; and (iii): at the high mass end, at least, classical bulges are not just scaled down ellipticals surrounded by disks.

  20. Globular Clusters in the Galactic Bulge

    Science.gov (United States)

    Bica, E.; Ortolani, S.; Barbuy, B.

    2016-06-01

    A view of the Galactic bulge by means of their globular clusters is fundamental for a deep understanding of its formation and evolution. Connections between the globular cluster and field star properties in terms of kinematics, orbits, chemical abundances, and ages should shed light on different stellar population components. Based on spatial distribution and metallicity, we define a probable best list of bulge clusters, containing 43 entries. Future work on newly discovered objects, mostly from the VVV survey, is suggested. These candidates might alleviate the issue of missing clusters on the far side of the bulge. We discuss the reddening law affecting the cluster distances towards the centre of the Galaxy, and conclude that the most suitable total-to-selective absorption value appears to be R V=3.2, in agreement with recent analyses. An update of elemental abundances for bulge clusters is provided.

  1. Theoretical Models of the Galactic Bulge

    CERN Document Server

    Shen, Juntai

    2015-01-01

    Near infrared images from the COBE satellite presented the first clear evidence that our Milky Way galaxy contains a boxy shaped bulge. Recent years have witnessed a gradual paradigm shift in the formation and evolution of the Galactic bulge. Bulges were commonly believed to form in the dynamical violence of galaxy mergers. However, it has become increasingly clear that the main body of the Milky Way bulge is not a classical bulge made by previous major mergers, instead it appears to be a bar seen somewhat end-on. The Milky Way bar can form naturally from a precursor disk and thicken vertically by the internal firehose/buckling instability, giving rise to the boxy appearance. This picture is supported by many lines of evidence, including the asymmetric parallelogram shape, the strong cylindrical rotation (i.e., nearly constant rotation regardless of the height above the disk plane), the existence of an intriguing X-shaped structure in the bulge, and perhaps the metallicity gradients. We review the major theor...

  2. EXPLORING THE UNUSUALLY HIGH BLACK-HOLE-TO-BULGE MASS RATIOS IN NGC 4342 AND NGC 4291: THE ASYNCHRONOUS GROWTH OF BULGES AND BLACK HOLES

    Energy Technology Data Exchange (ETDEWEB)

    Bogdan, Akos; Forman, William R.; Kraft, Ralph P.; Li, Zhiyuan; Vikhlinin, Alexey; Nulsen, Paul E. J.; Jones, Christine [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Zhuravleva, Irina; Churazov, Eugene [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-str. 1, 85741 Garching bei Muenchen (Germany); Mihos, J. Christopher; Harding, Paul [Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106 (United States); Guo, Qi [Partner Group of the Max Planck Institute for Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Schindler, Sabine, E-mail: abogdan@cfa.harvard.edu [Institut fuer Astro- und Teilchenphysik, Universitaet Innsbruck, Technikerstrasse 25, 6020 Innsbruck (Austria)

    2012-07-10

    We study two nearby early-type galaxies, NGC 4342 and NGC 4291, that host unusually massive black holes relative to their low stellar mass. The observed black-hole-to-bulge mass ratios of NGC 4342 and NGC 4291 are 6.9{sup +3.8}{sub -2.3}% and 1.9% {+-} 0.6%, respectively, which significantly exceed the typical observed ratio of {approx}0.2%. As a consequence of the exceedingly large black-hole-to-bulge mass ratios, NGC 4342 and NGC 4291 are Almost-Equal-To 5.1{sigma} and Almost-Equal-To 3.4{sigma} outliers from the M{sub .}-M{sub bulge} scaling relation, respectively. In this paper, we explore the origin of the unusually high black-hole-to-bulge mass ratio. Based on Chandra X-ray observations of the hot gas content of NGC 4342 and NGC 4291, we compute gravitating mass profiles, and conclude that both galaxies reside in massive dark matter halos, which extend well beyond the stellar light. The presence of dark matter halos around NGC 4342 and NGC 4291 and a deep optical image of the environment of NGC 4342 indicate that tidal stripping, in which {approx}> 90% of the stellar mass was lost, cannot explain the observed high black-hole-to-bulge mass ratios. Therefore, we conclude that these galaxies formed with low stellar masses, implying that the bulge and black hole did not grow in tandem. We also find that the black hole mass correlates well with the properties of the dark matter halo, suggesting that dark matter halos may play a major role in regulating the growth of the supermassive black holes.

  3. The formation of galaxy bulges: Spectrophotometric constraints

    Science.gov (United States)

    Prugniel, Ph.; Maubon, G.; Simien, F.

    2001-01-01

    We have measured Mg2, Fe 5270 and Fe 5335 spectrophotometric indices (LICK system) in the bulge of 89 galaxies, mostly spirals from the Héraudeau (\\cite{her96}) sample. The indices are reduced to a null velocity dispersion and normalized to an aperture of 0.2 h-1 kpc. The mean errors are 0.009 mag on Mg2, and 0.3 Å on the iron indices. These measurements almost double the amount of similar data already available on spiral galaxies. Our data confirm the existence of the relation between Mg2, and sigma0, the central stellar velocity dispersion; we find an even tighter relation between Mg2, and Vmrot, the maximum rotational velocity of the galaxy, deduced from HI observations. For the most massive bulges, these correlations may be interpreted as a mass-metallicity relation. However, the presence of young stellar populations, traced by the detection of [OIII] lambda 5007 Å, emission, provides clear evidence that age effects do play a role. Since the contribution of the young population is anti-correlated to the mass of the galaxy, it continues the Mg2, vs. sigma0 , relation toward the low-sigma0, region and globally increases its slope. We also present evidence for a new positive correlation between Fe indices and sigma0, and for a significant correlation between the line-strength indices and the total or disk luminosity. We propose to model the whole sequence of bulges within the folowing framework: bulges are composed of a primary population formed prior to the disk, during the initial collapse, and of a secondary population formed during its evolution. The whole family of bulges can be classified into three classes: (A) the bulges dominated by young populations are generally small, have ionized gas, low velocity dispersion and low line strengths; (B) the bulges dominated by the primary population lie along the mass-metallicity sequence defined for elliptical galaxies; and (C) the bulges where the secondary population is significant are less Mg-over-abundant than

  4. The macho project: 45 candidate microlensing events from the first-year Galactic bulge data

    Energy Technology Data Exchange (ETDEWEB)

    Alcock, C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Center for Particle Astrophysics, University of California, Berkeley, California 94720 (United States)] Allsman, R.A. [Supercomputing Facility, Australian National University, Canberra, A.C.T. 0200 (Australia)] Alves, D. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] Axelrod, T.S. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Mount Stromlo and Siding Spring Observatories, Australian National University, Weston, A.C.T. 2611 (Australia); Cook, K.H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Center for Particle Astrophysics, University of California, Berkeley, California 94720 (United States)] Freeman, K.C. [Mount Stromlo and Siding Spring Observatories, Australian National University, Weston, A.C.T. 2611 (Australia); Guern, J.; Lehner, M.J. [Center for Particle Astrophysics, University of California, Berkeley, California 94720 (United States)] [Department of Physics, University of California, San Diego, California 92093 (United States)] Marshall, S.L. [Center for Particle Astrophysics, University of California, Berkeley, California 94720 (United States)] [Department of Physics, University of California, Santa Barbara, California 93106 (United States)] Park, H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] Perlmutter, S. [Center for Particle Astrophysics, University of California, Berkeley, California 94720 (United States)] Peterson, B.A. [Mount Stromlo and Siding Spring Observatories, Australian National University, Weston, ACT 2611 (Australia)] Pratt, M.R. [Center for Particle Astrophysics, University of California, Berkeley, California 94720 (United States)] [Department of Physics, University of California, Santa Barbara, California 93106 (United States)

    1997-04-01

    We report the detection of 45 candidate microlensing events in fields toward the Galactic bulge. These come from the analysis of 24 fields containing 12.6 million stars observed for 190 days in 1993. Many of these events are of extremely high signal-to-noise ratio and are remarkable examples of gravitational microlensing. The distribution of peak magnifications is shown to be consistent with the microlensing interpretation of these events. Using a subsample of 1.3 million {open_quotes}clump giant{close_quotes} stars whose distance and detection efficiency are well known, we find 13 events and estimate the microlensing optical depth toward the Galactic bulge as {tau}{sub bulge}=3.9{sub {minus}1.2}{sup +1.8}{times}10{sup {minus}6} averaged over an area of {approximately}12deg{sup 2} centered at Galactic coordinates l=2.55{degree} and b=3.64{degree}. This is similar to the value reported by the OGLE collaboration and is marginally higher than current theoretical models for {tau}{sub bulge}. The optical depth is also seen to increase significantly for decreasing {vert_bar}b{vert_bar}. These results demonstrate that obtaining large numbers of microlensing events toward the Galactic bulge is feasible, and that the study of such events will have important consequences for the structure of the Galaxy and its dark halo. {copyright} {ital 1997} {ital The American Astronomical Society}

  5. The Demographics of galactic bulges in the SDSS database

    CERN Document Server

    Kim, Keunho; Jeong, Hyunjin; Aragon-Salamanca, Alfonso; Smith, Rory; Yi, Sukyoung K

    2016-01-01

    We present a new database of our two-dimensional bulge-disk decompositions for 14,233 galaxies drawn from SDSS DR12 in order to examine the properties of bulges residing in the local universe ($0.005 < z < 0.05$). We performed decompositions in $g$ and $r$ bands by utilizing the {\\sc{galfit}} software. The bulge colors and bulge-to-total ratios are found to be sensitive to the details in the decomposition technique, and hence we hereby provide full details of our method. The $g-r$ colors of bulges derived are almost constantly red regardless of bulge size except for the bulges in the low bulge-to-total ratio galaxies ($B/T_{\\rm r} \\lesssim 0.3$). Bulges exhibit similar scaling relations to those followed by elliptical galaxies, but the bulges in galaxies with lower bulge-to-total ratios clearly show a gradually larger departure in slope from the elliptical galaxy sequence. The scatters around the scaling relations are also larger for the bulges in galaxies with lower bulge-to-total ratios. Both the depa...

  6. Are there carbon stars in the Bulge ?

    OpenAIRE

    Ng, Y. K.

    1998-01-01

    The bulge carbon stars have been a mystery since their discovery, because they are about 2.5mag too faint to be regarded as genuine AGB stars, if located inside the metal-rich bulge (m-M=14.5mag). Part of the mystery can be solved if these carbon stars are related to the Sagittarius dwarf galaxy (SDG; m-M=17.0mag). They are in that case not old and metal-rich, but young, ~0.1 Gyr, with SMC-like metallicity. The sigma_RV=113+/-14 km/s radial velocity dispersion of the stars appears to be consi...

  7. Enzyme oscillation can enhance the thermodynamic efficiency of cellular metabolism: Consequence of anti-phase coupling between reaction flux and affinity

    CERN Document Server

    Himeoka, Yusuke

    2015-01-01

    Cells generally convert nutrient resources to useful products via energy transduction. Accordingly, the thermodynamic efficiency of this conversion process is one of the most essential characteristics of living organisms. However, although these processes occur under conditions of dynamic metabolism, most studies of cellular thermodynamic efficiency have been restricted to examining steady states; thus, the relevance of dynamics to this efficiency has not yet been elucidated. Here, we develop a simple model of metabolic reactions with anabolism-catabolism coupling catalysed by enzymes. Through application of external oscillation in the enzyme abundances, the thermodynamic efficiency of metabolism was found to be improved. This result is in strong contrast with that observed in the oscillatory input, in which the efficiency always decreased with oscillation. This improvement was effectively achieved by separating the anabolic and catabolic reactions, which tend to disequilibrate each other, and taking advantag...

  8. Bulge formation in disk galaxies with MOND

    CERN Document Server

    Combes, F

    2014-01-01

    The formation of galaxies and their various components can be stringent tests of dark matter models and of gravity theories. In the standard cold dark matter (CDM) model, spheroids are formed through mergers in a strongly hierarchical scenario, and also in the early universe through dynamical friction in clumpy galaxies. More secularly, pseudo-bulges are formed by the inner vertical resonance with bars. The high efficiency of bulge formation is in tension with observations in the local universe of a large amount of bulge-less spiral galaxies. In the present work, the formation of bulges in very gas-rich galaxies, as those in the early universe, is studied in the Milgrom's MOdified Newtonian Dynamics (MOND), through multi-grid simulations of the non-linear gravity, including the gas dissipation, star formation and feedback. Clumpy disks are rapidly formed, as in their Newtonian equivalent systems. However, the dynamical friction is not as efficient, in the absence of dark matter halos, and the clumps have no t...

  9. Enzyme oscillation can enhance the thermodynamic efficiency of cellular metabolism: consequence of anti-phase coupling between reaction flux and affinity

    Science.gov (United States)

    Himeoka, Yusuke; Kaneko, Kunihiko

    2016-04-01

    Cells generally convert nutrient resources to products via energy transduction. Accordingly, the thermodynamic efficiency of this conversion process is one of the most essential characteristics of living organisms. However, although these processes occur under conditions of dynamic metabolism, most studies of cellular thermodynamic efficiency have been restricted to examining steady states; thus, the relevance of dynamics to this efficiency has not yet been elucidated. Here, we develop a simple model of metabolic reactions with anabolism–catabolism coupling catalyzed by enzymes. Through application of external oscillation in the enzyme abundances, the thermodynamic efficiency of metabolism was found to be improved. This result is in strong contrast with that observed in the oscillatory input, in which the efficiency always decreased with oscillation. This improvement was effectively achieved by separating the anabolic and catabolic reactions, which tend to disequilibrate each other, and taking advantage of the temporal oscillations so that each of the antagonistic reactions could progress near equilibrium. In this case, anti-phase oscillation between the reaction flux and chemical affinity through oscillation of enzyme abundances is essential. This improvement was also confirmed in a model capable of generating autonomous oscillations in enzyme abundances. Finally, the possible relevance of the improvement in thermodynamic efficiency is discussed with respect to the potential for manipulation of metabolic oscillations in microorganisms.

  10. EXPLORING THE UNUSUALLY HIGH BLACK-HOLE-TO-BULGE MASS RATIOS IN NGC 4342 AND NGC 4291: THE ASYNCHRONOUS GROWTH OF BULGES AND BLACK HOLES

    International Nuclear Information System (INIS)

    We study two nearby early-type galaxies, NGC 4342 and NGC 4291, that host unusually massive black holes relative to their low stellar mass. The observed black-hole-to-bulge mass ratios of NGC 4342 and NGC 4291 are 6.9+3.8–2.3% and 1.9% ± 0.6%, respectively, which significantly exceed the typical observed ratio of ∼0.2%. As a consequence of the exceedingly large black-hole-to-bulge mass ratios, NGC 4342 and NGC 4291 are ≈5.1σ and ≈3.4σ outliers from the M.-Mbulge scaling relation, respectively. In this paper, we explore the origin of the unusually high black-hole-to-bulge mass ratio. Based on Chandra X-ray observations of the hot gas content of NGC 4342 and NGC 4291, we compute gravitating mass profiles, and conclude that both galaxies reside in massive dark matter halos, which extend well beyond the stellar light. The presence of dark matter halos around NGC 4342 and NGC 4291 and a deep optical image of the environment of NGC 4342 indicate that tidal stripping, in which ∼> 90% of the stellar mass was lost, cannot explain the observed high black-hole-to-bulge mass ratios. Therefore, we conclude that these galaxies formed with low stellar masses, implying that the bulge and black hole did not grow in tandem. We also find that the black hole mass correlates well with the properties of the dark matter halo, suggesting that dark matter halos may play a major role in regulating the growth of the supermassive black holes.

  11. Thermodynamics of chemical free energy generation in off-axis hydrothermal vent systems and its consequences for compartmentalization and the emergence of life

    CERN Document Server

    Simoncini, E; Gallori, E; .,

    2010-01-01

    In this paper we demonstrate how chemical free energy can be produced by a geological process. We provide a thermodynamic framework in which to assess how life emerged at the off-axis hydrothermal vent system; the RNA - clays system has been investigated from the entropic point of view, showing that the stabilization of the system in a state further away from equilibrium state, by an inorganic heterogeneous compartmetalization phenomena, is able to produce chemical free energy useful for RNA self - replication.

  12. Red galaxies with pseudo-bulges in the SDSS: closer to disk galaxies or to classical bulges?

    CERN Document Server

    Ribeiro, B; Antón, S; Gomes, J M; Papaderos, P

    2015-01-01

    Pseudo-bulges are expected to markedly differ from classical, quasi-monolithically forming bulges in their star formation history (SFH) and chemical abundance patterns. To test this simple expectation, we carry out a comparative structural and spectral synthesis analysis of 106 red, massive galaxies issued from the SDSS, subdivided into bulgeless, pseudo-bulge and classical bulge galaxies according to their photometric characteristics, and further obeying a specific selection to minimize uncertainties in the analysis and ensure an unbiased derivation and comparison of SFHs. Our 2D photometry analysis suggests that disks underlying pseudo-bulges typically have larger exponential scale lengths than bulgeless galaxies, despite similar integral disk luminosities. Spectral synthesis models of the stellar emission within the 3" SDSS fiber aperture reveal a clear segregation of bulgeless and pseudo-bulge galaxies from classical bulges on the luminosity-weighted planes of age-metallicity and mass-metallicity, though ...

  13. The hydraulic bulge tester in fracture studies

    International Nuclear Information System (INIS)

    The theory and practice of hydrostatic bulge testing of thin diaphragms is reviewed. Circular, elliptical and rectangular orifices are considered in terms of pressure vs height of dome plots, strain-distributions etc. Differences in modes of failure (location of necks, existence or not of pressure peaks) between circular and rectangular diaphragms are highlighted both for metals and polymers. The use of the bulger to construct forming limit diagrams (FLD) and fracture forming limit diagrams (FFLD) is described. How bulging is used for both fracture initiating and propagation studies is indicated, particularly as it may relate to the prospect for results from a 'giant' bulger of 1 m diameter orifice to be used for investigating thick plate. (author)

  14. Statistical thermodynamics

    International Nuclear Information System (INIS)

    The contents of this book are thermodynamics on the law of thermodynamics, classical thermodynamics and molecule thermodynamics, basics of molecule thermodynamics, molecule and assembly partition function, molecule partition function, classical molecule partition function, thermodynamics function for ideal assembly in fixed system, thermodynamics function for ideal assembly in running system, Maxwell-Boltzmann's law of distribution, chemical equilibrium like calculation of equilibrium constant and theory of absolute reaction rate.

  15. Explaining the Formation of Bulges with MOND

    Science.gov (United States)

    Combes, Françoise

    In the cold dark matter (CDM) paradigm, bulges easily form through galaxy mergers, either major or minor, or through clumpy discs in the early universe, where clumps are driven to the center by dynamical friction. Also pseudobulges, with a more discy morphology and kinematics, can form more slowly through secular evolution of a bar, where resonant stars are elevated out of the plane, in a peanut/box shape. As a result, in CDM cosmological simulations, it is very difficult to find a bulgeless galaxy, while they are observed very frequently in the local universe. A different picture emerges in alternative models of the missing mass problem. In MOND (MOdified Newtonian Dynamics), galaxy mergers are much less frequent, since the absence of dark matter halos reduces the dynamical friction between two galaxies. Also, while clumpy galaxies lead to rapid classical bulge formation in CDM, the inefficient dynamical friction with MOND in the early-universe galaxies prevents the clumps to coalesce together in the center to form spheroids. This leads to less frequent and less massive classical bulges. Bars in MOND are more frequent and stronger, and have a more constant pattern speed, which modifies significantly the pseudobulge morphology. The fraction of pseudobulges is expected to be dominant in MOND.

  16. Explaining the formation of bulges with MOND

    CERN Document Server

    Combes, F

    2015-01-01

    In the cold dark matter (CDM) paradigm, bulges easily form through galaxy mergers, either major or minor, or through clumpy disks in the early universe, where clumps are driven to the center by dynamical friction. Also pseudo-bulges, with a more disky morphology and kinematics, can form more slowly through secular evolution of a bar, where resonant stars are elevated out of the plane, in a peanut/box shape. As a result, in CDM cosmological simulations, it is very difficult to find a bulgeless galaxy, while they are observed very frequently in the local universe. A different picture emerges in alternative models of the missing mass problem. In MOND (MOdified Newtonian Dynamics), galaxy mergers are much less frequent, since the absence of dark matter halos reduces the dynamical friction between two galaxies. Also, while clumpy galaxies lead to rapid classical bulge formation in CDM, the inefficient dynamical friction with MOND in the early-universe galaxies prevents the clumps to coalesce together in the center...

  17. Are there carbon stars in the Bulge?

    CERN Document Server

    Ng, Y K

    1998-01-01

    The bulge carbon stars have been a mystery since their discovery, because they are about 2.5mag too faint to be regarded as genuine AGB stars, if located inside the metal-rich bulge (m-M=14.5mag). Part of the mystery can be solved if these carbon stars are related to the Sagittarius dwarf galaxy (SDG; m-M=17.0mag). They are in that case not old and metal-rich, but young, ~0.1 Gyr, with SMC-like metallicity. The sigma_RV=113+/-14 km/s radial velocity dispersion of the stars appears to be consistent with bulge membership. On the other hand, a similar velocity dispersion could be the result from an induced star formation event when the SDG crosses the galactic midplane. It is suggested that the carbon stars are tracers of such an event and that they therefore are located at distances related to the SDG. However, the majority of the carbon stars are not member of the SDG, nor are they similar to the C-stars which are member of the SDG. The radial velocities can be used to determine a possible membership to the SD...

  18. Manganese abundances in Galactic bulge red giants

    CERN Document Server

    Barbuy, B; Zoccali, M; Minniti, D; Renzini, A; Ortolani, S; Gomez, A; Trevisan, M; Dutra, N

    2013-01-01

    Manganese is mainly produced in type II SNe during explosive silicon burning, in incomplete Si-burning regions, and depends on several nucleosynthesis environment conditions, such as mass cut beween the matter ejected and falling back onto the remnant, electron and neutron excesses, mixing fallback, and explosion energy. Manganese is also produced in type Ia SNe. The aim of this work is the study of abundances of the iron-peak element Mn in 56 bulge giants, among which 13 are red clump stars. Four bulge fields along the minor axis are inspected. The study of abundances of Mn-over-Fe as a function of metallicity in the Galactic bulge may shed light on its production mechanisms. High-resolution spectra were obtained using the FLAMES+UVES spectrograph on the Very Large Telescope. The spectra were obtained within a program to observe 800 stars using the GIRAFFE spectrograph, together with the present UVES spectra. We aim at identifying the chemical evolution of manganese, as a function of metallicity, in the Gala...

  19. Secular- and merger-built bulges in barred galaxies

    CERN Document Server

    Mendez-Abreu, J; Corsini, E M; Aguerri, J A L

    2014-01-01

    (Abridged) We study the incidence, as well as the nature, of composite bulges in a sample of 10 face-on barred galaxies to constrain the formation and evolutionary processes of the central regions of disk galaxies. We analyze the morphological, photometric, and kinematic properties of each bulge. Then, by using a case-by-case analysis we identify composite bulges and classify every component into a classical or pseudobulge. In addition, bar-related boxy/peanut (B/P) structures were also identified and characterised. We find only three galaxies hosting a single-component bulge (two pseudobulges and one classical bulge). We find evidence of composite bulges coming in two main types based on their formation: secular-built and merger- and secular-built. We call secular-built to composite bulges made of entirely by structures associated with secular processes such as pseudo bulges, central disks, or B/P bulges. We find four composite bulges of this kind in our sample. On the other hand, merger- and secular-built b...

  20. Characterization of the winter midwestern particulate nitrate bulge.

    Science.gov (United States)

    Pitchford, Marc L; Poirot, Richard L; Schichtel, Bret A; Maim, William C

    2009-09-01

    A previously unobserved multi-state region of elevated particulate nitrate concentration was detected as a result of the expansion of the Interagency Monitoring of Protected Visual Environments (IMPROVE) network of remote-area particulate matter (PM) speciation monitoring sites into the midwestern United States that began in 2002. Mean winter ammonium nitrate concentrations exceed 4 microg/m3 in a region centered in Iowa, which makes it responsible for as much as half of the particle light extinction. Before these observations, particulate nitrate in the United States was only observed to be a dominant component of the fine PM (PM2.5) in parts of California and some urban areas. Comparisons of the spatial patterns of particulate nitrate with spatial patterns of ammonia and nitrogen oxide emissions suggest that the nitrate bulge is the result of the high emissions of ammonia associated with animal agriculture in the Midwest. Nitrate episodes at several locations in the eastern United States are shown to be associated with transport pathways over the Midwest, suggesting long-range transport of either ammonia or ammonium nitrate. Thermodynamic equilibrium modeling conducted by others on data from the Midwest shows the relative importance of atmospheric ammonia and nitric acid in the production of PM2.5. This is a particular concern as the sulfur dioxide emissions in the United States are reduced, which increases the amount of ammonia available for ammonium nitrate production. PMID:19785273

  1. Quantum Thermodynamics

    OpenAIRE

    Ronnie Kosloff

    2013-01-01

    Quantum thermodynamics addresses the emergence of thermodynamic laws from quantum mechanics. The viewpoint advocated is based on the intimate connection of quantum thermodynamics with the theory of open quantum systems. Quantum mechanics inserts dynamics into thermodynamics, giving a sound foundation to finite-time-thermodynamics. The emergence of the 0-law, I-law, II-law and III-law of thermodynamics from quantum considerations is presented. The emphasis is on consistency between the two the...

  2. The Demographics of galactic bulges in the SDSS database

    OpenAIRE

    Kim, Keunho; Oh, Sree; Jeong, Hyunjin; Aragon-Salamanca, Alfonso; Smith, Rory; Yi, Sukyoung K.

    2016-01-01

    We present a new database of our two-dimensional bulge-disk decompositions for 14,233 galaxies drawn from SDSS DR12 in order to examine the properties of bulges residing in the local universe ($0.005 < z < 0.05$). We performed decompositions in $g$ and $r$ bands by utilizing the {\\sc{galfit}} software. The bulge colors and bulge-to-total ratios are found to be sensitive to the details in the decomposition technique, and hence we hereby provide full details of our method. The $g-r$ colors of b...

  3. Which bulges are favoured by barred S0 galaxies?

    CERN Document Server

    Barway, Sudhanshu; Vaghmare, Kaustubh; Kembhavi, Ajit K

    2016-01-01

    S0 galaxies are known to host classical bulges with a broad range of size and mass, while some such S0s are barred and some not. The origin of the bars has remained as a long-standing problem -- what made bar formation possible in certain S0s? By analysing a large sample of S0s with classical bulges observed by the Spitzer space telescope, we find that most of our barred S0s host comparatively low-mass classical bulges, typically with bulge-to-total ratio ($B/T$) less than $0.5$; whereas S0s with more massive classical bulges than these do not host any bar. Furthermore, we find that amongst the barred S0s, there is a trend for the longer and massive bars to be associated with comparatively bigger and massive classical bulges -- possibly suggesting bar growth being facilitated by these classical bulges. In addition, we find that the bulge effective radius is always less than the bar effective radius --indicating an interesting synergy between the host classical bulge and bars being maintained while bar growth ...

  4. FORMATION AND EVOLUTION OF THE GALACTIC BULGE

    Directory of Open Access Journals (Sweden)

    M. Zoccali

    2009-01-01

    Full Text Available Despite its importance as the only galactic spheroid fully resolved in stars, our knowledge of the Galacticbulge has been historically quite poor. This was mainly due to the stellar crowding, to the heavy interstellar absorption in the plane, and to the foreground disk contamination. However, in the last few years, with the use of near IR detectors, 8 meter class (or space based telescopes, and the advent of multi-object spectrographs, we have learnt how to minimize the above e ects. This paper reviews the basic properties (structural parameters, age, chemical content of the Galactic bulge, as determined in the last 4{5 years.

  5. Bulges of disk galaxies at intermediate redshifts. I. Samples with and without bulges in the Groth Strip Survey

    OpenAIRE

    L. Domínguez Palmero; M. Balcells; Erwin, P; Prieto, M.; Cristóbal Hornillos, D.; Eliche Moral, María del Carmen; Guzmán, R.

    2008-01-01

    Context. Analysis of bulges to redshifts of up to z∽1 have provided ambiguous results as to whether bulges as a class are old structures akin to elliptical galaxies or younger products of the evolution of their host disks. Aims. We aim to define a sample of intermediate-z disk galaxies harbouring central bulges, and a complementary sample of disk galaxies without measurable bulges. We intend to provide colour profiles for both samples, as well as measurements of nuclear, disk, and global colo...

  6. The zCOSMOS Redshift Survey: evolution of the light in bulges and discs since z~0.8

    CERN Document Server

    Tasca, L A M; Fevre, O Le; Ilbert, O; Lilly, S J; Zamorani, G; Lopez-Sanjuan, C; Ho, L C; Bardelli, S; Cattaneo, A; Cucciati, O; Farrah, D; Iovino, A; Koekemoer, A M; Liu, C T; Massey, R; Renzini, A; Taniguchi, Y; Welikala, N; Zucca, E; Carollo, C M; Contini, T; Kneib, J P; Mainieri, V; Scodeggio, M; Bolzonella, M; Bongiorno, A; Caputi, K; de la Torre, S; Franzetti, P; Garilli, B; Guzzo, L; Kampczyk, P; Knobel, C; Kovavc, K; Lamareille, F; Borgne, J -F Le; Brun, V Le; Maier, C; Mignoli, M; Pello, R; Peng, Y; Montero, E Perez; Rich, R M; Tanaka, M; Vergani, D; Bordoloi, R; Cappi, A; Cimatti, A; Coppa, G; McCracken, H J; Moresco, M; Pozzetti, L; Sanders, D; Sheth, K

    2014-01-01

    We studied the chronology of galactic bulge and disc formation by analysing the relative contributions of these components to the B-band rest-frame luminosity density at different epochs. We present the first estimate of the evolution of the fraction of rest-frame B-band light in galactic bulges and discs since redshift z~0.8. We performed a bulge-to-disc decomposition of HST/ACS images of 3266 galaxies in the zCOSMOS-bright survey with spectroscopic redshifts in the range 0.7 < z < 0.9. We find that the fraction of B-band light in bulges and discs is $(26 \\pm 4)%$ and $(74 \\pm 4)%$, respectively. When compared with rest-frame B-band measurements of galaxies in the local Universe in the same mass range ($10^{9} M_{\\odot}\\lessapprox M \\lessapprox 10^{11.5} M_{\\odot}$), we find that the B-band light in discs decreases by ~30% from z~0.7-0.9 to z~0, while the light from the bulge increases by ~30% over the same period of time. We interpret this evolution as the consequence of star formation and mass assemb...

  7. Bulge-driven Fueling of Seed Black Holes

    Science.gov (United States)

    Park, KwangHo; Ricotti, Massimo; Natarajan, Priyamvada; Bogdanović, Tamara; Wise, John H.

    2016-02-01

    We examine radiation-regulated accretion onto intermediate-mass and massive black holes (BHs) embedded in a bulge component. Using spherically symmetric one-dimensional radiation-hydrodynamics simulations, we track the growth of BHs accreting from a cold, neutral gas reservoir with temperature {T}∞ ={10}4 K. We find that the accretion rate of BHs embedded in bulges is proportional to {r}{{B,eff}}/{r}{{B}}, where rB,eff is the increased effective Bondi radius that includes the gravitational potential of the bulge, and rB is the Bondi radius of the BH. The radiative feedback from the BH suppresses the cold accretion rate to ˜1% of the Bondi rate when a bulge is not considered. However, we find that the BH fueling rate increases rapidly when the bulge mass Mbulge is greater than the critical value of ˜106 M⊙ and is proportional to {r}{{B,eff}}/{r}{{B}}≃ {M}{{bulge}}/{M}{{BH}}, where {M}{{BH}} is the BH mass. Since the critical bulge mass is independent of the central BH mass, the growth rate of BHs with masses {M}{{BH}}={10}2, 104, and 106 M⊙ exhibits distinct dependencies on the bulge-to-BH mass ratio. Our results imply that light seed BHs (≲102 M⊙), which might be the remnants of the Pop III stars, cannot grow through accretion coevally with the early assembly of the bulge of the host galaxies until the bulge reaches the critical mass. However, massive BH seeds (≳105 M⊙), which may form via direct collapse, are more likely to be embedded in a supercritical bulge, and thus can grow efficiently coupling to the host galaxies and driving the early evolution of the MBH-σ relationship.

  8. The Millennium Galaxy Catalogue: The severe attenuation of bulge flux by dusty spiral discs

    CERN Document Server

    Driver, Simon P

    2007-01-01

    Using the Millennium Galaxy Catalogue we quantify the dependency of the disc and bulge luminosity functions on galaxy inclination. Using a contemporary dust model we show that our results are consistent with galaxy discs being optically thick in their central regions (tau_B^f=3.8+/-0.7). As a consequence the measured B-band fluxes of bulges can be severely attenuated by 50% to 95% depending on disc inclination. We argue that a galaxy's optical appearance can be radically transformed by simply removing the dust, e.g. during cluster infall, with mid-type galaxies becoming earlier, redder, and more luminous. Finally we derive the mean photon escape fraction from the integrated galaxy population over the 0.1micron to 2.1 micron range, and use this to show that the energy of starlight absorbed by dust (in our model) is in close agreement with the total far-IR emission.

  9. Bars rejuvenating bulges? Evidence from stellar population analysis

    CERN Document Server

    Coelho, Paula

    2011-01-01

    We obtained stellar ages and metallicities via spectrum fitting for a sample of 575 bulges with spectra available from the Sloan Digital Sky Survey. The structural properties of the galaxies have been studied in detail in Gadotti (2009b) and the sample contains 251 bulges in galaxies with bars. Using the whole sample, where galaxy stellar mass distributions for barred and unbarred galaxies are similar, we find that bulges in barred and unbarred galaxies occupy similar loci in the age vs. metallicity plane. However, the distribution of bulge ages in barred galaxies shows an excess of populations younger than ~ 4 Gyr, when compared to bulges in unbarred galaxies. Kolmogorov-Smirnov statistics confirm that the age distributions are different with a significance of 99.94%. If we select sub-samples for which the bulge stellar mass distributions are similar for barred and unbarred galaxies, this excess vanishes for galaxies with bulge mass log M < 10.1 M_Sun while for more massive galaxies we find a bimodal bulg...

  10. Stellar Ages through the Corners of the Boxy Bulge

    CERN Document Server

    Valenti, E; Renzini, A; Brown, T M; Gonzalez, O; Minniti, D; Debattista, Victor P; Mayer, L

    2013-01-01

    In some scenarios for the formation of the Milky Way bulge the stellar population at the edges of the boxy bulge may be younger than those on the minor axis, or close to the Galactic center. So far the only bulge region where deep color-magnitude diagrams have been obtained is indeed along the minor axis. To overcome this limitation, we aim at age-dating the bulge stellar populations far away from the bulge minor axis. Color-magnitude diagrams and luminosity functions have been obtained from deep near-IR VLT/HAWK-I images taken at the two Southern corners of the boxy bulge, i.e., near the opposite edges of the Galactic bar. The foreground disk contamination has been statistically removed using a pure disk field observed with the same instrument and located approximately at similar Galactic latitudes of the two bulge fields, and 30deg in longitude away from the Galactic center. For each bulge field, mean reddening and distance are determined using the position of red clump stars, and the metallicity distributi...

  11. Bulge-driven Fueling of Seed Black Holes

    CERN Document Server

    Park, KwangHo; Natarajan, Priyamvada; Bogdanović, Tamara; Wise, John H

    2015-01-01

    We examine radiation-regulated accretion onto intermediate-mass and massive black holes (BHs) embedded in a bulge component. Using spherically symmetric one-dimensional radiation-hydrodynamics simulations, we track the growth of BHs accreting from a cold, neutral gas reservoir with temperature T=10^4 K. We find that the accretion rate of BHs embedded in bulges is proportional to r_{B,eff}/r_B, where r_{B,eff} is the increased effective Bondi radius that includes the gravitational potential of the bulge, and r_B is the Bondi radius of the BH. The radiative feedback from the BH suppresses the cold accretion rate to ~1 percent of the Bondi rate when a bulge is not considered. However, we find that the BH fueling rate increases rapidly when the bulge mass M_bulge is greater than the critical value of 10^6 M_sun and is proportional to M_bulge. Since the critical bulge mass is independent of the central BH mass M_{BH}, the growth rate of BHs with masses of 10^2, 10^4, and 10^6 M_sun exhibits distinct dependencies o...

  12. Colors of intermediate z bulges in the goya Survey

    Directory of Open Access Journals (Sweden)

    L. Domínguez-Palmero

    2007-01-01

    Full Text Available The chronology of bulge and disk formation is a major unsolved issue in galaxy forma- tion, which impacts on our global understand- ing of the Hubble sequence. We present col- ors of the nuclear regions of intermediate- redshift disk galaxies, with the aim of obtain- ing empirical information of ages of bulges at 0:1 < z < 1:3.

  13. The bulge luminosity for low-mass black holes

    CERN Document Server

    Jiang, Yanfei; Ho, Luis

    2011-01-01

    We study the scaling between bulge magnitude and central black hole (BH) mass in galaxies with virial BH masses 10^7 solar mass. Specfically, bulges span a much wider range of bulge luminosity, and on average the luminosity is larger, at fixed black hole mass. The trend holds both for the active galaxies from Bentz et al. and the inactive sample of Gultekin et al. and cannot be explained by differences in stellar populations, as it persists when we use dynamical bulge masses. Put another way, the ratio between bulge and BH mass is much larger than $\\sim 1000$ for our sample. This is consistent with recent suggestions that black hole mass does not scale with the pseudobulge luminosity. The low-mass scaling relations appear to flatten, consistent with predictions from Volonteri & Natarajan for massive seed BHs.

  14. Natures of a clump-origin bulge: a pseudobulge-like but old metal-rich bulge

    CERN Document Server

    Inoue, Shigeki

    2011-01-01

    Bulges in spiral galaxies have been supposed to be classified into two types: classical bulges or pseudobulges. Classical bulges are thought to form by galactic merger with bursty star formation, whereas pseudobulges are suggested to form by secular evolution due to spiral arms and a barred structure funneling gas into the galactic centre. Noguchi (1998, 1999) suggested another bulge formation scenario, `clump-origin bulge'. He demonstrated using a numerical simulation that a galactic disc suffers dynamical instability to form clumpy structures in the early stage of disc formation since the premature disc is expected to be highly gas-rich, then the clumps are sucked into the galactic centre by dynamical friction and merge into a single bulge at the centre. This bulge formation scenario expected happen only at the high-redshift is different from the galactic merger and the secular evolution. Therefore, clump-origin bulges may have their own unique properties. We perform a high-resolution N-body/smoothed partic...

  15. Variable stars in the MACHO bulge database

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, P. J.; Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T. S.; Becker, A.; Bennett, D. P.; Cook, K. H., Drake, A.; Freeman, K. C.; Griest, K.; Lehner, M. J.; Marshall, S. L.; Minniti, D.; Peterson, B. A.; Pratt, M. R.; Rodgers, A. W.; Stubbs, C. W.; Sutherland, W.; Tomaney, A.; Vandehei, T.; Welch, D.

    1998-10-01

    The MACHO Project has been monitoring large fields in the direction of the Galactic bulge, the LMC and SMC for over 6 years. The nightly observations of this microlensing survey provide very large databases for astronomers. The MACHO database contains {approximately}5 Terabytes of data as of mid-1998. For comparison, the HST Archive contains about {approximately}2 Tb, and the Sloan. Digital Sky Survey will reach {approximately}1.0 Tb. Our database can be used to attack a variety of astrophysical problems, and has produced results relevant to microlensing, galactic structure, and stellar evolution. Of particular importance are the large numbers of variable stars (tens of thousands) found as byproducts of the microlensing search. In years to come, the microlensing databases will play a dominant role in variable star science. Important science can still be done with limited resources, even in places with no access to large telescopes (all you need is computer).

  16. The formation of the Galactic bulge of the Milky Way

    Directory of Open Access Journals (Sweden)

    Freeman K.

    2012-02-01

    Full Text Available We aim to determine if the bulge formed via mergers as predicted by Cold Dark Matter (CDM theory, or from disk instabilities, as suggested by its boxy shape, or both processes. We are observing about 28,000 bulge stars in fields that span longitudes of − 31 to + 26° and latitudes of − 5° to − 10°, targeting mostly red clump giants and we are measuring stellar velocities and chemical abundances. We have almost concluded our observations and have analysed data of 23,000 stars. We find a cylindrical rotation profile for the bulge which blends smoothly out into the disk and from the [Fe/H] results we find the bulge to be comprised of separate components, with an underlying slowly rotating metal poor subsample which we believe to be the inner halo stars and metal weak thick disk. We find only a small [Fe/H] gradient with latitude in the bulge, of − 0.07dex/kpc. This weak gradient does not necessarily support a merger origin for our bulge and the composite nature of the bulge is consistent with formation out of the thin disk as per instability formation models.

  17. The Large-Scale Extinction Map of the Galactic Bulge from the MACHO Project Photometry

    CERN Document Server

    Popowski, P; Becker, A; Popowski, Piotr; Cook, Kem; Becker, Andrew

    2003-01-01

    We present a (V-R)-based reddening map of about 43 square degrees of the Galactic bulge/bar. The map is constructed using template image photometry from the MACHO microlensing survey, contains 9717 resolution elements, and is based on (V-R)-color averages of the entire color-magnitude diagrams (CMDs) in 4 by 4 arc-minute tiles. The conversion from the observed color to the reddening follows from an assumption that CMDs of all bulge fields would look similar in the absence of extinction. Consequently, the difference in observed color between various fields originates from varying contribution of the disk extinction summed along different lines of sight. We check that our (V-R) colors correlate very well with visual extinction derived by Stanek in Baade's Window. We show that a dusty disk obeying a cosec|b| extinction law, E(V-R) = 0.0274 cosec|b|, provides a good approximation to the extinction toward the MACHO bulge/bar fields. The large-scale (V-R)-color and visual extinction map presented here will be made ...

  18. Thermodynamic aspects of rock friction

    CERN Document Server

    Mitsui, Noa

    2013-01-01

    Rate- and state-dependent friction law for velocity-step tests is analyzed from a thermodynamic point of view. A simple macroscopic non-equilibrium thermodynamic model with a single internal variable reproduces instantaneous jump and relaxation. Velocity weakening appears as a consequence of a plasticity related nonlinear coefficient. Permanent part of displacement corresponds to plastic strain, and relaxation effects are analogous to creep in thermodynamic rheology.

  19. Surface thermodynamics

    International Nuclear Information System (INIS)

    Basic thermodynamics of a system consisting of two bulk phases with an interface. Solid surfaces: general. Discussion of experimental data on surface tension and related concepts. Adsorption thermodynamics in the Gibbsian scheme. Adsorption on inert solid adsorbents. Systems with electrical charges: chemistry and thermodynamics of imperfect crystals. Thermodynamics of charged surfaces. Simple models of charge transfer chemisorption. Adsorption heat and related concepts. Surface phase transitions

  20. Entanglement Thermodynamics

    OpenAIRE

    Alishahiha, Mohsen; Allahbakhshi, Davood; Naseh, Ali

    2013-01-01

    Entanglement entropy is a statistical entropy measuring information loss due to coarse-graining corresponding to a spatial division of a system. In this paper we construct a thermodynamics (entanglement thermodynamics) which includes the entanglement entropy as the entropy variable, for a massless scalar field in Minkowski, Schwarzschild and Reissner-Nordstr{\\"o}m spacetimes to understand the statistical origin of black-hole thermodynamics. It is shown that the entanglement thermodynamics in ...

  1. Mapping a stellar disk into a boxy bulge: The outside-in part of the Milky Way bulge formation

    CERN Document Server

    Di Matteo, P; Gomez, A; van Damme, L; Combes, F; Halle, A; Semelin, B; Lehnert, M D; Katz, D

    2014-01-01

    By means of idealized, dissipationless N-body simulations which follow the formation and subsequent buckling of a stellar bar, we study the characteristics of boxy/peanut-shaped bulges and compare them with the properties of the stellar populations in the Milky Way bulge. The main results of our modeling, valid for the general family of boxy/peanut shaped bulges, are the following: (i) because of the redistribution of stars in the disk initiated at the epoch of bar formation, it is the whole stellar disk, from the innermost regions to the outer Lindblad resonance of the stellar bar, that is mapped into a boxy bulge; (ii) the contribution of stars to the local bulge density depends on their birth radius: stars born in the innermost disk tend to dominate the innermost regions of the boxy bulge, while stars originating closer to the OLR dominate the outer regions of the boxy/peanut structure; (iii) stellar birth radii are imprinted in the bulge kinematics, the larger the birth radii of stars ending up in the bul...

  2. Galactic bulge M giants. II. Content and structure of the bulge between b = -3 deg and -12 deg

    International Nuclear Information System (INIS)

    JHKL colors and CO and H2O indices for a sample of 250 M giants derived from surveys along the minor axis of the Galaxy at latitudes between -3 deg and -12 deg are presented and studied. The bolometric magnitudes for the stars are calculated. The effects of latitude on the colors, magnitudes, and indices are examined. The bolometric luminosity function for each bulge field is provided and the influence of latitude on luminosity is analyzed. Long-period variables in the bulge, the search for IRAS sources in the surveyed fields, and the IR surface brightness of the bulge are discussed. 74 refs

  3. Non linear finite element simulation of complex bulge forming processes

    OpenAIRE

    Mac Donald, Bryan J

    2000-01-01

    Bulge forming is a manufacturing process that is becoming increasingly important as a technology that can be used to produce seamless, lightweight and near-net-shape industrial components. The process is being increasingly applied in the automotive and aerospace industries where the demands for increased structural strength and decreased vehicle weight make it a very attractive manufacturing method. This work is concerned with increasing knowledge of the deformation mechanisms during bulg...

  4. MACHO RR lyrae in the inner halo and bulge

    Energy Technology Data Exchange (ETDEWEB)

    Drake, A.; Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T.S.; Becker, A.; Bennett, D. P.; Cook, K. H.; Freeman, K. C.; Griest, K.; Lehner, M. J.; Marshall, S. L.; Minniti, D.; Peterson, B. A.; Pratt, M. R.; Quinn, P. J.; Rodgers, A. W.; Stubbs, C. W.; Sutherland, W.; Tomaney, A.; Vandehei, T.; Welch, D.

    1998-10-01

    The RR Lyrse in the bulge have been proposed to be the oldest populations in the Milky Way, tracers of how the galaxy formed. We study here the distribution of ?{approximately}1600 bulge RR Lyrae stars found by the MACHO Project. The RR Lyrae with 0.4 ? R ? 3 kpc show a density law that is well fit by the extension of the metal-poor stellar halo present in the outer regions of the Milky Way.

  5. Is the Galactic bulge devoid of planets?

    CERN Document Server

    Penny, Matthew T; Clanton, Christian

    2016-01-01

    Using a sample of 31 microlensing exoplanet hosts, we investigate whether or not the distances to these systems conform to the Galactic distribution of planets expected from a model. We derive the expected distribution of distances from a simulated microlensing survey, correcting (roughly) for the dominant selection effects that affect the detection sensitivity to planets as a function of their distance, and compare with the observed distribution using Anderson-Darling (AD) hypothesis testing. We find that the AD test rejects the hypothesis that the observed sample is drawn from our model distribution of distances with p-value $5.0\\times10^{-4}$. Interestingly, we find that an AD test can not reject ($p=0.18$) the hypothesis that the observed sample is drawn from a model distribution where only disk stars host planets (i.e., a model where there are no bulge planets), though AD tests of the relative proper motion distributions indicate tension with this extreme hypothesis. Allowing the relative abundance of pl...

  6. Polarization in microlensing towards the Galactic bulge

    CERN Document Server

    Ingrosso, G; De Paolis, F; Jetzer, Ph; Nucita, A A; Strafella, F; Zakharov, A F

    2012-01-01

    Gravitational microlensing, when finite size source effects are relevant, provides an unique tool for the study of source star stellar atmospheres through an enhancement of a characteristic polarization signal. This is due to the differential magnification induced during the crossing of the source star. In this paper we consider a specific set of reported highly magnified, both single and binary exoplanetary systems, microlensing events towards the Galactic bulge and evaluate the expected polarization signal. To this purpose, we consider several polarization models which apply to different types of source stars: hot, late type main sequence and cool giants. As a result we compute the polarization signal P,which goes up to P=0.04% for late type stars and up to a few percent for cool giants, depending on the underlying physical polarization processes and atmosphere model parameters. Given a I band magnitude at maximum magnification of about 12, and a typical duration of the polarization signal up to 1 day, we c...

  7. SuperMassive Black Holes in Bulges

    CERN Document Server

    Sarzi, M; Shields, J C; Rudnick, G; Ho, L C; McIntosh, D H; Filippenko, A V; Sargent, W L W; Sarzi, Marc; Rix, Hans-Walter; Shields, Joseph C.; Rudnick, Greg; Ho, Luis C.; Intosh, Daniel H. Mc; Filippenko, Alexei V.; Sargent, Wallace L. W.

    2001-01-01

    We present spatially extended gas kinematics at parsec-scale resolution for the nuclear regions of four nearby disk galaxies, and model them as rotation of a gas disk in the joint potential of the stellar bulge and a putative central black hole. The targets were selected from a larger set of long-slit spectra obtained with the Hubble Space Telescope as part of the Survey of Nearby Nuclei with STIS (SUNNS). They represents the 4 galaxies (of 24) that display symmetric gas velocity curves consistent with a rotating disk. We derive the stellar mass distribution from the STIS acquisition images adopting the stellar mass-to-light ratio normalized so as to match ground-based velocity dispersion measurements over a large aperture. Subsequently, we constrain the mass of a putative black hole by matching the gas rotation curve, following two distinct approaches. In the most general case we explore all the possible disk orientations, alternatively we constrain the gas disk orientation from the dust-lane morphology at s...

  8. Chemical similarities between Galactic bulge and local thick disk red giant stars

    OpenAIRE

    Melendez, J.; Asplund, M.; Alves-Brito, A.; Cunha, K.; B. Barbuy; Bessell, M. S.; Chiappini, C.; Freeman, K. C.; Ramirez, I.; Smith, V.V.; Yong, D.

    2008-01-01

    The evolution of the Milky Way bulge and its relationship with the other Galactic populations is still poorly understood. The bulge has been suggested to be either a merger-driven classical bulge or the product of a dynamical instability of the inner disk. To probe the star formation history, the initial mass function and stellar nucleosynthesis of the bulge, we performed an elemental abundance analysis of bulge red giant stars. We also completed an identical study of local thin disk, thick d...

  9. Hiding its age: the case for a younger bulge

    CERN Document Server

    Haywood, M; Snaith, O; Calamida, A

    2016-01-01

    The determination of the age of the bulge has led to two contradictory results. On the one side, the color-magnitude diagrams in different bulge fields seem to indicate a uniformly old ($>$10 Gyr) population. On the other side, individual ages derived from dwarfs observed through microlensing events seem to indicate a large spread, from $\\sim$ 2 to $\\sim$ 13 Gyr. Because the bulge is now recognised as being mainly a boxy peanut-shaped bar, it is suggested that disk stars are one of its main constituents, and therefore also stars with ages significantly younger than 10 Gyr. Other arguments as well point to the fact that the bulge cannot be exclusively old, and in particular cannot be a burst population, as it is usually expected if the bulge was the fossil remnant of a merger phase in the early Galaxy. In the present study, we show that given the range of metallicities observed in the bulge, a uniformly old population would be reflected into a significant spread in color at the turn-off which is not observed. ...

  10. Extended thermodynamics

    CERN Document Server

    Müller, Ingo

    1993-01-01

    Physicists firmly believe that the differential equations of nature should be hyperbolic so as to exclude action at a distance; yet the equations of irreversible thermodynamics - those of Navier-Stokes and Fourier - are parabolic. This incompatibility between the expectation of physicists and the classical laws of thermodynamics has prompted the formulation of extended thermodynamics. After describing the motifs and early evolution of this new branch of irreversible thermodynamics, the authors apply the theory to mon-atomic gases, mixtures of gases, relativistic gases, and "gases" of phonons and photons. The discussion brings into perspective the various phenomena called second sound, such as heat propagation, propagation of shear stress and concentration, and the second sound in liquid helium. The formal mathematical structure of extended thermodynamics is exposed and the theory is shown to be fully compatible with the kinetic theory of gases. The study closes with the testing of extended thermodynamics thro...

  11. Resonant Orbits and the High Velocity Peaks toward the Bulge

    Science.gov (United States)

    Molloy, Matthew; Smith, Martin C.; Evans, N. Wyn; Shen, Juntai

    2015-10-01

    We extract the resonant orbits from an N-body bar that is a good representation of the Milky Way, using the method recently introduced by Molloy et al. By decomposing the bar into its constituent orbit families, we show that they are intimately connected to the boxy-peanut shape of the density. We highlight the imprint due solely to resonant orbits on the kinematic landscape toward the Galactic center. The resonant orbits are shown to have distinct kinematic features and may be used to explain the cold velocity peak seen in the Apache Point Observatory Galactic Evolution Experiment commissioning data. We show that high velocity peaks are a natural consequence of the motions of stars in the 2:1 orbit family and that stars on other higher order resonances can contribute to the peaks. The locations of the peaks vary with bar angle and, with the tacit assumption that the observed peaks are due to the 2:1 family, we find that the locations of the high velocity peaks correspond to bar angles in the range {10}\\circ ≲ {θ }{bar}≲ 25^\\circ . However, some important questions about the nature of the peaks remain, such as their apparent absence in other surveys of the Bulge and the deviations from symmetry between equivalent fields in the north and south. We show that the absence of a peak in surveys at higher latitudes is likely due to the combination of a less prominent peak and a lower number density of bar supporting orbits at these latitudes.

  12. Investigation into the factors that influence inverse bulging effect during sheet hydro-mechanical deep drawing

    Directory of Open Access Journals (Sweden)

    Lang Lihui

    2015-01-01

    Full Text Available The factors that influence inverse bulging effect during sheet hydro-mechanical deep drawing are especially researched in this paper. According to the different inverse bulging process, two modes can be singled: the initial inverse bulging (IIB and the local inverse bulging (LIB. IIB includes two parameters: inverse bulging height ratio (HIb/t and inverse bulging pressure ratio (PIb/t. LIB is influenced by IIB and has a direct relationship with liquid chamber pressure in the forming process. The optimal inverse bulging parameters of hemispherical bottom cylindrical part and flat bottom cylindrical part are obtained by numerical simulation. Process parameters including the clearance between the punch and the blank holder and the blank holder entrance radius that have a large influence on inverse bulging effect are optimized, so as to make inverse bulging effect behave better in hydroforming process. Finally, the accuracy of the numerical simulation results was verified by experiments.

  13. General thermodynamics

    CERN Document Server

    Olander, Donald

    2007-01-01

    The book’s methodology is unified, concise, and multidisciplinary, allowing students to understand how the principles of thermodynamics apply to all technical fields that touch upon this most fundamental of scientific theories. It also offers a rigorous approach to the quantitative aspects of thermodynamics, accompanied by clear explanations to help students transition smoothly from the physical concepts to their mathematical representations

  14. Black hole thermodynamics in finite time

    CERN Document Server

    Gruber, Christine

    2016-01-01

    Finite-time thermodynamics provides the means to revisit ideal thermodynamic equilibrium processes in the light of reality and investigate the energetic "price of haste", i.e. the consequences of carrying out a process in finite time, when perfect equilibrium cannot be awaited due to economic reasons or the nature of the process. Employing the formalism of geometric thermodynamics, a lower bound on the energy dissipated during a process is derived from the thermodynamic length of that process. The notion of length is hereby defined via a metric structure on the space of equilibrium thermodynamics, spanned by a set of thermodynamic variables describing the system. Since the aim of finite-time thermodynamics is to obtain realistic limitations on idealized scenarios, it is a useful tool to reassess the efficiency of thermodynamic processes. We examine its implications for black hole thermodynamics, in particular scenarios inspired by the Penrose process, a thought experiment by which work can be extracted from a...

  15. Bulge growth through disk instabilities in high-redshift galaxies

    CERN Document Server

    Bournaud, Frederic

    2015-01-01

    The role of disk instabilities, such as bars and spiral arms, and the associated resonances, in growing bulges in the inner regions of disk galaxies have long been studied in the low-redshift nearby Universe. There it has long been probed observationally, in particular through peanut-shaped bulges. This secular growth of bulges in modern disk galaxies is driven by weak, non-axisymmetric instabilities: it mostly produces pseudo-bulges at slow rates and with long star-formation timescales. Disk instabilities at high redshift (z>1) in moderate-mass to massive galaxies (10^10 to a few 10^11 Msun of stars) are very different from those found in modern spiral galaxies. High-redshift disks are globally unstable and fragment into giant clumps containing 10^8-10^9 Msun of gas and stars each, which results in highly irregular galaxy morphologies. The clumps and other features associated to the violent instability drive disk evolution and bulge growth through various mechanisms, on short timescales. The giant clumps can...

  16. The 3D structure of the Galactic bulge

    CERN Document Server

    Zoccali, M

    2016-01-01

    We review the observational evidences concerning the three-dimensional structure of the Galactic bulge. Although the inner few kpc of our Galaxy are normally referred to as {\\it the bulge}, all the observations demonstrate that this region is dominated by a bar, i.e., the bulge is a bar. The bar has a boxy/peanut (X\\--shaped) structure in its outer regions, while it seems to become less and less elongated in its innermost region. A thinner and longer structure departing from the main bar has also been found, although the observational evidences that support the scenario of two separate structures has been recently challenged. Metal poor stars ([Fe/H]$\\lesssim -0.5$ dex) trace a different structure, and also have different kinematics.

  17. The lack of carbon stars in the Galactic bulge

    Institute of Scientific and Technical Information of China (English)

    Zhu Chun-Hua; Lv Guo-Liang; Wang Zhao-Jun; Zhang Jun

    2008-01-01

    In order to explain the lack of carbon stars in the Galactic bulge, we have made a detailed study of thermal pulseasymptotic giant branch (TP-AGB) stars by using a population synthesis code. The effects of the oxygen overabundance and the mass loss rate on the ratio of the number of carbon stars to that of oxygen stars in the Galactic bulge are discussed. We find that the oxygen overabundance which is about twice as large as that in the solar neighbourhood (close to the present observations) is insufficient to explain the rareness of carbon stars in the bulge. We suggest that the large mass loss rate may serve as a controlling factor in the ratio of the number of carbon stars to that of oxygen stars.

  18. Counterparts to the Nuclear Bulge X-ray source population

    CERN Document Server

    Gosling, Andrew J; Blundell, Katherine M; Lucas, Phil

    2008-01-01

    We present an initial matching of the source positions of the Chandra Nuclear Bulge X-ray sources to the new UKIDSS-GPS near-infrared survey of the Nuclear Bulge. This task is made difficult by the extremely crowded nature of the region, despite this, we find candidate counterparts to ~50% of the X-ray sources. We show that detection in the J-band for a candidate counterpart to an X-ray source preferentially selects those candidate counterparts in the foreground whereas candidate counterparts with only detections in the H and K-bands are more likely to be Nuclear Bulge sources. We discuss the planned follow-up for these candidate counterparts.

  19. Near-Infrared Bulge-Disk Correlations of Lenticular Galaxies

    CERN Document Server

    Barway, Sudhanshu; Kembhavi, Ajit K; Mayya, Y D

    2008-01-01

    We consider the luminosity and environmental dependence of structural parameters of lenticular galaxies in the near-infrared K band. Using a two-dimensional galaxy image decomposition technique, we extract bulge and disk structural parameters for a sample of 36 lenticular galaxies observed by us in the K band. By combining data from the literature for field and cluster lenticulars with our data, we study correlations between parameters that characterise the bulge and the disk as a function of luminosity and environment. We find that scaling relations such as the Kormendy relation, photometric plane and other correlations involving bulge and disk parameters show a luminosity dependence. This dependence can be explained in terms of galaxy formation models in which faint lenticulars (M_T > -24.5) formed via secular formation processes that likely formed the pseudobulges of late-type disk galaxies, while brighter lenticulars (M_T < -24.5) formed through a different formation mechanism most likely involving maj...

  20. Myelographic differentiation of bulging disk from herniated disk

    International Nuclear Information System (INIS)

    Among the many causes producing lower back pain herniated nucleus pulposus and bulging disk have occupied large percentages and uniformly showed defect on lateral aspect of contrast filled thecal sac. But it is essential to differentiate each conditions from the other because of their different treatment methods. Differentiation at metrizamide myelography between a diffusely bulging disk (unlikely to cause nerve root compression) and a herniated disk is based on the curvature, extent, and multiplicity of the extradural deformity of the anterolateral margin of the contrast filled sac and on the presence of fusiform widening of the most distal part of the affected nerve root. The deformities caused by a bulging disk are round, usually symmetrical (although occasionally more prominent on one side), do not extend above or below the disk space, and can show multiple level involvement; the nerve root is uniform in caliber and normal in size (although some of severe bulging show fusiform sidening of the most distal part of the affected nerve root). The deformities caused by a herniated disk is angular and extends cephadol and/or caudal to the level of the disk space; the affected nerve root is usually widened in its most distal visible part. A consecutive series of 50 patients with low back pain and no past history of back surgery who did metrizamide myelography underwent spine CT and/or laminectomy. Using the criteria listed above for differentiation of bulging from herniated disk on metrizamide myelography, the myelographic diagnosis was correct in 32 (22 patients) of 34 (24 patients) (95%) surgically and/or computed tomographically confirmed bulging disks and in all 26 (100%) surgically and/or computed tomographically confirmed herniated disks.

  1. Chemodynamical analysis of bulge stars for simulated disc galaxies

    OpenAIRE

    A. Rahimi; Kawata, D.; Brook, Chris B.; Gibson, Brad K.

    2009-01-01

    We analyse the kinematics and chemistry of the bulge stars of two simulated disc galaxies using our chemodynamical galaxy evolution code GCD+. First we compare stars that are born inside the galaxy with those that are born outside the galaxy and are accreted into the centre of the galaxy. Stars that originate outside of the bulge are accreted into it early in its formation within 3 Gyrs so that these stars have high [alpha/Fe] as well as having a high total energy reflecting their accretion t...

  2. Spin-up of massive classical bulges during secular evolution

    Science.gov (United States)

    Saha, Kanak; Gerhard, Ortwin; Martinez-Valpuesta, Inma

    2016-04-01

    Context. Classical bulges in spiral galaxies are known to rotate, but the origin of this observed rotational motion is not well understood. It has been shown recently that a low-mass classical bulge (ClB) in a barred galaxy can acquire rotation by absorbing a significant fraction of the angular momentum emitted by the bar. Aims: Our aim here is to investigate whether bars can also spin up more massive ClBs during the secular evolution of the bar, and to study the kinematics and dynamics of these ClBs. Methods: We use a set of self-consistent N-body simulations to study the interaction of ClBs with a bar that forms self-consistently in the disk. We use orbital spectral analysis to investigate the angular momentum gain by the classical bulge stars. Results: We show that the ClBs gain on average 2-6% of the disk's initial angular momentum within the bar region. Most of this angular momentum gain occurs via low-order resonances, particularly 5:2 resonant orbits. A density wake forms in the ClB which corotates and aligns with the bar at the end of the evolution. The spin-up process creates a characteristic linear rotation profile and mild tangential anisotropy in the ClB. The induced rotation is small in the centre, but is significant beyond ~2 bulge half mass radii, where it leads to mass-weighted V/σ ~ 0.2, and reaches a local Vmax/σin ~ 0.5 at around the scale of the bar. The resulting V/σ is tightly correlated with the ratio of the bulge size to the bar size. In all models, a box/peanut bulge forms suggesting that composite bulges may be common. Conclusions: Bar-bulge resonant interaction in barred galaxies can provide some spin-up of massive ClBs, but the process appears to be less efficient than for low-mass ClBs. Further angular momentum transfer due to nuclear bars or gas inflow would be required to explain the observed rotation if it is not primordial.

  3. The lack of carbon stars in the Galactic bulge

    OpenAIRE

    Chunhua, Zhu; Guoliang, Lv; Zhaojun, Wang; Jun, Zhang

    2008-01-01

    In order to explain the lack of carbon stars in the Galactic bulge, we have made a detailed study of thermal pulse - asymptotic giant branch stars by using a population synthesis code. The effects of the oxygen overabundance and the mass loss rate on the ratio of the number of carbon stars to that of oxygen stars in the Galactic bulge are discussed. We find that the oxygen overabundance which is about twice as large as that in the solar neighbourhood (close to the present observations) is ins...

  4. Ongoing massive star formation in the bulge of M51

    OpenAIRE

    Lamers, H. J. G. L. M.; Panagia, N.; Scuderi, S.; Romaniello, M.; Spaans, M.; de Wit, W.J.M.; Krishner, R.

    2001-01-01

    We studied the HST-WFPC2 observations of the inner kpc of the interacting galaxy M51 in six bands from 2550 to 8140 Angstrom. The images show an oval shaped area ("bulge") of 11x16 arcsec or 450x650 pc around the nucleus, dominated by a smooth population of old stars with overimposed dust lanes. We found 30 bright point-like sources in the bulge of M51; many of these are bright in the UV. They are located in elongated "strings" which follow the general pattern of the dust lanes. The spectral ...

  5. Atmospheric thermodynamics

    CERN Document Server

    Iribarne, J V

    1973-01-01

    The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

  6. Continuum thermodynamics

    CERN Document Server

    Wilmanski, Krzysztof

    2008-01-01

    This book is a unique presentation of thermodynamic methods of construction of continuous models. It is based on a uniform approach following from the entropy inequality and using Lagrange multipliers as auxiliary quantities in its evaluation. It covers a wide range of models - ideal gases, thermoviscoelastic fluids, thermoelastic and thermoviscoelastic solids, plastic polycrystals, miscible and immiscible mixtures, and many others. The structure of phenomenological thermodynamics is justified by a systematic derivation from the Liouville equation, through the BBGKY-hierarchy-derived Boltzmann

  7. Reconciling the Galactic Bulge Turnoff Age Discrepancy with Enhanced Helium Enrichment

    CERN Document Server

    Nataf, David M

    2011-01-01

    We show that the factor $\\sim$2 discrepancy between spectroscopic and photometric age determinations of the Galactic bulge main-sequence turnoff can be naturally explained by positing an elevated helium enrichment for the bulge relative to that assumed by standard isochrones. We obtain an upper bound on the helium enrichment parameter of the bulge $({\\Delta}Y/{\\Delta}Z)_{\\rm{Bulge}} \\lesssim 5.0$ given the requirement that the spectroscopic and photometric ages be consistent and the limiting condition of instantaneous star formation. The corresponding mean age for the bulge is $t_{\\rm{Bulge}} \\approx 10$ Gyr. We discuss phenomenological evidence that the bulge may have had a chemical evolution that is distinct from the solar neighborhood in this manner, and we make several testable predictions. Should this emerging picture of the bulge as helium-enhanced hold, it will require the development of new isochrones, new model atmospheres, and modified analysis and cosmological interpretation of the integrated light...

  8. What planetary nebulae tell us about helium and the CNO elements in Galactic bulge stars

    OpenAIRE

    Buell, James F.

    2012-01-01

    Thermally pulsing asymptotic giant branch (TP-AGB) models of bulge stars are calculated using a synthetic model. The goal is to infer typical progenitor masses and compositions by reproducing the typical chemical composition and central star masses of planetary nebulae (PNe) in the Galactic bulge. The AGB tip luminosity and the observation that the observed lack of bright carbon stars in the bulge are matched by the models. Five sets of galactic bulge PNe were analyzed to find typical abundan...

  9. The disc origin of the Milky Way bulge

    CERN Document Server

    Di Matteo, P

    2016-01-01

    The Galactic bulge, that is the prominent out-of-plane over-density present in the inner few kiloparsecs of the Galaxy, is a complex structure, as the morphology, kinematics, chemistry and ages of its stars indicate. To understand the nature of its main components -- those at [Fe/H] >~ -1 dex -- it is necessary to make an inventory of the stellar populations of the Galactic disc(s), and of their borders : the chemistry of the disc at the solar vicinity, well known from detailed studies of stars over many years, is not representative of the whole disc. This finding, together with the recent revisions of the mass and sizes of the thin and thick discs, constitutes a major step in understanding the bulge complexity. N-body models of a boxy/peanut-shaped bulge formed from a thin disc through the intermediary of a bar have been successful in interpreting a number of global properties of the Galactic bulge, but they fail in reproducing the detailed chemo-kinematic relations satisfied by its components and their morp...

  10. The Metallicity Distribution of the Milky Way Bulge

    CERN Document Server

    Ness, M

    2015-01-01

    The Galactic bulge of the Milky Way is made up of stars with a broad range of metallicity, -3.0 < [Fe/H] < 1 dex. The mean of the Metallicity Distribution Function (MDF) decreases as a function of height z from the plane and, more weakly, with galactic radius. The most metal rich stars in the inner Galaxy are concentrated to the plane and the more metal poor stars are found predominantly further from the plane, with an overall vertical gradient in the mean of the MDF of about -0.45 dex/kpc. This vertical gradient is believed to reflect the changing contribution with height of different populations in the inner-most region of the Galaxy. The more metal rich stars of the bulge are part of the boxy/peanut structure and comprise stars in orbits which trace out the underlying X-shape. There is still a lack of consensus on the origin of the metal poor stars ([Fe/H] < -0.5) in the region of the bulge. Some studies attribute the more metal poor stars of the bulge to the thick disk and stellar halo that are p...

  11. MAPPING THE X-SHAPED MILKY WAY BULGE

    International Nuclear Information System (INIS)

    We analyzed the distribution of the red clump (RC) stars throughout the Galactic bulge using Two Micron All Sky Survey data. We mapped the position of the RC in 1 deg2 fields within the area |l| ≤ 8.05 and 3.05 ≤ |b| ≤ 8.05, for a total of 170 deg2. The single RC seen in the central area splits into two components at high Galactic longitudes in both hemispheres, produced by two structures at different distances along the same line of sight. The X-shape is clearly visible in the Z-X plane for longitudes close to the l = 00 axis. Crude measurements of the space densities of RC stars in the bright and faint RC populations are consistent with the adopted RC distances, providing further supporting evidence that the X-structure is real, and that there is approximate front-back symmetry in our bulge fields. We conclude that the Milky Way bulge has an X-shaped structure within |l| ∼0, seen almost edge-on with respect to the line of sight. Additional deep near-infrared photometry extending into the innermost bulge regions combined with spectroscopic data is needed in order to discriminate among the different possibilities that can cause the observed X-shaped structure.

  12. Type-Ia Supernova-driven Galactic Bulge Wind

    CERN Document Server

    Tang, Shikui; Mac Low, Mordecai-Mark; Joung, M Ryan

    2009-01-01

    Stellar feedback in galactic bulges plays an essential role in shaping the evolution of galaxies. To quantify this role and facilitate comparisons with X-ray observations, we conduct 3D hydrodynamical simulations with the adaptive mesh refinement code, FLASH, to investigate the physical properties of hot gas inside a galactic bulge, similar to that of our Galaxy or M31. We assume that the dynamical and thermal properties of the hot gas are dominated by mechanical energy input from SNe, primarily Type Ia, and mass injection from evolved stars as well as iron enrichment from SNe. We study the bulge-wide outflow as well as the SN heating on scales down to ~4 pc. An embedding scheme that is devised to plant individual SNR seeds, allows to examine, for the first time, the effect of sporadic SNe on the density, temperature, and iron ejecta distribution of the hot gas as well as the resultant X-ray morphology and spectrum. We find that the SNe produce a bulge wind with highly filamentary density structures and patch...

  13. Stochastic thermodynamics

    Science.gov (United States)

    Eichhorn, Ralf; Aurell, Erik

    2014-04-01

    'Stochastic thermodynamics as a conceptual framework combines the stochastic energetics approach introduced a decade ago by Sekimoto [1] with the idea that entropy can consistently be assigned to a single fluctuating trajectory [2]'. This quote, taken from Udo Seifert's [3] 2008 review, nicely summarizes the basic ideas behind stochastic thermodynamics: for small systems, driven by external forces and in contact with a heat bath at a well-defined temperature, stochastic energetics [4] defines the exchanged work and heat along a single fluctuating trajectory and connects them to changes in the internal (system) energy by an energy balance analogous to the first law of thermodynamics. Additionally, providing a consistent definition of trajectory-wise entropy production gives rise to second-law-like relations and forms the basis for a 'stochastic thermodynamics' along individual fluctuating trajectories. In order to construct meaningful concepts of work, heat and entropy production for single trajectories, their definitions are based on the stochastic equations of motion modeling the physical system of interest. Because of this, they are valid even for systems that are prevented from equilibrating with the thermal environment by external driving forces (or other sources of non-equilibrium). In that way, the central notions of equilibrium thermodynamics, such as heat, work and entropy, are consistently extended to the non-equilibrium realm. In the (non-equilibrium) ensemble, the trajectory-wise quantities acquire distributions. General statements derived within stochastic thermodynamics typically refer to properties of these distributions, and are valid in the non-equilibrium regime even beyond the linear response. The extension of statistical mechanics and of exact thermodynamic statements to the non-equilibrium realm has been discussed from the early days of statistical mechanics more than 100 years ago. This debate culminated in the development of linear response

  14. Bulges of disk galaxies at intermediate redshifts. I. Samples with and without bulges in the Groth Strip Survey

    CERN Document Server

    Dominguez-Palmero, L; Erwin, P; Prieto, M; Cristobal-Hornillos, D; Eliche-Moral, M C; Guzmán, R

    2008-01-01

    We aim to define a sample of intermediate-z disk galaxies harbouring central bulges, and a complementary sample of disk galaxies without measurable bulges. We intend to provide colour profiles for both samples, as well as measurements of nuclear, disk, and global colours, which may be used to constrain the relative ages of bulges and disks. We select a diameter-limited sample of galaxies in images from the HST/WFPC2 Groth Strip survey, which is divided into two subsamples of higher and lower inclination to assess the role of dust in the measures quantities. Mergers are visually identified and excluded. We take special care to control the pollution by ellipticals. The bulge sample is defined with a criterion based on nuclear surface brightness excess over the inward extrapolation of the exponential law fitted to the outer regions of the galaxies. We extract colour profiles on the semi-minor axis least affected by dust in the disk, and measure nuclear colours at 0.85 kpc from the centre over those profiles. Dis...

  15. Stellar populations of classical and pseudo-bulges for a sample of isolated spiral galaxies

    CERN Document Server

    Zhao, Yinghe

    2011-01-01

    In this paper we present the stellar population synthesis results for a sample of 75 bulges in isolated spiral Sb-Sc galaxies, using the spectroscopic data from the Sloan Digital Sky Survey and the STARLIGHT code. We find that both pseudo-bulges and classical bulges in our sample are predominantly composed of old stellar populations, with mean mass-weighted stellar age around 10 Gyr. While the stellar population of pseudo-bulges is, in general, younger than that of classical bulges, the difference is not significant, which indicates that it is hard to distinguish pseudo-bulges from classical bulges, at least for these isolated galaxies, only based on their stellar populations. Pseudo-bulges have star formation activities with relatively longer timescale than classical bulges, indicating that secular evolution is more important in this kind of systems. Our results also show that pseudo-bulges have a lower stellar velocity dispersion than their classical counterparts, which suggests that classical bulges are mo...

  16. Thermodynamic restrictions on the constitutive equations of electromagnetic theory

    Science.gov (United States)

    Coleman, B. D.; Dill, E. H.

    1971-01-01

    Thermodynamics second law restrictions on constitutive equations of electromagnetic theory for nonlinear materials with long-range gradually fading memory, considering dissipation principle consequences

  17. Effect of tube size on electromagnetic tube bulging

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The commercial finite code ANSYS was employed for the simulation of the electromagnetic tube bulging process. The finite element model and boundary conditions were thoroughly discussed. ANSYS/EMAG was used to model the time varying electromagnetic field in order to obtain the radial and axial magnetic pressure acting on the tube. The magnetic pressure was then used as boundary conditions to model the high velocity deformation of various length tube with ANSYS/LSDYNA. The time space distribution of magnetic pressure on various length tubes was presented. Effect of tube size on the distribution of radial magnetic pressure and axial magnetic pressure and high velocity deformation were discussed. According to the radial magnetic pressure ratio of tube end to tube center and corresponding dimensionless length ratio of tube to coil, the free electromagnetic tube bulging was studied in classification. The calculated results show good agreements with practice.

  18. The effect of massive disks on bulge isophotes

    Science.gov (United States)

    Monet, D. G.; Schechter, P. L.; Richstone, D. O.

    1981-04-01

    Massive disks produce flattened equipotentials. Unless the stars in a galaxy bulge are preferentially hotter in the z direction than in the plane, the isophotes will be at least as flat as the equipotentials. The comparison of two galaxy models having flat rotation curves with the available surface photometry for five external galaxies does not restrict the mass fraction which might reside in the disk. However, star counts in our own Galaxy indicate that unless the disk terminates close to the solar circle, no more than half the mass within that circle lies in the disk. The remaining half must lie either in the bulge or, more probably, in a third dark, round, dynamically distinct component.

  19. High precision microlensing maps of the Galactic bulge

    CERN Document Server

    Kerins, E; Marshall, D J

    2008-01-01

    We present detailed maps of the microlensing optical depth and event density over an area of 195 sq. deg towards the Galactic bulge. The maps are computed from synthetic stellar catalogues generated from the Besancon Galaxy Model, which comprises four stellar populations and a three-dimensional extinction map calibrated against the Two-Micron All-Sky Survey. The optical depth maps have a resolution of 15 arcminutes, corresponding to the angular resolution of the extinction map. We compute optical depth and event density maps for all resolved sources above I=19, for unresolved (difference image) sources magnified above this limit, and for bright standard candle sources in the bulge. We show that the resulting optical depth contours are dominated by extinction effects, exhibiting fine structure in stark contrast to previous theoretical optical depth maps. Optical depth comparisons between Galactic models and optical microlensing survey measurements cannot safely ignore extinction or assume it to be smooth. We s...

  20. Bulging of cans containing plutonium residues. Summary report

    International Nuclear Information System (INIS)

    In 1994, two cans in the Lawrence Livermore National Laboratory Plutonium Facility were found to be bulging as a result of the generation of gases form the plutonium ash residues contained in the cans. This report describes the chronology of this discovery, the response actions that revealed other pressurized cans, the analysis of the causes, the short-term remedial action, a followup inspection of the short-term storage packages, and a review of proposed long-term remedial options

  1. Bulging of cans containing plutonium residues. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Van Konynenburg, R.A.; Wood, D.H.; Condit, R.H.; Shikany, S.D.

    1996-03-01

    In 1994, two cans in the Lawrence Livermore National Laboratory Plutonium Facility were found to be bulging as a result of the generation of gases form the plutonium ash residues contained in the cans. This report describes the chronology of this discovery, the response actions that revealed other pressurized cans, the analysis of the causes, the short-term remedial action, a followup inspection of the short-term storage packages, and a review of proposed long-term remedial options.

  2. Determination of flow stress by the hydraulic bulge test

    OpenAIRE

    J. Slota; Spišák, E.

    2008-01-01

    In sheet metal forming operations the mechanical properties of the sheet metal (stress-strain curve, flow stress) greatly influence metal flow and product quality. Accurate determination of the stress-strain relationship is important in process simulation by finite element method. In this paper the sheet thickness gradation in different points of the hemisphere formed in the bulge test is analysed, both theoretically and experimentally. A precise determination of sheet thickness at the pole i...

  3. PROPER MOTIONS IN THE GALACTIC BULGE: PLAUT'S WINDOW

    Directory of Open Access Journals (Sweden)

    K. Vieira

    2009-01-01

    Full Text Available A proper motion study of a eld of 20' x20' inside Plaut's low extinction window (l,b=(0 ;-8 , has been completed. Relative proper motions and photographic BV photometry have been derived for -21; 000 stars reaching to V - 20:5 mag, based on the astrometric reduction of 43 photographic plates, spanning over 21 years of epoch di erence. Proper motion errors are typically 1 mas yr-1. Cross-referencing with the 2MASS catalog yielded a sample of - 8700 stars, from which predominantly disk and bulge subsamples were selected photometrically from the JH color-magnitude diagram. The two samples exhibited di erent proper-motion distributions, with the disk displaying the expected re ex solar motion. Galactic rotation was also detected for stars between -2 and -3 kpc from us. The bulge sample, represented by red giants, has an intrinsic proper motion dispersion of (l; b = (3:39; 2:91 = (0:11; 0:09 mas yr-1, which is in good agreement with previous results. A mean distance of 6:37+0:87 -0:77 kpc has been estimated for the bulge sample, based on the observed K magnitude of the horizontal branch red clump. The metallicity [M=H] distribution was also obtained for a subsample of 60 bulge giants stars, based on calibrated photometric indices. The observed [M=H] shows a peak value at [M=H]-0:1 with an extended metal poor tail and around 30% of the stars with supersolar metallicity. No change in proper motion dispersion was observed as a function of [M=H]. We are currently in the process of obtaining CCD UBV RI photometry for the entire proper-motion sample of - 21; 000 stars.

  4. The bulge-disc decomposition of AGN host galaxies

    Science.gov (United States)

    Bruce, V. A.; Dunlop, J. S.; Mortlock, A.; Kocevski, D. D.; McGrath, E. J.; Rosario, D. J.

    2016-05-01

    We present the results from a study of the morphologies of moderate luminosity X-ray-selected active galactic nuclei (AGN) host galaxies in comparison to a carefully mass-matched control sample at 0.5 hosts are by a potential nuclear contribution from the AGN itself. We find that the AGN hosts are indistinguishable from the general galaxy population except that beyond z ≃ 1.5 they have significantly higher bulge fractions. Even including nuclear sources in our modelling, the probability of this result arising by chance is ˜1 × 10-5, alleviating concerns that previous, purely single Sérsic, analyses of AGN hosts could have been spuriously biased towards higher bulge fractions. This data set also allows us to further probe the physical nature of these point-source components; we find no strong correlation between the point-source component and AGN activity. Our analysis of the bulge and disc fractions of these AGN hosts in comparison to a mass-matched control sample reveals a similar morphological evolutionary track for both the active and non-active populations, providing further evidence in favour of a model where AGN activity is triggered by secular processes.

  5. The Structure of the Milky Way's Bar Outside the Bulge

    CERN Document Server

    Wegg, Christopher; Portail, Matthieu

    2015-01-01

    While it is incontrovertible that the inner Galaxy contains a bar, its structure near the Galactic plane has remained uncertain, where extinction from intervening dust is greatest. We investigate here the Galactic bar outside the bulge, the long bar, using red clump giant (RCG) stars from UKIDSS, 2MASS, VVV, and GLIMPSE. We match and combine these surveys to investigate a wide area in latitude and longitude, |b|<9deg and |l|<40deg. We find: (1) The bar extends to l~25deg at |b|~5deg from the Galactic plane, and to l~30deg at lower latitudes. (2) The long bar has an angle to the line-of-sight in the range (28-33)deg, consistent with studies of the bulge at |l|<10deg. (3) The scale-height of RCG stars smoothly transitions from the bulge to the thinner long bar. (4) There is evidence for two scale heights in the long bar. We find a ~180pc thin bar component reminiscent of the old thin disk near the sun, and a ~45pc super-thin bar component which exists predominantly towards the bar end. (5) Constructing...

  6. Study of extremely reddened AGB stars in the Galactic bulge

    CERN Document Server

    Jiménez-Esteban, F M

    2015-01-01

    Context. Extremely reddened AGB stars lose mass at high rates of >10^-5 Msun/yr. This is the very last stage of AGB evolution, in which stars in the mass range 2.0--4.0 Msun (for solar metallicity) should have been converted to C stars already. The extremely reddened AGB stars in the Galactic bulge are however predominantly O-rich, implying that they might be either low-mass stars or stars at the upper end of the AGB mass range. Aims. To determine the mass range of the most reddened AGB stars in the Galactic bulge. Methods. Using Virtual Observatory tools, we constructed spectral energy distributions of a sample of 37 evolved stars in the Galactic bulge with extremely red IRAS colours. We fitted DUSTY models to the observational data to infer the bolometric fluxes. Applying individual corrections for interstellar extinction and adopting a common distance, we determined luminosities and mass-loss rates, and inferred the progenitor mass range from comparisons with AGB evolutionary models. Results. The observed ...

  7. ISO Mid-Infrared spectroscopy of Galactic Bulge AGB stars

    CERN Document Server

    Blommaert, J A D L; Okumura, K; Ganesh, S; Omont, A; Cami, J; Glass, I S; Habing, H J; Schultheis, M; Simon, G; Van Loon, J T; Blommaert, Joris A.D.L.; Groenewegen, Martin A.T.; Okumura, Koryo; Ganesh, Shashikiran; Omont, Alain; Cami, Jan; Glass, Ian S.; Habing, Harm J.; Schultheis, Mathias; Simon, Guy; Loon, Jacco Th. van

    2006-01-01

    To study the nature of Bulge AGB stars and in particular their circumstellar dust, we have analysed mid-infrared spectra obtained with the ISOCAM CVF spectrometer in three Bulge fields. The ISOCAM 5-16.5 micron CVF spectra were obtained as part of the ISOGAL infrared survey of the inner Galaxy. A classification of the shape of the 10 micron dust feature was made for each case. The spectra of the individual sources were modelled using a radiative transfer model. Different combinations of amorphous silicates and aluminium-oxide dust were used in the modelling. Spectra were obtained for 29 sources of which 26 are likely to be Bulge AGB stars. Our modelling shows that the stars suffer mass loss rates in the range of 10^{-8} - 5 x 10^{-7} Msun / yr, which is at the low end of the mass-loss rates experienced on the Thermally Pulsing AGB. The luminosities range from 1,700 to 7,700 Lsun as expected for a population of AGB stars with Minit of 1.5 - 2Msun. In agreement with the condensation sequence scenario, we find t...

  8. Alpha-Bulges in G Protein-Coupled Receptors

    Directory of Open Access Journals (Sweden)

    Rob van der Kant

    2014-05-01

    Full Text Available Agonist binding is related to a series of motions in G protein-coupled receptors (GPCRs that result in the separation of transmembrane helices III and VI at their cytosolic ends and subsequent G protein binding. A large number of smaller motions also seem to be associated with activation. Most helices in GPCRs are highly irregular and often contain kinks, with extensive literature already available about the role of prolines in kink formation and the precise function of these kinks. GPCR transmembrane helices also contain many α-bulges. In this article we aim to draw attention to the role of these α-bulges in ligand and G-protein binding, as well as their role in several aspects of the mobility associated with GPCR activation. This mobility includes regularization and translation of helix III in the extracellular direction, a rotation of the entire helix VI, an inward movement of the helices near the extracellular side, and a concerted motion of the cytosolic ends of the helices that makes their orientation appear more circular and that opens up space for the G protein to bind. In several cases, α-bulges either appear or disappear as part of the activation process.

  9. GAMA: Stellar Mass Assembly in Galaxy Bulges and Disks

    Science.gov (United States)

    Moffett, Amanda J.; Driver, Simon P.; Lange, Rebecca; Robotham, Aaron; Kelvin, Lee; GAMA Team

    2016-01-01

    The Galaxy And Mass Assembly (GAMA) survey has to date obtained spectra, redshifts, and 21-band multi-facility photometry for over 200,000 galaxies in five survey regions that total nearly 300 square degrees on sky. We consider here a low-redshift (zteam. In order to quantify the separate bulge and disk properties of these galaxies, we apply a large-scale automated procedure for fitting images with 2D, multi-component structure models, including evaluation of fit convergence using a grid of input parameter values for each galaxy. From this analysis, we calculate the total bulge and disk contributions to the local galaxy stellar mass budget and derive mass-size relations for both pure spheroid/disk systems and the separate bulge/disk components of multi-component galaxies. We further examine the fraction of total stellar mass assembled in spheroid and disk structures as a function of galaxy environment, where environment is quantified on multiple scales from membership in large-scale filaments to groups/clusters and down to local pairings. We then discuss the effect of environmental conditions on the mechanisms of stellar mass assembly, including the implied balance between merger accumulation and in situ mass growth in different environment regimes.

  10. The Black Hole - Bulge Mass Relation in Megamaser Host Galaxies

    CERN Document Server

    Läsker, Ronald; Seth, Anil; van de Ven, Glenn; Braatz, James A; Henkel, Christian; Lo, K Y

    2016-01-01

    We present HST images for nine megamaser disk galaxies with the primary goal of studying photometric BH-galaxy scaling relations. The megamaser disks provide the highest-precision extragalactic BH mass measurements, while our high-resolution HST imaging affords us the opportunity to decompose the complex nuclei of their late-type hosts in detail. Based on the morphologies and shapes of the galaxy nuclei, we argue that most of these galaxies' central regions contain secularly evolving components (pseudo-bulges), and in many cases we photometrically identify co-existing "classical" bulge components as well. Using these decompositions, we draw the following conclusions: (1) The megamaser BH masses span two orders of magnitude ($10^6$ -- $10^8 M_\\odot$) while the stellar mass of their spiral host galaxies are all $\\sim 10^{11} M_\\odot$ within a factor of three; (2) the BH masses at a given bulge mass or total stellar mass in the megamaser host spiral galaxies tend to be lower than expected, when compared to an ex...

  11. YOUNG STARS IN AN OLD BULGE: A NATURAL OUTCOME OF INTERNAL EVOLUTION IN THE MILKY WAY

    International Nuclear Information System (INIS)

    The center of our disk galaxy, the Milky Way, is dominated by a boxy/peanut-shaped bulge. Numerous studies of the bulge based on stellar photometry have concluded that the bulge stars are exclusively old. The perceived lack of young stars in the bulge strongly constrains its likely formation scenarios, providing evidence that the bulge is a unique population that formed early and separately from the disk. However, recent studies of individual bulge stars using the microlensing technique have reported that they span a range of ages, emphasizing that the bulge may not be a monolithic structure. In this Letter we demonstrate that the presence of young stars that are located predominantly nearer to the plane is expected for a bulge that has formed from the disk via dynamical instabilities. Using an N-body+ smoothed particle hydrodynamics simulation of a disk galaxy forming out of gas cooling inside a dark matter halo and forming stars, we find a qualitative agreement between our model and the observations of younger metal-rich stars in the bulge. We are also able to partially resolve the apparent contradiction in the literature between results that argue for a purely old bulge population and those that show a population comprised of a range in ages; the key is where to look

  12. Solvation thermodynamics

    CERN Document Server

    Ben-Naim, Arieh

    1987-01-01

    This book deals with a subject that has been studied since the beginning of physical chemistry. Despite the thousands of articles and scores of books devoted to solvation thermodynamics, I feel that some fundamen­ tal and well-established concepts underlying the traditional approach to this subject are not satisfactory and need revision. The main reason for this need is that solvation thermodynamics has traditionally been treated in the context of classical (macroscopic) ther­ modynamics alone. However, solvation is inherently a molecular pro­ cess, dependent upon local rather than macroscopic properties of the system. Therefore, the starting point should be based on statistical mechanical methods. For many years it has been believed that certain thermodynamic quantities, such as the standard free energy (or enthalpy or entropy) of solution, may be used as measures of the corresponding functions of solvation of a given solute in a given solvent. I first challenged this notion in a paper published in 1978 b...

  13. An Observational Guide to Identifying Pseudobulges and Classical Bulges in Disk Galaxies

    CERN Document Server

    Fisher, David B

    2015-01-01

    In this review our aim is to summarize the observed properties of pseudobulges and classical bulges. We utilize an empirical approach to studying the properties of bulges in disk galaxies, and restrict our analysis to statistical proper- ties. A clear bimodality is observed in a number of properties including morphology, structural properties, star formation, gas content & stellar population, and kinematics. As well as summarizing known methods to identify pseudobulges and classical bulges we also show new results, including absorption line indices that can be used to identify different bulge types. We conclude by summarizing those properties that isolate pseudobulges from classical bulges. Our intention is to describe a practical, easy to use, list of criteria for identifying bulge types.

  14. Effect of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Temperature is one of the key parameters for BT20 titanium alloy cylindrical workpiece manufactured by vacuum hot bulge forming. A two-dimensional nonlinear thermo-mechanical coupled FE model was established. Numerical simulation of vacuum hot bulge forming process of titanium alloy cylindrical workpiece was carried out using FE analysis software MSC Marc. The effects of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece were analyzed by numerical simulation.The simulated results show that the Y-direction displacement and the equivalent plastic strain of the workpiece increase with increasing bulge temperature. The residual stress decreases with increasing bulge temperature. The optimal temperature range of BT20 titanium alloy during vacuum hot bulge forming is 750-850 ℃. The corresponding experiments were carried out. The simulated results agreed well with the experimental results.

  15. Research on aluminum alloy sheet thermoplastic deformation behavior based upon warm bulging test

    Science.gov (United States)

    Cai, Gaoshen; Zhou, Xiaojun; Lang, Lihui; Alexandrov, Sergei

    2016-02-01

    The rate of fluid pressure variation is a crucial factor to indicate the forming speed and the pressure rate is applied to be one factor that can influence the deformation of material in warm sheet hydroforming. In this study, warm bulging test was conducted to obtain bulging pressure-height curves with different temperatures and pressure rates. Fitting the bulging pressure-equivalent strain curves obtained using bulging test with surface fitting method, the fitted equation of bulging pressure on equivalent strain and pressure rate was achieved, and the fitting result shows a good accordance with experimental and calculated values. Then, the relation between pressure rate and strain rate was obtained. The results of warm bulging test indicated that the deformation behavior of metal material is sensitive to pressure rate, which is of great significance for warm sheet hydroforming.

  16. Ecosystem thermodynamics

    International Nuclear Information System (INIS)

    Ecology is no more a descriptive and self-sufficient science. Many viewpoints are needed simultaneously to give a full coverage of such complex systems: ecosystems. These viewpoints come from physics, chemistry, and nuclear physics, without a new far from equilibrium thermodynamics and without new mathematical tools such as catastrophe theory, fractal theory, cybernetics and network theory, the development of ecosystem science would never have reached the point of today. Some ideas are presented about the importance that concept such as energy, entropy, exergy information and none equilibrium have in the analysis of processes taking place in ecosystems

  17. The growth of disks and bulges during hierarchical galaxy formation. I: fast evolution vs secular processes

    Science.gov (United States)

    Tonini, C.; Mutch, S. J.; Croton, D. J.; Wyithe, J. S. B.

    2016-04-01

    We present a theoretical model for the evolution of mass, angular momentum and size of galaxy disks and bulges, and we implement it into the semi-analytic galaxy formation code SAGE. The model follows both secular and violent evolutionary channels, including smooth accretion, disk instabilities, minor and major mergers. We find that the combination of our recipe with hierarchical clustering produces two distinct populations of bulges: merger-driven bulges, akin to classical bulges and ellipticals, and instability-driven bulges, akin to secular (or pseudo-)bulges. The model mostly reproduces the mass-size relation of gaseous and stellar disks, the evolution of the mass-size relation of ellipticals, the Faber-Jackson relation, and the magnitude-colour diagram of classical and secular bulges. The model predicts only a small overlap of merger-driven and instability-driven components in the same galaxy, and predicts different bulge types as a function of galaxy mass and disk fraction. Bulge type also affects the star formation rate and colour at a given luminosity. The model predicts a population of merger-driven red ellipticals that dominate both the low-mass and high-mass ends of the galaxy population, and span all dynamical ages; merger-driven bulges in disk galaxies are dynamically old and do not interfere with subsequent evolution of the star-forming component. Instability-driven bulges dominate the population at intermediate galaxy masses, especially thriving in massive disks. The model green valley is exclusively populated by instability-driven bulge hosts. Through the present implementation the mass accretion history is perceivable in the galaxy structure, morphology and colours.

  18. The growth of discs and bulges during hierarchical galaxy formation - I. Fast evolution versus secular processes

    Science.gov (United States)

    Tonini, C.; Mutch, S. J.; Croton, D. J.; Wyithe, J. S. B.

    2016-07-01

    We present a theoretical model for the evolution of mass, angular momentum and size of galaxy discs and bulges, and we implement it into the semi-analytic galaxy formation code, Semi-Analytic Galaxy Evolution. The model follows both secular and violent evolutionary channels, including smooth accretion, disc instabilities, minor and major mergers. We find that the combination of our recipe with hierarchical clustering produces two distinct populations of bulges: merger-driven bulges, akin to classical bulges and ellipticals, and instability-driven bulges, akin to secular (or pseudo-)bulges. The model mostly reproduces the mass-size relation of gaseous and stellar discs, the evolution of the mass-size relation of ellipticals, the Faber-Jackson relation, and the magnitude-colour diagram of classical and secular bulges. The model predicts only a small overlap of merger-driven and instability-driven components in the same galaxy, and predicts different bulge types as a function of galaxy mass and disc fraction. Bulge type also affects the star formation rate and colour at a given luminosity. The model predicts a population of merger-driven red ellipticals that dominate both the low-mass and high-mass ends of the galaxy population, and span all dynamical ages; merger-driven bulges in disc galaxies are dynamically old and do not interfere with subsequent evolution of the star-forming component. Instability-driven bulges dominate the population at intermediate galaxy masses, especially thriving in massive discs. The model green valley is exclusively populated by instability-driven bulge hosts. Through the present implementation, the mass accretion history is perceivable in the galaxy structure, morphology and colours.

  19. Young stars in an old bulge: a natural outcome of internal evolution in the Milky Way

    CERN Document Server

    Ness, M; Bensby, T; Feltzing, S; Roskar, R; Cole, D R; Johnson, J A; Freeman, K

    2014-01-01

    The center of our disk galaxy, the Milky Way, is dominated by a boxy/peanut-shaped bulge. Numerous studies of the bulge based on stellar photometry have concluded that the bulge stars are exclusively old. The perceived lack of young stars in the bulge strongly constrains its likely formation scenarios, providing evidence that the bulge is a unique population that formed early and separately from the disk. However, recent studies of individual bulge stars using the microlensing technique have reported that they span a range of ages, emphasizing that the bulge may not be a monolithic structure. In this letter we demonstrate that the presence of young stars that are located predominantly near the plane is expected for a bulge that has formed from the disk via dynamical instabilities. Using an N-body+SPH simulation of a disk galaxy forming out of gas cooling inside a dark matter halo and forming stars, we find a qualitative agreement between our model and the observations of young metal-rich stars in the bulge. W...

  20. The growth of disks and bulges during hierarchical galaxy formation. I: fast evolution vs secular processes

    CERN Document Server

    Tonini, Chiara; Croton, Darren J; Wyithe, J Stuart B

    2016-01-01

    We present a theoretical model for the evolution of mass, angular momentum and size of galaxy disks and bulges, and we implement it into the semi-analytic galaxy formation code SAGE. The model follows both secular and violent evolutionary channels, including smooth accretion, disk instabilities, minor and major mergers. We find that the combination of our recipe with hierarchical clustering produces two distinct populations of bulges: merger-driven bulges, akin to classical bulges and ellipticals, and instability-driven bulges, akin to secular (or pseudo-)bulges. The model can successfully reproduce the mass-size relation of gaseous and stellar disks, the evolution of the mass-size relation of ellipticals, the Faber-Jackson relation, and the magnitude-colour diagram of classical and secular bulges. The model predicts only a small overlap of merger-driven and instability-driven components in the same galaxy, and predicts different bulge types as a function of galaxy mass and disk fraction. Bulge type also affe...

  1. The structure of the Milky Way's bar outside the bulge

    Science.gov (United States)

    Wegg, Christopher; Gerhard, Ortwin; Portail, Matthieu

    2015-07-01

    While it is incontrovertible that the inner Galaxy contains a bar, its structure near the Galactic plane has remained uncertain, where extinction from intervening dust is greatest. We investigate here the Galactic bar outside the bulge, the long bar, using red clump giant (RCG) stars from United Kingdom Infrared Deep Sky Survey, Two Micron All Sky Survey, Vista Variables in the Via Lactea and Galactic Legacy Infrared Midplane Survey Extraordinaire. We match and combine these surveys to investigate a wide area in latitude and longitude, |b| ≤ 9° and |l| ≤ 40°. We find (i) the bar extends to l ˜ 25° at |b| ˜ 5° from the Galactic plane, and to l ˜ 30° at lower latitudes; (ii) the long bar has an angle to the line-of-sight in the range (28°-33°), consistent with studies of the bulge at |l| thin bar component reminiscent of the old thin disc near the Sun, and a ˜45 pc superthin bar components which exist predominantly towards the bar end; (v) constructing parametric models for the red clump magnitude distributions, we find a bar half-length of 5.0 ± 0.2 kpc for the two-component bar, and 4.6 ± 0.3 kpc for the thin bar component alone. We conclude that the Milky Way contains a central box/peanut bulge which is the vertical extension of a longer, flatter bar, similar as seen in both external galaxies and N-body models.

  2. Effect of processing parameters on bulge-forming Polycarbonate parts

    Institute of Scientific and Technical Information of China (English)

    HOU Zhen-xiu; WU Jing; LIU Zhi; LI Xiao-dong; Z. R. Wang

    2007-01-01

    According to the data of the experiment made in mechauical tensile of Polycarbonate in high temperature, experiments were done to polycarbonate sheet by hot gas pressure bulge-forming. It was found that selecting and combination of the processing parameters were vital to the quality. In the experiments and numerical simulation with the software of DYNAFORM, the processing parameters have been studied. The results showed that the method of discontinuous pressure and pressure preservation advantage the forming; when temperature and pressure meet the forming conditions, the longer time of pressure preservation promotes sufficient forming.

  3. Signatures of bulge triaxiality from kinematics in Baade's window

    Science.gov (United States)

    Zhao, Hongsheng; Spergel, David N.; Rich, R. Michael

    1994-01-01

    We study a sample of 62 Baade's Window, (l,b) = (1, -4)deg, K giants that have published proper motions, radial velocity, and metallicity. Using R(sub 0) = 8 kpc, we construct the velocity ellipsoids, namely the 3x3 velocity dispersion tensors, for the metal rich stars ((Fe/H) greater than or equal to 0) and metal poor stars ((Fe/H) less than or equal to -0.2). After diagonalizing the tensor, we find a vertex deviation characteristic of a nonaxisymmetric system. Eigenvalues for the two velocity ellipsoids (sigma(sub 1), sigma(sub 2), sigma(sub 3)) are (126, 89, 65) +/- 13 km/s for the metal rich sample and (154, 77, 83) +/- 25 km/s for the metal poor sample with their long axes pointing to two nearly perpendicular directions (l(sub v), b(sub v)) = (-65 +/- 9 deg, +14 +/- 9 deg) and (l(sub v), b(sub v)) = (25 +/- 14 deg, -11 +/- 14 deg), respectively. The vertex deviations of the velocity ellipsoids cannot be consistently explained by any oblate model. We are able to reject the hypothesis that the metal poor and metal rich populations are drawn from the same distribution at better than the 97% confidence level. We populate orbits in a realistic bar potential with a Gaussian velocity distribution, allowing us to simulate and interpret observations. We conclude that the data are consistent with a triaxial bulge pointing towards (l,b) with l less than 0 deg and b = 0 deg as suggested by earlier work on gas dynamics and the observed light distribution. We also predict that low latitude (absolute value of b less than or equal to 4 deg) bulge fields should show the vertex deviation more strongly and would therefore be the best locations for future proper motion studies. In the classification scheme of Athanassoula et al. (1983) the metal rich stars appear to occupy the B-family orbits which rotate in the prograde sense in the rest frame and have boxy shapes that are aligned with and supporting the bar. The metal poor stars in the sample lag behind the metal rich bulge and

  4. Natural thermodynamics

    Science.gov (United States)

    Annila, Arto

    2016-02-01

    The principle of increasing entropy is derived from statistical physics of open systems assuming that quanta of actions, as undividable basic build blocks, embody everything. According to this tenet, all systems evolve from one state to another either by acquiring quanta from their surroundings or by discarding quanta to the surroundings in order to attain energetic balance in least time. These natural processes result in ubiquitous scale-free patterns: skewed distributions that accumulate in a sigmoid manner and hence span log-log scales mostly as straight lines. Moreover, the equation for least-time motions reveals that evolution is by nature a non-deterministic process. Although the obtained insight in thermodynamics from the notion of quanta in motion yields nothing new, it accentuates that contemporary comprehension is impaired when modeling evolution as a computable process by imposing conservation of energy and thereby ignoring that quantum of actions are the carriers of energy from the system to its surroundings.

  5. Thermodynamics of Benford's First Digit Law

    CERN Document Server

    Lemons, Don S

    2016-01-01

    Iafrate, Miller, and Strauch [Equipartition and a Distribution for Numbers: A Statistical Model for Benford's Law," arXiv:1503.08259] construct and test a statistical model for partitioning a conserved quantity. One consequence of their model is Benford's law. This Comment amplifies their work by exploring its thermodynamic consequences.

  6. The metallicity distribution of bulge clump giants in Baade's Window

    CERN Document Server

    Hill, V; Gomez, A; Zoccali, M; Schultheis, M; Babusiaux, C; Royer, F; Barbuy, B; Arenou, F; Minniti, D; Ortolani, S

    2011-01-01

    We seek to constrain the formation of the Galactic bulge by means of analysing the detailed chemical composition of a large sample of red clump stars in Baade's window. We measure [Fe/H] in a sample of 219 bulge red clump stars from R=20000 resolution spectra obtained with FLAMES/GIRAFFE at the VLT, using an automatic procedure, differentially to the metal-rich local reference star muLeo. For a subsample of 162 stars, we also derive [Mg/H] from spectral synthesis around the MgI triplet at 6319A. The Fe and Mg metallicity distributions are both asymmetric, with median values of +0.16 and +0.21 respectively. The iron distribution is clearly bimodal, as revealed both by a deconvolution (from observational errors) and a Gaussian decomposition. The decomposition of the observed Fe and Mg metallicity distributions into Gaussian components yields two populations of equal sizes (50% each): a metal-poor component centred around [Fe/H]=-0.30 and [Mg/H]=-0.06 with a large dispersion and a narrow metal-rich component cen...

  7. 2D kinematic signatures of boxy/peanut bulges

    CERN Document Server

    Iannuzzi, Francesca

    2015-01-01

    We study the imprints of boxy/peanut structures on the 2D line-of-sight kinematics of simulated disk galaxies. The models under study belong to a family with varying initial gas fraction and halo triaxiality, plus few other control runs with different structural parameters; the kinematic information was extracted using the Voronoi-binning technique and parametrised up to the fourth order of a Gauss-Hermite series. Building on a previous work for the long-slit case, we investigate the 2D kinematic behaviour in the edge-on projection as a function of the boxy/peanut strength and position angle; we find that for the strongest structures the highest moments show characteristic features away from the midplane in a range of position angles. We also discuss the masking effect of a classical bulge and the ambiguity in discriminating kinematically this spherically-symmetric component from a boxy/peanut bulge seen end-on. Regarding the face-on case, we extend existing results to encompass the effect of a second bucklin...

  8. Dynamics of the Galactic Bulge using Planetary Nebulae

    CERN Document Server

    Beaulieu, S F; Kálnay, A J; Saha, P; Zhao, H S; Beaulieu, Sylvie F.; Freeman, Kenneth C.; Kalnajs, Agris J.; Saha, Prasenjit; Zhao, HongSheng

    2000-01-01

    Evidence for a bar at the center of the Milky Way triggered a renewed enthusiasm for dynamical modelling of the Galactic bar-bulge. Our goal is to compare the kinematics of a sample of tracers, planetary nebulae, widely distributed over the bulge with the corresponding kinematics for a range of models of the inner Galaxy. Three of these models are N-body barred systems arising from the instabilities of a stellar disk (Sellwood, Fux and Kalnajs), and one is a Schwarzschild system constructed to represent the 3D distribution of the COBE/DIRBE near-IR light and then evolved as an N-body system for a few dynamical times (Zhao). For the comparison of our data with the models, we use a new technique developed by Saha (1998). The procedure finds the parameters of each model, i.e. the solar galactocentric distance R_o in model units, the orientation angle phi, the velocity scale (in km/s per model unit), and the solar tangential velocity which best fit the data.

  9. Stellar Populations of Bulges in 14 Cluster Disc Galaxies

    CERN Document Server

    Morelli, L; Pizzella, A; Méndez-Abreu, J; Corsini, E M; Coccato, L; Saglia, R P; Sarzi, M; Bertola, F

    2008-01-01

    Photometry and long-slit spectroscopy are presented for 14 S0 and spiral galaxies of the Fornax, Eridanus and Pegasus cluster, and NGC 7582 group. The structural parameters of the galaxies are derived from the R-band images by performing a two-dimensional photometric decomposition of the surface-brightness distribution. This is assumed to be the sum of the contribution of a bulge and disc component characterized by elliptical and concentric isophotes with constant (but possibly different) ellipticity and position angles. The rotation curves and velocity dispersion profiles are measured from the spectra obtained along the major axis of galaxies. The radial profiles of the Hb, Mg, and Fe line-strength indices are presented too. Correlations between the central values of Mgd, , Hb, and sigma are found. The age, metallicity and alpha/Fe enhancement of the stellar population in the center and at the radius where bulge and disc give the same contribution to the total surface brightness are obtained using stellar po...

  10. Two Pseudobulges in the "Boxy Bulge" Galaxy NGC 5746

    CERN Document Server

    Barentine, John C

    2012-01-01

    Galaxy formation and growth under the {\\Lambda}CDM paradigm is expected to proceed in a hierarchical, bottom-up fashion by which small galaxies grow into large galaxies; this mechanism leaves behind large "classical bulges" kinematically distinct from "pseudobulges" grown by internal, secular processes. We use archival data (Spitzer 3.6 \\mum wavelength, Hubble Space Telescope H-band, Two Micron All Sky Survey Ks-band, and Sloan Digital Sky Survey gri-band) to measure composite minor- and major-axis surface brightness profiles of the almost-edgeon spiral galaxy NGC 5746. These light profiles span a large range of radii and surface brightnesses to reveal an inner, high surface brightness stellar component that is distinct from the well-known boxy bulge. It is well fitted by S\\'ersic functions with indices n = 0.99 \\pm 0.08 and 1.17 \\pm 0.24 along the minor and major axes, respectively. Since n < 2, we conclude that this innermost component is a secularly-evolved pseudobulge that is distinct from the boxy pse...

  11. OGLE Atlas of Classical Novae I. Galactic Bulge Objects

    CERN Document Server

    Mroz, P; Poleski, R; Soszynski, I; Szymanski, M K; Pietrzynski, G; Wyrzykowski, L; Ulaczyk, K; Kozlowski, S; Pietrukowicz, P; Skowron, J

    2015-01-01

    Classical novae eruptions are possible sources of lithium formation and gamma-rays emission. The remnant systems of novae eruptions can also become Type Ia supernovae. The contribution of novae to these phenomena depends on nova rates that are not well established for the Galaxy. Here, we directly measure the Galactic bulge nova rate of $13.9 \\pm 2.6$ yr$^{-1}$. This measurement is much more accurate than any previous measurement of this kind thanks to multiple years of bulge monitoring by the OGLE survey. Our sample consists of 39 novae eruptions, $\\sim$1/3 of which are OGLE-based discoveries. The long-term monitoring allows us to not only measure the nova rate but also to study in detail the light curves of 39 eruptions and over 80 post-nova candidates. We measured orbital periods for 9 post-novae and 9 novae, in 14 cases we procured the first estimates. The OGLE survey is very sensitive to the frequently erupting recurrent novae. We did not found any object similar to M31 2008-12a, which erupts once a year...

  12. Proper Motions in the Galactic Bulge: Plaut's Window

    CERN Document Server

    Vieira, Katherine; Mendez, Rene A; Rich, R Michael; Girard, Terrence M; Korchagin, Vladimir I; van Altena, William; Majewski, Steven R; Bergh, Sidney van den

    2007-01-01

    A proper motion study of a field of 20' x 20' inside Plaut's low extinction window (l,b)=(0 deg,-8 deg), has been completed. Relative proper motions and photographic BV photometry have been derived for ~21,000 stars reaching to V~20.5 mag, based on the astrometric reduction of 43 photographic plates, spanning over 21 years of epoch difference. Proper motion errors are typically 1 mas/yr and field dependent systematics are below 0.2 mas/yr. Cross-referencing with the 2MASS catalog yielded a sample of ~8,700 stars, from which predominantly disk and bulge subsamples were selected photometrically from the JH color-magnitude diagram. The two samples exhibited different proper-motion distributions, with the disk displaying the expected reflex solar motion as a function of magnitude. Galactic rotation was also detected for stars between ~2 and ~3 kpc from us. The bulge sample, represented by red giants, has an intrinsic proper motion dispersion of (sigma_l,sigma_b)=(3.39, 2.91)+/-(0.11,0.09) mas/yr, which is in good...

  13. The metal content of the bulge globular cluster NGC 6528

    Science.gov (United States)

    Zoccali, M.; Barbuy, B.; Hill, V.; Ortolani, S.; Renzini, A.; Bica, E.; Momany, Y.; Pasquini, L.; Minniti, D.; Rich, R. M.

    2004-08-01

    High resolution spectra of five stars in the bulge globular cluster NGC 6528 were obtained at the 8m VLT UT2-Kueyen telescope with the UVES spectrograph. Out of the five stars, two of them showed evidence of binarity. The target stars belong to the horizontal and red giant branch stages, at 4000 elemental ratios for this template bulge cluster, as a basis for the fundamental calibration of metal-rich populations. The present analysis provides a metallicity [Fe/H] = -0.1±0.2 and the α-elements O, Mg and Si, show [α/Fe] ≈ +0.1, whereas Ca and Ti are around the solar value or below, resulting in an overall metallicity Z ≈ Z⊙. Observations collected both at the European Southern Observatory, Paranal and La Silla, Chile (ESO programme 65.L-0340) and with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, operated by AURA Inc. under contract to NASA. Tables \\ref{targets}, \\ref{logobs}, \\ref{tablines} and Fig. \\ref{chart} are only available in electronic form at http://www.edpsciences.org

  14. The Calcium Triplet metallicity calibration for galactic bulge stars

    CERN Document Server

    Vasquez, S; Hill, V; Gonzalez, O A; Saviane, I; Rejkuba, M; Battaglia, G

    2015-01-01

    We present a new calibration of the Calcium II Triplet equivalent widths versus [Fe/H], constructed upon K giant stars in the Galactic bulge. This calibration will be used to derive iron abundances for the targets of the GIBS survey, and in general it is especially suited for solar and supersolar metallicity giants, typical of external massive galaxies. About 150 bulge K giants were observed with the GIRAFFE spectrograph at VLT, both at resolution R~20,000 and at R~6,000. In the first case, the spectra allowed us to perform direct determination of Fe abundances from several unblended Fe lines, deriving what we call here high resolution [Fe/H] measurements. The low resolution spectra allowed us to measure equivalent widths of the two strongest lines of the near infrared Calcium II triplet at 8542 and 8662 A. By comparing the two measurements we derived a relation between Calcium equivalent widths and [Fe/H] that is linear over the metallicity range probed here, -1<[Fe/H]<+0.7. By adding a small second or...

  15. Stellar Populations of Late-Type Bulges at z=1 in the HUDF

    CERN Document Server

    Hathi, N P; Pasquali, A; Malhotra, S; Rhoads, J E; Pirzkal, N; Windhorst, R A; Xu, C

    2008-01-01

    We take advantage of the exceptional depth of the Hubble Ultra Deep Field (HUDF) images and the deep GRism ACS Program for Extragalactic Science (GRAPES) grism spectroscopy to explore the stellar populations of 34 bulges belonging to late-type galaxies at z=0.8-1.3. We selected these galaxies based on the presence of a noticeable Balmer break (at 4000 A) in their GRAPES spectra, and by visual inspection of the HUDF images. The narrow extraction of these GRAPES spectra around the galaxy center enable us to study the spectrum of the bulges in these late-type galaxies. The 4000 A break in the bulges spectra allows us to estimate the bulges redshifts and stellar ages. We first used the HUDF images to measure bulges color and Sersic index, and then we analyze the bulges spectra by fitting stellar population models. Our results show that, (1) the average age of late-type bulges in our sample is ~1.3 Gyr and stellar masses are in the range of log(M)=6.5-10 solar, (2) late-type bulges are younger and less massive com...

  16. Breast tissue bulge and lesion visibility during stereotactic biopsy – A phantom study

    International Nuclear Information System (INIS)

    Background: During mammography guided stereotactic breast biopsy a bulge of tissue can form in the paddle needle biopsy aperture. This bulge has been estimated to have a height of up to 30% of the breast itself. During clinical biopsy we have noticed that lesions can appear to be less visible when tissue bulges are evident. This can make biopsy more difficult in some cases. Objectives: This experiment investigates how lesion visibility varies with breast bulge magnitude. Method: Using a phantom to represent breast and breast bulge, lesion visibility was assessed using a two alternative forced choice methodology. To mimic clinical conditions, imaging was performed on a full field digital mammography system with the biopsy paddle attached using an automatic exposure device. Organ dose (breast) was estimated. Results: As breast bulge increases lesion visibility decreases; organ dose increases as breast bulge magnitude increases. Conclusion: Consideration should be given to the impact of breast bulge magnitude and lesion visibility when performing image guided biopsy. Advances in knowledge: The authors found no similar studies and the results of this study demonstrate a potential clinical risk

  17. Bulge formation and necking in a polymer tube under dynamic expansion

    DEFF Research Database (Denmark)

    Lindgreen, Britta; Tvergaard, Viggo; Needleman, Alan

    2008-01-01

    imposed loading are prescribed: (i) a pressure that increases linearly with time and (ii) a change in enclosed volume that increases linearly with time. For both loading conditions, an axisymmetric bulge develops on the tube followed by necking in the bulge. The necks propagate in both the circumferential...

  18. β-Bulges: extensive structural analyses of β-sheets irregularities.

    Science.gov (United States)

    Craveur, Pierrick; Joseph, Agnel Praveen; Rebehmed, Joseph; de Brevern, Alexandre G

    2013-10-01

    β-Sheets are quite frequent in protein structures and are stabilized by regular main-chain hydrogen bond patterns. Irregularities in β-sheets, named β-bulges, are distorted regions between two consecutive hydrogen bonds. They disrupt the classical alternation of side chain direction and can alter the directionality of β-strands. They are implicated in protein-protein interactions and are introduced to avoid β-strand aggregation. Five different types of β-bulges are defined. Previous studies on β-bulges were performed on a limited number of protein structures or one specific family. These studies evoked a potential conservation during evolution. In this work, we analyze the β-bulge distribution and conservation in terms of local backbone conformations and amino acid composition. Our dataset consists of 66 times more β-bulges than the last systematic study (Chan et al. Protein Science 1993, 2:1574-1590). Novel amino acid preferences are underlined and local structure conformations are highlighted by the use of a structural alphabet. We observed that β-bulges are preferably localized at the N- and C-termini of β-strands, but contrary to the earlier studies, no significant conservation of β-bulges was observed among structural homologues. Displacement of β-bulges along the sequence was also investigated by Molecular Dynamics simulations. PMID:23904395

  19. Consequence analysis

    International Nuclear Information System (INIS)

    The objectives of this paper are to: Provide a realistic assessment of consequences; Account for plant and site-specific characteristics; Adjust accident release characteristics to account for results of plant-containment analysis; Produce conditional risk curves for each of five health effects; and Estimate uncertainties

  20. Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. IV. Two bulge populations

    CERN Document Server

    Bensby, T; Meléndez, J; Gould, A; Feltzing, S; Asplund, M; Johnson, J A; Lucatello, S; Yee, J C; Ramírez, I; Cohen, J G; Thompson, I; Gal-Yam, A; Sumi, T; Bond, I A

    2011-01-01

    [ABRIDGED] Based on high-resolution (R~42000 to 48000) and high signal-to-noise (S/N~50 to 150) spectra obtained with UVES/VLT, we present detailed elemental abundances (O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, Y, and Ba) and stellar ages for 26 microlensed dwarf and subgiant stars in the Galactic bulge. The analysis is based on equivalent width measurements and standard 1-D LTE MARCS model stellar atmospheres. We also present NLTE Li abundances based on line synthesis of the 7Li line at 670.8 nm. We show that the bulge metallicity distribution (MDF) is double-peaked; one peak at [Fe/H]= -0.6 and one at [Fe/H]=+0.3, and with a dearth of stars around solar metallicity. This is in contrast to the MDF derived from red giants in Baade's window, which peaks at this exact value. A simple significance test shows that it is extremely unlikely to have such a gap in the microlensed dwarf star MDF if the dwarf stars are drawn from the giant star MDF. To resolve this issue we discuss several possibilities, but we can n...

  1. The chemical evolution of the Galactic Bulge seen through micro-lensing events

    Directory of Open Access Journals (Sweden)

    Lucatello S.

    2012-02-01

    Full Text Available Galactic bulges are central to understanding galaxy formation and evolution. Here we report on recent studies using micro-lensing events to obtain spectra of high resolution and moderately high signal-to-noise ratios of dwarf stars in the Galactic bulge. Normally this is not feasible for the faint turn-off stars in the Galactic bulge, but micro-lensing offers this possibility. Elemental abundance trends in the Galactic bulge as traced by dwarf stars are very similar to those seen for dwarf stars in the solar neighbourhood. We discuss the implications of the ages and metallicity distribution function derived for the micro-lensed dwarf stars in the Galactic bulge.

  2. Elliptical Galaxies and Bulges of Disk Galaxies: Summary of Progress and Outstanding Issues

    CERN Document Server

    Kormendy, John

    2015-01-01

    This is the summary chapter of a review book on galaxy bulges. Bulge properties and formation histories are more varied than those of ellipticals. I emphasize two advances: 1 - "Classical bulges" are observationally indistinguishable from ellipticals, and like them, are thought to form by major galaxy mergers. "Disky pseudobulges" are diskier and more actively star-forming (except in S0s) than are ellipticals. Theys are products of the slow ("secular") evolution of galaxy disks: bars and other nonaxisymmetries move disk gas toward the center, where it starbursts and builds relatively flat, rapidly rotating components. This secular evolution is a new area of galaxy evolution work that complements hierarchical clustering. 2 - Disks of high-redshift galaxies are unstable to the formation of mass clumps that sink to the center and merge - an alternative channel for the formation of classical bulges. I review successes and unsolved problems in the formation of bulges+ellipticals and their coevolution (or not) with...

  3. Disk and Bulge Morphology of WFPC2 galaxies The HST Medium Deep Survey database

    CERN Document Server

    Ratnatunga, K U; Ostrander, E J; Ratnatunga, Kavan U.; Griffiths, Richard E.; Ostrander, Eric J.

    1999-01-01

    Quantitative morphological and structural parameters are estimated for galaxies detected in HST observations of WFPC2 survey fields. A modeling approach based on maximum likelihood has been developed for two-dimensional decomposition of faint under-sampled galaxy images into components of disk and bulge morphology. Decomposition can be achieved for images down to F814W (I) hour. We discuss details of the fitting procedure, and present the observed distributions of magnitude, color, effective half-light radius, disk and bulge axis ratios, bulge/(disk+bulge) flux ratio, bulge/disk half-light radius ratio and surface brightness. We also discuss the various selection limits on the measured parameters. The Medium Deep Survey catalogs and images of random pure parallel fields and other similar archival primary WFPC2 fields have been made available via the Internet with a searchable browser interface to the database at http://archive.stsci.edu/mds/

  4. Why the Milky Way's bulge is not only a bar formed from a cold thin disk

    CERN Document Server

    Di Matteo, P; Haywood, M; Combes, F; Lehnert, M D; Ness, M; Snaith, O N; Katz, D; Semelin, B

    2014-01-01

    By analyzing a N-body simulation of a bulge formed simply via a bar instability mechanism operating on a kinematically cold stellar disk, and by comparing the results of this analysis with the structural and kinematic properties of the main stellar populations of the Milky Way bulge, we conclude that the bulge of our Galaxy is not a pure stellar bar formed from a pre-existing thin stellar disk, as some studies have recently suggested. On the basis of several arguments emphasized in this paper, we propose that the bulge population which, in the Milky Way, is observed not to be part of the peanut structure corresponds to the old galactic thick disk, thus implying that the Milky Way is a pure thin+thick disk galaxy, with only a possible limited contribution of a classical bulge.

  5. Properties of Disks and Bulges of Spiral and Lenticular Galaxies in the Sloan Digital Sky Survey

    CERN Document Server

    Oohama, N; Fukugita, M; Yasuda, N; Nakamura, O

    2009-01-01

    A bulge-disk decomposition is made for 737 spiral and lenticular galaxies drawn from a SDSS galaxy sample for which morphological types are estimated. We carry out the bulge-disk decomposition using the growth curve fitting method. It is found that bulge properties, effective radius, effective surface brightness, and also absolute magnitude, change systematically with the morphological sequence; from early to late types, the size becomes somewhat larger, and surface brightness and luminosity fainter. In contrast disks are nearly universal, their properties remaining similar among disk galaxies irrespective of detailed morphologies from S0 to Sc. While these tendencies were often discussed in previous studies, the present study confirms them based on a large homogeneous magnitude-limited field galaxy sample with morphological types estimated. The systematic change of bulge-to-total luminosity ratio, $B/T$, along the morphological sequence is therefore not caused by disks but mostly by bulges. It is also shown ...

  6. Thermodynamics of the Earth

    International Nuclear Information System (INIS)

    Applications of elementary thermodynamic principles to the dynamics of the Earth lead to robust, quantitative conclusions about the tectonic effects that arise from convection. The grand pattern of motion conveys deep heat to the surface, generating mechanical energy with a thermodynamic efficiency corresponding to that of a Carnot engine operating over the adiabatic temperature gradient between the heat source and sink. Referred to the total heat flux derived from the Earth's silicate mantle, the efficiency is 24% and the power generated, 7.7 x 1012 W, causes all the material deformation apparent as plate tectonics and the consequent geological processes. About 3.5% of this is released in seismic zones but little more than 0.2% as seismic waves. Even major earthquakes are only localized hiccups in this motion. Complications that arise from mineral phase transitions can be used to illuminate details of the motion. There are two superimposed patterns of convection, plate subduction and deep mantle plumes, driven by sources of buoyancy, negative and positive respectively, at the top and bottom of the mantle. The patterns of motion are controlled by the viscosity contrasts (>104 : 1) at these boundaries and are self-selected as the least dissipative mechanisms of heat transfer for convection in a body with very strong viscosity variation. Both are subjects of the thermodynamic efficiency argument. Convection also drives the motion in the fluid outer core that generates the geomagnetic field, although in that case there is an important energy contribution by compositional separation, as light solute is rejected by the solidifying inner core and mixed into the outer core, a process referred to as compositional convection. Uncertainty persists over the core energy balance because thermal conduction is a drain on core energy that has been a subject of diverse estimates, with attendant debate over the need for radiogenic heat in the core. The geophysical approach to

  7. A TWO-PHASE SCENARIO FOR BULGE ASSEMBLY IN ΛCDM COSMOLOGIES

    International Nuclear Information System (INIS)

    We analyze and compare the bulges of a sample of L * spiral galaxies in hydrodynamical simulations in a cosmological context, using two different codes, P-DEVA and GASOLINE. The codes regulate star formation in very different ways, with P-DEVA simulations inputting low star formation efficiency under the assumption that feedback occurs on subgrid scales, while the GASOLINE simulations have feedback that drives large-scale outflows. In all cases, the marked knee shape in mass aggregation tracks, corresponding to the transition from an early phase of rapid mass assembly to a later slower one, separates the properties of two populations within the simulated bulges. The bulges analyzed show an important early starburst resulting from the collapse-like fast phase of mass assembly, followed by a second phase with lower star formation, driven by a variety of processes such as disk instabilities and/or mergers. Classifying bulge stellar particles identified at z = 0 into old and young according to these two phases, we found bulge stellar sub-populations with distinct kinematics, shapes, stellar ages, and metal contents. The young components are more oblate, generally smaller, more rotationally supported, with higher metallicity and less alpha-element enhanced than the old ones. These results are consistent with the current observational status of bulges, and provide an explanation for some apparently paradoxical observations, such as bulge rejuvenation and metal-content gradients observed. Our results suggest that bulges of L * galaxies will generically have two bulge populations that can be likened to classical and pseudo-bulges, with differences being in the relative proportions of the two, which may vary due to galaxy mass and specific mass accretion and merger histories.

  8. A TWO-PHASE SCENARIO FOR BULGE ASSEMBLY IN {Lambda}CDM COSMOLOGIES

    Energy Technology Data Exchange (ETDEWEB)

    Obreja, A.; Dominguez-Tenreiro, R.; Brook, C. [Departamento de Fisica Teorica, Universidad Autonoma de Madrid, E-28049 Cantoblanco Madrid (Spain); Martinez-Serrano, F. J.; Domenech-Moral, M.; Serna, A. [Departamento de Fisica y Arquitectura de Computadores, Universidad Miguel Hernandez, E-03202 Elche (Spain); Molla, M. [Departamento de Investigacion Basica, CIEMAT, E-28040 Madrid (Spain); Stinson, G., E-mail: aura.obreja@uam.es [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117, Heidelberg (Germany)

    2013-01-20

    We analyze and compare the bulges of a sample of L {sub *} spiral galaxies in hydrodynamical simulations in a cosmological context, using two different codes, P-DEVA and GASOLINE. The codes regulate star formation in very different ways, with P-DEVA simulations inputting low star formation efficiency under the assumption that feedback occurs on subgrid scales, while the GASOLINE simulations have feedback that drives large-scale outflows. In all cases, the marked knee shape in mass aggregation tracks, corresponding to the transition from an early phase of rapid mass assembly to a later slower one, separates the properties of two populations within the simulated bulges. The bulges analyzed show an important early starburst resulting from the collapse-like fast phase of mass assembly, followed by a second phase with lower star formation, driven by a variety of processes such as disk instabilities and/or mergers. Classifying bulge stellar particles identified at z = 0 into old and young according to these two phases, we found bulge stellar sub-populations with distinct kinematics, shapes, stellar ages, and metal contents. The young components are more oblate, generally smaller, more rotationally supported, with higher metallicity and less alpha-element enhanced than the old ones. These results are consistent with the current observational status of bulges, and provide an explanation for some apparently paradoxical observations, such as bulge rejuvenation and metal-content gradients observed. Our results suggest that bulges of L {sub *} galaxies will generically have two bulge populations that can be likened to classical and pseudo-bulges, with differences being in the relative proportions of the two, which may vary due to galaxy mass and specific mass accretion and merger histories.

  9. Understanding AGB evolution in Galactic bulge stars from high-resolution infrared spectroscopy

    Science.gov (United States)

    Uttenthaler, S.; Blommaert, J. A. D. L.; Wood, P. R.; Lebzelter, T.; Aringer, B.; Schultheis, M.; Ryde, N.

    2015-08-01

    An analysis of high-resolution near-infrared spectra of a sample of 45 asymptotic giant branch (AGB) stars towards the Galactic bulge is presented. The sample consists of two subsamples, a larger one in the inner and intermediate bulge, and a smaller one in the outer bulge. The data are analysed with the help of hydrostatic model atmospheres and spectral synthesis. We derive the radial velocity of all stars, and the atmospheric chemical mix ([Fe/H], C/O, 12C/13C, Al, Si, Ti, and Y) where possible. Our ability to model the spectra is mainly limited by the (in)completeness of atomic and molecular line lists, at least for temperatures down to Teff ≈ 3100 K. We find that the subsample in the inner and intermediate bulge is quite homogeneous, with a slightly subsolar mean metallicity and only few stars with supersolar metallicity, in agreement with previous studies of non-variable M-type giants in the bulge. All sample stars are oxygen-rich, C/O isotopic ratios suggest that third dredge-up (3DUP) is absent among the sample stars, except for two stars in the outer bulge that are known to contain technetium. These stars are also more metal-poor than the stars in the intermediate or inner bulge. Current stellar masses are determined from linear pulsation models. The masses, metallicities and 3DUP behaviour are compared to AGB evolutionary models. We conclude that these models are partly in conflict with our observations. Furthermore, we conclude that the stars in the inner and intermediate bulge belong to a more metal-rich population that follows bar-like kinematics, whereas the stars in the outer bulge belong to the metal-poor, spheroidal bulge population.

  10. Thermodynamics of Error Correction

    Science.gov (United States)

    Sartori, Pablo; Pigolotti, Simone

    2015-10-01

    Information processing at the molecular scale is limited by thermal fluctuations. This can cause undesired consequences in copying information since thermal noise can lead to errors that can compromise the functionality of the copy. For example, a high error rate during DNA duplication can lead to cell death. Given the importance of accurate copying at the molecular scale, it is fundamental to understand its thermodynamic features. In this paper, we derive a universal expression for the copy error as a function of entropy production and work dissipated by the system during wrong incorporations. Its derivation is based on the second law of thermodynamics; hence, its validity is independent of the details of the molecular machinery, be it any polymerase or artificial copying device. Using this expression, we find that information can be copied in three different regimes. In two of them, work is dissipated to either increase or decrease the error. In the third regime, the protocol extracts work while correcting errors, reminiscent of a Maxwell demon. As a case study, we apply our framework to study a copy protocol assisted by kinetic proofreading, and show that it can operate in any of these three regimes. We finally show that, for any effective proofreading scheme, error reduction is limited by the chemical driving of the proofreading reaction.

  11. Thermodynamics of Radiation Modes

    Science.gov (United States)

    Pina, Eduardo; de la Selva, Sara Maria Teresa

    2010-01-01

    We study the equilibrium thermodynamics of the electromagnetic radiation in a cavity of a given volume and temperature. We found three levels of description, the thermodynamics of one mode, the thermodynamics of the distribution of frequencies in a band by summing over the frequencies in it and the global thermodynamics by summing over all the…

  12. Gamma rays from the galactic bulge and large extra dimensions

    International Nuclear Information System (INIS)

    An intriguing feature of extra dimensions is the possible production of Kaluza-Klein gravitons by nucleon-nucleon bremsstrahlung, in the course of core collapse of massive stars, with gravitons then being trapped around the newly born neutron stars and decaying into two gamma rays, making neutron stars gamma-ray sources. We strengthen the limits on the radius of compactification of extra dimensions for a small number n of them, or alternatively the fundamental scale of quantum gravity, considering the gamma-ray emission of the whole population of neutron stars sitting in the Galactic bulge, instead of the closest member of this category. For n=1 the constraint on the compactification radius is R<400 μm

  13. Lensing of unresolved stars towards the Galactic Bulge

    CERN Document Server

    Alard, C

    1996-01-01

    Previous calculations of the rates and optical depths due to microlensing only considered resolved stars. However, if a faint unresolved star lens is close enough to a resolved star, the event will be seen by the microlensing experiments and attributed to the bighter star. The blending biases the duration, making the contribution of the unresolved stars very significant for short events. This contribution is confused with lensing by brown dwarfs. The exact rates of these blended events are extremly sensitive to the limiting magnitude achieved in the microlensing search. Appropriate calculations of the optical depth and rates are provided here, and illustrated in the case of the DUO and OGLE experiments. The additional contribution of unresolved stars is very significant and probably explains the high optical depth and rates observed towards the Galactic Bulge. The blended unresolved event can be identified using either the color shift or the light curve shape. However, neither of these two methods is apropria...

  14. Variability of Optical Counterparts in the Chandra Galactic Bulge Survey

    CERN Document Server

    Britt, Christopher T; Johnson, C B; Baldwin, A; Jonker, P G; Nelemans, G; Torres, M A P; Maccarone, T; Steeghs, D; Greiss, S; Heinke, C; Bassa, C G; Collazzi, A; Villar, A; Gabb, M; Gossen, L

    2014-01-01

    We present optical lightcurves of variable stars consistent with the positions of X-ray sources identified with the Chandra X-ray Observatory for the Chandra Galactic Bulge Survey. Using data from the Mosaic-II instrument on the Blanco 4m Telescope at CTIO, we gathered time-resolved photometric data on timescales from $\\sim2$ hr to 8 days over the $\\frac{3}{4}$ of the X-ray survey containing sources from the initial GBS catalog. Among the lightcurve morphologies we identify are flickering in interacting binaries, eclipsing sources, dwarf nova outbursts, ellipsoidal variations, long period variables, spotted stars, and flare stars. $87\\%$ of X-ray sources have at least one potential optical counterpart. $24\\%$ of these candidate counterparts are detectably variable; a much greater fraction than expected for randomly selected field stars, which suggests that most of these variables are real counterparts. We discuss individual sources of interest, provide variability information on candidate counterparts, and di...

  15. 2D kinematic signatures of boxy/peanut bulges

    Science.gov (United States)

    Iannuzzi, Francesca; Athanassoula, E.

    2015-07-01

    We study the imprints of boxy/peanut structures on the 2D line-of-sight kinematics of simulated disc galaxies. The models under study belong to a family with varying initial gas fraction and halo triaxiality, plus few other control runs with different structural parameters; the kinematic information was extracted using the Voronoi-binning technique and parametrized up to the fourth order of a Gauss-Hermite series. Building on a previous work for the long-slit case, we investigate the 2D kinematic behaviour in the edge-on projection as a function of the boxy/peanut strength and position angle; we find that for the strongest structures the highest moments show characteristic features away from the mid-plane in a range of position angles. We also discuss the masking effect of a classical bulge and the ambiguity in discriminating kinematically this spherically symmetric component from a boxy/peanut bulge seen end-on. Regarding the face-on case, we extend existing results to encompass the effect of a second buckling and find that this phenomenon spurs an additional set of even deeper minima in the fourth moment. Finally, we show how the results evolve when inclining the disc away from perfectly edge-on and face-on. The behaviour of stars born during the course of the simulations is discussed and confronted to that of the pre-existing disc. The general aim of our study is providing a handle to identify boxy/peanut structures and their properties in latest generation Integral Field Unit observations of nearby disc galaxies.

  16. Mathematical foundations of thermodynamics

    CERN Document Server

    Giles, R; Stark, M; Ulam, S

    2013-01-01

    Mathematical Foundations of Thermodynamics details the core concepts of the mathematical principles employed in thermodynamics. The book discusses the topics in a way that physical meanings are assigned to the theoretical terms. The coverage of the text includes the mechanical systems and adiabatic processes; topological considerations; and equilibrium states and potentials. The book also covers Galilean thermodynamics; symmetry in thermodynamics; and special relativistic thermodynamics. The book will be of great interest to practitioners and researchers of disciplines that deal with thermodyn

  17. Impact of the terminal bulges of HIV-1 cTAR DNA on its stability and the destabilizing activity of the nucleocapsid protein NCp7.

    Science.gov (United States)

    Beltz, Hervé; Azoulay, Joel; Bernacchi, Serena; Clamme, Jean-Pierre; Ficheux, Damien; Roques, Bernard; Darlix, Jean-Luc; Mély, Yves

    2003-04-18

    Reverse transcription of HIV-1 genomic RNA to double-stranded DNA by reverse transcriptase (RT) is a critical step in HIV-1 replication. This process relies on two viral proteins, the RT enzyme and nucleocapsid protein NCp7 that has well documented nucleic acid chaperone properties. At the beginning of the linear DNA synthesis, the newly made minus-strand strong-stop DNA ((-)ssDNA) is transferred to the 3'end of the genomic RNA by means of an hybridization reaction between transactivation response element (TAR) RNA and cTAR DNA sequences. Since both TAR sequences exhibit stable hairpin structures, NCp7 needs to destabilize the TAR structures in order to chaperone their hybridization. To further characterize the relationships between TAR stability and NC-mediated destabilization, the role of the A(49) and G(52) bulged residues in cTAR DNA stability was investigated. The stability of cTAR and mutants where one or the two terminal bulges were replaced by base-pairs as well as the NCp7-mediated destabilization of these cTAR sequences were examined. Thermodynamic data indicate that the two bulges cooperatively destabilize cTAR by reducing the stacking interactions between the bases. This causes a free energy change of about 6.4 kcal/mol and seems to be critical for NC activity. Time-resolved fluorescence data of doubly labelled cTAR derivatives suggest that NC-mediated melting of cTAR ends propagates up to the 10C.A(44) mismatch or T(40) bulge. Fluorescence correlation spectroscopy using two-photon excitation was also used to monitor cTAR ends fraying by NC. Results show that NC causes a very significant increase of cTAR ends fraying, probably limited to the terminal base-pair in the case of cTAR mutants. Since the TAR RNA and cTAR DNA bulges or mismatches appear well conserved among all HIV-1 strains, the present data support the notion of a co-evolutionary relationship between TAR and NC activity. PMID:12684000

  18. Considerations on non equilibrium thermodynamics of interactions

    Science.gov (United States)

    Lucia, Umberto

    2016-04-01

    Nature can be considered the "first" engineer! For scientists and engineers, dynamics and evolution of complex systems are not easy to predict. A fundamental approach to study complex system is thermodynamics. But, the result is the origin of too many schools of thermodynamics with a consequent difficulty in communication between thermodynamicists and other scientists and, also, among themselves. The solution is to obtain a unified approach based on the fundamentals of physics. Here we suggest a possible unification of the schools of thermodynamics starting from two fundamental concepts of physics, interaction and flows.

  19. Heavy elements Ba, La, Ce, Nd, and Eu in 56 Galactic bulge red giants

    CERN Document Server

    Van der Swaelmen, M; Hill, V; Zoccali, M; Minniti, D; Ortolani, S; Gomez, A

    2016-01-01

    Aims. The aim of this work is the study of abundances of the heavy elements Ba, La, Ce, Nd, and Eu in 56 bulge giants (red giant branch and red clump) with metallicities ranging from -1.3 dex to 0.5 dex. Methods. We obtained high-resolution spectra of our giant stars using the FLAMES-UVES spectrograph on the Very Large Telescope. We inspected four bulge fields along the minor axis. Results. We measure the chemical evolution of heavy elements, as a function of metallicity, in the Galactic bulge. Conclusions. The [Ba, La, Ce, Nd/Fe] vs. [Fe/H] ratios decrease with increasing metallicity, in which aspect they differ from disc stars. In our metal-poor bulge stars, La and Ba are enhanced relative to their thick disc counterpart, while in our metal-rich bulge stars La and Ba are underabundant relative to their disc counterpart. Therefore, this contrast between bulge and discs trends indicates that bulge and (solar neighbourhood) thick disc stars could behave differently. An increase in [La, Nd/Eu] with increasing m...

  20. NMR Analysis of RNA Bulged Structures: Tabu Search Application in NOE Signal Assignment

    International Nuclear Information System (INIS)

    Bulges are the most frequently occurring RNA secondary structural elements of high functional importance. At present, they are known to participate in the process of RNA folding, RNA-RNA and RNA-protein interactions. It has been shown that bulges can induce destabilization in RNA duplexes and the extent of the destabilization depends on many factors such as the size of the bulge, the nature of the bulge bases, and the flanking residues. However, relatively very little is known about these structural elements. Only several studies have been performed to address the preferred conformations of bulged residues in DNA and RNA duplexes. The knowledge of spatial structure of RNA bulges in solution requires application of NMR spectroscopy. A considerable part of NMR analytical process of RNA fragment is based on automatic methods. However, manual assistance is still essential in resonance assignment. Thus, there has been a great need to introduce automatic procedures also at this level. We propose a tabu search algorithm being a tool for an automatic resonance assignment. The assignment is determined by NOE pathways, which can be constructed in aromatic/anomeric region of 2D NOESY spectrum generated during NMR experiment. Computational tests demonstrate performance of the tabu search applied to the experimental spectra of RNA bulged duplexes. (author)

  1. The EMBLA Survey - Metal-poor stars in the Galactic bulge

    Science.gov (United States)

    Howes, Louise M.; Asplund, Martin; Keller, Stefan C.; Casey, Andrew R.; Yong, David; Lind, Karin; Frebel, Anna; Hays, Austin; Alves-Brito, Alan; Bessell, Michael S.; Casagrande, Luca; Marino, Anna F.; Nataf, David M.; Owen, Christopher I.; Da Costa, Gary S.; Schmidt, Brian P.; Tisserand, Patrick

    2016-04-01

    Cosmological models predict the oldest stars in the Galaxy should be found closest to the centre of the potential well, in the bulge. The EMBLA Survey successfully searched for these old, metal-poor stars by making use of the distinctive SkyMapper photometric filters to discover candidate metal-poor stars in the bulge. Their metal-poor nature was then confirmed using the AAOmega spectrograph on the AAT. Here we present an abundance analysis of 10 bulge stars with -2.8 <[Fe/H]<- 1.7 from MIKE/Magellan observations, in total determining the abundances of 22 elements. Combining these results with our previous high-resolution data taken as part of the Gaia-ESO Survey, we have started to put together a picture of the chemical and kinematic nature of the most metal-poor stars in the bulge. The currently available kinematic data is consistent with the stars belonging to the bulge, although more accurate measurements are needed to constrain the stars' orbits. The chemistry of these bulge stars deviates from that found in halo stars of the same metallicity. Two notable differences are the absence of carbon-enhanced metal-poor bulge stars, and the alpha-element abundances exhibit a large intrinsic scatter and include stars which are underabundant in these typically enhanced elements.

  2. Bulge and Clump Evolution in Hubble Ultra Deep Field Clump Clusters, Chains and Spiral Galaxies

    CERN Document Server

    Elmegreen, Bruce G; Fernandez, Maria Ximena; Lemonias, Jenna Jo

    2008-01-01

    Clump clusters and chain galaxies in the Hubble Ultra Deep Field are examined for bulges in the NICMOS images. Approximately 50% of the clump clusters and 30% of the chains have relatively red and massive clumps that could be young bulges. Magnitudes and colors are determined for these bulge-like objects and for the bulges in spiral galaxies, and for all of the prominent star-formation clumps in these three galaxy types. The colors are fitted to population evolution models to determine the bulge and clump masses, ages, star-formation rate decay times, and extinctions. The results indicate that bulge-like objects in clump cluster and chain galaxies have similar ages and 2 to 5 times larger masses compared to the star-formation clumps, while the bulges in spirals have ~6 times larger ages and 20 to 30 times larger masses than the clumps. All systems appear to have an underlying red disk population. The masses of star-forming clumps are typically in a range from 10^7 to 10^8 Msun; their ages have a wide range ar...

  3. The Molecular Gas Density in Galaxy Centers and How It Connects to Bulges

    CERN Document Server

    Fisher, David B; Drory, Niv; Combes, Francoise; Blitz, Leo; Wong, Tony

    2012-01-01

    In this paper we present gas density, star formation rate, stellar masses, and bulge disk decompositions for a sample of 60 galaxies. Our sample is the combined sample of BIMA SONG, CARMA STING, and PdBI NUGA surveys. We study the effect of using CO-to-H_2 conversion factors that depend on the CO surface brightness, and also that of correcting star formation rates for diffuse emission from old stellar populations. We estimate that star formation rates in bulges are typically lower by 20% when correcting for diffuse emission. We find that over half of the galaxies in our sample have molecular gas surface density >100 M_sun pc^-2. We find a trend between gas density of bulges and bulge Sersic index; bulges with lower Sersic index have higher gas density. Those bulges with low Sersic index (pseudobulges) have gas fractions that are similar to that of disks. We also find that there is a strong correlation between bulges with the highest gas surface density and the galaxy being barred. However, we also find that c...

  4. Superplasticity and Superplastic Bulging Behavior of ZrO2/Ni Nanocomposite

    Institute of Scientific and Technical Information of China (English)

    DING Shui; LV Hongjun; ZHANG Kaifeng

    2011-01-01

    ZrO2/Ni nanocomposite was produced by pulse electrodeposition and its superplastic properties were investigated by the tensile and bulging tests. The as-deposited nickel matrix has a narrow grain size distribution with a mean grain size of 45 nm. A maximum elongation of 605% was observed at 723 K and a strain rate of 1.67 × 10-3s-1 by tensile test. Superplastic bulging tests were subsequently performed using dies with diameters of 1 mm and 5 mm respectively based on the optimal superplastic forming temperature. The effects of forming temperature and gas pressure on bulging process were experimentally investigated. The results indicated that ZrO2/Ni nanocomposite samples can be readily bulged at 723 K with H/d value (defined as dome apex height over the die diameter) larger than 0.5, indicating that the nanocomposite has good bulging ability. SEM and TEM were used to examine the microstructure of the as-deposited and bulged samples. The observations showed that significant grain coarsening occurs during superplastic bulging, and the microstructure is found to depend on the forming temperature.

  5. Demographics of galactic bulges in the local universe through optical windows

    Science.gov (United States)

    Kim, Keunho; Oh, Sree; Jeong, Hyunjin; Yi, Sukyoung

    2016-01-01

    We present our results of two-dimensional bulge-disk decompositions for 14,659 galaxies drawn from SDSS DR12 in order to examine properties of bulges residing in the local universe (0.005 0.2) show almost constant (g-r) colors regardless of their size. We also investigated the scaling relations (Kormendy and Faber-Jackson relations), which ellipticals are generally known to follow, for all of our sample bulges. Specifically, we have found that low B/T (0.1population on the tilt with Hβ absorption line strengths and found that a significant tilt (at least more than ~ 30 % of the tilt) mainly arises from the effect of young stellar population in bulges. This implies that bulges are basically virialized systems irrespective of their size and thus the scatters about the scaling relations are a result of the presence of young stellar population preferentially in low B/T bulges. Drawn from our results, bulges seem very similar to ellipticals, although they are thought to be formed through the different formation mechanisms.

  6. Stellar populations of bulges in galaxies with a low surface-brightness disc

    Science.gov (United States)

    Morelli, L.; Corsini, E. M.; Pizzella, A.; Dalla Bontà, E.; Coccato, L.; Méndez-Abreu, J.

    2015-03-01

    The radial profiles of the Hβ, Mg, and Fe line-strength indices are presented for a sample of eight spiral galaxies with a low surface-brightness stellar disc and a bulge. The correlations between the central values of the line-strength indices and velocity dispersion are consistent to those known for early-type galaxies and bulges of high surface-brightness galaxies. The age, metallicity, and α/Fe enhancement of the stellar populations in the bulge-dominated region are obtained using stellar population models with variable element abundance ratios. Almost all the sample bulges are characterized by a young stellar population, on-going star formation, and a solar α/Fe enhancement. Their metallicity spans from high to sub-solar values. No significant gradient in age and α/Fe enhancement is measured, whereas only in a few cases a negative metallicity gradient is found. These properties suggest that a pure dissipative collapse is not able to explain formation of all the sample bulges and that other phenomena, like mergers or acquisition events, need to be invoked. Such a picture is also supported by the lack of a correlation between the central value and gradient of the metallicity in bulges with very low metallicity. The stellar populations of the bulges hosted by low surface-brightness discs share many properties with those of high surface-brightness galaxies. Therefore, they are likely to have common formation scenarios and evolution histories. A strong interplay between bulges and discs is ruled out by the fact that in spite of being hosted by discs with extremely different properties, the bulges of low and high surface-brightness discs are remarkably similar.

  7. Using 3D Spectroscopy to Probe the Orbital Structure of Composite Bulges

    CERN Document Server

    Erwin, Peter; Thomas, Jens; Fabricius, Maximilian; Bender, Ralf; Rusli, Stephanie; Nowak, Nina; Beckman, John E; Beltrán, Juan Carlos Vega

    2014-01-01

    Detailed imaging and spectroscopic analysis of the centers of nearby S0 and spiral galaxies shows the existence of "composite bulges", where both classical bulges and disky pseudobulges coexist in the same galaxy. As part of a search for supermassive black holes in nearby galaxy nuclei, we obtained VLT-SINFONI observations in adaptive-optics mode of several of these galaxies. Schwarzschild dynamical modeling enables us to disentangle the stellar orbital structure of the different central components, and to distinguish the differing contributions of kinematically hot (classical bulge) and kinematically cool (pseudobulge) components in the same galaxy.

  8. Why the Milky Way's bulge is not only a bar formed from a cold thin disk

    OpenAIRE

    Di Matteo, P; Gomez, A.; Haywood, M.; Combes, F; Lehnert, M. D.; Ness, M.; Snaith, O. N.; Katz, D.; Semelin, B.

    2014-01-01

    By analyzing a N-body simulation of a bulge formed simply via a bar instability mechanism operating on a kinematically cold stellar disk, and by comparing the results of this analysis with the structural and kinematic properties of the main stellar populations of the Milky Way bulge, we conclude that the bulge of our Galaxy is not a pure stellar bar formed from a pre-existing thin stellar disk, as some studies have recently suggested. On the basis of several arguments emphasized in this paper...

  9. Retrieving Bulge and Disk Parameters and Asymptotic Magnitudes from the Growth Curves of Galaxies

    CERN Document Server

    Okamura, S; Shimasaku, K; Yagi, M; Weinberg, D H; Okamura, Sadanori; Yasuda, Naoki; Shimasaku, Kazuhiro; Yagi, Masafumi; Weinberg, David H.

    1998-01-01

    We show that the growth curves of galaxies can be used to determine their bulge and disk parameters and bulge-to-total luminosity ratios, in addition to their conventional asymptotic magnitudes, provided that the point spread function is accurately known and signal-to-noise ratio is modest (S/N$\\gtrsim30$). The growth curve is a fundamental quantity that most future large galaxy imaging surveys will measure. Bulge and disk parameters retrieved from the growth curve will enable us to perform statistical studies of luminosity structure for a large number of galaxies.

  10. Classical and statistical thermodynamics

    CERN Document Server

    Rizk, Hanna A

    2016-01-01

    This is a text book of thermodynamics for the student who seeks thorough training in science or engineering. Systematic and thorough treatment of the fundamental principles rather than presenting the large mass of facts has been stressed. The book includes some of the historical and humanistic background of thermodynamics, but without affecting the continuity of the analytical treatment. For a clearer and more profound understanding of thermodynamics this book is highly recommended. In this respect, the author believes that a sound grounding in classical thermodynamics is an essential prerequisite for the understanding of statistical thermodynamics. Such a book comprising the two wide branches of thermodynamics is in fact unprecedented. Being a written work dealing systematically with the two main branches of thermodynamics, namely classical thermodynamics and statistical thermodynamics, together with some important indexes under only one cover, this treatise is so eminently useful.

  11. Spectrophotometry of Planetary Nebulae in the Bulge of M31

    Science.gov (United States)

    Roth, Martin M.; Becker, Thomas; Kelz, Andreas; Schmoll, Jürgen

    2004-03-01

    We introduce crowded-field integral field (3D) spectrophotometry as a useful technique for the study of resolved stellar populations in nearby galaxies. The spectroscopy of individual extragalactic stars, which is now feasible with efficient instruments and large telescopes, is confronted with the observational challenge of accurately subtracting the bright, spatially and wavelength-dependent nonuniform background of the underlying galaxy. As a methodological test, we present a pilot study with selected extragalactic planetary nebulae (XPNe) in the bulge of M31, demonstrating how 3D spectroscopy is able to improve the limited accuracy of background subtraction that one would normally obtain with classical slit spectroscopy. It is shown that because of the absence of slit effects, 3D spectroscopy is a most suitable technique for spectrophometry. We present spectra and line intensities for five XPNe in M31, obtained with the MPFS instrument at the Russian 6 m Bolshoi Teleskop Azimutal'nij, INTEGRAL at the William Herschel Telescope , and PMAS at the Calar Alto 3.5 m telescope. The results for two of our targets, for which data are available in the literature, are compared with previously published emission-line intensities. The three remaining PNe have been observed spectroscopically for the first time. One object is shown to be a previously misidentified supernova remnant. Our monochromatic Hα maps are compared with direct Fabry-Pérot and narrowband filter images of the bulge of M31, verifying the presence of filamentary emission of the interstellar medium in the vicinity of our objects. We present an example of a flux-calibrated and continuum-subtracted filament spectrum and demonstrate how the interstellar medium component introduces systematic errors in the measurement of faint diagnostic PN emission lines when conventional observing techniques are employed. It is shown how these errors can be eliminated with 3D spectroscopy, using the full two

  12. Abundance Ratios in the Galactic Bulge and Super Metal-Rich Type II Nucle osynthesis

    CERN Document Server

    Fulbright, J P; McWilliam, A; Fulbright, Jon P.; William, Andrew Mc

    2004-01-01

    We present abundance results from our Keck/HIRES observations of giants in the Galactic Bulge. We confirm that the metallicity distribution of giants in the low-reddening bulge field Baade's Window can be well-fit by a closed-box enrichment model. We also confirm previous observations that find enhanced [Mg/Fe], [Si/Fe] and [Ca/Fe] for all bulge giants, including those at super-solar metallicities. However, we find that the [O/Fe] ratios of metal-rich bulge dwarfs decrease with increasing metallicity, contrary to what is expected if the enhancements of the other $\\alpha$-elements is due to Type II supernovae enrichment. We suggest that the decrease in oxygen production may be due to mass loss in the pre-supernova evolution of metal-rich progenitors.

  13. Before the Bar: Kinematic Detection of a Spheroidal Metal-poor Bulge Component

    Science.gov (United States)

    Kunder, Andrea; Rich, R. M.; Koch, A.; Storm, J.; Nataf, D. M.; De Propris, R.; Walker, A. R.; Bono, G.; Johnson, C. I.; Shen, Juntai; Li, Z.-Y.

    2016-04-01

    We present 947 radial velocities of RR Lyrae variable stars in four fields located toward the Galactic bulge, observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay (BRAVA-RR). We show that these RR Lyrae stars (RRLs) exhibit hot kinematics and null or negligible rotation and are therefore members of a separate population from the bar/pseudobulge that currently dominates the mass and luminosity of the inner Galaxy. Our RRLs predate these structures and have metallicities, kinematics, and spatial distribution that are consistent with a “classical” bulge, although we cannot yet completely rule out the possibility that they are the metal-poor tail of a more metal-rich ([{Fe}/{{H}}]∼ -1 dex) halo–bulge population. The complete catalog of radial velocities for the BRAVA-RR stars is also published electronically.

  14. Accounting for selection effects in the BH-bulge relations: No evidence for cosmological evolution

    CERN Document Server

    Schulze, Andreas

    2013-01-01

    The redshift evolution of the black hole - bulge relations is an essential observational constraint for models of black hole - galaxy coevolution. In addition to the observational challenges for these studies, conclusions are complicated by the influence of selection effects. We demonstrate that there is presently no statistical significant evidence for cosmological evolution in the black hole-bulge relations, once these selection effects are taken into account and corrected for. We present a fitting method, based on the bivariate distribution of black hole mass and galaxy property, that accounts for the selection function in the fitting and is therefore able to recover the intrinsic black hole - bulge relation unbiased. While prior knowledge is restricted to a minimum, we at least require knowledge of either the sample selection function and the mass dependence of the active fraction, or the spheroid distribution function and the intrinsic scatter in the black hole - bulge relation. We employed our fitting r...

  15. APOGEE Kinematics I: Overview of the Kinematics of the Galactic Bulge as Mapped by APOGEE

    CERN Document Server

    Ness, M; Johnson, J A; Athanassoula, E; Majewski, S R; Perez, A E Garcia; Bird, J; Nidever, D; Schneider, Donald P; Sobeck, J; Frinchaboy, P; Pan, Kaike; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey

    2015-01-01

    We present the stellar kinematics across the Galactic bulge and into the disk at positive longitudes from the SDSS-III APOGEE spectroscopic survey of the Milky Way. APOGEE includes extensive coverage of the stellar populations of the bulge along the mid-plane and near-plane regions. From these data, we have produced kinematic maps of 10,000 stars across longitudes 0 deg -0.5 have dispersion and rotation profiles that are similar to that of N-body models of boxy/peanut bulges. There is a smooth kinematic transition from the thin bar and boxy bulge (l,|b|) -1.0, and the chemodynamics across (l,b) suggests the stars in the inner Galaxy with [Fe/H] > -1.0 have an origin in the disk.

  16. Before the Bar: Kinematic Detection of A Spheroidal Metal-Poor Bulge Component

    CERN Document Server

    Kunder, Andrea; Storm, J; Nataf, D M; De Propris, R; Walker, A R; Bono, G; Johnson, C I; Shen, J; Li, Z Y

    2016-01-01

    We present 947 radial velocities of RR Lyrae variable stars in four fields located toward the Galactic bulge, observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay (BRAVA-RR). We show that these RR Lyrae stars exhibit hot kinematics and null or negligible rotation and are therefore members of a separate population from the bar/pseudobulge that currently dominates the mass and luminosity of the inner Galaxy. Our RR Lyrae stars predate these structures, and have metallicities, kinematics, and spatial distribution that are consistent with a "classical" bulge, although we cannot yet completely rule out the possibility that they are the metal-poor tail of a more metal rich ([Fe/H] ~ -1 dex) halo-bulge population. The complete catalog of radial velocities for the BRAVA-RR stars is also published electronically.

  17. Nonlinear Local Bending Response and Bulging Factors for Longitudinal Cracks in Pressurized Cylindrical Shells

    Science.gov (United States)

    Rose, Cheryl A.; Young, Richard D.; Starnes, James H., Jr.

    1999-01-01

    Results of a geometrically nonlinear finite element parametric study to determine curvature correction factors or "bulging factors" that account for increased stresses due to curvature for longitudinal cracks in unstiffened pressurized cylindrical shells are presented. Geometric parameters varied in the study include the shell radius, the shell wall thickness, and the crack length. The major results are presented in graphs of the bulging factor as a function of the applied load and as a function of geometric parameters that include the shell radius, the shell thickness and the crack length. The computed bulging factors are compared with solutions based on linear shallow shell theory, and with semi-empirical solutions that approximately account for the nonlinear deformation in the vicinity of the crack. The effect of biaxial loads on the computed bulging factors is also discussed.

  18. Choice & Consequence

    DEFF Research Database (Denmark)

    Khan, Azam

    To move toward environmental sustainability, we propose that a computational approach may be needed due to the complexity of resource production and consumption. While digital sensors and predictive simulation has the potential to help us to minimize resource consumption, the indirect relation be...... principles of data analysis and instructional interface design, to both simulation systems and decision support interfaces. We hope that projects such as these will help people to understand the link between their choices and the consequences of their decisions....... between cause and effect in complex systems complicates decision making. To address this issue, we examine the central role that data-driven decision making could play in critical domains such as sustainability or medical treatment. We developed systems for exploratory data analysis and data visualization...... to support hypothesis generation, hypothesis testing, and decision making. In addition to sensors in buildings, infrastructure, or the environment, we also propose the instrumentation of user interfaces to help measure performance in decision making applications. We show the benefits of applying...

  19. Elemental abundances in AGB stars and the formation of the Galactic bulge

    OpenAIRE

    Wood P.R.; Ryde N.; Lebzelter T.; Blommaert J.A.D.L.; Uttenthaler S.; Schultheis M.; Aringer B.

    2012-01-01

    We obtained high-resolution near-IR spectra of 45 AGB stars located in the Galactic bulge. The aim of the project is to determine key elemental abundances in these stars to help constrain the formation history of the bulge. A further aim is to link the photospheric abundances to the dust species found in the winds of the stars. Here we present a progress report of the analysis of the spectra.

  20. Flank bulge following supracostal percutaneous nephrolithotomy: A report of 2 cases

    Science.gov (United States)

    Lantz, Andrea G.; Pace, Kenneth T.; Honey, R. John D’A.

    2013-01-01

    Damage to intercostal nerves during surgical procedures has been associated with a postoperative flank bulge, due to denervation of the anterolateral abdominal wall musculature. This complication has not been reported following percutaneous nephrolithotomy (PCNL). We are aware of 3 cases, but have details on 2 cases of postoperative flank bulge following supracostal PCNL which are reported here. We also suggest how this complication could potentially be minimized. PMID:24032069

  1. Inverse Approach to Evaluate the Tubular Material Parameters Using the Bulging Test

    OpenAIRE

    Yulong Ge; Xiaoxing Li; Lihui Lang

    2015-01-01

    Tubular material parameters are required for both part manufactory process planning and finite element simulations. The bulging test is one of the most credible ways to detect the property parameters for tubular material. The inverse approach provides more effective access to the accurate material evaluation than with direct identifications. In this paper, a newly designed set of bulging test tools is introduced. An inverse procedure is adopted to determine the tubular material properties in ...

  2. Mechanical Analysis of Dead Load Crown and Structure Parameter of Hydraulic Elastic Bulging Roll

    Institute of Scientific and Technical Information of China (English)

    ZHAO Chang-cai; LI Wei-min; LIU Zhu-bai

    2003-01-01

    The dead load crown of hydraulic elastic bulging roll was discussed using the theory of elastically supported beam, and the dead load experiment was carried out. The theoretical calculation is consistent with the experimental result. The structure parameters for the thickness of roll sleeve, the length of the oil groove and the crown of roll were discussed. The fundamental principle of determining the parameters was put forward. The theoretical basis of the application of the hydraulic elastic bulging roll was established.

  3. Elliptical Galaxies and Bulges of Disc Galaxies: Summary of Progress and Outstanding Issues

    Science.gov (United States)

    Kormendy, John

    Bulge components of disc galaxies are the high-density centers interior to their outer discs. Once thought to be equivalent to elliptical galaxies, their observed properties and formation histories turn out to be richer and more varied than those of ellipticals. This book reviews progress in many areas of bulge studies. Two advances deserve emphasis: (1) Observations divide bulges into "classical bulges" that look indistinguishable from ellipticals and "pseudobulges" that are discier and (except in S0s) more actively star-forming than are ellipticals. Classical bulges and ellipticals are thought to form by major galaxy mergers. Discy pseudobulges are a product of the slow ("secular") evolution of galaxy discs. Nonaxisymmetries such as bars and oval distortions transport some disc gas toward the center, where it starbursts and builds a dense central component that is discier in structure than are classical bulges. Secular evolution explains many regular structures (e.g., rings) seen in galaxy discs. It is a new area of galaxy evolution work that complements hierarchical clustering. (2) Studies of high-redshift galaxies reveal that their discs are so gas-rich that they are violently unstable to the formation of mass clumps that sink to the center and merge. This is an alternative channel for the formation of classical bulges. This chapter summarizes big-picture successes and unsolved problems in the formation of bulges and ellipticals and their coevolution (or not) with supermassive black holes. I present an observer's perspective on simulations of cold dark matter galaxy formation including baryonic physics. Our picture of the quenching of star formation is becoming general and secure at redshifts z 1000 in mass but that differ from each other as we observe over that whole range. A related difficulty is how hierarchical clustering makes so many giant, bulgeless galaxies in field but not cluster environments. I present arguments that we rely too much on star

  4. Thermodynamics of the Earth

    Science.gov (United States)

    Stacey, Frank D.

    2010-04-01

    Applications of elementary thermodynamic principles to the dynamics of the Earth lead to robust, quantitative conclusions about the tectonic effects that arise from convection. The grand pattern of motion conveys deep heat to the surface, generating mechanical energy with a thermodynamic efficiency corresponding to that of a Carnot engine operating over the adiabatic temperature gradient between the heat source and sink. Referred to the total heat flux derived from the Earth's silicate mantle, the efficiency is 24% and the power generated, 7.7 × 1012 W, causes all the material deformation apparent as plate tectonics and the consequent geological processes. About 3.5% of this is released in seismic zones but little more than 0.2% as seismic waves. Even major earthquakes are only localized hiccups in this motion. Complications that arise from mineral phase transitions can be used to illuminate details of the motion. There are two superimposed patterns of convection, plate subduction and deep mantle plumes, driven by sources of buoyancy, negative and positive respectively, at the top and bottom of the mantle. The patterns of motion are controlled by the viscosity contrasts (>104 : 1) at these boundaries and are self-selected as the least dissipative mechanisms of heat transfer for convection in a body with very strong viscosity variation. Both are subjects of the thermodynamic efficiency argument. Convection also drives the motion in the fluid outer core that generates the geomagnetic field, although in that case there is an important energy contribution by compositional separation, as light solute is rejected by the solidifying inner core and mixed into the outer core, a process referred to as compositional convection. Uncertainty persists over the core energy balance because thermal conduction is a drain on core energy that has been a subject of diverse estimates, with attendant debate over the need for radiogenic heat in the core. The geophysical approach to

  5. Heat and thermodynamics

    CERN Document Server

    Saxena, A K

    2014-01-01

    Heat and thermodynamics aims to serve as a textbook for Physics, Chemistry and Engineering students. The book covers basic ideas of Heat and Thermodynamics, Kinetic Theory and Transport Phenomena, Real Gases, Liquafaction and Production and Measurement of very Low Temperatures, The First Law of Thermodynamics, The Second and Third Laws of Thermodynamics and Heat Engines and Black Body Radiation. KEY FEATURES Emphasis on concepts Contains 145 illustrations (drawings), 9 Tables and 48 solved examples At the end of chapter exercises and objective questions

  6. The Galactic Bulge Survey: outline and X-ray observations

    CERN Document Server

    Jonker, P G; Nelemans, G; Steeghs, D; Torres, M A P; Maccarone, T J; Hynes, R I; Greiss, S; Clem, J; Dieball, A; Mikles, V J; Britt, C T; Gossen, L; Collazzi, A C; Wijnands, R; Zand, J J M In 't; Mendez, M; Rea, N; Kuulkers, E; Ratti, E M; van Haaften, L M; Heinke, C; Ozel, F; Groot, P J; Verbunt, F

    2011-01-01

    We introduce the Galactic Bulge Survey (GBS) and we provide the Chandra source list for the region that has been observed to date. Among the goals of the GBS are constraining the neutron star equation of state and the black hole mass distribution via the identification of eclipsing neutron star and black hole low-mass X-ray binaries. The latter goal will, in addition, be obtained by significantly enlarging the number of black hole systems for which a black hole mass can be derived. Further goals include constraining X-ray binary formation scenarios, in particular the common envelope phase and the occurrence of kicks, via source-type number counts and an investigation of the spatial distribution of X-ray binaries, respectively. The GBS targets two strips of 6x1 degrees (12 square degrees in total), one above (1

  7. Star Clusters in Pseudo-Bulges of Spiral Galaxies

    CERN Document Server

    Di Nino, Daiana; Stiavelli, Massimo; Carollo, C Marcella; Scarlata, Claudia; Wyse, Rosemary F G

    2009-01-01

    We present a study of the properties of the star-cluster systems around pseudo-bulges of late-type spiral galaxies using a sample of 11 galaxies with distances from 17 to 37 Mpc. Star clusters are identified from multiband HST ACS and WFPC2 imaging data by combining detections in 3 bands (F435W and F814W with ACS and F606W with WFPC2). The photometric data are then compared to population synthesis models to infer the masses and ages of the star clusters. Photometric errors and completeness are estimated by means of artificial source Monte Carlo simulations. Dust extinction is estimated by considering F160W NICMOS observations of the central regions of the galaxies, augmenting our wavelength coverage. In all galaxies we identify star clusters with a wide range of ages, from young (age 100-250 Myr), more massive, red clusters. Some of the latter might likely evolve into objects similar to the Milky Way's globular clusters. We compute the specific frequencies for the older clusters with respect to the galaxy an...

  8. Identification of 5 Interacting Binaries in the Galactic Bulge Survey

    CERN Document Server

    Britt, C T; Hynes, R I; Jonker, P G; Maccarone, T J; Greiss, S; Steeghs, D; Groot, P; Knigge, C; Dieball, A; Nelemans, G; Mikles, V J; Gossen, L

    2013-01-01

    We present optical lightcurves, spectroscopy, and classification of five X-ray sources in the Chandra Galactic Bulge Survey [CXOGBS J174009.1-284725 (CX5), CXOGBS J173935.7-272935 (CX18), CXOGBS J173946.9-271809 (CX28), CXOGBS J173729.1-292804 (CX37), CXOGBS J174607.6-261547 (CX561)]. These objects were selected based on bright optical counterparts which were quickly found to have emission lines in their optical spectra. This paper presents an illustration of GBS optical follow-up, targeting emission line objects. Of these five objects, four exhibit photometric variability in the Sloan r' band. CX5 shows a tentative period of 2.1 hours and is clearly an Intermediate Polar (IP). CX28 and CX37 both exhibit flickering with no clear period. Both are suggested to also be IPs. CX18 was observed to undergo 2 dwarf nova outbursts. Finally, CX561 shows no detectable variability, although its characteristics would be consistent with either a quiescent Low Mass X-ray Binary or Cataclysmic Variable.

  9. A Search for Novae in the Bulge of M31

    Science.gov (United States)

    Rector, T. A.; Jacoby, G. H.; Corbett, D. L.; Denham, M.; RBSE Nova Search Team

    1999-12-01

    We present the initial results of a program currently underway to search for nova in local group galaxies with the KPNO 0.9-meter telescope. The long-term goal is to accurately determine if the nova rate varies for galaxies of different Hubble type. Ciardullo et al. claim that nova rates are very similar when normalized to the total galaxy K-band luminosity. However, Della Valle et al. claim the rates are different by up to a factor of four, with early-type galaxies being deficient in novae. Here we present novae found from eighteen epochs of observations of the bulge of M31. The observations span from September 1995 to July 1999. The results presented here are part of an NSF-funded research-based science education program (RBSE) operated by NOAO, wherein middle- and high-school science students learn astronomy and inquiry-based learning skills by participating in actual research. The novae presented here were discovered by students participating in the RBSE program.

  10. A new look at the kinematics of the bulge from an N-body model

    CERN Document Server

    Gomez, A; Stefanovitch, N; Haywood, M; Combes, F; Katz, D; Babusiaux, C

    2016-01-01

    (Abridged) By using an N-body simulation of a bulge that was formed via a bar instability mechanism, we analyse the imprints of the initial (i.e. before bar formation) location of stars on the bulge kinematics, in particular on the heliocentric radial velocity distribution of bulge stars. Four different latitudes were considered: $b=-4^\\circ$, $-6^\\circ$, $-8^\\circ$, and $-10^\\circ$, along the bulge minor axis as well as outside it, at $l=\\pm5^\\circ$ and $l=\\pm10^\\circ$. The bulge X-shaped structure comprises stars that formed in the disk at different locations. Stars formed in the outer disk, beyond the end of the bar, which are part of the boxy peanut-bulge structure may show peaks in the velocity distributions at positive and negative heliocentric radial velocities with high absolute values that can be larger than 100 $\\rm km$ $\\rm s^{-1}$, depending on the observed direction. In some cases the structure of the velocity field is more complex and several peaks are observed. Stars formed in the inner disk, t...

  11. DEMOGRAPHICS OF BULGE TYPES WITHIN 11 Mpc AND IMPLICATIONS FOR GALAXY EVOLUTION

    International Nuclear Information System (INIS)

    We present an inventory of galaxy bulge types (elliptical galaxy, classical bulge, pseudobulge, and bulgeless galaxy) in a volume-limited sample within the local 11 Mpc sphere using Spitzer 3.6 μm and Hubble Space Telescope data. We find that whether counting by number, star formation rate, or stellar mass, the dominant galaxy type in the local universe has pure disk characteristics (either hosting a pseudobulge or being bulgeless). Galaxies that contain either a pseudobulge or no bulge combine to account for over 80% of the number of galaxies above a stellar mass of 109 Msun. Classical bulges and elliptical galaxies account for ∼1/4, and disks for ∼3/4 of the stellar mass in the local 11 Mpc. About 2/3 of all star formation in the local volume takes place in galaxies with pseudobulges. Looking at the fraction of galaxies with different bulge types as a function of stellar mass, we find that the frequency of classical bulges strongly increases with stellar mass, and comes to dominate above 1010.5 Msun. Galaxies with pseudobulges dominate at 109.5-1010.5 Msun. Yet lower-mass galaxies are most likely to be bulgeless. If pseudobulges are not a product of mergers, then the frequency of pseudobulges in the local universe poses a challenge for galaxy evolution models.

  12. The Chemical Composition of the Galactic Bulge and Implications for its Evolution

    CERN Document Server

    McWilliam, Andrew

    2016-01-01

    The average bulge [Fe/H] and [Mg/H] are +0.06 and +0.17 dex, respectively, in Baade's Window, roughly 0.2 dex higher than the thin disk and ~0.7 dex higher than the local thick disk metallicity. This suggests a higher effective yield in the bulge, perhaps due to more efficient retention of supernova ejecta. The bulge vertical [Fe/H] gradient, at ~0.5 dex/kpc, appears to be due to a changing mixture of sub-populations (near +0.3 dex and -0.3 dex and one possibly near -0.7 dex) with latitude. The bulge is enhanced in O, Mg, Si, Ca, Ti, and Al relative to the sun, with [alpha/Fe]=+0.15 dex at [Fe/H]=0.0 dex. Below [Fe/H]~-0.5 dex, the bulge and local thick disk compositions are very similar, but small [Mg/Fe] and possibly [/Fe] enhancements, low [La/Eu] ratios and large [Cu/Fe], relative to the thick disk suggest slightly higher SFR in the bulge. However, these composition differences could simply be due to measurement errors and non-LTE effects. Unfortunately, comparison with the thick disk near solar [Fe/H] su...

  13. A high-velocity bulge RR Lyrae variable on a halo-like orbit

    CERN Document Server

    Kunder, Andrea; Hawkins, Keith; Poleski, Radek; Storm, Jesper; Johnson, Christian I; Shen, Juntai; Li, Zhao-Yu; Cordero, Maria Jose; Nataf, David M; Bono, Giuseppe; Walker, Alistair R; Koch, Andreas; De Propris, Roberto; Udalski, Andrzej; Szymanski, Michal K; Soszynski, Igor; Pietrzynski, Grzegorz; Ulaczyk, Krzysztof; Wyrzykowski, Lukasz; Pietrukowicz, Pawel; Skowron, Jan; Kozlowski, Szymon; Mroz, Przemyslaw

    2015-01-01

    We report on the RR Lyrae variable star, MACHO 176.18833.411, located toward the Galactic bulge and observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay (BRAVA-RR), which has the unusual radial velocity of -372 +- 8 km/s and true space velocity of -482 +- 22 km/s relative to the Galactic rest frame. Located less than 1 kpc from the Galactic center and toward a field at (l,b)=(3,-2.5), this pulsating star has properties suggesting it belongs to the bulge RR Lyrae star population yet a velocity indicating it is abnormal, at least with respect to bulge giants and red clump stars. We show that this star is most likely a halo interloper and therefore suggest that halo contamination is not insignificant when studying metal-poor stars found within the bulge area, even for stars within 1 kpc of the Galactic center. We discuss the possibility that MACHO 176.18833.411 is on the extreme edge of the bulge RR Lyrae radial velocity distribution, and also consider a more exotic scenario in which it...

  14. The origin of the split red clump in the Galactic bulge of the Milky Way

    CERN Document Server

    Ness, M; Athanassoula, E; Wylie-de-Boer, E; Bland-Hawthorn, J; Lewis, G F; Yong, D; Asplund, M; Lane, R R; Kiss, L L; Ibata, R

    2012-01-01

    Near the minor axis of the Galactic bulge, at latitudes b -0.5 in the two higher-latitude fields, but not in the field at b = -5 degrees. Stars with [Fe/H] < -0.5 do not show the split. We compare the spatial distribution and kinematics of the clump stars with predictions from an evolutionary N-body model of a bulge that grew from a disk via bar-related instabilities. The density distribution of the peanut-shaped model is depressed near its minor axis. This produces a bimodal distribution of stars along the line of sight through the bulge near its minor axis, very much as seen in our observations. The observed and modelled kinematics of the two groups of stars are also similar. We conclude that the split red clump of the bulge is probably a generic feature of boxy/peanut bulges that grew from disks, and that the disk from which the bulge grew had relatively few stars with [Fe/H] < -0.5

  15. The EMBLA Survey -- Metal-poor stars in the Galactic bulge

    CERN Document Server

    Howes, Louise M; Keller, Stefan C; Casey, Andrew R; Yong, David; Lind, Karin; Frebel, Anna; Hays, Austin; Alves-Brito, Alan; Bessell, Michael S; Casagrande, Luca; Marino, Anna F; Nataf, David M; Owen, Christopher I; Da Costa, Gary S; Schmidt, Brian P; Tisserand, Patrick

    2016-01-01

    Cosmological models predict the oldest stars in the Galaxy should be found closest to the centre of the potential well, in the bulge. The EMBLA Survey successfully searched for these old, metal-poor stars by making use of the distinctive SkyMapper photometric filters to discover candidate metal-poor stars in the bulge. Their metal-poor nature was then confirmed using the AAOmega spectrograph on the AAT. Here we present an abundance analysis of 10 bulge stars with -2.8<[Fe/H]<-1.7 from MIKE/Magellan observations, in total determining the abundances of 22 elements. Combining these results with our previous high-resolution data taken as part of the Gaia-ESO Survey, we have started to put together a picture of the chemical and kinematic nature of the most metal-poor stars in the bulge. The currently available kinematic data is consistent with the stars belonging to the bulge, although more accurate measurements are needed to constrain the stars' orbits. The chemistry of these bulge stars deviates from that ...

  16. Introduction to applied thermodynamics

    CERN Document Server

    Helsdon, R M; Walker, G E

    1965-01-01

    Introduction to Applied Thermodynamics is an introductory text on applied thermodynamics and covers topics ranging from energy and temperature to reversibility and entropy, the first and second laws of thermodynamics, and the properties of ideal gases. Standard air cycles and the thermodynamic properties of pure substances are also discussed, together with gas compressors, combustion, and psychrometry. This volume is comprised of 16 chapters and begins with an overview of the concept of energy as well as the macroscopic and molecular approaches to thermodynamics. The following chapters focus o

  17. Twenty lectures on thermodynamics

    CERN Document Server

    Buchdahl, H A

    2013-01-01

    Twenty Lectures on Thermodynamics is a course of lectures, parts of which the author has given various times over the last few years. The book gives the readers a bird's eye view of phenomenological and statistical thermodynamics. The book covers many areas in thermodynamics such as states and transition; adiabatic isolation; irreversibility; the first, second, third and Zeroth laws of thermodynamics; entropy and entropy law; the idea of the application of thermodynamics; pseudo-states; the quantum-static al canonical and grand canonical ensembles; and semi-classical gaseous systems. The text

  18. Thermodynamics for dummies

    CERN Document Server

    Pauken, Mike

    2011-01-01

    Take some heat off the complexity of thermodynamics Does the mere thought of thermodynamics make you sweat? It doesn't have to! This hands-on guide helps you score your highest in a thermodynamics course by offering easily understood, plain-English explanations of how energy is used in things like automobiles, airplanes, air conditioners, and electric power plants. Thermodynamics 101 - take a look at some examples of both natural and man-made thermodynamic systems and get a handle on how energy can be used to perform work Turn up the heat - discover how to use the firs

  19. Rational extended thermodynamics

    CERN Document Server

    Müller, Ingo

    1998-01-01

    Ordinary thermodynamics provides reliable results when the thermodynamic fields are smooth, in the sense that there are no steep gradients and no rapid changes. In fluids and gases this is the domain of the equations of Navier-Stokes and Fourier. Extended thermodynamics becomes relevant for rapidly varying and strongly inhomogeneous processes. Thus the propagation of high­ frequency waves, and the shape of shock waves, and the regression of small-scale fluctuation are governed by extended thermodynamics. The field equations of ordinary thermodynamics are parabolic while extended thermodynamics is governed by hyperbolic systems. The main ingredients of extended thermodynamics are • field equations of balance type, • constitutive quantities depending on the present local state and • entropy as a concave function of the state variables. This set of assumptions leads to first order quasi-linear symmetric hyperbolic systems of field equations; it guarantees the well-posedness of initial value problems and f...

  20. The age of the young bulge-like population in the stellar system Terzan5: linking the Galactic bulge to the high-z Universe

    CERN Document Server

    Ferraro, F R; Dalessandro, E; Lanzoni, B; Origlia, L; Rich, R M; Mucciarelli, A; -,

    2016-01-01

    The Galactic bulge is dominated by an old, metal rich stellar population. The possible presence and the amount of a young (a few Gyr old) minor component is one of the major issues debated in the literature. Recently, the bulge stellar system Terzan 5 was found to harbor three sub-populations with iron content varying by more than one order of magnitude (from 0.2 up to 2 times the solar value), with chemical abundance patterns strikingly similar to those observed in bulge field stars. Here we report on the detection of two distinct main sequence turn-off points in Terzan 5, providing the age of the two main stellar populations: 12 Gyr for the (dominant) sub-solar component and 4.5 Gyr for the component at super-solar metallicity. This discovery classifies Terzan 5 as a site in the Galactic bulge where multiple bursts of star formation occurred, thus suggesting a quite massive progenitor possibly resembling the giant clumps observed in star forming galaxies at high redshifts. This connection opens a new route ...

  1. Supermassive black holes and their host galaxies. I. Bulge luminosities from dedicated near-infrared data

    Energy Technology Data Exchange (ETDEWEB)

    Läsker, Ronald; Van de Ven, Glenn [Max-Planck Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany); Ferrarese, Laura, E-mail: laesker@mpia.de [NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E2E7 (Canada)

    2014-01-01

    In an effort to secure, refine, and supplement the relation between central supermassive black hole masses, M {sub •}, and the bulge luminosities of their host galaxies, L {sub bul}, we obtained deep, high spatial resolution K-band images of 35 nearby galaxies with securely measured M {sub •}, using the wide-field WIRCam imager at the Canada-France-Hawaii-Telescope. A dedicated data reduction and sky subtraction strategy was adopted to estimate the brightness and structure of the sky, a critical step when tracing the light distribution of extended objects in the near-infrared. From the final image product, bulge and total magnitudes were extracted via two-dimensional profile fitting. As a first order approximation, all galaxies were modeled using a simple Sérsic-bulge+exponential-disk decomposition. However, we found that such models did not adequately describe the structure that we observed in a large fraction of our sample galaxies which often include cores, bars, nuclei, inner disks, spiral arms, rings, and envelopes. In such cases, we adopted profile modifications and/or more complex models with additional components. The derived bulge magnitudes are very sensitive to the details and number of components used in the models, although total magnitudes remain almost unaffected. Usually, but not always, the luminosities and sizes of the bulges are overestimated when a simple bulge+disk decomposition is adopted in lieu of a more complex model. Furthermore, we found that some spheroids are not well fit when the ellipticity of the Sérsic model is held fixed. This paper presents the details of the image processing and analysis, while we discuss how model-induced biases and systematics in bulge magnitudes impact the M {sub •}-L {sub bul} relation in a companion paper.

  2. Bulge Growth and Quenching Since Z=2.5 in Candels/3D-HST

    Science.gov (United States)

    Lang, Phillip; Wuyts, Stijn; Somerville, Rachel S.; Schreiber, Natascha M. Foerster; Genzel, Reinhard; Bell, Eric F.; Brammer, Gabe; Dekel, Avishai; Faber, Sandra M.; Ferguson, Henry C.; Grogin, Norman A.; Kocevski, Dale D.; Koekemoer, Anton M.; Lutz, Dieter; McGrath, Elizabeth J.; Momcheva, Ivelina; Nelson, Erica J.; Primack, Joel R.; Rosario, David J.; Skelton, Rosalind E.; Tacconi, Linda J.; van Dokkum, Peter G.; Whitaker, Katherine E.

    2014-01-01

    Exploiting the deep high-resolution imaging of all 5 CANDELS fields, and accurate redshift informationprovided by 3D-HST, we investigate the relation between structure and stellar populations fora mass-selected sample of 6764 galaxies above 1010 M, spanning the redshift range 0.5 z 2.5.For the first time, we fit 2-dimensional models comprising a single Sersic fit and two-component (i.e.,bulge + disk) decompositions not only to the H-band light distributions, but also to the stellar massmaps reconstructed from resolved stellar population modeling. We confirm that the increased bulgeprominence among quiescent galaxies, as reported previously based on rest-optical observations, remainsin place when considering the distributions of stellar mass. Moreover, we observe an increaseof the typical Sersic index and bulge-to-total ratio (with median BT reaching 40-50) among starforminggalaxies above 1011 M. Given that quenching for these most massive systems is likely tobe imminent, our findings suggest that significant bulge growth precedes a departure from the starformingmain sequence. We demonstrate that the bulge mass (and ideally knowledge of the bulge andtotal mass) is a more reliable predictor of the star-forming versus quiescent state of a galaxy thanthe total stellar mass. The same trends are predicted by the state-of-the-art semi-analytic model bySomerville et al. In the latter, bulges and black holes grow hand in hand through merging andordisk instabilities, and AGN-feedback shuts off star formation. Further observations will be requiredto pin down star formation quenching mechanisms, but our results imply they must be internal to thegalaxies and closely associated with bulge growth.

  3. Comparing the properties of the X-shaped bulges of NGC 4710 and the Milky Way with MUSE

    Science.gov (United States)

    Gonzalez, O. A.; Gadotti, D. A.; Debattista, V. P.; Rejkuba, M.; Valenti, E.; Zoccali, M.; Coccato, L.; Minniti, D.; Ness, M.

    2016-06-01

    Context. Our view of the structure of the Milky Way and, in particular, its bulge is obscured by the intervening stars, dust, and gas in the disc. While great progress in understanding the bulge has been achieved with past and ongoing observations, the comparison of its global chemodynamical properties with respect to those of bulges seen in external galaxies has yet to be accomplished. Aims: We used the Multi Unit Spectroscopic Explorer (MUSE) instrument installed on the Very Large Telescope (VLT) to obtain spectral and imaging coverage of NGC 4710. The wide area and excellent sampling of the MUSE integral field spectrograph allows us to investigate the dynamical properties of the X-shaped bulge of NGC 4710 and compare it with the properties of the X-shaped bulge of the Milky Way. Methods: We measured the radial velocities, velocity dispersion, and stellar populations using a penalised pixel full spectral fitting technique adopting simple stellar populations models, on a 1' × 1' area centred on the bulge of NGC 4710. We constructed the velocity maps of the bulge of NGC 4710 and investigated the presence of vertical metallicity gradients. These properties were compared to those of the Milky Way bulge and to a simulated galaxy with a boxy-peanut bulge. Results: We find the line-of-sight velocity maps and 1D rotation curves of the bulge of NGC 4710 to be remarkably similar to those of the Milky Way bulge. Some specific differences that were identified are in good agreement with the expectations from variations in the bar orientation angle. The bulge of NGC 4710 has a boxy-peanut morphology with a pronounced X-shape, showing no indication of any additional spheroidally distributed bulge population, in which we measure a vertical metallicity gradient of 0.35 dex/kpc. Conclusions: The general properties of NGC 4710 are very similar to those observed in the Milky Way bulge. However, it has been suggested that the Milky Way bulge has an additional component that is

  4. Thermodynamical journey in plant biology

    Directory of Open Access Journals (Sweden)

    Adelin eBarbacci

    2015-06-01

    Full Text Available Nonequilibrium irreversible thermodynamics constitute a meaningful point of view suitable to explore life with a rich paradigm. This analytical framework can be used to span the gap from molecular processes to plant function and shows great promise to create a holistic description of life. Since living organisms dissipate energy, exchange entropy and matter with their environment, they can be assimilated to dissipative structures. This concept inherited from nonequilibrium thermodynamics has four properties which defines a scale independent framework suitable to provide a simpler and more comprehensive view of the highly complex plant biology. According to this approach, a biological process is modeled as an avalanche of dissipative structures. Each dissipative structure, corresponds to an unitary biological process, which is initiated by the amplification of a fluctuation. Evolution of the process leads to the breakage of the system symmetry and to the export of entropy. Exporting entropy to the surrounding environment corresponds to collecting information about it. Biological actors which break the symmetry of the system and which store information are by consequence, key actors on which experiments and data analysis focus most. This paper aims at illustrating properties of dissipative structure through familiar examples and thus initiating the dialogue between nonequilibrium thermodynamics and plant biology.

  5. A new look at the kinematics of the bulge from an N-body model

    Science.gov (United States)

    Gómez, A.; Di Matteo, P.; Stefanovitch, N.; Haywood, M.; Combes, F.; Katz, D.; Babusiaux, C.

    2016-05-01

    By using an N-body simulation of a bulge that was formed via a bar instability mechanism, we analyse the imprints of the initial (i.e. before bar formation) location of stars on the bulge kinematics, in particular on the heliocentric radial velocity distribution of bulge stars. Four different latitudes were considered: b = -4°, -6°, -8°, and -10°, along the bulge minor axis as well as outside it, at l = ± 5° and l = ± 10°. The bulge X-shaped structure comprises stars that formed in the disk at different locations. Stars formed in the outer disk, beyond the end of the bar, which are part of the boxy peanut-bulge structure may show peaks in the velocity distributions at positive and negative heliocentric radial velocities with high absolute values that can be larger than 100 km s-1, depending on the observed direction. In some cases the structure of the velocity field is more complex and several peaks are observed. Stars formed in the inner disk, the most numerous, contribute predominantly to the X-shaped structure and present different kinematic characteristics. They display a rather symmetric velocity distribution and a smaller fraction of high-velocity stars. The stellar stream motion, which is induced by the bar changes with the star initial position, can reach more than 40 km s-1 for stars that originated in the external disk, depending on the observed direction. Otherwise it is smaller than approximately 20 km s-1. In all cases, it decreases from b = -4° to -10°. Our results may enable us to interpret the cold high-velocity peak observed in the APOGEE commissioning data, as well as the excess of high-velocity stars in the near and far arms of the X-shaped structure at l = 0° and b = -6°. When compared with real data, the kinematic picture becomes more complex due to the possible presence in the observed samples of classical bulge and/or thick disk stars. Overall, our results point to the existence of complex patterns and structures in the bulge

  6. The influence of changes in cervical lordosis on bulging disk and spinal stenosis: functional MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Joon; Eun, Choong Ki [Pusan Paik Hospital, Inje Univ. College of Medicine, Pusan (Korea, Republic of)

    2001-05-01

    To assess the effect of lordotic curve change of the cervical spine on disk bulging and spinal stenosis by means of functional cervical MR imaging at the flexion and extension position. Using a 1.5T imager, kinematic MR examinations of 25 patients with degenerative spondylosis (average age, 41 years) were performed at the neutral, flexed and extended position of the cervical spine. Sagittal T2-weighted turbo spin-echo images were obtained during each of the three phases. Lordotic angle, bulging thickness of the disk, AP diameter of the spinal canal, and distance between the disk and spinal cord were measured on the workstation at each disk level. After qualitative independent observation of disk bulging, one of four grades(0, normal; 1, mild; 2, moderate; 3, marked) was assigned at each phase, and after further comparative observation, one of five scores (-2, prominent decrease; -1, mild decrease; 0, no change; 1, notable increase; 2 prominent increase) was also assigned. In addition, bulging thickness of the disk was measured and compared at the neutral, flexed, and extended positions. Average angles of the cervical spine were 160.5{+-}5.9 deg (neutral position, lordotic angle); 185.4{+-}8.5 deg (flexion, kyphotic angle); and 143.7{+-}6.7 deg (extension, lordotic angle). Average grades of disk bulging were 0.55 at the neutral position. 0.16 at flexion, and 0.7 at extension. Comparative observation showed that average scores of disk bulging were -0.39 at flexion and 0.31 at extension. The bulging thickness of the disk decreased by 24.2% at flexion and increased by 30.3% at extension, while the diameter of the spinal canal increased by 4.5% at flexion and decreased by 3.6% at extension. The distance from the posterior margin of the disk to the anterior margin of the spinal cord decreased at both flexion(6.6%) and extension(19.1%). Functional MRI showed that compared with the neutral position, disk bulging and spinal stenosis are less prominent at flexion and

  7. The influence of changes in cervical lordosis on bulging disk and spinal stenosis: functional MR imaging

    International Nuclear Information System (INIS)

    To assess the effect of lordotic curve change of the cervical spine on disk bulging and spinal stenosis by means of functional cervical MR imaging at the flexion and extension position. Using a 1.5T imager, kinematic MR examinations of 25 patients with degenerative spondylosis (average age, 41 years) were performed at the neutral, flexed and extended position of the cervical spine. Sagittal T2-weighted turbo spin-echo images were obtained during each of the three phases. Lordotic angle, bulging thickness of the disk, AP diameter of the spinal canal, and distance between the disk and spinal cord were measured on the workstation at each disk level. After qualitative independent observation of disk bulging, one of four grades(0, normal; 1, mild; 2, moderate; 3, marked) was assigned at each phase, and after further comparative observation, one of five scores (-2, prominent decrease; -1, mild decrease; 0, no change; 1, notable increase; 2 prominent increase) was also assigned. In addition, bulging thickness of the disk was measured and compared at the neutral, flexed, and extended positions. Average angles of the cervical spine were 160.5±5.9 deg (neutral position, lordotic angle); 185.4±8.5 deg (flexion, kyphotic angle); and 143.7±6.7 deg (extension, lordotic angle). Average grades of disk bulging were 0.55 at the neutral position. 0.16 at flexion, and 0.7 at extension. Comparative observation showed that average scores of disk bulging were -0.39 at flexion and 0.31 at extension. The bulging thickness of the disk decreased by 24.2% at flexion and increased by 30.3% at extension, while the diameter of the spinal canal increased by 4.5% at flexion and decreased by 3.6% at extension. The distance from the posterior margin of the disk to the anterior margin of the spinal cord decreased at both flexion(6.6%) and extension(19.1%). Functional MRI showed that compared with the neutral position, disk bulging and spinal stenosis are less prominent at flexion and accentuated

  8. An introduction to equilibrium thermodynamics

    CERN Document Server

    Morrill, Bernard; Hartnett, James P; Hughes, William F

    1973-01-01

    An Introduction to Equilibrium Thermodynamics discusses classical thermodynamics and irreversible thermodynamics. It introduces the laws of thermodynamics and the connection between statistical concepts and observable macroscopic properties of a thermodynamic system. Chapter 1 discusses the first law of thermodynamics while Chapters 2 through 4 deal with statistical concepts. The succeeding chapters describe the link between entropy and the reversible heat process concept of entropy; the second law of thermodynamics; Legendre transformations and Jacobian algebra. Finally, Chapter 10 provides a

  9. Bulges and disks in the local Universe. Linking the galaxy structure to star formation activity

    CERN Document Server

    Morselli, L; Erfanianfar, G; Concas, A

    2016-01-01

    Galaxy morphology and star formation activity are strictly linked, in the way that bulge-dominated galaxies are in general quiescent, while disk dominated galaxies are actively star-forming. In this paper, we study the properties of bulges and disks as a function of the position of galaxies in the star formation rate (SFR) - stellar mass ($M_{\\star}$) plane. Our sample is built on the SDSS DR7 catalogue, and the bulge-disk decomposition is the one of Simard et al. (2011). We find that at a given stellar mass the Main Sequence (MS) is populated by galaxies with the lowest B/T ratios. The B/T on the MS increases with increasing stellar mass, thus confirming previous results in literature. In the upper envelop of the MS, the average B/T is higher than that of MS counterparts at fixed stellar mass. This indicates that starburst galaxies have a significant bulge component. In addition, bulges above the MS are characterised by blue colours, whereas, if on the MS or below it, they are mostly red and dead. The disks ...

  10. Composite Stellar Populations and Element by Element Abundances in the Milky Way Bulge and Elliptical Galaxies

    CERN Document Server

    Tang, Baitian; Davis, A Bianca

    2014-01-01

    This paper explores the integrated-light characteristics of the Milky Way (MW) bulge and to what extent they match those of elliptical galaxies in the local universe. We model composite stellar populations with realistic abundance distribution functions (ADFs), tracking the trends of individual elements as a function of overall heavy element abundance as actually observed in MW bulge stars. The resultant predictions for absorption feature strengths from the MW bulge mimic elliptical galaxies better than solar neighborhood stars do, but the MW bulge does not match elliptical galaxies, either. Comparing bulge versus elliptical galaxies, Fe, Ti, and Mg trend about the same for both but C, Na, and Ca seem irreconcilably different. Exploring the behavior of abundance compositeness leads to the concepts of "red lean" where a narrower ADF appears more metal rich than a wide one, and "red spread" where the spectral difference between wide and narrow ADFs increases as the ADF peak is moved to more metal-rich values. T...

  11. A case against an X-shaped structure in the Milky Way young bulge

    CERN Document Server

    Lopez-Corredoira, Martin

    2016-01-01

    CONTEXT. A number of recent papers have claimed the discovery of an X-shape structure in the bulge of our Galaxy in the population of the red clumps. AIMS. We endeavor to analyze the stellar density of bulge stars in the same regions using a different stellar population that is characteristic of the young bulge ($\\lesssim 5$ Gyr). Particularly, we use F0-F5 main-sequence stars with distances derived through photometric parallax. METHODS. We extract these stars from extinction-corrected color-magnitude diagrams in the near-infrared of VISTA-VVV data in some bulge regions and calculate the densities along the line of sight. We take the uncertaintity in the photometric parallax and the contamination of other sources into account, and we see that these errors do not avoid the detection of a possible double peak along some lines of sight as expected for a X-shape bulge if it existed. RESULTS. Only a single peak in the density distribution along the line of sight is observed, so apparently there is no X-shape struc...

  12. The First Detection of Blue Straggler Stars in the Milky Way Bulge

    CERN Document Server

    Clarkson, William I; Anderson, Jay; Rich, R Michael; Smith, T Ed; Brown, Thomas M; Bond, Howard E; Livio, Mario; Minniti, Dante; Renzini, Alvio; Zoccali, Manuela

    2011-01-01

    We report the first detections of Blue Straggler Stars (BSS) in the bulge of the Milky Way galaxy. Proper motions from extensive space-based observations along a single sight-line allow us to separate a sufficiently clean and well-characterized bulge sample that we are able to detect a small population of bulge objects in the region of the color-magnitude diagram commonly occupied young objects and blue strgglers. However, variability measurements of these objects clearly establish that a fraction of them are blue stragglers. Out of the 42 objects found in this region of the color-magnitude diagram, we estimate that at least 18 are genuine BSS. We normalize the BSS population by our estimate of the number of horizontal branch stars in the bulge in order to compare the bulge to other stellar systems. The BSS fraction is clearly discrepant from that found in stellar clusters. The blue straggler population of dwarf spheroidals remains a subject of debate; some authors claim an anticorrelation between the normali...

  13. The number of tidal dwarf satellite galaxies in dependence of bulge index

    CERN Document Server

    Lopez-Corredoira, Martin

    2015-01-01

    We show that a significant correlation (up to 5sigma) emerges between the bulge index, defined to be larger for larger bulge/disk ratio, in spiral galaxies with similar luminosities in the Galaxy Zoo 2 of SDSS and the number of tidal-dwarf galaxies in the catalogue by Kaviraj et al. (2012). In the standard cold or warm dark-matter cosmological models the number of satellite galaxies correlates with the circular velocity of the dark matter host halo. In generalized-gravity models without cold or warm dark matter such a correlation does not exist, because host galaxies cannot capture in-falling dwarf galaxies due to the absence of dark-matter-induced dynamical friction. However, in such models a correlation is expected to exist between the bulge mass and the number of satellite galaxies, because bulges and tidal-dwarf satellite galaxies form in encounters between host galaxies. This is not predicted by dark matter models in which bulge mass and the number of satellites are a priori uncorrelated because higher b...

  14. Clues to the Formation of Lenticular Galaxies Using Spectroscopic Bulge-Disk Decomposition

    CERN Document Server

    Johnston, Evelyn J; Merrifield, Michael R; Bedregal, Alejandro G

    2013-01-01

    Lenticular galaxies have long been thought of as evolved spirals, but the processes involved to quench the star formation are still unclear. By studying the individual star formation histories of the bulges and disks of lenticulars, it is possible to look for clues to the processes that triggered their transformation from spirals. To accomplish this feat, we present a new method for spectroscopic bulge-disk decomposition, in which a long-slit spectrum is decomposed into two one-dimensional spectra representing purely the bulge and disk light. We present preliminary results from applying this method to lenticular galaxies in the Virgo and Fornax Clusters, in which we show that the most recent star formation activity in these galaxies occurred within the bulges. We also find that the star formation timescales of the bulges are longer than the disks, and that more massive galaxies take longer to lose their gas during the transformation. These results point towards slow processes, such as ram-pressure stripping o...

  15. Understanding AGB evolution in Galactic bulge stars from high-resolution infrared spectroscopy

    CERN Document Server

    Uttenthaler, S; Wood, P R; Lebzelter, T; Aringer, B; Schultheis, M; Ryde, N

    2015-01-01

    An analysis of high-resolution near-infrared spectra of a sample of 45 asymptotic giant branch (AGB) stars towards the Galactic bulge is presented. The sample consists of two subsamples, a larger one in the inner and intermediate bulge, and a smaller one in the outer bulge. The data are analysed with the help of hydrostatic model atmospheres and spectral synthesis. We derive the radial velocity of all stars, and the atmospheric chemical mix ([Fe/H], C/O, $^{12}$C/$^{13}$C, Al, Si, Ti, and Y) where possible. Our ability to model the spectra is mainly limited by the (in)completeness of atomic and molecular line lists, at least for temperatures down to $T_{\\rm eff}\\approx3100$ K. We find that the subsample in the inner and intermediate bulge is quite homogeneous, with a slightly sub-solar mean metallicity and only few stars with super-solar metallicity, in agreement with previous studies of non-variable M-type giants in the bulge. All sample stars are oxygen-rich, C/O$<$1.0. The C/O and carbon isotopic ratios...

  16. VizieR Online Data Catalog: SDSS bulge, disk and total stellar mass estimates (Mendel+, 2014)

    Science.gov (United States)

    Mendel, J. T.; Simard, L.; Palmer, M.; Ellison, S. L.; Patton, D. R.

    2014-01-01

    We present a catalog of bulge, disk, and total stellar mass estimates for ~660000 galaxies in the Legacy area of the Sloan Digital Sky Survey Data (SDSS) Release 7. These masses are based on a homogeneous catalog of g- and r-band photometry described by Simard et al. (2011, Cat. J/ApJS/196/11), which we extend here with bulge+disk and Sersic profile photometric decompositions in the SDSS u, i, and z bands. We discuss the methodology used to derive stellar masses from these data via fitting to broadband spectral energy distributions (SEDs), and show that the typical statistical uncertainty on total, bulge, and disk stellar mass is ~0.15 dex. Despite relatively small formal uncertainties, we argue that SED modeling assumptions, including the choice of synthesis model, extinction law, initial mass function, and details of stellar evolution likely contribute an additional 60% systematic uncertainty in any mass estimate based on broadband SED fitting. We discuss several approaches for identifying genuine bulge+disk systems based on both their statistical likelihood and an analysis of their one-dimensional surface-brightness profiles, and include these metrics in the catalogs. Estimates of the total, bulge and disk stellar masses for both normal and dust-free models and their uncertainties are made publicly available here. (4 data files).

  17. A CATALOG OF BULGE, DISK, AND TOTAL STELLAR MASS ESTIMATES FOR THE SLOAN DIGITAL SKY SURVEY

    International Nuclear Information System (INIS)

    We present a catalog of bulge, disk, and total stellar mass estimates for ∼660,000 galaxies in the Legacy area of the Sloan Digital Sky Survey Data (SDSS) Release 7. These masses are based on a homogeneous catalog of g- and r-band photometry described by Simard et al., which we extend here with bulge+disk and Sérsic profile photometric decompositions in the SDSS u, i, and z bands. We discuss the methodology used to derive stellar masses from these data via fitting to broadband spectral energy distributions (SEDs), and show that the typical statistical uncertainty on total, bulge, and disk stellar mass is ∼0.15 dex. Despite relatively small formal uncertainties, we argue that SED modeling assumptions, including the choice of synthesis model, extinction law, initial mass function, and details of stellar evolution likely contribute an additional 60% systematic uncertainty in any mass estimate based on broadband SED fitting. We discuss several approaches for identifying genuine bulge+disk systems based on both their statistical likelihood and an analysis of their one-dimensional surface-brightness profiles, and include these metrics in the catalogs. Estimates of the total, bulge and disk stellar masses for both normal and dust-free models and their uncertainties are made publicly available here

  18. Extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way.

    Science.gov (United States)

    Howes, L M; Casey, A R; Asplund, M; Keller, S C; Yong, D; Nataf, D M; Poleski, R; Lind, K; Kobayashi, C; Owen, C I; Ness, M; Bessell, M S; Da Costa, G S; Schmidt, B P; Tisserand, P; Udalski, A; Szymański, M K; Soszyński, I; Pietrzyński, G; Ulaczyk, K; Wyrzykowski, Ł; Pietrukowicz, P; Skowron, J; Kozłowski, S; Mróz, P

    2015-11-26

    The first stars are predicted to have formed within 200 million years after the Big Bang, initiating the cosmic dawn. A true first star has not yet been discovered, although stars with tiny amounts of elements heavier than helium ('metals') have been found in the outer regions ('halo') of the Milky Way. The first stars and their immediate successors should, however, preferentially be found today in the central regions ('bulges') of galaxies, because they formed in the largest over-densities that grew gravitationally with time. The Milky Way bulge underwent a rapid chemical enrichment during the first 1-2 billion years, leading to a dearth of early, metal-poor stars. Here we report observations of extremely metal-poor stars in the Milky Way bulge, including one star with an iron abundance about 10,000 times lower than the solar value without noticeable carbon enhancement. We confirm that most of the metal-poor bulge stars are on tight orbits around the Galactic Centre, rather than being halo stars passing through the bulge, as expected for stars formed at redshifts greater than 15. Their chemical compositions are in general similar to typical halo stars of the same metallicity although intriguing differences exist, including lower abundances of carbon. PMID:26560034

  19. Thermodynamic Stability of Wormholes

    CERN Document Server

    Sajadi, S N

    2016-01-01

    In the context of GR, we study the thermodynamic stability of evolving Lorentzian wormholes at the apparent horizon. The average pressure of the anisotrropic components is considered as the pressure of the wormhole. According to the requirements of stable equilibrium in conventional thermodynamics, we calculate the heat capacity at constant pressure and Gibbs free energy and analyze the local and global thermodynamic stability of the wormhole.

  20. The consequence of maximum thermodynamic efficiency in Daisyworld.

    Science.gov (United States)

    Pujol, Toni

    2002-07-01

    The imaginary planet of Daisyworld is the simplest model used to illustrate the implications of the Gaia hypothesis. The dynamics of daisies and their radiative interaction with the environment are described by fundamental equations of population ecology theory and physics. The parameterization of the turbulent energy flux between areas of different biological cover is similar to the diffusive-type approximation used in simple climate models. Here I show that the small variation of the planetary diffusivity adopted in the classical version of Daisyworld limits the range of values for the solar insolation for which biota may grow in the planet. Recent studies suggest that heat transport in a turbulent medium is constrained to maximize its efficiency. This condition is almost equivalent to maximizing the rate of entropy production due to non-radiative sources. Here, I apply the maximum entropy principle (MEP) to Daisyworld. I conclude that the MEP sets the maximum range of values for the solar insolation with a non-zero amount of daisies. Outside this range, daisies cannot grow in the planet for any physically realistic climate distribution. Inside this range, I assume a distribution of daisies in agreement with the MEP. The results substantially enlarge the range of climate stability, due to the biota, in comparison to the classical version of Daisyworld. A very stable temperature is found when two different species grow in the planet. PMID:12183130

  1. Methods of thermodynamics

    CERN Document Server

    Reiss, Howard

    1997-01-01

    Since there is no shortage of excellent general books on elementary thermodynamics, this book takes a different approach, focusing attention on the problem areas of understanding of concept and especially on the overwhelming but usually hidden role of ""constraints"" in thermodynamics, as well as on the lucid exposition of the significance, construction, and use (in the case of arbitrary systems) of the thermodynamic potential. It will be especially useful as an auxiliary text to be used along with any standard treatment.Unlike some texts, Methods of Thermodynamics does not use statistical m

  2. The geometry of thermodynamics

    CERN Document Server

    Quevedo, Hernando

    2007-01-01

    We present a review of the main aspects of geometrothermodynamics, an approach which allows us to associate a specific Riemannian structure to any classical thermodynamic system. In the space of equilibrium states, we consider a Legendre invariant metric, which is given in terms of the fundamental equation of the corresponding thermodynamic system, and analyze its geometric properties in the case of the van der Waals gas, and black holes. We conclude that the geometry of this particular metric reproduces the thermodynamic behavior of the van der Waals gas, and the Reissner-Nordstr\\"om black hole, but it is not adequate for the thermodynamic description of Kerr black holes.

  3. Thermodynamic nonextensivity in a closed string gas

    International Nuclear Information System (INIS)

    Well-known results in string thermodynamics show that there is always a negative specific heat phase in the microcanonical description of a gas of closed free strings whenever there are no winding modes present. We will carefully compute the number of strings in the gas to show how this negative specific heat is related to the fact that the system does not have thermodynamic extensivity. We will also discuss the consequences for a system of having a microcanonical negative specific heat versus the exact result that such a thing cannot happen in any canonical (fixed temperature) description

  4. Analysis of materials properties of niobium tube from the results of a virtual bulge test

    Science.gov (United States)

    Kim, H. S.; Sumption, Michael; Lim, H.; Collings, E. W.

    2012-06-01

    Hydroforming has been selected as a technique for the seamless fabrication of multicell superconducting radiofrequency (SRF) cavities. For the successful application of this technique to cavity fabrication, it is essential to understand deformation behavior of tubes under hydroforming conditions. Input to the finite-element modeling (FEM) which generally precedes the actual hydroforming process requires the constitutive properties of the tube material. This information may be obtained from the results of hydraulic bulge testing. The present paper provides an example of this activity. In order to verify the steps to be taken in analyzing future bulge-test data a circular argument recovers the original constitutive properties from the results of an FEM-based "virtual bulge test".

  5. Long-Lived Spiral Structure for Galaxies with Intermediate Size Bulges

    CERN Document Server

    Saha, Kanak

    2016-01-01

    Spiral structure in disk galaxies is modeled with nine collisionless N-body simulations including live disks, halos, and bulges with a range of masses. Two of these simulations make long-lasting and strong two-arm spiral wave modes that last for $\\sim5$ Gyr with constant pattern speed. These two had a light stellar disk and the largest values of the Toomre $Q$ parameter in the inner region at the time the spirals formed, suggesting the presence of a Q-barrier to wave propagation resulting from the bulge. The relative bulge mass in these cases is about 10\\%. Models with weak two-arm spirals had pattern speeds that followed the radial dependence of the Inner Lindblad Resonance.

  6. Discovery of Five New R. Coronae Borealis Stars in the MACHO Galactic Bulge Database

    Energy Technology Data Exchange (ETDEWEB)

    Zaniewshi, A; Clayton, G C; Welch, D; Gordon, K D; Minniti, D; Cook, K

    2005-06-16

    We have identified five new R Coronae Borealis (RCB) stars in the Galactic bulge using the MACHO Project photometry database, raising the total number of known Galactic RCB stars to about 40. We have obtained spectra to confirm the identifications. The fact that four out of the five newly identified RCB stars are ''cool'' (T{sub eff} < 6000 K) rather than ''warm'' (T{sub eff} > 6000 K) suggests that the preponderance of warm RCB stars among the existing sample is a selection bias. These cool RCB stars are redder and fainter than their warm counterparts and may have been missed in surveys done with blue plates. Based on the number of new RCB stars discovered in the MACHO bulge fields, there may be {approx}250 RCB stars in the reddened ''exclusion'' zone toward the bulge.

  7. The Controversial Star-Formation History and Helium Enrichment of the Milky Way Bulge

    CERN Document Server

    Nataf, David M

    2015-01-01

    The stellar population of the Milky Way bulge is thoroughly studied, with a plethora of measurements from virtually the full suite of instruments available to astronomers. It is thus perhaps surprising that alongside well-established results lies some substantial uncertainty in its star-formation history. Cosmological models predict the bulge to host the Galaxy's oldest stars for [Fe/H]$\\lesssim -1$, and this is demonstrated by RR Lyrae stars and globular cluster observations. There is consensus that bulge stars with [Fe/H]$\\lesssim0$ are older than $t \\approx10$ Gyr. However, at super-solar metallicity, there is a substantial unresolved discrepancy. Data from spectroscopic measurements of the main-sequence turnoff and subgiant branch, the abundances of asymptotic giant branch stars, the period distribution of Mira variables, the chemistry and central-star masses of planetary nebulae, all suggest a substantial intermediate-age population ($t \\approx 3$ Gyr). This is in conflict with predictions from cosmologi...

  8. Kinematics and abundances of K giants in the nuclear bulge of the Galaxy

    International Nuclear Information System (INIS)

    Radial velocities have been determined for 53 K giants in Baade's window, which belong to the nuclear bulge population and have abundances derived from low resolution spectra. Additional radial velocities for an overlapping sample of 71 bulge K giants show the same dependence of velocity dispersion on abundance; in both samples, the lower velocity dispersion of the metal-rich giants is found to be significant at a level above 90 percent. Extant data support the hypothesis that both M giants and IRAS bulge sources follow steep density laws similar to that which has been predicted for the metal-rick K giants. The abundance distribution of 88 K giants in Baade's window is noted to be notably well fitted by the simple, closed box model of chemical evolution. 85 refs

  9. Stellar Population Gradients in Bulges along the Hubble Sequence: I. The Data

    CERN Document Server

    Gorgas, J; Goudfrooij, P

    2007-01-01

    This is the first paper presenting our long-term project aimed at studying the nature of bulges through the analysis of their stellar population gradients. We present deep spectroscopic observations along the minor axis and the data reduction for a sample of 32 bulges of edge-on spiral galaxies. We explain in detail our procedures to measure their dynamical parameters (rotation curves and velocity dispersion profiles) and line-strength indices, including the conversion to the Lick/IDS system. Tables giving the values of the dynamical parameters and line-strength indices at each galactocentric radius are presented (in electronic form) for each galaxy of the sample. The derived line-strength gradients from this dataset will be analyzed in a forthcoming paper to set constraints on the different scenarios for the formation of the bulges.

  10. A Fossil Bulge Globular Cluster revealed by VLT Multi-Conjugate Adaptive Optics

    CERN Document Server

    Ortolani, Sergio; Momany, Yazan; Saviane, Ivo; Bica, Eduardo; Jilkova, Lucie; Salerno, Gustavo Malta; Jungwiert, Bruno

    2011-01-01

    The globular cluster HP1 is projected on the bulge, very close to the Galactic center. The Multi-Conjugate Adaptive Optics (MCAO) Demonstrator (MAD) at the Very Large Telescope (VLT) allowed to acquire high resolution deep images that, combined with first epoch New Technology Telescope (NTT) data, enabled to derive accurate proper motions. The cluster and bulge field stellar contents were disentangled by means of this process, and produced unprecedented definition in the color-magnitude diagrams for this cluster. The metallicity of [Fe/H] ~ -1.0 from previous spectroscopic analysis is confirmed, which together with an extended blue horizontal branch, imply an age older than the halo average. Orbit reconstruction results suggest that HP1 is spatially confined within the bulge.

  11. Red Variables in Globular Clusters: Comparison with the Bulge and the LMC

    CERN Document Server

    Matsunaga, N; Tanabé, T; Fukushi, H; Ita, Y

    2005-01-01

    We are conducting a project aimed at surveys and repeated observations of red variables (or long-period variables) in globular clusters. Using the IRSF/SIRIUS near-infrared facility located at South Africa, we are observing 145 globular clusters that are accessible from the site. In this contribution, we present our observations and preliminary results. We have discovered many red variables, especially in the Bulge region, whose memberships to the clusters remain to be confirmed. Using a sample of all red variables (both already known and newly discovered ones) in globular clusters except those projected to the Bulge region, we produce a log P-K diagram and compare it with those for the Bulge and the Large Magellanic Cloud. A prominent feature is that the bright part of overtone-pulsators' sequence (B+ and C') is absent.

  12. Red variables in globular clusters . Comparison with the Bulge and the LMC

    Science.gov (United States)

    Matsunaga, N.; Nakada, Y.; Tanabé, T.; Fukushi, H.; Ita, Y.

    We are conducting a project aimed at surveys and repeated observations of red variables (or long-period variables) in globular clusters. Using the IRSF/SIRIUS near-infrared facility located at South Africa, we are observing 145 globular clusters that are accessible from the site. In this contribution, we present our observations and preliminary results. We have discovered many red variables, especially in the Bulge region, whose memberships to the clusters remain to be confirmed. Using a sample of all red variables (both already known and newly discovered ones) in globular clusters except those projected to the Bulge region, we produce a log P-K diagram and compare it with those for the Bulge and the Large Magellanic Cloud. A prominent feature is that the bright part of overtone-pulsators' sequence (B+ and C\\prime) is absent. We discuss its implication on the evolution of red variables.

  13. Detached Red Giant Eclipsing Binary Twins: Rosetta Stones to the Galactic Bulge

    CERN Document Server

    Nataf, David M; Pinsonneault, Marc H

    2012-01-01

    We identify 34 highly-probable detached, red giant eclipsing binary pairs among 315 candidates in Devor's catalog of $\\sim$10,000 OGLE-II eclipsing binaries. We estimate that there should be at least 200 such systems in OGLE-III. We show that spectroscopic measurements of the metallicities and radial-velocity-derived masses of these systems would independently constrain both the age-metallicity and helium-metallicity relations of the Galactic Bulge, potentially breaking the age-helium degeneracy that currently limits our ability to characterize the Bulge stellar population. Mass and metallicity measurements alone would be sufficient to immediately validate or falsify recent claims about the age and helium abundance of the Bulge. A spectroscopic survey of these systems would constrain models of Milky Way assembly, as well as provide significant auxiliary science on research questions such as mass loss on the red giant branch. We discuss the theoretical uncertainties in stellar evolution models that would need ...

  14. BULGE AND CLUMP EVOLUTION IN HUBBLE ULTRA DEEP FIELD CLUMP CLUSTERS, CHAINS AND SPIRAL GALAXIES

    International Nuclear Information System (INIS)

    Clump clusters and chain galaxies in the Hubble Ultra Deep Field (UDF) are examined for bulges in Near-Infrared Camera Multi-Object Spectrometer images. Approximately 50% of the clump clusters and 30% of the chains have relatively red and massive clumps that could be young bulges. Magnitudes and colors are determined for these bulgelike objects and for the bulges in spiral galaxies, and for all of the prominent star formation clumps in these three galaxy types. The colors are fitted to population evolution models to determine the bulge and clump masses, ages, star formation rate decay times, and extinctions. The results indicate that bulgelike objects in clump clusters and chain galaxies have similar ages and two to five times larger masses compared to the star formation clumps, while the bulges in spirals have roughly six times larger ages and 20 to 30 times larger masses than the clumps. All systems appear to have an underlying red disk population. The masses of star-forming clumps are typically in a range from 107 to 108 M sun; their ages have a wide range around ∼102 Myr. Ages and extinctions both decrease with redshift. Star formation is probably the result of gravitational instabilities in the disk gas, in which case the large clump mass in the UDF is the result of a high gas velocity dispersion, 30 km s-1 or more, combined with a high gas mass column density, ∼100 M sun pc-2. Because clump clusters and chains dominate disk galaxies beyond z ∼ 1, the observations suggest that these types represent an early phase in the formation of modern spiral galaxies, when the bulge and inner disk formed.

  15. Mechanical problems of superplastic fill-forming bulge solved by one-dimensional tensile and two-dimensional free bulging constitutive equations

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Because of the strong structural sensitivity of superplasticity, the deformation rule must be affected by stress-state. It is necessary to prove whether one-dimensional tensile constitutive equation can be directly generalized to deal with the two-dimensional mechanical problems or not. In this paper, theoretical results of fill-forming bulge have been derived from both one-dimensional tensile and two-dimensional bulging constitutive equation with variable m value. By comparing theoretical analysis and experimental results made on typical superplastic alloy Zn-wt22%Al, it is shown that one-dimensional tensile constitutive equation cannot be directly generalized to deal with two-dimensional mechanical questions. A method to correct deviation between theoretical and experimental results is also proposed.

  16. Identification of a novel HIV-1 TAR RNA bulge binding protein.

    OpenAIRE

    B. Baker; Muckenthaler, M; Vives, E.; Blanchard, A.; Braddock, M; Nacken, W.; Kingsman, A J; Kingsman, S M

    1994-01-01

    The Tat protein binds to TAR RNA to stimulate the expression of the human immunodeficiency virus type 1 (HIV-1) genome. Tat is an 86 amino acid protein that contains a short region of basic residues (aa49-aa57) that are required for RNA binding and TAR is a 59 nucleotide stem-loop with a tripyrimidine bulge in the upper stem. TAR is located at the 5' end of all viral RNAs. In vitro, Tat specifically interacts with TAR by recognising the sequence of the bulge and upper stem, with no requiremen...

  17. The thermodynamic solar energy

    International Nuclear Information System (INIS)

    The thermodynamic solar energy is the technic in the whole aiming to transform the solar radiation energy in high temperature heat and then in mechanical energy by a thermodynamic cycle. These technic are most often at an experimental scale. This paper describes and analyzes the research programs developed in the advanced countries, since 1980. (A.L.B.)

  18. Heat and thermodynamics

    CERN Document Server

    Brewster, Hilary D

    2009-01-01

    Thermodynamics is an exciting and fascinating subject that deals with energy, which is essential for sustenance of life, and Thermodynamics has long been an essential part of Engineering Curricula all over the world. It has a broad application area ranging from Microscopic Organisms to common Household Appliances, Transportation Vehicles, and Power Generation Systems.

  19. Comparing the properties of the X-shaped bulges of NGC 4710 and the Milky Way with MUSE

    CERN Document Server

    Gonzalez, O A; Debattista, V P; Rejkuba, M; Valenti, E; Zoccali, M; Coccato, L; Minniti, D; Ness, M

    2016-01-01

    We used the new ESO VLT instrument MUSE to obtain spectral and imaging coverage of NGC 4710. The wide area and excellent sampling of the MUSE integral field spectrograph allows us to investigate the dynamical properties of the X-shaped bulge of NGC 4710 and compare it with the properties of the Milky Way's own X-shaped bulge. We measured the radial velocities, velocity dispersion, and stellar populations using a penalized pixel full spectral fitting technique adopting simple stellar populations models, on a 1' x 1' area centred on the bulge of NGC 4710. We have constructed the velocity maps of the bulge of NGC 4710 and we investigated the presence of vertical metallicity gradients. These properties were compared to those of the Milky Way bulge and as well as to a simulated galaxy with boxy/peanut bulge. We find the line-of-sight velocity maps and 1D rotation curves of the bulge of NGC 4710 to be remarkably similar to those of the Milky Way bulge. Some specific differences that were identified are in good agre...

  20. Applied chemical engineering thermodynamics

    CERN Document Server

    Tassios, Dimitrios P

    1993-01-01

    Applied Chemical Engineering Thermodynamics provides the undergraduate and graduate student of chemical engineering with the basic knowledge, the methodology and the references he needs to apply it in industrial practice. Thus, in addition to the classical topics of the laws of thermodynamics,pure component and mixture thermodynamic properties as well as phase and chemical equilibria the reader will find: - history of thermodynamics - energy conservation - internmolecular forces and molecular thermodynamics - cubic equations of state - statistical mechanics. A great number of calculated problems with solutions and an appendix with numerous tables of numbers of practical importance are extremely helpful for applied calculations. The computer programs on the included disk help the student to become familiar with the typical methods used in industry for volumetric and vapor-liquid equilibria calculations.

  1. Thermodynamics an engineering approach

    CERN Document Server

    Cengel, Yunus A

    2014-01-01

    Thermodynamics, An Engineering Approach, eighth edition, covers the basic principles of thermodynamics while presenting a wealth of real-world engineering examples so students get a feel for how thermodynamics is applied in engineering practice. This text helps students develop an intuitive understanding by emphasizing the physics and physical arguments. Cengel and Boles explore the various facets of thermodynamics through careful explanations of concepts and use of numerous practical examples and figures, having students develop necessary skills to bridge the gap between knowledge and the confidence to properly apply their knowledge. McGraw-Hill is proud to offer Connect with the eighth edition of Cengel/Boles, Thermodynamics, An Engineering Approach. This innovative and powerful new system helps your students learn more efficiently and gives you the ability to assign homework problems simply and easily. Problems are graded automatically, and the results are recorded immediately. Track individual stude...

  2. Thermodynamics of complexity

    DEFF Research Database (Denmark)

    Westerhoff, Hans V.; Jensen, Peter Ruhdal; Snoep, Jacky L.

    1998-01-01

    Thermodynamics has always been a remarkable science in that it studies macroscopic properties that are only partially determined by the properties of individual molecules. Entropy and free energy only exist in constellations of more than a single molecule (degree of freedom). They are the so...... state, For a true understanding of this BioComplexity, modem thermodynamic concepts and methods (nonequilibrium thermodynamics, metabolic and hierarchical control analysis) will be needed. We shall propose to redefine nonequilibrium thermodynamics as: The science that aims at understanding the behaviour...... of nonequilibrium systems by taking into account both the molecular properties and the emergent properties that are due to (dys)organisation. This redefinition will free nonequilibrium thermodynamics from the limitations imposed by earlier near-equilibrium assumptions, resolve the duality with...

  3. Bulge mass is king: The dominant role of the bulge in determining the fraction of passive galaxies in the Sloan Digital Sky Survey

    CERN Document Server

    Bluck, Asa F L; Ellison, Sara L; Moreno, Jorge; Simard, Luc; Patton, David R; Starkenburg, Else

    2014-01-01

    We investigate the origin of galaxy bimodality by quantifying the relative role of intrinsic and environmental drivers to the cessation (or `quenching') of star formation in over half a million local Sloan Digital Sky Survey (SDSS) galaxies. Our sample contains a wide variety of galaxies at z=0.02-0.2, with stellar masses of 8 < log(M*/M_sun) < 12, spanning the entire morphological range from pure disks to spheroids, and over four orders of magnitude in local galaxy density and halo mass. We utilise published star formation rates and add to this recent GIM2D photometric and stellar mass bulge + disk decompositions from our group. We find that the passive fraction of galaxies increases steeply with stellar mass, halo mass, and bulge mass, with a less steep dependence on local galaxy density and bulge-to-total stellar mass ratio (B/T). At fixed internal properties, we find that central and satellite galaxies have different passive fraction relationships. For centrals, we conclude that there is less variat...

  4. The Thermodynamics of General and Local Anesthesia

    Science.gov (United States)

    Græsbøll, Kaare; Sasse-Middelhoff, Henrike; Heimburg, Thomas

    2014-05-01

    General anesthetics are known to cause depression of the freezing point of transitions in biomembranes. This is a consequence of ideal mixing of the anesthetic drugs in the membrane fluid phase and exclusion from the solid phase. Such a generic law provides physical justification of the famous Meyer-Overton rule. We show here that general anesthetics, barbiturates and local anesthetics all display the same effect on melting transitions. Their effect is reversed by hydrostatic pressure. Thus, the thermodynamic behavior of local anesthetics is very similar to that of general anesthetics. We present a detailed thermodynamic analysis of heat capacity profiles of membranes in the presence of anesthetics. This analysis is able to describe experimentally observed calorimetric profiles and permits prediction of the anesthetic features of arbitrary molecules. In addition, we discuss the thermodynamic origin of the cutoff-effect of long-chain alcohols and the additivity of the effect of general and local anesthetics.

  5. The thermodynamics of general and local anesthesia

    CERN Document Server

    Graesboll, Kaare; Heimburg, Thomas

    2014-01-01

    General anesthetics are known to cause depression of the freezing point of transitions in biomembranes. This is a consequence of ideal mixing of the anesthetic drugs in the membrane fluid phase and exclusion from the solid phase. Such a generic law provides physical justification of the famous Meyer-Overton rule. We show here that general anesthetics, barbiturates and local anesthetics all display the same effect on melting transitions. Their effect is reversed by hydrostatic pressure. Thus, the thermodynamic behavior of local anesthetics is very similar to that of general anesthetics. We present a detailed thermodynamic analysis of heat capacity profiles of membranes in the presence of anesthetics. This analysis is able to describe experimentally observed calorimetric profiles and permits prediction of the anesthetic features of arbitrary molecules. In addition, we discuss the thermodynamic origin of the cutoff-effect of long-chain alcohols and the additivity of the effect of general and local anesthetics.

  6. Kinetics of bulge bases in small RNAs and the effect of pressure on it.

    Science.gov (United States)

    Kumar, Pradeep; Lehmann, Jean; Libchaber, Albert

    2012-01-01

    Due to their self-catalytic properties, small RNAs with bulge bases are hypothesized to be primordial molecules which could form elementary translation systems. Using molecular dynamics simulations, we study the binding propensity of small RNAs by calculating the free energy barrier corresponding to the looped out conformations of bulge bases, which presumably act as the binding sites for ligands in these small RNAs. We find that base flipping kinetics can proceed at atmospheric pressure but with a very small propensity. Furthermore, the free energy barrier associated with base flipping depends on the stacking with neighboring bases. Next, we studied the base flipping kinetics with pressure. We find that the free energy associated with base looping out increases monotonically as the pressure is increased. Furthermore, we calculate the mean first-passage time of conformational looping out of the bulge base using the diffusion of reaction coordinate associated with the base flipping on the underlying free energy surface. We find that the mean first-passage time associated with bulge looping out increases slowly upon increasing pressures P up to 2000 atm but changes dramatically for P>2000 atm. Finally, we discuss our results in the light of the role of hydration shell of water around RNA. Our results are relevant for the RNA world hypothesis. PMID:22916118

  7. Finite Element Analysis of Bulge Forming of Laser Welding Dimple Jacket

    Directory of Open Access Journals (Sweden)

    Peisi ZHONG

    2015-11-01

    Full Text Available The stress-strain states of the model of laser welded dimple jacket is analyzed using ANSYS/LS-DYNA in order to determine the relation between bulging height and pressure and to achieve the controllability of pressure distension of the jacket. It is shown that in the same conditions, the bulging height increases with the increasing of the bulging pressure and the space of honeycomb. And it will decrease when the thickness of jacket plate changing larger. A table showing the relation between bulging height and pressure is obtained. An experiment using a test panel is conducted to certify the reliability of finite element analysis. It turns out that the data of finite element analysis is coincident with experimental data, which support finite element method based ANSYS/LS-DYNA can be an efficient way to research the laser welded dimple jacket. The relation table is useful as guidance for the fabrication process.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9704

  8. Bulge Formation by the Coalescence of Giant Clumps in Primordial Disk Galaxies

    CERN Document Server

    Elmegreen, Bruce G; Elmegreen, Debra Meloy

    2008-01-01

    Gas-rich disks in the early universe are highly turbulent and have giant star-forming clumps. Models suggest the clumps form by gravitational instabilities, and if they resist disruption by star formation, then they interact, lose angular momentum, and migrate to the center to form a bulge. Here we study the properties of the bulges formed by this mechanism. They are all thick, slowly rotating, and have a high Sersic index, like classical bulges. Their rapid formation should also give them relatively high alpha-element abundances. We consider fourteen low-resolution models and four high-resolution models, three of which have supernova feedback. All models have an active halo, stellar disk, and gaseous disk, three of the models have a pre-existing bulge and three others have a cuspy dark matter halo. All show the same basic result except the one with the highest feedback, in which the clumps are quickly destroyed and the disk thickens too much. The coalescence of massive disk clumps in the center of a galaxy i...

  9. The growth of galactic bulges through mergers in LCDM haloes revisited. I. Present-day properties

    CERN Document Server

    Zavala, Jesus; Firmani, Claudio; Boylan-Kolchin, Michael

    2012-01-01

    (Abridged) We use the combined data-sets of the Millennium I and II N-body cosmological simulations to revisit the impact of mergers in the growth of bulges in central galaxies in the LCDM scenario. To do so, we seed galaxies within the growing CDM haloes at each epoch using empirical relations to assign stellar and gaseous masses, and an analytical treatment to estimate the transfer of stellar mass to the bulge after a galaxy merger. Our results show that this model roughly reproduces the observed correlation between the bulge-to-total (B/T) mass ratio and stellar mass in present-day central galaxies as well as their observed demographics, although low-mass B/T < 0.1 (bulgeless) galaxies might be scarce relative to the observed abundance. In our merger-driven scenario, bulges have a composite stellar population made of (i) stars acquired from infalling satellites, (ii) stars transferred from the primary disc due to the strong merger-induced perturbations, and (iii) newly formed stars in starbursts trigger...

  10. Light, Alpha, and Fe-Peak Element Abundances in the Galactic Bulge

    CERN Document Server

    Johnson, Christian I; Kobayashi, Chiaki; Kunder, Andrea; Koch, Andreas

    2014-01-01

    We present radial velocities and chemical abundances of O, Na, Mg, Al, Si, Ca, Cr, Fe, Co, Ni, and Cu for a sample of 156 red giant branch stars in two Galactic bulge fields centered near (l,b)=(+5.25,-3.02) and (0,-12). The (+5.25,-3.02) field also includes observations of the bulge globular cluster NGC 6553. The results are based on high resolution (R~20,000), high signal-to-noise (S/N>70) FLAMES-GIRAFFE spectra obtained through the ESO archive. However, we only selected a subset of the original observations that included spectra with both high S/N and that did not show strong TiO absorption bands. The present work extends previous analyses of this data set beyond Fe and the alpha-elements Mg, Si, Ca, and Ti. While we find reasonable agreement with past work, the data presented here indicate that the bulge may exhibit a different chemical composition than the local thick disk, especially at [Fe/H]>-0.5. In particular, the bulge [alpha/Fe] ratios may remain enhanced to a slightly higher [Fe/H] than the thick...

  11. What planetary nebulae tell us about helium and the CNO elements in Galactic bulge stars

    CERN Document Server

    Buell, James F

    2012-01-01

    Thermally pulsing asymptotic giant branch (TP-AGB) models of bulge stars are calculated using a synthetic model. The goal is to infer typical progenitor masses and compositions by reproducing the typical chemical composition and central star masses of planetary nebulae (PNe) in the Galactic bulge. The AGB tip luminosity and the observation that the observed lack of bright carbon stars in the bulge are matched by the models. Five sets of galactic bulge PNe were analyzed to find typical abundances and central star of planetary nebulae (CSPN) masses. These global parameters were matched by the AGB models. These sets are shown to be consistent with the most massive CSPN having the largest abundances of helium and heavy elements. The CSPN masses of the most helium rich (He/H$\\ga$0.130 or $Y\\ga0.34$) PNe are estimated to be between 0.58 and 0.62$ {\\rm M}_{\\sun}$. The oxygen abundance in form $\\log{\\rm (O/H)}+12$ of these highest mass CSPN is estimated to be $\\approx$8.85. TP-AGB models with ZAMS masses between 1.2 ...

  12. The growth of galactic bulges through mergers in LCDM haloes revisited. II. Morphological mix evolution

    CERN Document Server

    Avila-Reese, Vladimir; Lacerna, Ivan

    2013-01-01

    The mass aggregation and merger histories of present-day distinct haloes selected from the cosmological Millennium Simulations I and II are mapped into stellar mass aggregation and galaxy merger histories of central galaxies by using empirical stellar-to-halo and stellar-to-gas mass relations. The growth of bulges driven by the galaxy mergers/interactions is calculated using analytical recipes. The predicted bulge demographics at redshift z~0 is consistent with observations (Zavala+2012). Here we present the evolution of the morphological mix (traced by the bulge-to-total mass ratio, B/T) as a function of mass up to z=3. This mix remains qualitatively the same up to z~1: B/T0.45 at large masses. At z>1, the fractions of disc-dominated and bulgeless galaxies increase strongly, and by z~2 the era of pure disc galaxies is reached. Bulge-dominated galaxies acquire such a morphology, and most of their mass, following a downsizing trend. Since our results are consistent with several recent observational studies of ...

  13. The Age and Structure of the Galactic Bulge from Mira Variables

    CERN Document Server

    Catchpole, Robin M; Feast, Michael W; Hughes, Shaun M G; Irwin, Mike; Alard, Christophe

    2015-01-01

    We report periods and JHKL observations for 648 oxygen-rich Mira variables found in two outer bulge fields at b=-7 degrees and l=+/-8 degrees and combine these with data on 8057 inner bulge Miras from the OGLE, Macho and 2MASS surveys, which are concentrated closer to the Galactic centre. Distance moduli are estimated for all these stars. Evidence is given showing that the bulge structure is a function of age. The longer period Miras (log P > 2.6, age about 5 Gyr and younger) show clear evidence of a bar structure inclined to the line of sight in both the inner and outer regions. The distribution of the shorter period (metal-rich globular cluster age) Miras, appears spheroidal in the outer bulge. In the inner region these old stars are also distributed differently from the younger ones and possibly suggest a more complex structure. These data suggest a distance to the Galactic centre, R0, of 8.9 kpc with an estimated uncertainty of 0.4 kpc. The possible effect of helium enrichment on our conclusions is discus...

  14. The Gaia-ESO survey: Metal-rich bananas in the bulge

    CERN Document Server

    Williams, Angus A; Molloy, Matthew; Kordopatis, Georges; Smith, M C; Shen, J; Gilmore, G; Randich, S; Bensby, T; Francois, P; Koposov, S E; Recio-Blanco, A; Bayo, A; Carraro, G; Casey, A; Costado, T; Franciosini, E; Hourihane, A; de Laverny, P; Lewis, J; Lind, K; Magrini, L; Monaco, L; Morbidelli, L; Sacco, G G; Worley, C; Zaggia, S; Mikolaitis, S

    2016-01-01

    We analyse the kinematics of $\\sim 2000$ giant stars in the direction of the Galactic bulge, extracted from the Gaia-ESO survey in the region $-10^\\circ \\lesssim \\ell \\lesssim 10^\\circ$ and $-11^\\circ \\lesssim b \\lesssim -3^\\circ$. We find distinct kinematic trends in the metal rich ($\\mathrm{[M/H]}>0$) and metal poor ($\\mathrm{[M/H]}<0$) stars in the data. The velocity dispersion of the metal-rich stars drops steeply with latitude, compared to a flat profile in the metal-poor stars, as has been seen previously. We argue that the metal-rich stars in this region are mostly on orbits that support the boxy-peanut shape of the bulge, which naturally explains the drop in their velocity dispersion profile with latitude. The metal rich stars also exhibit peaky features in their line-of-sight velocity histograms, particularly along the minor axis of the bulge. We propose that these features are due to stars on resonant orbits supporting the boxy-peanut bulge. This conjecture is strengthened through the comparison ...

  15. Peanuts, brezels and bananas: food for thought on the orbital structure of the Galactic bulge

    CERN Document Server

    Portail, M; Gerhard, O

    2015-01-01

    Recent observations have discovered the presence of a Box/Peanut or X-shape structure in the Galactic bulge. Such Box/Peanut structures are common in external disc galaxies, and are well-known in N-body simulations where they form following the buckling instability of a bar. From studies of analytical potentials and N-body models it has been claimed in the past that Box/Peanut bulges are supported by "bananas", or x1v1 orbits. We present here a set of N-body models where instead the peanut bulge is mainly supported by brezel-like orbits, allowing strong peanuts to form with short extent relative to the bar length. This shows that stars in the X-shape do not necessarily stream along banana orbits which follow the arms of the X-shape. The brezel orbits are also found to be the main orbital component supporting the peanut shape in our recent Made-to-Measure dynamical models of the Galactic bulge. We also show that in these models the fraction of stellar orbits that contribute to the X-structure account for 40-45...

  16. The Gaia-ESO Survey: Metal-rich Bananas in the Bulge

    Science.gov (United States)

    Williams, Angus A.; Evans, N. W.; Molloy, Matthew; Kordopatis, Georges; Smith, M. C.; Shen, J.; Gilmore, G.; Randich, S.; Bensby, T.; Francois, P.; Koposov, S. E.; Recio-Blanco, A.; Bayo, A.; Carraro, G.; Casey, A.; Costado, T.; Franciosini, E.; Hourihane, A.; de Laverny, P.; Lewis, J.; Lind, K.; Magrini, L.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Worley, C.; Zaggia, S.; Mikolaitis, Š.

    2016-06-01

    We analyze the kinematics of ˜2000 giant stars in the direction of the Galactic bulge, extracted from the Gaia-ESO survey in the region -10^\\circ ≲ {\\ell }≲ 10^\\circ and -11^\\circ ≲ b≲ -3^\\circ . We find distinct kinematic trends in the metal-rich ([{{M}}/{{H}}]\\gt 0) and metal-poor ([{{M}}/{{H}}]\\lt 0) stars in the data. The velocity dispersion of the metal-rich stars drops steeply with latitude, compared to a flat profile in the metal-poor stars, as has been seen previously. We argue that the metal-rich stars in this region are mostly on orbits that support the boxy–peanut shape of the bulge, which naturally explains the drop in their velocity dispersion profile with latitude. The metal-rich stars also exhibit peaky features in their line of sight velocity histograms, particularly along the minor axis of the bulge. We propose that these features are due to stars on resonant orbits supporting the boxy–peanut bulge. This conjecture is strengthened through the comparison of the minor axis data with the velocity histograms of resonant orbits generated in simulations of buckled bars. The “banana” or 2:1:2 orbits provide strongly bimodal histograms with narrow velocity peaks that resemble the Gaia-ESO metal-rich data.

  17. Pixel Lensing Search For Bright Microlensing Events and Variables in the Galactic Bulge

    CERN Document Server

    Gould, A; Gould, Andrew

    1997-01-01

    We describe a new method to search for gravitational microlensing toward the Galactic bulge that employs a small camera rather than a conventional telescope and probes new regions of parameter space. The small aperture (~65 mm) permits detection of stellar flux variations corresponding to magnitudes 715. The large pixel size (~10") and ~(6 deg)^2 field of view allows observation of the entire bulge with a few pointings. With this large pixel size (and with the even larger 30" PSF that we advocate) most bulge stars are unresolved, so one is in the regime of pixel lensing: microlensing and other forms of stellar variation are detected from the difference of pixel counts in successive images. We identify three principal uses of such a search. First, the observations are analogous to normal pixel lensing observations of the bulge of M31, but are carried out under conditions where the detected events can be followed up in detail. This permits crucial checks on the systematics of the M31 searches. Second, the searc...

  18. Mapping the outer bulge with RRab stars from the VVV Survey

    CERN Document Server

    Gran, F; Saito, R K; Zoccali, M; Gonzalez, O A; Navarrete, C; Catelan, M; Ramos, R Contreras; Elorrieta, F; Eyheramendy, S; Jordán, A

    2016-01-01

    The VISTA Variables in the V\\'ia L\\'actea (VVV) is a near-IR time-domain survey of the Galactic bulge and southern plane. One of the main goals of this survey is to reveal the 3D structure of the Milky Way through their variable stars. Particularly the RR Lyrae stars have been massively discovered in the inner regions of the bulge ($-8^\\circ \\lesssim b \\lesssim -1^\\circ$) by optical surveys such as OGLE and MACHO but leaving an unexplored window of more than $\\sim 47$ sq deg ($-10.0^\\circ \\lesssim \\ell \\lesssim +10.7^\\circ$ and $-10.3^\\circ \\lesssim b \\lesssim -8.0^\\circ$) observed by the VVV Survey. Our goal is to characterize the RR Lyrae stars in the outer bulge in terms of their periods, amplitudes, Fourier coefficients, and distances, in order to evaluate the 3D structure of the bulge in this area. The distance distribution of RR Lyrae stars will be compared to the one of red clump stars that is known to trace a X-shaped structure in order to determine if these two different stellar populations share the...

  19. Stellar density profile and mass of the Milky Way Bulge from VVV data

    CERN Document Server

    Valenti, E; Gonzalez, O A; Minniti, D; Alonso-Garcia, J; Marchetti, E; Hempel, M; Renzini, A; Rejkuba, M

    2015-01-01

    We present the first stellar density profile of the Milky Way bulge reaching latitude $b=0^\\circ$. It is derived by counting red clump stars within the colour\\--magnitude diagram constructed with the new PSF-fitting photometry from VISTA Variables in the V\\'\\i a L\\'actea (VVV) survey data. The new stellar density map covers the area between $|l|\\leq 10^\\circ$ and $|b|\\leq 4.5^\\circ$ with unprecedented accuracy, allowing to establish a direct link between the stellar kinematics from the Giraffe Inner Bulge Spectroscopic Survey (GIBS) and the stellar mass density distribution. In particular, the location of the central velocity dispersion peak from GIBS matches a high overdensity in the VVV star count map. By scaling the total luminosity function (LF) obtained from all VVV fields to the LF from Zoccali et al.(2003), we obtain the first fully empirical estimate of the mass in stars and remnants of the Galactic bulge. The Milky Way bulge stellar mass within ($|b|<9.5^\\circ$, $|l|<10^\\circ$) is $2.0\\pm0.3\\ti...

  20. A two-phase scenario for bulge assembly in LCDM cosmologies

    CERN Document Server

    Obreja, A; Brook, C; Martínez-Serrano, F J; Doménech-Moral, M; Serna, A; Mollá, M; Stinson, G

    2012-01-01

    We analyze and compare the bulges of a sample of L* spiral galaxies in hydrodynamical simulations in a cosmological context, using two different codes, P-DEVA and GASOLINE. The codes regulate star formation in very different ways, with P-DEVA simulations inputing low star formation efficiency under the assumption that feedback occurs on subgrid scales, while the GASOLINE simulations have feedback which drives large scale outflows. In all cases, the marked knee-shape in mass aggregation tracks, corresponding to the transition from an early phase of rapid mass assembly to a later slower one, separates the properties of two populations within the simulated bulges. The bulges analyzed show an important early starburst resulting from the collapse-like fast phase of mass assembly, followed by a second phase with lower star formation, driven by a variety of processes such as disk instabilities and/or mergers. Classifying bulge stellar particles identified at z=0 into old and young according to these two phases, we f...

  1. Longitude distribution of bulge M giants - the mass and large-scale structure of the spheroid

    International Nuclear Information System (INIS)

    Star counts obtained from a survey of late-type giants along b = -6 deg confirm the extreme rarity of carbon stars relative to M giants in the bulge and the large excess of M stars near the galactic meridian over that expected from the disk. The results constrain the axial ratio of the bulge to between 0.6 and 0.8, and suggest that the usual representation of the spheroid using an R exp 1/4 law with an effective radius of 1/3 solar radius is inadequate to explain the large stellar density in the bulge. A simple mass model of the Galaxy and an observationally determined M/L ratio are used to determine the external appearance of the galactic spheroid. The absolute magnitude of the spheroid is found to be -20.3 + or - 0.3. The luminosity and size of the galactic bulge indicate that the Milky Way may be closer in morphology to NGC 4565 than to M31. 83 refs

  2. Zinc abundances in Galactic bulge field red giants: implications for DLA systems

    CERN Document Server

    Barbuy, B; da Silveira, C R; Hill, V; Zoccali, M; Minniti, D; Renzini, A; Ortolani, S; Gomez, A

    2015-01-01

    Zinc in stars is an important reference element because it is a proxy to Fe in studies of damped Lyman-alpha systems, permitting a comparison of chemical evolution histories of bulge stellar populations and DLAs. In terms of nucleosynthesis, it behaves as an alpha element because it is enhanced in metal-poor stars. The aim of this work is to derive the iron-peak element Zn abundances in 56 bulge giants from high resolution spectra. These results are compared with data from other bulge samples, as well as from disk and halo stars, and damped Lyman-alpha systems, in order to better understand the chemical evolution in these environments. High-resolution spectra were obtained using FLAMES+UVES on the Very Large Telescope. We find [Zn/Fe]=+0.24+-0.02 in the range -1.3 -0.1, it shows a spread of -0.60 < [Zn/Fe] < +0.15, with most of these stars having low [Zn/Fe]<0.0. These low zinc abundances at the high metallicity end of the bulge define a decreasing trend in [Zn/Fe] with increasing metallicities. A c...

  3. The Gaia-ESO Survey: Metal-rich Bananas in the Bulge

    Science.gov (United States)

    Williams, Angus A.; Evans, N. W.; Molloy, Matthew; Kordopatis, Georges; Smith, M. C.; Shen, J.; Gilmore, G.; Randich, S.; Bensby, T.; Francois, P.; Koposov, S. E.; Recio-Blanco, A.; Bayo, A.; Carraro, G.; Casey, A.; Costado, T.; Franciosini, E.; Hourihane, A.; de Laverny, P.; Lewis, J.; Lind, K.; Magrini, L.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Worley, C.; Zaggia, S.; Mikolaitis, Š.

    2016-06-01

    We analyze the kinematics of ∼2000 giant stars in the direction of the Galactic bulge, extracted from the Gaia-ESO survey in the region -10^\\circ ≲ {\\ell }≲ 10^\\circ and -11^\\circ ≲ b≲ -3^\\circ . We find distinct kinematic trends in the metal-rich ([{{M}}/{{H}}]\\gt 0) and metal-poor ([{{M}}/{{H}}]\\lt 0) stars in the data. The velocity dispersion of the metal-rich stars drops steeply with latitude, compared to a flat profile in the metal-poor stars, as has been seen previously. We argue that the metal-rich stars in this region are mostly on orbits that support the boxy–peanut shape of the bulge, which naturally explains the drop in their velocity dispersion profile with latitude. The metal-rich stars also exhibit peaky features in their line of sight velocity histograms, particularly along the minor axis of the bulge. We propose that these features are due to stars on resonant orbits supporting the boxy–peanut bulge. This conjecture is strengthened through the comparison of the minor axis data with the velocity histograms of resonant orbits generated in simulations of buckled bars. The “banana” or 2:1:2 orbits provide strongly bimodal histograms with narrow velocity peaks that resemble the Gaia-ESO metal-rich data.

  4. COSMIC-LAB: Terzan 5 as a fossil remnant of the Galactic bulge formation epoch

    CERN Document Server

    Massari, Davide

    2014-01-01

    The formation and evolution of galaxy bulges is one of the most debated topics in the modern astrophysics. One approach to address this issue is to look at the Galactic bulge since it is the closest. According to some theoretical models, our bulge may have built up from the merger of substructures formed from the fragmentation of a gaseous disk in the early phases of Galactic evolution. We may have discovered the remnant of one of these substructures in the stellar system Terzan 5. In fact, Terzan 5 hosts two stellar populations with quite different iron abundances, thus suggesting it once was far more massive than today. Moreover, its peculiar chemistry strikingly resembles that observed in the Galactic bulge. In this Thesis we performed a detailed photometric and spectroscopic analysis of this cluster to determine its formation and evolution. Form the photometric point of view we built a high-resolution differential reddening map in the direction of the system and we measured relative proper motions to sepa...

  5. Extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way

    CERN Document Server

    Howes, L M; Asplund, M; Keller, S C; Yong, D; Nataf, D M; Poleski, R; Lind, K; Kobayashi, C; Owen, C I; Ness, M; Bessell, M S; Da Costa, G S; Schmidt, B P; Tisserand, P; Udalski, A; Szymański, M K; Soszyński, I; Pietrzyński, G; Ulaczyk, K; Wyrzykowski, Ł; Pietrukowicz, P; Skowron, J; Kozłowski, S; Mróz, P

    2015-01-01

    The first stars are predicted to have formed within 200 million years after the Big Bang, initiating the cosmic dawn. A true first star has not yet been discovered, although stars with tiny amounts of elements heavier than helium ('metals') have been found in the outer regions ('halo') of the Milky Way. The first stars and their immediate successors should, however, preferentially be found today in the central regions ('bulges') of galaxies, because they formed in the largest over-densities that grew gravitationally with time. The Milky Way bulge underwent a rapid chemical enrichment during the first 1-2 billion years, leading to a dearth of early, metal-poor stars. Here we report observations of extremely metal-poor stars in the Milky Way bulge, including one star with an iron abundance about 10,000 times lower than the solar value without noticeable carbon enhancement. We confirm that the most metal-poor bulge stars are on tight orbits around the Galactic Centre, rather than being halo stars passing through...

  6. Dynamical Modelling of the Galactic Bulge and Bar: Pattern Speed, Stellar, and Dark Matter Mass Distributions

    CERN Document Server

    Portail, Matthieu; Wegg, Christopher; Ness, Melissa

    2016-01-01

    We construct a large set of dynamical models of the galactic bulge, bar and inner disk using the Made-to-Measure method. Our models are constrained to match the red clump giant density from a combination of the VVV, UKIDSS and 2MASS infrared surveys together with stellar kinematics in the bulge from the BRAVA and OGLE surveys, and in the entire bar region from the ARGOS survey. We are able to recover the bar pattern speed and the stellar and dark matter mass distributions in the bar region, thus recovering the entire galactic effective potential. We find a bar pattern speed of $39.0 \\pm 3.5 \\,\\rm{km\\,s^{-1}\\,kpc^{-1}}$, placing the bar corotation radius at $6.1 \\pm 0.5 \\, \\rm{kpc}$ and making the Milky Way bar a typical fast rotator. We evaluate the stellar mass of the long bar and bulge structure to be $M_{\\rm{bar/bulge}} = 1.88 \\pm 0.12 \\times 10^{10} \\, \\rm{M}_{\\odot}$, larger than the mass of disk in the bar region, $M_{\\rm{inner\\ disk}} = 1.29\\pm0.12 \\times 10^{10} \\, \\rm{M}_{\\odot}$. The total dynamical...

  7. Thermodynamics I essentials

    CERN Document Server

    REA, The Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Thermodynamics I includes review of properties and states of a pure substance, work and heat, energy and the first law of thermodynamics, entropy and the second law of thermodynamics

  8. Advanced thermodynamics engineering

    CERN Document Server

    Annamalai, Kalyan; Jog, Milind A

    2011-01-01

    Thermolab Excel-Based Software for Thermodynamic Properties and Flame Temperatures of Fuels IntroductionImportance, Significance and LimitationsReview of ThermodynamicsMathematical BackgroundOverview of Microscopic/NanothermodynamicsSummaryAppendix: Stokes and Gauss Theorems First Law of ThermodynamicsZeroth LawFirst Law for a Closed SystemQuasi Equilibrium (QE) and Nonquasi-equilibrium (NQE) ProcessesEnthalpy and First LawAdiabatic Reversible Process for Ideal Gas with Constant Specific HeatsFirst Law for an Open SystemApplications of First Law for an Open SystemIntegral and Differential Form

  9. Modern engineering thermodynamics

    CERN Document Server

    Balmer, Robert T

    2010-01-01

    Designed for use in a standard two-semester engineering thermodynamics course sequence. The first half of the text contains material suitable for a basic Thermodynamics course taken by engineers from all majors. The second half of the text is suitable for an Applied Thermodynamics course in mechanical engineering programs. The text has numerous features that are unique among engineering textbooks, including historical vignettes, critical thinking boxes, and case studies. All are designed to bring real engineering applications into a subject that can be somewhat abstract and mathematica

  10. Thermodynamics of quantum strings

    CERN Document Server

    Morgan, M J

    1994-01-01

    A statistical mechanical analysis of an ideal gas of non-relativistic quantum strings is presented, in which the thermodynamic properties of the string gas are calculated from a canonical partition function. This toy model enables students to gain insight into the thermodynamics of a simple 'quantum field' theory, and provides a useful pedagogical introduction to the more complicated relativistic string theories. A review is also given of the thermodynamics of the open bosonic string gas and the type I (open) superstring gas. (author)

  11. Non-equilibrium thermodynamics

    CERN Document Server

    Groot, S R De

    2011-01-01

    The study of thermodynamics is especially timely today, as its concepts are being applied to problems in biology, biochemistry, electrochemistry, and engineering. This book treats irreversible processes and phenomena - non-equilibrium thermodynamics.S. R. de Groot and P. Mazur, Professors of Theoretical Physics, present a comprehensive and insightful survey of the foundations of the field, providing the only complete discussion of the fluctuating linear theory of irreversible thermodynamics. The application covers a wide range of topics: the theory of diffusion and heat conduction, fluid dyn

  12. Light, alpha, and Fe-peak element abundances in the galactic bulge

    International Nuclear Information System (INIS)

    We present radial velocities and chemical abundances of O, Na, Mg, Al, Si, Ca, Cr, Fe, Co, Ni, and Cu for a sample of 156 red giant branch stars in two Galactic bulge fields centered near (l, b) = (+5.25,–3.02) and (0,–12). The (+5.25,–3.02) field also includes observations of the bulge globular cluster NGC 6553. The results are based on high-resolution (R ∼ 20,000), high signal-to-noise ration (S/N ≳ 70) FLAMES-GIRAFFE spectra obtained through the European Southern Observatory archive. However, we only selected a subset of the original observations that included spectra with both high S/N and that did not show strong TiO absorption bands. This work extends previous analyses of this data set beyond Fe and the α-elements Mg, Si, Ca, and Ti. While we find reasonable agreement with past work, the data presented here indicate that the bulge may exhibit a different chemical composition than the local thick disk, especially at [Fe/H] ≳ –0.5. In particular, the bulge [α/Fe] ratios may remain enhanced to a slightly higher [Fe/H] than the thick disk, and the Fe-peak elements Co, Ni, and Cu appear enhanced compared to the disk. There is also some evidence that the [Na/Fe] (but not [Al/Fe]) trends between the bulge and local disk may be different at low and high metallicity. We also find that the velocity dispersion decreases as a function of increasing [Fe/H] for both fields, and do not detect any significant cold, high-velocity populations. A comparison with chemical enrichment models indicates that a significant fraction of hypernovae may be required to explain the bulge abundance trends, and that initial mass functions that are steep, top-heavy (and do not include strong outflow), or truncated to avoid including contributions from stars >40 M ☉ are ruled out, in particular because of disagreement with the Fe-peak abundance data. For most elements, the NGC 6553 stars exhibit abundance trends nearly identical to comparable metallicity bulge field stars

  13. Bursty stellar populations and obscured active galactic nuclei in galaxy bulges

    Science.gov (United States)

    Wild, Vivienne; Kauffmann, Guinevere; Heckman, Tim; Charlot, Stéphane; Lemson, Gerard; Brinchmann, Jarle; Reichard, Tim; Pasquali, Anna

    2007-10-01

    We investigate trends between the recent star formation history and black hole growth in galaxy bulges in the Sloan Digital Sky Survey. The galaxies lie at 0.01 4.0 kpc diameter of the galaxy. We find strong trends between black hole growth, as measured by dust-attenuation-corrected [O III] luminosity, and the recent star formation history of the bulges. 56 per cent of the bulges are quiescent with no signs of recent or ongoing star formation and, while almost half of all active galactic nuclei (AGN) lie within these bulges, they contribute only ~10 per cent to the total black hole growth in the local Universe. At the other extreme, the AGN contained within the ~4 per cent of galaxy bulges that are undergoing or have recently undergone the strongest starbursts, contribute at least 10-20 per cent of the total black hole growth. Much of this growth occurs in AGN with high amounts of dust extinction and thus the precise numbers remain uncertain. The remainder of the black hole growth (>60 per cent) is contributed by bulges with more moderate recent or ongoing star formation. The strongest accreting black holes reside in bulges with a wide range in recent star formation history. We conclude that our results support the popular hypothesis for black hole growth occurring through gas inflow into the central regions of galaxies, followed by a starburst and triggering of the AGN. However, while this is a significant pathway for the growth of black holes, it is not the dominant one in the present-day Universe. More unspectacular processes are apparently responsible for the majority of this growth. In order to arrive at these conclusions we have developed a set of new high signal-to-noise ratio (S/N) optical spectral indicators, designed to allow a detailed study of stellar populations which have undergone recent enhanced star formation. Working in the rest-frame wavelength range 3750-4150 Å, ideally suited to many recent and ongoing spectroscopic surveys at low and high

  14. Unveiling the Boxy Bulge and Bar of the Andromeda Spiral Galaxy

    Science.gov (United States)

    Beaton, R. L.; Athanassoula, E.; Majewski, S. R.; Guhathakurta, P.; Skrutskie, M. F.; Patterson, R. J.; Bureau, M.

    2005-12-01

    For the past 50 years a number of studies have suggested that the center of M31 may be barred. These optical studies, however, have been hampered by the highly inclined (i=77.5o) disk of M31 and the obscuring effects of its embedded dust, which strongly influence the observed isophotal structure of the M31 center. We analyze a new near-infrared survey of M31 by the Two Micron All Sky Survey (2MASS) 6X program. These data, covering the full extent of the optical disk, present a view of the central structure of M31 almost completely unfettered by dust. This new portrait vividly reveals a central bulge dominating the near infrared light profile from 3 to 1000 arcsecs along the semi-major axis, and with a number of interesting properties: (1) prominent boxy isophotes across the extent of the bulge, (2) a position angle inclined by about 10o from that of the M31 disk, (3) strong isophotal twisting in the innermost regions of the bulge, and (4) the presence of ansae symmetrically extending beyond the bulge along the position angle of the galaxy disk. In other highly inclined disks such properties have been associated with the presence of central bars obscured by projection effects. In the case of M31, these features have been well reproduced in a fully self consistent N-body simulation of a barred galaxy with a boxy bulge. The models further suggest the existence of an additional classical bulge component at the center of M31, and imply that the bar itself extends beyond the observationally established extent of the boxy bulge. This publication makes use of data products from 2MASS, which is a joint project of U Mass and IPAC/CalTech, funded by NASA and the NSF. This work was supported by NSF grants AST-0307842 and AST-0307966, as well as a SIM Key Project grant, NASA/JPL contract 1228235. MFS acknowledges support from NASA/JPL contract 1234021. This work was also partially supported by the Celerity Foundation. EA thanks the INSU/CNRS, the Région PACA and the University

  15. Are Bulges and Disks Real? Decomposing Spectral Data Cubes Into Their Astrophysical Components

    Science.gov (United States)

    Merrifield, Michael; Tabor, Martha; Aragon-Salamanca, Alfonso; Cappellari, Michele; Johnston, Evelyn

    2016-01-01

    Decomposing galaxies photometrically into bulge and disk components is now a well-established technique, but it remains unclear how distinct and real these components are, and how they relate to each other. To address these questions, we have been developing novel techniques to extract the various structural components from integral field unit (IFU) spectral observations of galaxies, in order to study simultaneously their spectral and spatial properties.As a first approach, by spatially decomposing each wavelength in a spectral data cube, we can discover how much light comes from the separate components as a function of wavelength, and hence derive unprecedentedly high quality spectra of bulge and disk for detailed analysis of their stellar populations.In addition, we have decomposed spectral data cubes by fitting the spectrum at each location with the sum of two components, with the spectral properties left entirely free to fit both kinematic and stellar population properties, subject only to the constraint that the relative flux contributions match those of a conventional bulge-disk decomposition.Initial results applied to MaNGA and other IFU surveys show the power of these techniques when applied to such high quality data. The first method allows us to understand the formation sequence of bulges and disks, with, for example, bulges showing the younger stellar populations in S0 galaxies, implying that this was where the last gasp of star formation occurred. The second technique reveals subtle population gradients within individual components, but also confirms that the decomposition into separate components is a credible procedure, as the resulting bulges and disks have entirely plausible kinematic properties that are in no way imposed by the decomposition.Although our initial application of these decomposition techniques has been to studying bulges and disks in S0 galaxies, the methods have much wider application to the spectral data cubes that MaNGA and other

  16. Localized bulging in an inflated cylindrical tube of arbitrary thickness - the effect of bending stiffness

    Science.gov (United States)

    Fu, Y. B.; Liu, J. L.; Francisco, G. S.

    2016-05-01

    We study localized bulging of a cylindrical hyperelastic tube of arbitrary thickness when it is subjected to the combined action of inflation and axial extension. It is shown that with the internal pressure P and resultant axial force F viewed as functions of the azimuthal stretch on the inner surface and the axial stretch, the bifurcation condition for the initiation of a localized bulge is that the Jacobian of the vector function (P , F) should vanish. This is established using the dynamical systems theory by first computing the eigenvalues of a certain eigenvalue problem governing incremental deformations, and then deriving the bifurcation condition explicitly. The bifurcation condition is valid for all loading conditions, and in the special case of fixed resultant axial force it gives the expected result that the initiation pressure for localized bulging is precisely the maximum pressure in uniform inflation. It is shown that even if localized bulging cannot take place when the axial force is fixed, it is still possible if the axial stretch is fixed instead. The explicit bifurcation condition also provides a means to quantify precisely the effect of bending stiffness on the initiation pressure. It is shown that the (approximate) membrane theory gives good predictions for the initiation pressure, with a relative error less than 5%, for thickness/radius ratios up to 0.67. A two-term asymptotic bifurcation condition for localized bulging that incorporates the effect of bending stiffness is proposed, and is shown to be capable of giving extremely accurate predictions for the initiation pressure for thickness/radius ratios up to as large as 1.2.

  17. First detection of the white dwarf cooling sequence of the galactic bulge

    Energy Technology Data Exchange (ETDEWEB)

    Calamida, A.; Sahu, K. C.; Anderson, J.; Casertano, S.; Brown, T.; Sokol, J.; Bond, H. E.; Ferguson, H.; Livio, M.; Valenti, J. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Cassisi, S.; Buonanno, R.; Pietrinferni, A. [Osservatorio Astronomico di Teramo—INAF, Via M. Maggini, I-64100 Teramo (Italy); Salaris, M. [Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Ferraro, I. [Osservatorio Astronomico di Roma—INAF, Via Frascati 33, I-00040 Monte Porzio Catone (Italy); Clarkson, W., E-mail: calamida@stsci.edu [University of Michigan-Dearborn, 4901 Evergreen Road, Dearborn, MI 48128 (United States)

    2014-08-01

    We present Hubble Space Telescope data of the low-reddening Sagittarius window in the Galactic bulge. The Sagittarius Window Eclipsing Extrasolar Planet Search field (∼3'× 3'), together with three more Advanced Camera for Surveys and eight Wide-Field Camera 3 fields, were observed in the F606W and F814W filters, approximately every two weeks for 2 yr, with the principal aim of detecting a hidden population of isolated black holes and neutron stars through astrometric microlensing. Proper motions were measured with an accuracy of ≈0.1 mas yr{sup –1} (≈4 km s{sup –1}) at F606W ≈ 25.5 mag, and better than ≈0.5 mas yr{sup –1} (≈20 km s{sup –1}) at F606W ≈ 28 mag, in both axes. Proper-motion measurements allowed us to separate disk and bulge stars and obtain a clean bulge color-magnitude diagram. We then identified for the first time a white dwarf (WD) cooling sequence in the Galactic bulge, together with a dozen candidate extreme horizontal branch stars. The comparison between theory and observations shows that a substantial fraction of the WDs (≈30%) are systematically redder than the cooling tracks for CO-core H-rich and He-rich envelope WDs. This evidence would suggest the presence of a significant number of low-mass WDs and WD-main-sequence binaries in the bulge. This hypothesis is further supported by the finding of two dwarf novae in outburst, two short-period (P ≲ 1 day) ellipsoidal variables, and a few candidate cataclysmic variables in the same field.

  18. Identification of a novel HIV-1 TAR RNA bulge binding protein.

    Science.gov (United States)

    Baker, B; Muckenthaler, M; Vives, E; Blanchard, A; Braddock, M; Nacken, W; Kingsman, A J; Kingsman, S M

    1994-08-25

    The Tat protein binds to TAR RNA to stimulate the expression of the human immunodeficiency virus type 1 (HIV-1) genome. Tat is an 86 amino acid protein that contains a short region of basic residues (aa49-aa57) that are required for RNA binding and TAR is a 59 nucleotide stem-loop with a tripyrimidine bulge in the upper stem. TAR is located at the 5' end of all viral RNAs. In vitro, Tat specifically interacts with TAR by recognising the sequence of the bulge and upper stem, with no requirement for the loop. However, in vivo the loop sequence is critical for activation, implying a requirement for accessory cellular TAR RNA binding factors. A number of TAR binding cellular factors have been identified in cell extracts and various models for the function of these factors have been suggested, including roles as coactivators and inhibitors. We have now identified a novel 38 kD cellular factor that has little general, single-stranded or double-stranded RNA binding activity, but that specifically recognises the bulge and upper stem region of TAR. The protein, referred to as BBP (bulge binding protein), is conserved in mammalian and amphibian cells and in Schizosaccharomyces pombe but is not found in Saccharomyces cerevisiae. BBP is an effective competitive inhibitor of Tat binding to TAR in vitro. Our data suggest that the bulge-stem recognition motif in TAR is used to mediate cellular factor/RNA interactions and indicates that Tat action might be inhibited by such competing reactions in vivo. PMID:8078772

  19. Electrochemical thermodynamic measurement system

    Science.gov (United States)

    Reynier, Yvan; Yazami, Rachid; Fultz, Brent T.

    2009-09-29

    The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

  20. Constructor Theory of Thermodynamics

    CERN Document Server

    Marletto, Chiara

    2016-01-01

    The laws of thermodynamics, powerful for countless purposes, are not exact: both their phenomenological and their statistical-mechanical versions are valid only at 'macroscopic scales', which are never defined. Here I propose a new, exact and scale-independent formulation of the first and second laws of thermodynamics, using the principles and tools of the recently proposed constructor theory. Specifically, I improve upon the axiomatic formulations of thermodynamics (Carath\\'eodory, 1909; Lieb and Yngvason, 1999) by proposing an exact and more general formulation of 'adiabatic accessibility'. This work provides an exact distinction between work and heat; it reveals an unexpected connection between information theory and the first law of thermodynamics (not just the second); it resolves the clash between the irreversibility of the 'cycle'-based second law and time-reversal symmetric dynamical laws. It also achieves the long-sought unification of the axiomatic version of the second law with Kelvin's.

  1. Workshop on Teaching Thermodynamics

    CERN Document Server

    1985-01-01

    It seemed appropriate to arrange a meeting of teachers of thermodynamics in the United Kingdom, a meeting held in the pleasant surroundings of Emmanuel College, Cambridge, in Sept~mber, 1984. This volume records the ideas put forward by authors, the discussion generated and an account of the action that discussion has initiated. Emphasis was placed on the Teaching of Thermodynamics to degree-level students in their first and second years. The meeting, a workshop for practitioners in which all were expected to take part, was remarkably well supported. This was notable in the representation of essentially every UK university and polytechnic engaged in teaching engineering thermodynamics and has led to a stimulating spread of ideas. By intention, the emphasis for attendance was put on teachers of engineering concerned with thermodynamics, both mechanical and chemical engineering disciplines. Attendance from others was encouraged but limited as follows: non-engineering acad­ emics, 10%, industrialists, 10%. The ...

  2. Thermodynamical Versus Optical Complementarity

    OpenAIRE

    Hiesmayr, Beatrix C.; Vedral, Vlatko

    2005-01-01

    We establish correspondence between macroscopic thermodynamical quantities and complementarity in wave interference. The well known visibility and predictability in a double slit--like experiment are shown to be connected to magnetic susceptibility and magnetization of a general interacting spin chain. This gives us the ability to analyze the tradeoff between thermodynamical quantities in the same information--theoretic way that is used in analyzing the wave--particle duality. We thus obtain ...

  3. Thermodynamics of Delta resonances

    OpenAIRE

    Weinhold, W; Friman, B.; Nörenberg, W.

    1997-01-01

    The thermodynamic potential of a system of pions and nucleons is computed including the piN interactions in the P33 channel. A consistent treatment of the width of the resonance in this channel, the Delta(1232) resonance, is explored in detail. In the low-density limit we recover the leading term of the virial expansion for the thermodynamic potential. An instructive diagrammatic interpretation of the contributions to the total baryon number is presented. Furthermore, we examine within a fire...

  4. Thermodynamics of decaying vacuum cosmologies

    CERN Document Server

    Lima, J A S

    1996-01-01

    The thermodynamic behavior of vacuum decaying cosmologies is investigated within a manifestly covariant formulation. Such a process corresponds to a continuous irreversible energy flow from the vacuum component to the created matter constituents. It is shown that if the specific entropy per particle remains constant during the process, the equilibrium relations are preserved. In particular, if the vacuum decays into photons, the energy density \\rho and average number density of photons n scale with the temperature as \\rho \\sim T^{4} and n \\sim T^{3}. The temperature law is determined and a generalized Planckian type form of the spectrum, which is preserved in the course of the evolution, is also proposed. Some consequences of these results for decaying vacuum FRW type cosmologies as well as for models with ``adiabatic'' photon creation are discussed.

  5. One-dimensional tensile constitutive equation cannot be directly generalized to deal with two-dimensional bulging mechanical problems

    Institute of Scientific and Technical Information of China (English)

    宋玉泉; 刘术梅

    2002-01-01

    Superplastic forming has been extensively applied to manufacture parts and components with complex shapes or high-precisions. However, superplastic formation is in multi-stress state. In a long time, uniaxial tensile constitutive equation has been directly generalized to deal with multi-stress state. Whether so doing is feasible or not needs to be proved in theory. This paper first summarizes the establishing processes of superplastic tensile and bulging constitutive equation with variable m, and, using the analytical expressions of equivalent stress ? and equivalent strain rateof free bulge based on the fundamentals of continuum medium plastic mechanics, derives the analytical expressions of optimum loading rules for superplastic free bulge. By comparing the quantitative results on typical superplastic alloy ZnAl22, it is shown that one-dimensional tensile constitutive equations cannot be directly generalized to deal with two-dimensional bulging quantitative mechanical problems; only superplastic bulging constitutive equation based on bulging stress state can be used to treat the quantitative mechanical problems of bulge.

  6. Galaxy And Mass Assembly (GAMA): understanding the wavelength dependence of galaxy structure with bulge-disc decompositions

    Science.gov (United States)

    Kennedy, Rebecca; Bamford, Steven P.; Häußler, Boris; Baldry, Ivan; Bremer, Malcolm; Brough, Sarah; Brown, Michael J. I.; Driver, Simon; Duncan, Kenneth; Graham, Alister W.; Holwerda, Benne W.; Hopkins, Andrew M.; Kelvin, Lee S.; Lange, Rebecca; Phillipps, Steven; Vika, Marina; Vulcani, Benedetta

    2016-08-01

    With a large sample of bright, low-redshift galaxies with optical-near-IR imaging from the GAMA survey we use bulge-disc decompositions to understand the wavelength-dependent behaviour of single-Sérsic structural measurements. We denote the variation in single-Sérsic index with wavelength as {N}, likewise for effective radius we use {R}. We find that most galaxies with a substantial disc, even those with no discernable bulge, display a high value of {N}. The increase in Sérsic index to longer wavelengths is therefore intrinsic to discs, apparently resulting from radial variations in stellar population and/or dust reddening. Similarly, low values of {R} (< 1) are found to be ubiquitous, implying an element of universality in galaxy colour gradients. We also study how bulge and disc colour distributions vary with galaxy type. We find that, rather than all bulges being red and all discs being blue in absolute terms, both components become redder for galaxies with redder total colours. We even observe that bulges in bluer galaxies are typically bluer than discs in red galaxies, and that bulges and discs are closer in colour for fainter galaxies. Trends in total colour are therefore not solely due to the colour or flux dominance of the bulge or disc.

  7. Galaxy And Mass Assembly (GAMA): Understanding the wavelength dependence of galaxy structure with bulge-disc decompositions

    Science.gov (United States)

    Kennedy, Rebecca; Bamford, Steven P.; Häußler, Boris; Baldry, Ivan; Bremer, Malcolm; Brough, Sarah; Brown, Michael J. I.; Driver, Simon; Duncan, Kenneth; Graham, Alister W.; Holwerda, Benne W.; Hopkins, Andrew M.; Kelvin, Lee S.; Lange, Rebecca; Phillipps, Steven; Vika, Marina; Vulcani, Benedetta

    2016-05-01

    With a large sample of bright, low-redshift galaxies with optical-near-IR imaging from the GAMA survey we use bulge-disc decompositions to understand the wavelength-dependent behavior of single-Sérsic structural measurements. We denote the variation in single-Sérsic index with wavelength as N, likewise for effective radius we use R. We find that most galaxies with a substantial disc, even those with no discernable bulge, display a high value of N. The increase in Sérsic index to longer wavelengths is therefore intrinsic to discs, apparently resulting from radial variations in stellar population and/or dust reddening. Similarly, low values of R (< 1) are found to be ubiquitous, implying an element of universality in galaxy colour gradients. We also study how bulge and disc colour distributions vary with galaxy type. We find that, rather than all bulges being red and all discs being blue in absolute terms, both components become redder for galaxies with redder total colours. We even observe that bulges in bluer galaxies are typically bluer than discs in red galaxies, and that bulges and discs are closer in colour for fainter galaxies. Trends in total colour are therefore not solely due to the colour or flux dominance of the bulge or disc.

  8. Thermodynamics of fractal universe

    Energy Technology Data Exchange (ETDEWEB)

    Sheykhi, Ahmad, E-mail: sheykhi@uk.ac.ir [Physics Department and Biruni Observatory, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of); Teimoori, Zeinab [Department of Physics, Shahid Bahonar University, P.O. Box 76175, Kerman (Iran, Islamic Republic of); Wang, Bin, E-mail: wang-b@sjtu.edu.cn [INPAC and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2013-01-29

    We investigate the thermodynamical properties of the apparent horizon in a fractal universe. We find that one can always rewrite the Friedmann equation of the fractal universe in the form of the entropy balance relation {delta}Q=T{sub h}dS{sub h}, where {delta}Q and T{sub h} are the energy flux and Unruh temperature seen by an accelerated observer just inside the apparent horizon. We find that the entropy S{sub h} consists two terms, the first one which obeys the usual area law and the second part which is the entropy production term due to nonequilibrium thermodynamics of fractal universe. This shows that in a fractal universe, a treatment with nonequilibrium thermodynamics of spacetime may be needed. We also study the generalized second law of thermodynamics in the framework of fractal universe. When the temperature of the apparent horizon and the matter fields inside the horizon are equal, i.e. T=T{sub h}, the generalized second law of thermodynamics can be fulfilled provided the deceleration and the equation of state parameters ranges either as -1 Less-Than-Or-Slanted-Equal-To q<0, -1 Less-Than-Or-Slanted-Equal-To w<-1/3 or as q<-1, w<-1 which are consistent with recent observations. We also find that for T{sub h}=bT, with b<1, the GSL of thermodynamics can be secured in a fractal universe by suitably choosing the fractal parameter {beta}.

  9. Thermodynamics of fractal universe

    International Nuclear Information System (INIS)

    We investigate the thermodynamical properties of the apparent horizon in a fractal universe. We find that one can always rewrite the Friedmann equation of the fractal universe in the form of the entropy balance relation δQ=ThdSh, where δQ and Th are the energy flux and Unruh temperature seen by an accelerated observer just inside the apparent horizon. We find that the entropy Sh consists two terms, the first one which obeys the usual area law and the second part which is the entropy production term due to nonequilibrium thermodynamics of fractal universe. This shows that in a fractal universe, a treatment with nonequilibrium thermodynamics of spacetime may be needed. We also study the generalized second law of thermodynamics in the framework of fractal universe. When the temperature of the apparent horizon and the matter fields inside the horizon are equal, i.e. T=Th, the generalized second law of thermodynamics can be fulfilled provided the deceleration and the equation of state parameters ranges either as −1⩽qh=bT, with b<1, the GSL of thermodynamics can be secured in a fractal universe by suitably choosing the fractal parameter β.

  10. Thermodynamics of Bioreactions.

    Science.gov (United States)

    Held, Christoph; Sadowski, Gabriele

    2016-06-01

    Thermodynamic principles have been applied to enzyme-catalyzed reactions since the beginning of the 1930s in an attempt to understand metabolic pathways. Currently, thermodynamics is also applied to the design and analysis of biotechnological processes. The key thermodynamic quantity is the Gibbs energy of reaction, which must be negative for a reaction to occur spontaneously. However, the application of thermodynamic feasibility studies sometimes yields positive Gibbs energies of reaction even for reactions that are known to occur spontaneously, such as glycolysis. This article reviews the application of thermodynamics in enzyme-catalyzed reactions. It summarizes the basic thermodynamic relationships used for describing the Gibbs energy of reaction and also refers to the nonuniform application of these relationships in the literature. The review summarizes state-of-the-art approaches that describe the influence of temperature, pH, electrolytes, solvents, and concentrations of reacting agents on the Gibbs energy of reaction and, therefore, on the feasibility and yield of biological reactions. PMID:27276551

  11. Modified siRNA Structure With a Single Nucleotide Bulge Overcomes Conventional siRNA-mediated Off-target Silencing

    OpenAIRE

    Dua, Pooja; Yoo, Jae Wook; Kim, Soyoun; Lee, Dong-ki

    2011-01-01

    Off-target gene silencing is a major concern when using RNA interference. Imperfect pairing of the antisense strand with unintended mRNA targets is one of the main causes of small interfering RNA (siRNA) off-target silencing. To overcome this, we have developed “bulge-siRNA,” a modified siRNA backbone structure with a single nucleotide (nt) bulge placed in the antisense strand. We found that siRNAs with a bulge at position 2 of the antisense strand were able to discriminate better between per...

  12. Zinc abundances in Galactic bulge field red giants: Implications for damped Lyman-α systems

    Science.gov (United States)

    Barbuy, B.; Friaça, A. C. S.; da Silveira, C. R.; Hill, V.; Zoccali, M.; Minniti, D.; Renzini, A.; Ortolani, S.; Gómez, A.

    2015-08-01

    Context. Zinc in stars is an important reference element because it is a proxy to Fe in studies of damped Lyman-α systems (DLAs), permitting a comparison of chemical evolution histories of bulge stellar populations and DLAs. In terms of nucleosynthesis, it behaves as an alpha element because it is enhanced in metal-poor stars. Abundance studies in different stellar populations can give hints to the Zn production in different sites. Aims: The aim of this work is to derive the iron-peak element Zn abundances in 56 bulge giants from high resolution spectra. These results are compared with data from other bulge samples, as well as from disk and halo stars, and damped Lyman-α systems, in order to better understand the chemical evolution in these environments. Methods: High-resolution spectra were obtained using FLAMES+UVES on the Very Large Telescope. We computed the Zn abundances using the Zn i lines at 4810.53 and 6362.34 Å. We considered the strong depression in the continuum of the Zn i 6362.34 Å line, which is caused by the wings of the Ca i 6361.79 Å line suffering from autoionization. CN lines blending the Zn i 6362.34 Å line are also included in the calculations. Results: We find [Zn/Fe] = +0.24 ± 0.02 in the range -1.3 < [Fe/H] < -0.5 and [Zn/Fe] = + 0.06 ± 0.02 in the range -0.5 < [Fe/H] < -0.1, whereas for [Fe/H] ≥ -0.1, it shows a spread of -0.60 < [Zn/Fe] < + 0.15, with most of these stars having low [Zn/Fe] < 0.0. These low zinc abundances at the high metallicity end of the bulge define a decreasing trend in [Zn/Fe] with increasing metallicities. A comparison with Zn abundances in DLA systems is presented, where a dust-depletion correction was applied for both Zn and Fe. When we take these corrections into account, the [Zn/Fe] vs. [Fe/H] of the DLAs fall in the same region as the thick disk and bulge stars. Finally, we present a chemical evolution model of Zn enrichment in massive spheroids, representing a typical classical bulge evolution

  13. Metal-poor stars towards the Galactic bulge: A population potpourri⋆

    Science.gov (United States)

    Koch, Andreas; McWilliam, Andrew; Preston, George W.; Thompson, Ian B.

    2016-03-01

    We present a comprehensive chemical abundance analysis of five red giants and two horizontal branch (HB) stars towards the southern edge of the Galactic bulge, at (l, b) ~ (0°,-11°). Based on high-resolution spectroscopy obtained with the Magellan/MIKE spectrograph, we derived up to 23 chemical element abundances and identify a mixed bag of stars, representing various populations in the central regions of the Galaxy. Although cosmological simulations predict that the inner Galaxy was host to the first stars in the Universe, we see no chemical evidence of the ensuing massive supernova explosions: all of our targets exhibit halo-like, solar [Sc/Fe] ratios, which is in contrast to the low values predicted from Population III nucleosynthesis. One of the targets is a CEMP-s star at [Fe/H] = -2.52 dex, and another target is a moderately metal-poor ([Fe/H] = -1.53 dex) CH star with strong enrichment in s-process elements (e.g., [Ba/Fe] = 1.35). These individuals provide the first contenders of these classes of stars towards the bulge. Four of the carbon-normal stars exhibit abundance patterns reminiscent of halo star across a metallicity range spanning -2.0 to -2.6 dex, i.e., enhanced α-elements and solar Fe-peak and neutron-capture elements, and the remaining one is a regular metal-rich bulge giant. The position, distance, and radial velocity of one of the metal-poor HB stars coincides with simulations of the old trailing arm of the disrupted Sagittarius dwarf galaxy. While their highly uncertain proper motions prohibit a clear kinematic separation, the stars' chemical abundances and distances suggest that these metal-poor candidates, albeit located towards the bulge, are not of the bulge, but rather inner halo stars on orbits that make them pass through the central regions. Thus, we caution similar claims of detections of metal-poor stars as true habitants of the bulge. This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas

  14. Resonant Orbits and the High Velocity Peaks Towards the Bulge

    CERN Document Server

    Molloy, Matthew; Evans, N Wyn; Shen, Juntai

    2015-01-01

    We extract the resonant orbits from an N-body bar that is a good representation of the Milky Way, using the method recently introduced by Molloy et al. (2015). By decomposing the bar into its constituent orbit families, we show that they are intimately connected to the boxy-peanut shape of the density. We highlight the imprint due solely to resonant orbits on the kinematic landscape towards the Galactic centre. The resonant orbits are shown to have distinct kinematic features and may be used to explain the cold velocity peak seen in the APOGEE commissioning data (Nidever et al. 2012). We show that high velocity peaks are a natural consequence of the motions of stars in the 2:1 orbit family. The locations of the peaks vary with bar angle and, with the tacit assumption that the observed peaks are due to the 2:1 family, we find that the locations of the high velocity peaks correspond to bar angles in the range 10 < theta_bar < 25 (deg). However, some important questions about the nature of the peaks remain...

  15. Deformation behavior of A6063 tube with initial thickness deviation in free hydraulic bulging

    Institute of Scientific and Technical Information of China (English)

    YANG Lian-fa; GUO Cheng; DENG Yang

    2006-01-01

    Experiment on seamless tubes of aluminum alloy A6063 with initial thickness deviation of 0-20% was conducted through a free hydraulic bulging with tube ends free. The influence of initial thickness deviation on the cross-section profile, thickness distribution, maximum internal pressure and maximum radial expansion was investigated. FEM simulation was also performed in order to examine and help explaining the experimental results. The results indicate that the internal pressure and maximum internal pressure appear to be little influenced by the initial thickness deviation, and that the cross-section profile of the bulged tube changes diversely and can not be a perfect circle. The results also suggest that the increase in initial thickness deviation may lead to a remarkable decrease in maximum radial expansion, and a rapid increase in thickness deviation and the center eccentricity of the inner and outer profiles.

  16. Stellar Sources in the ISOGAL Inner Galactic Bulge Field (=00, =-10)

    Indian Academy of Sciences (India)

    D. Κ. Ojha; A. Omont; S. Ganesh; G. Simon; Μ. Schultheis

    2000-06-01

    ISOGAL is a survey at 7 and 15 μm with ISOCAM of the inner galactic disk and bulge of our Galaxy. The survey covers ∼ 22 deg2 in selected areas of the central = ± 30 degree of the inner Galaxy. In this paper, we report the study of a small ISOGAL field in the inner galactic bulge (=0°, =-1°, area = 0.033deg2). Using the multicolor near-infrared data (IJK) of DENIS (DEep Near Infrared Southern Sky Survey) and mid-infrared ISOGAL data, we discuss the nature of the ISOGAL sources. The various color-color and color-magnitude diagrams are discussed in the paper. While most of the detected sources are red giants (RGB tip stars), a few of them show an excess in J-K and K-[15] colors with respect to the red giant sequence. Most of them are probably AGB stars with large mass-loss rates.

  17. Mechanical properties measurement of silicon nitride thin films using the bulge test

    Science.gov (United States)

    Lee, Hun Kee; Ko, Seong Hyun; Han, Jun Soo; Park, HyunChul

    2007-12-01

    The mechanical properties of silicon nitride films are investigated. Freestanding films of silicon nitride are fabricated using the MEMS technique. The films were deposited onto (100) silicon wafers by LPCVD (Low Pressure Chemical Vapor Deposition). Square and rectangular membranes are made by anisotropic etching of the silicon substrates. Then the bulge test for silicon nitride film was carried out. The thickness of specimens was 0.5, 0.75 and 1μm respectively. By testing both square and rectangular membranes, the reliability and valiant-ness of bulge test with regard to the shape of specimens was investigated. Also considering residual stress in the films, one can evaluate the Young's modulus from experimental load-deflection curves. Young's modulus of the silicon nitride films was about 232GPa. The residual stress is below 100MPa.

  18. Bladder Bulge: Unifying Old and New Sonographic Bladder Wall Abnormalities in Ureterolithiasis

    Directory of Open Access Journals (Sweden)

    Scott Bomann

    2012-12-01

    Full Text Available As long as CT remains the first line imaging modality in suspected ureterolithiasis, emergency physicians will continue to perform the majority of renal colic ultrasound studies in a search for hydronephrosis. Hydronephrosis, however, is not always present and emergency physicians may not find it as useful as would be expected. Through this case series of seven patients, we present what we believe to be commonly present and easily acquired sonographic bladder wall findings in ureterolithiasis. These abnormalities are not routinely taught in emergency ultrasound and have not been reported in the emergency medicine literature. One variant, in fact, may be a novel finding unto itself. Due to their similar appearance, we propose to unify these findings under the name “bladder bulge.” This sign can be seen on axial views as an inward bulging or focal thickening of the bladder wall on the affected side, at the uretovesical junction.

  19. Structure of the Galactic Bulge: Is the Milky Way a Double-barred Galaxy?

    Energy Technology Data Exchange (ETDEWEB)

    Nishiyama, Shogo [National Astronomical Observatory of Japan, Mitaka, Tokyo (Japan); Nagata, Tetsuya [Department of Astronomy, Kyoto University, Kyoto (Japan)

    2006-12-15

    Using the data of the IRSF/SIRIUS infrared survey along the Galactic plane ( l {<=} 10.{sup 0}5 at b = +1{sup 0}), we find a distinct structure, which is probably a secondary bar, inside the primary bar of our Galaxy. The apparent magnitude peak of Bulge red clump stars changes continuously from K{sub S} {approx} 13.5 (l = -10{sup 0}) to K{sub S} {approx} 12.3 (l = +10{sup 0}), and this can be explained by the bar structure of the Galactic Bulge. However, the apparent magnitude changes by only {approx} 0.1 mag over the central 8{sup 0}, and this indicates that there is a distinct structure inside the primary bar. In the process of the distance derivation, we have used the infrared extinction law in the J, H, and K{sub S} bands toward the Galactic center newly determined from our survey.

  20. Structure of the Galactic Bulge: Is the Milky Way a Double-barred Galaxy?

    International Nuclear Information System (INIS)

    Using the data of the IRSF/SIRIUS infrared survey along the Galactic plane ( l ≤ 10.05 at b = +10), we find a distinct structure, which is probably a secondary bar, inside the primary bar of our Galaxy. The apparent magnitude peak of Bulge red clump stars changes continuously from KS ∼ 13.5 (l = -100) to KS ∼ 12.3 (l = +100), and this can be explained by the bar structure of the Galactic Bulge. However, the apparent magnitude changes by only ∼ 0.1 mag over the central 80, and this indicates that there is a distinct structure inside the primary bar. In the process of the distance derivation, we have used the infrared extinction law in the J, H, and KS bands toward the Galactic center newly determined from our survey

  1. Analysis of photometric uncertainties in the OGLE-IV Galactic Bulge microlensing survey data

    CERN Document Server

    Skowron, J; Kozłowski, S; Szymański, M K; Mróz, P; Wyrzykowski, Ł; Poleski, R; Pietrukowicz, P; Ulaczyk, K; Pawlak, M; Soszyński, I

    2016-01-01

    We present a statistical assessment of both, observed and reported, photometric uncertainties in the OGLE-IV Galactic bulge microlensing survey data. This dataset is widely used for the detection of variable stars, transient objects, discovery of microlensing events, and characterization of the exo-planetary systems. Large collections of RR Lyrae stars and Cepheids discovered by the OGLE project toward the Galactic bulge provide light curves based on this dataset. We describe the method of analysis, and provide the procedure, which can be used to update preliminary photometric uncertainties, provided with the light curves, to the ones reflecting the actual observed scatter at a given magnitude and for a given CCD detector of the OGLE-IV camera.This is of key importance for data modeling, in particular, for the correct estimation of the goodness of fit.

  2. Statistical thermodynamics of alloys

    CERN Document Server

    Gokcen, N A

    1986-01-01

    This book is intended for scientists, researchers, and graduate students interested in solutions in general, and solutions of metals in particular. Readers are assumed to have a good background in thermodynamics, presented in such books as those cited at the end of Chapter 1, "Thermo­ dynamic Background." The contents of the book are limited to the solutions of metals + metals, and metals + metalloids, but the results are also appli­ cable to numerous other types of solutions encountered by metallurgists, materials scientists, geologists, ceramists, and chemists. Attempts have been made to cover each topic in depth with numerical examples whenever necessary. Chapter 2 presents phase equilibria and phase diagrams as related to the thermodynamics of solutions. The emphasis is on the binary diagrams since the ternary diagrams can be understood in terms of the binary diagrams coupled with the phase rule, and the Gibbs energies of mixing. The cal­ culation of thermodynamic properties from the phase diagrams is ...

  3. Discrete Thermodynamics of Lasers

    CERN Document Server

    Zilbergleyt, B

    2007-01-01

    The paper offers a discrete thermodynamic model of lasers. Laser is an open system; its equilibrium is based on a balance of two thermodynamic forces, one related to the incoming pumping power and another to the emitted light. The basic expression for such equilibrium is a logistic map, graphical solutions to which are pitchfork bifurcation diagrams. As pumping force increases, the relative populations on the ground and lasing branches tend to zero and unity correspondingly. An interesting feature of this model is the line spectrum of the up and down transitions between the branches beyond bifurcation point. Even in a simple case of 2-level laser with only 2 possible transition types (up and down), the spectra look like sets of the line packets, starting well before the population inversion. This effect is an independent confirmation of the Einstein's prohibition on practical realization of 2-level laser. Multilevel lasers may be approached by employing the idea of thermodynamic activity for the emitting atom...

  4. Pulsating variable stars in the MACHO bulge database: the semiregular variables

    Energy Technology Data Exchange (ETDEWEB)

    Minniti, D.; Alcock, C.; Allsman, R.A. [and others

    1997-11-01

    We review the pulsating stars contained in the top 24 fields of the MACHO bulge database, with special emphasis on the red semireg-ular stars. Based on period, amplitude and color cuts, we have selected a sample of 2000 semireguku variables with 15 < P < 100 days. Their period-luminosity relation is studied, as well ss their spatial distribution. We find that they follow the bar, unlike the RR Lyrae in these fields.

  5. Chemical abundances in a high-velocity RR Lyrae star near the bulge

    Science.gov (United States)

    Hansen, C. J.; Rich, R. M.; Koch, A.; Xu, S.; Kunder, A.; Ludwig, H.-G.

    2016-05-01

    Low-mass variable high-velocity stars are interesting study cases for many aspects of Galactic structure and evolution. Until recently, the only known high- or hyper-velocity stars were young stars thought to originate from the Galactic center. Wide-area surveys such as APOGEE and BRAVA have found several low-mass stars in the bulge with Galactic rest-frame velocities higher than 350 km s-1. In this study we present the first abundance analysis of a low-mass RR Lyrae star that is located close to the Galactic bulge, with a space motion of ~-400 km s-1. Using medium-resolution spectra, we derived abundances (including upper limits) of 11 elements. These allowed us to chemically tag the star and discuss its origin, although our derived abundances and metallicity, at [Fe/H] =-0.9 dex, do not point toward one unambiguous answer. Based on the chemical tagging, we cannot exclude that it originated in the bulge. However, its retrograde orbit and the derived abundances combined suggest that the star was accelerated from the outskirts of the inner (or even outer) halo during many-body interactions. Other possible origins include the bulge itself, or the star might have been stripped from a stellar cluster or the Sagittarius dwarf galaxy when it merged with the Milky Way. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  6. 3D Spectrophotometry of Planetary Nebulae in the Bulge of M31

    OpenAIRE

    Roth, M. M.; Becker, T; Kelz, A.; Schmoll, J.

    2003-01-01

    We introduce crowded field integral field (3D) spectrophotometry as a useful technique for the study of resolved stellar populations in nearby galaxies. As a methodological test, we present a pilot study with selected extragalactic planetary nebulae (XPN) in the bulge of M31, demonstrating how 3D spectroscopy is able to improve the limited accuracy of background subtraction which one would normally obtain with classical slit spectroscopy. It is shown that due to the absence of slit effects, 3...

  7. The Youth Bulge in Egypt: An Intersection of Demographics, Security, and the Arab Spring

    Directory of Open Access Journals (Sweden)

    Dan LaGraffe

    2012-01-01

    Full Text Available During the Arab Spring, Egyptians revolted against decades of poor governance and failed institutions. A wide range of grievances contributed to the eventual fall of the Mubarak regime, and most of these grievances were influenced by the demographic composition of the Egyptian population. This paper argues that the youth bulge in Egypt played a major role in the political transition and as such serves as the prime example of the intersection of demographics, security, and the Arab Spring.

  8. The Youth Bulge in Egypt: An Intersection of Demographics, Security, and the Arab Spring

    OpenAIRE

    Dan LaGraffe

    2012-01-01

    During the Arab Spring, Egyptians revolted against decades of poor governance and failed institutions. A wide range of grievances contributed to the eventual fall of the Mubarak regime, and most of these grievances were influenced by the demographic composition of the Egyptian population. This paper argues that the youth bulge in Egypt played a major role in the political transition and as such serves as the prime example of the intersection of demographics, security, and the Arab Spring.

  9. Red Variables in Globular Clusters: Comparison with the Bulge and the LMC

    OpenAIRE

    Matsunaga, N; Nakada, Y; Tanabe, T; Fukushi, H.; Ita, Y.

    2005-01-01

    We are conducting a project aimed at surveys and repeated observations of red variables (or long-period variables) in globular clusters. Using the IRSF/SIRIUS near-infrared facility located at South Africa, we are observing 145 globular clusters that are accessible from the site. In this contribution, we present our observations and preliminary results. We have discovered many red variables, especially in the Bulge region, whose memberships to the clusters remain to be confirmed. Using a samp...

  10. Genetically Induced Cell Death in Bulge Stem Cells Reveals Their Redundancy for Hair and Epidermal Regeneration

    OpenAIRE

    Driskell, Iwona; Oeztuerk-Winder, Feride; Humphreys, Peter; Frye, Michaela

    2014-01-01

    Adult mammalian epidermis contains multiple stem cell populations in which quiescent and more proliferative stem and progenitor populations coexist. However, the precise interrelation of these populations in homeostasis remains unclear. Here, we blocked the contribution of quiescent keratin 19 (K19)-expressing bulge stem cells to hair follicle formation through genetic ablation of the essential histone methyltransferase Setd8 that is required for the maintenance of adult skin. Deletion of Set...

  11. TWO RED CLUMPS AND THE X-SHAPED MILKY WAY BULGE

    International Nuclear Information System (INIS)

    From Two Micron All Sky Survey infrared photometry, we find two red clump (RC) populations coexisting in fields toward the Galactic bulge at latitudes |b|>5.05, ranging over ∼130 in longitude and 200 in latitude. These RC peaks indicate two stellar populations separated by ∼2.3 kpc; at (l, b) = (+1, - 8) the two RCs are located at 6.5 and 8.8 ± 0.2 kpc. The double-peaked RC is inconsistent with a tilted bar morphology. Most of our fields show the two RCs at roughly constant distance with longitude, also inconsistent with a tilted bar; however, an underlying bar may be present. Stellar densities in the two RCs change dramatically with longitude: on the positive longitude side the foreground RC is dominant, while the background RC dominates negative longitudes. A line connecting the maxima of the foreground and background populations is tilted to the line of sight by ∼200±40, similar to claims for the tilt of a Galactic bar. The distance between the two RCs decreases toward the Galactic plane; seen edge-on the bulge is X-shaped, resembling some extragalactic bulges and the results of N-body simulations. The center of this X is consistent with the distance to the Galactic center, although better agreement would occur if the bulge is 2-3 Gyr younger than 47 Tuc. Our observations may be understood if the two RC populations emanate, nearly tangentially, from the Galactic bar ends, in a funnel shape. Alternatively, the X, or double funnel, may continue to the Galactic center. From the Sun, this would appear peanut/box shaped, but X-shaped when viewed tangentially.

  12. The Black Hole–Bulge Mass Relation in Megamaser Host Galaxies

    Science.gov (United States)

    Läsker, Ronald; Greene, Jenny E.; Seth, Anil; van de Ven, Glenn; Braatz, James A.; Henkel, Christian; Lo, K. Y.

    2016-07-01

    We present Hubble Space Telescope (HST) images for nine megamaser disk galaxies with the primary goal of studying photometric BH-galaxy scaling relations. The megamaser disks provide the highest-precision extragalactic BH mass measurements, while our high-resolution HST imaging affords us the opportunity to decompose the complex nuclei of their late-type hosts in detail. Based on the morphologies and shapes of the galaxy nuclei, we argue that most of these galaxies’ central regions contain secularly evolving components (pseudo-bulges), and in many cases we photometrically identify co-existing “classical” bulge components as well. Using these decompositions, we draw the following conclusions. (1) The megamaser BH masses span two orders of magnitude (106–{10}8 {M}ȯ ) while the stellar mass of their spiral host galaxies are all ˜ {10}11 {M}ȯ within a factor of three. (2) The BH masses at a given bulge mass or total stellar mass in the megamaser host spiral galaxies tend to be lower than expected when compared to an extrapolation of the BH-bulge relation based on early-type galaxies. (3) The observed large intrinsic scatter of BH masses in the megamaser host galaxies raises the question of whether scaling relations exist in spiral galaxies. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 12185.

  13. Black hole starvation and bulge evolution in a Milky Way-like galaxy

    Science.gov (United States)

    Bonoli, Silvia; Mayer, Lucio; Kazantzidis, Stelios; Madau, Piero; Bellovary, Jillian; Governato, Fabio

    2016-07-01

    We present a new zoom-in hydrodynamical simulation, `ErisBH', which features the same initial conditions, resolution, and sub-grid physics as the close Milky Way-analogue `Eris' (Guedes et al. 2011), but it also includes prescriptions for the formation, growth and feedback of supermassive black holes. This enables a detailed study of black hole evolution and the impact of active galactic nuclei (AGN) feedback in a late-type galaxy. At z = 0, the main galaxy of ErisBH hosts a central black hole of 2.6 × 106 M⊙, which correlates to the bulge mass and the galaxy's central velocity dispersion similarly to what is observed in the Milky Way and in pseudobulges. During its evolution, the black hole grows mostly through mergers with black holes brought in by accreted satellite galaxies and very little by gas accretion (due to the modest amount of gas that reaches the central regions). AGN feedback is weak and it affects only the central 1-2 kpc. Yet, it limits the growth of the bulge, which results in a rotation curve that, in the inner ˜ 10 kpc, is flatter than that of Eris. We find that ErisBH is more prone to instabilities than Eris, due to its smaller bulge and larger disc. At z ˜ 0.3, an initially small bar grows to be of a few disc scalelengths in size. The formation of the bar causes a small burst of star formation in the inner few hundred pc, provides new gas to the central black hole and causes the bulge to have a boxy/peanut morphology by z = 0.

  14. Supermassive Black Holes and Their Host Galaxies - I. Bulge luminosities from dedicated near-infrared data

    OpenAIRE

    Läsker, Ronald; Ferrarese, Laura; van de Ven, Glenn

    2013-01-01

    In an effort to secure, refine and supplement the relation between central Supermassive Black Hole masses (Mbh), and the bulge luminosities of their host galaxies, (Lbul), we obtained deep, high spatial resolution K-band images of 35 nearby galaxies with securely measured Mbh, using the wide-field WIRCam imager at the Canada-France-Hawaii-Telescope (CFHT). A dedicated data reduction and sky subtraction strategy was adopted to estimate the brightness and structure of the sky, a critical step w...

  15. A Radiation-Hydrodynamical Model for Supermassive Black Hole-to-Bulge Mass Relation and Quasar Formation

    OpenAIRE

    Umemura, Masayuki

    2001-01-01

    As a potential mechanism to build up supermassive black holes (BHs) in a spheroidal system, we consider the radiation drag effect by bulge stars, which extracts angular momentum from interstellar gas and thus allows the gas to accrete onto the galactic center. With incorporating radiation hydrodynamical equation with simple stellar evolution, it is shown that the BH-to-bulge mass ratio, $f_{BH}$, is basically determined by a fundamental constant, that is, the energy conversion efficiency for ...

  16. Orientation-specific cis complementation by bulge- and loop-mutated human immunodeficiency virus type 1 TAR RNAs.

    OpenAIRE

    Braddock, M; Powell, R; Sutton, J.; Kingsman, A J; Kingsman, S M

    1994-01-01

    Tat activates human immunodeficiency type 1 gene expression by binding to TAR RNA. TAR comprises a partially base paired stem and hexanucleotide loop with a tripyrimidine bulge in the upper stem. In vitro, Tat binds to the bulge and upper stem, with no requirement for the loop. However, in vivo, loop sequences are critical for activation, implying that a loop binding cellular factor may be involved in the activation pathway. Given that activation appears to be a two-component system comprisin...

  17. Concise chemical thermodynamics

    CERN Document Server

    Peters, APH

    2010-01-01

    EnergyThe Realm of ThermodynamicsEnergy BookkeepingNature's Driving ForcesSetting the Scene: Basic IdeasSystem and SurroundingsFunctions of StateMechanical Work and Expanding GasesThe Absolute Temperature Scale Forms of Energy and Their Interconversion Forms of Renewable Energy Solar Energy Wind Energy Hydroelectric Power Geothermal Energy Biomass Energy References ProblemsThe First Law of Thermodynamics Statement of the First Law Reversible Expansion of an Ideal GasConstant-Volume ProcessesConstant-Pressure ProcessesA New Function: EnthalpyRelationship between ?H and ?UUses and Conventions of

  18. Dense molecular thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J.D.; Shaw, M.S.; Holian, B.L.

    1983-01-01

    We are examining the thermodynamics of dense molecular fluids from the theoretical view. Our interests range from modeling single-species, spherically symmetric, atomic systems, through adding the complication of nonspherical molecular potentials, to mixing various molecular species with the inclusion of chemistry. We discuss what has been accomplished and evaluate the directions to be taken in attacking the unsolved problems. The various theoretical approaches, both analytic and numerical, are presented. We finish with a discussion of the recent advance in treating nonspherical molecular potentials with effective spherical potentials in the calculation of thermodynamics.

  19. Introductory statistical thermodynamics

    CERN Document Server

    Dalarsson, Nils; Golubovic, Leonardo

    2011-01-01

    Introductory Statistical Thermodynamics is a text for an introductory one-semester course in statistical thermodynamics for upper-level undergraduate and graduate students in physics and engineering. The book offers a high level of detail in derivations of all equations and results. This information is necessary for students to grasp difficult concepts in physics that are needed to move on to higher level courses. The text is elementary, self contained, and mathematically well-founded, containing a number of problems with detailed solutions to help students to grasp the more difficult

  20. Knowledgedynamics and Thermodynamics

    Directory of Open Access Journals (Sweden)

    Constantin BRATIANU

    2008-01-01

    Full Text Available The purpose of this paper is to present a metaphorical analysis for Knowledgedynamics using the main concepts of Thermodynamics. Following the Andriessen's method we are going to define Thermodynamics as a source domain, and Knowledgedynamics as the target domain. Our analysis will discover the semantic kernel of this metaphor and the way in which we can benefit of it. In the same time, we shall demonstrate the complexity of the knowledge domain and the fact that this metaphorical analysis should constitute only a first step in defining the concepts and the laws of the new field of study.

  1. Viscoplasticity: A thermodynamic formulation

    Science.gov (United States)

    Freed, A. D.; Chaboche, J. L.

    1989-01-01

    A thermodynamic foundation using the concept of internal state variables is given for a general theory of viscoplasticity, as it applies to initially isotropic materials. Three fundamental internal state variables are admitted. They are: a tensor valued back stress for kinematic effects, and the scalar valued drag and yield strengths for isotropic effects. All three are considered to phenomenologically evolve according to competitive processes between strain hardening, strain induced dynamic recovery, and time induced static recovery. Within this phenomenological framework, a thermodynamically admissible set of evolution equations is put forth. This theory allows each of the three fundamental internal variables to be composed as a sum of independently evolving constituents.

  2. Thermodynamics of copper uranogermanate

    International Nuclear Information System (INIS)

    Standard formation heat of copper uranogermanate at 298.15 K and standard dehydration enthalpies of its crystallohydrates are determined by the method of reaction calorimetry. By the method of adiabatic vacuum calorimetry in 80-300 K interval heat capacity is studied and thermodynamic functions are calculated of Cu(HGeUO6)2·6H2O. Its standard entropy and Gibbs formation function at 298.15 K are calculated. Standard thermodynamic functions of reactions of synthesis and thermal decomposition of copper uranogermanate are calculated and analyzed

  3. Thermodynamics II essentials

    CERN Document Server

    REA, The Editors of

    2013-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Thermodynamics II includes review of thermodynamic relations, power and refrigeration cycles, mixtures and solutions, chemical reactions, chemical equilibrium, and flow through nozzl

  4. A New Thermodynamics from Nuclei to Stars

    Directory of Open Access Journals (Sweden)

    Dieter H.E. Gross

    2004-03-01

    Full Text Available Abstract: Equilibrium statistics of Hamiltonian systems is correctly described by the microcanonical ensemble. Classically this is the manifold of all points in the N-body phase space with the given total energy. Due to Boltzmann's principle, eS=tr(δ(E-H, its geometrical size is related to the entropy S(E,N,.... This definition does not invoke any information theory, no thermodynamic limit, no extensivity, and no homogeneity assumption, as are needed in conventional (canonical thermo-statistics. Therefore, it describes the equilibrium statistics of extensive as well of non-extensive systems. Due to this fact it is the fundamental definition of any classical equilibrium statistics. It can address nuclei and astrophysical objects as well. All kind of phase transitions can be distinguished sharply and uniquely for even small systems. It is further shown that the second law is a natural consequence of the statistical nature of thermodynamics which describes all systems with the same -- redundant -- set of few control parameters simultaneously. It has nothing to do with the thermodynamic limit. It even works in systems which are by far than any thermodynamic "limit".

  5. Irreversible thermodynamics in multiscale stochastic dynamical systems

    Science.gov (United States)

    Santillán, Moisés; Qian, Hong

    2011-04-01

    This work extends the results of a recently developed theory of a rather complete thermodynamic formalism for discrete-state, continuous-time Markov processes with and without detailed balance. We investigate whether and in what way the thermodynamic structure is invariant in a multiscale stochastic system, that is, whether the relations between thermodynamic functions of state and process variables remain unchanged when the system is viewed at different time scales and resolutions. Our results show that the dynamics on a fast time scale contribute an entropic term to the internal energy function uS(x) for the slow dynamics. Based on the conditional free energy uS(x), we can then treat the slow dynamics as if the fast dynamics is nonexistent. Furthermore, we show that the free energy, which characterizes the spontaneous organization in a system without detailed balance, is invariant with or without the fast dynamics: The fast dynamics is assumed to reach stationarity instantaneously on the slow time scale; it has no effect on the system’s free energy. The same cannot be said for the entropy and the internal energy, both of which contain the same contribution from the fast dynamics. We also investigate the consequences of time-scale separation in connection to the concepts of quasi-stationarity and steady adiabaticity introduced in the phenomenological steady-state thermodynamics.

  6. Mechanics of membrane bulging during cell-wall disruption in Gram-negative bacteria

    Science.gov (United States)

    Daly, Kristopher E.; Huang, Kerwyn Casey; Wingreen, Ned S.; Mukhopadhyay, Ranjan

    2011-04-01

    The bacterial cell wall is a network of sugar strands crosslinked by peptides that serve as the primary structure for bearing osmotic stress. Despite its importance in cellular survival, the robustness of the cell wall to network defects has been relatively unexplored. Treatment of the Gram-negative bacterium Escherichia coli with the antibiotic vancomycin, which disrupts the crosslinking of new material during growth, leads to the development of pronounced bulges and eventually of cell lysis. Here, we model the mechanics of the bulging of the cytoplasmic membrane through pores in the cell wall. We find that the membrane undergoes a transition between a nearly flat state and a spherical bulge at a critical pore radius of ~20 nm. This critical pore size is large compared to the typical distance between neighboring peptides and glycan strands, and hence pore size acts as a constraint on network integrity. We also discuss the general implications of our model to membrane deformations in eukaryotic blebbing and vesiculation in red blood cells.

  7. Mapping the Three-Dimensional "X-Shaped Structure" in Models of the Galactic Bulge

    CERN Document Server

    Li, Zhao-Yu

    2015-01-01

    Numerical simulations have shown that the X-shaped structure in the Milky Way bulge can naturally arise from the bar instability and buckling instability. To understand the influence of the buckling amplitude on the morphology of the X-shape, we analyze three self-consistent numerical simulations of barred galaxies with different buckling amplitudes (strong, intermediate and weak). We derive the three-dimensional density with an adaptive kernel smoothing technique. The face-on iso-density surfaces are all elliptical, while in the edge-on view, the morphology of buckled bars transitions with increasing radius, from a central boxy core to a peanut bulge and then to an extended thin bar. Based on these iso-density surfaces at different density levels, we find no clear evidence for a well-defined structure shaped like a letter X. The X-shaped structure is more peanut-like, whose visual perception is probably enhanced by the pinched inner concave iso-density contours. The peanut bulge can reproduce qualitatively t...

  8. Brightness variations of the northern 630nm intertropical arc and the midnight pressure bulge over Eritrea

    Directory of Open Access Journals (Sweden)

    R. H. Wiens

    2004-09-01

    Full Text Available The nightglow brightness at 630nm from the thermospheric O(1D layer was monitored nightly at Asmara, Eritrea (15.4° N, 39.9° E, 7° N dip with an all-sky imager. Averages of north-south strips of the images enabled contour plots of brightness on a latitude vs. local time grid. The contours show the movement of the intertropical arc southward before midnight, staying just north of Asmara after midnight, and gradually brightening to a maximum at 02:00h local civil time, 02:00 LT, after which it disappears before dawn. It is argued that all features of the plots can be explained by known mechanisms capable of driving ions along magnetic field lines, including the fountain effect, summer to winter transequatorial winds, and the midnight pressure bulge.

    The 02:00 LT brightness maximum is the most striking and the most persistent feature in the data. The persistence of the location of the 02:00 LT brightening is attributed to a pressure bulge centered on the geographic equator at midnight and extending to higher latitudes with increasing local time in both the winter and the summer hemispheres. The bulge is shown to be stronger near solstice than near equinox, confirming earlier work.

  9. Chemical abundances in a high velocity RR Lyrae star near the bulge

    CERN Document Server

    Hansen, Camilla Juul; Koch, Andreas; Xu, Siyi; Kunder, Andrea; Ludwig, Hans-Guenter

    2016-01-01

    Low-mass, variable, high-velocity stars are interesting study cases for many aspects of Galactic structure and evolution. Until recently, the only known high- or hyper-velocity stars were young stars thought to originate from the Galactic centre. Wide-area surveys like APOGEE and BRAVA have found several low-mass stars in the bulge with Galactic rest-frame velocities larger than 350 km/s. In this study we present the first abundance analysis of a low-mass, RR Lyrae star, located close to the Galactic bulge, with a space motion of ~ -400 km/s. Using medium-resolution spectra, we derive abundances (including upper limits) of 11 elements. These allow us to chemically tag the star and discuss its origin, although our derived abundances and metallicity, at [Fe/H] =-0.9 dex, do not point toward one unambiguous answer. Based on the chemical tagging, we cannot exclude that it originated in the bulge. However, combining its retrograde orbit and the derived abundances suggests that the star was accelerated from the out...

  10. Supermassive Black Holes and Their Host Galaxies - I. Bulge luminosities from dedicated near-infrared data

    CERN Document Server

    Läsker, Ronald; van de Ven, Glenn

    2013-01-01

    In an effort to secure, refine and supplement the relation between central Supermassive Black Hole masses (Mbh), and the bulge luminosities of their host galaxies, (Lbul), we obtained deep, high spatial resolution K-band images of 35 nearby galaxies with securely measured Mbh, using the wide-field WIRCam imager at the Canada-France-Hawaii-Telescope (CFHT). A dedicated data reduction and sky subtraction strategy was adopted to estimate the brightness and structure of the sky, a critical step when tracing the light distribution of extended objects in the near-infrared. From the final image product, bulge and total magnitudes were extracted via two-dimensional profile fitting. As a first order approximation, all galaxies were modeled using a simple Sersic-bulge + exponential-disk decomposition. However, we found that such models did not adequately describe the structure that we observe in a large fraction of our sample galaxies which often include cores, bars, nuclei, inner disks, spiral arms, rings and envelope...

  11. DISCOVERY OF A PAIR OF CLASSICAL CEPHEIDS IN AN INVISIBLE CLUSTER BEYOND THE GALACTIC BULGE

    International Nuclear Information System (INIS)

    We report the discovery of a pair of extremely reddened classical Cepheid variable stars located in the Galactic plane behind the bulge, using near-infrared (NIR) time-series photometry from the VISTA Variables in the Vía Láctea Survey. This is the first time that such objects have ever been found in the opposite side of the Galactic plane. The Cepheids have almost identical periods, apparent brightnesses, and colors. From the NIR Leavitt law, we determine their distances with ∼1.5% precision and ∼8% accuracy. We find that they have a same total extinction of A(V)≃32 mag, and are located at the same heliocentric distance of 〈d〉=11.4±0.9 kpc, and less than 1 pc from the true Galactic plane. Their similar periods indicate that the Cepheids are also coeval, with an age of ∼48±3 Myr, according to theoretical models. They are separated by an angular distance of only 18.″3, corresponding to a projected separation of ∼1 pc. Their position coincides with the expected location of the Far 3 kpc Arm behind the bulge. Such a tight pair of similar classical Cepheids indicates the presence of an underlying young open cluster that is both hidden behind heavy extinction and disguised by the dense stellar field of the bulge. All our attempts to directly detect this “invisible cluster” have failed, and deeper observations are needed. (letters)

  12. The Formation of Bulges, Discs and Two Component Galaxies in the CANDELS Survey at z < 3

    CERN Document Server

    Margalef-Bentabol, Berta; Mortlock, Alice; Hartley, Will; Duncan, Kenneth; Ferguson, Harry C; Koekemoer, Anton M; Dekel, Avishai; Primack, Joel R

    2016-01-01

    We examine a sample of 1495 galaxies in the CANDELS fields to determine the evolution of two component galaxies, including bulges and discs, within massive galaxies at the epoch 1 < z < 3 when the Hubble sequence forms. We fit all of our galaxies' light profiles with a single S\\'ersic fit, as well as with a combination of exponential and S\\'ersic profiles. The latter is done in order to describe a galaxy with an inner and an outer component, or bulge and disc component. We develop and use three classification methods (visual, F-test and the RFF) to separate our sample into 1-component galaxies (disc/spheroids-like galaxies) and 2-component galaxies (galaxies formed by an 'inner part' or bulge and an 'outer part' or disc). We then compare the results from using these three different ways to classify our galaxies. We find that the fraction of galaxies selected as 2-component galaxies increases on average 50 per cent from the lowest mass bin to the most massive galaxies, and decreases with redshift by a fa...

  13. Stellar variability in low-extinction regions towards the Galactic Bulge

    CERN Document Server

    Dominici, T P; Medina-Tanco, G A; Teixeira, R G; Benevides-Soares, P

    1999-01-01

    Intensive monitoring of low-extinction windows towards the galactic bulge has provided in the last years valuable information for studies about the dynamics, kinematics and formation history of this part of the galaxy, mainly by characterizing the bulge stellar populations (Paczy\\'nski, 1996). Since 1997, we have been conducting an intensive photometric-astrometric survey of the galactic bulge, with the monitoring of about 120000 stars in 12 windows uniformly distributed in galactic latitude and longitude (Blanco & Terndrup, 1989 e Blanco, 1988) never before submitted to this kind of survey. For this purpose, we have used the IAG/USP CCD Meridian Circle of the Abrahão de Moraes Observatory. The main objective of this work is the identification and classification of variable objects. In this work we present the set up and development of the necessary tools for a project like this and the posterior analysis of our data. We briefly describe the construction of a program to organize and detect variables amon...

  14. The Effects of Gas on Morphological Transformation in Mergers: Implications for Bulge and Disk Demographics

    CERN Document Server

    Hopkins, Philip F; Cox, Thomas J; Hernquist, Lars; Jogee, Shardha; Keres, Dusan; Ma, Chung-Pei; Robertson, Brant; Stewart, Kyle

    2009-01-01

    Transformation of disks into spheroids via mergers is a well-accepted element of galaxy formation models. However, recent simulations have shown that bulge formation is suppressed in increasingly gas-rich mergers. We investigate the global implications of these results in a cosmological framework, using independent approaches: empirical halo-occupation models (where galaxies are populated in halos according to observations) and semi-analytic models. In both, ignoring the effects of gas in mergers leads to the well-known over-production of spheroids at low masses: low and intermediate-mass galaxies are inescapably predicted to be bulge-dominated (B/T~0.5 at <10^10 M_sun, with almost no 'bulgeless' systems), even if they have avoided major mergers. Including the different physical behavior of gas in mergers immediately leads to a dramatic change: bulge formation is suppressed in low-mass galaxies, which are observed to be gas-rich (giving B/T~0.1 at <10^10 M_sun, with a number of bulgeless galaxies in goo...

  15. Optical Gravitational Lensing Experiment. The Distance Scale Galactic Bulge - LMC - SMC

    CERN Document Server

    Udalski, A

    1998-01-01

    We analyze the mean luminosity of three samples of field RRab Lyr stars observed in the course of the OGLE microlensing experiment: 73 stars from the Galactic bulge and 110 and 128 stars from selected fields in the LMC and SMC, respectively. The fields are the same as in the recent distance determination to the Magellanic Clouds with the red clump stars method by Udalski et al (1998). We determine the relative distance scale d_{GB}:d_{LMC}:d_{SMC} equal to: (0.194+/-0.010):1.00:(1.30+/-0.08). We calibrate our RR Lyr distance scale with the recent calibration of Gould and Popowski (1998) based on statistical parallaxes. We obtain the following distance moduli to the Galactic bulge, LMC and SMC: m-M=14.53+/-0.15, m-M=18.09+/-0.16 and m-M=18.66+/-0.16 mag. We use the RR Lyr mean V-band luminosity at the Galactic bulge metallicity as the reference brightness and analyze the mean, I-band luminosity of the red clump stars in objects with different ages and metallicities. We add to our analysis the metal poor Carina...

  16. Ultraviolet spectrophotometry of 2A 1822-371 - A bulge on the accretion disk

    Science.gov (United States)

    Mason, K. O.; Cordova, F. A.

    1982-01-01

    It is suggested that the 5.57-hour modulation of the X-ray source 2A 1822-371 is caused by the combined effects of (1) an occultation of the emitting region by a companion star, and (2) a bulge on the accretion disk surrounding the X-ray source. It is speculated that the changing aspect of the X-ray-heated inner face of the bulge with orbital phase may also contribute to the modulation at UV and optical wavelengths. The bulge's position angle suggests it to have been the result of turbulence caused by the impact of a gas stream transferring matter from the companion, and 2A 1822-371 is held to provide the most direct indication extant of such a structure in an accretion disk. It is speculated that comparison of high-time resolution UV observations with optical and X-ray light curves will allow further deductions as to the size, structure and location of the far-UV emitting region.

  17. Chemistry of the Most Metal-poor Stars in the Bulge and the z > 10 Universe

    CERN Document Server

    Casey, Andrew R

    2015-01-01

    Metal-poor stars in the Milky Way are local relics of the epoch of the first stars and the first galaxies. However, a low metallicity does not prove that a star formed in this ancient era, as metal-poor stars form over a range of redshift in different environments. Theoretical models of Milky Way formation have shown that at constant metallicity, the oldest stars are those closest to the center of the Galaxy on the most tightly-bound orbits. For that reason, the most metal-poor stars in the bulge of the Milky Way provide excellent tracers of the chemistry of the high-redshift universe. We report the dynamics and detailed chemical abundances of three stars in the bulge with [Fe/H] $\\lesssim-2.7$, two of which are the most metal-poor stars in the bulge in the literature. We find that with the exception of scandium, all three stars follow the abundance trends identified previously for metal-poor halo stars. These three stars have the lowest [Sc II/Fe] abundances yet seen in $\\alpha$-enhanced giant stars in the G...

  18. The morphologies of massive galaxies from z~3 - Witnessing the 2 channels of bulge growth

    CERN Document Server

    Huertas-Company, Marc; Mei, Simona; Shankar, Francesco; Bernardi, Mariangela; Daddi, Emanuele; Barro, Guillermo; Cabrera-Vives, Guillermo; Cattaneo, Andrea; Dimauro, Paola; Gravet, Romaric

    2015-01-01

    [abridged] We quantify the morphological evolution of z~0 massive galaxies ($M*/M_\\odot\\sim10^{11}$) from z~3 in the 5 CANDELS fields. The progenitors are selected using abundance matching techniques to account for the mass growth. The morphologies strongly evolve from z~3. At z3-4) and small effective radii ($R_e$~1 kpc) pointing towards an early formation through gas-rich mergers or VDI. Between z~ 2.5 and z~0, they rapidly increase their size by a factor of ~4-5, become all passive but their global morphology remains unaltered. The structural evolution is independent of the gas fractions, suggesting that it is driven by ex-situ events. The remaining 60% experience a gradual morphological transformation, from clumpy disks to more regular bulge+disks systems, essentially happening at z>1. It results in the growth of a significant bulge component (n~3) for 2/3 of the systems possibly through the migration of clumps while the remaining 1/3 keeps a rather small bulge (n~1.5-2). The transition phase between dist...

  19. The Controversial Star-Formation History and Helium Enrichment of the Milky Way Bulge

    Science.gov (United States)

    Nataf, David M.

    2016-06-01

    The stellar population of the Milky Way bulge is thoroughly studied, with a plethora of measurements from virtually the full suite of instruments available to astronomers. It is thus perhaps surprising that alongside well-established results lies some substantial uncertainty in its star-formation history. Cosmological models predict the bulge to host the Galaxy's oldest stars for [Fe/H] ≲ -1, and this is demonstrated by RR Lyrae stars and globular cluster observations. There is consensus that bulge stars with [Fe/H] ≲ 0 are older than t ≈ 10 Gyr. However, at super-solar metallicity, there is a substantial unresolved discrepancy. Data from spectroscopic measurements of the main-sequence turnoff and subgiant branch, the abundances of asymptotic giant branch stars, the period distribution of Mira variables, the chemistry and central-star masses of planetary nebulae, all suggest a substantial intermediate-age population (t ≈ 3 Gyr). This is in conflict with predictions from cosmologically motivated chemical evolution models and photometric studies of the main-sequence turnoff region, which both suggest virtually no stars younger than t ≈ 8 Gyr. A possible resolution to this conflict is enhanced helium-enrichment, as this would shift nearly all of the age estimates in the direction of decreasing discrepancy.

  20. The WFC3 Galactic Bulge Treasury Program: A First Look at Resolved Stellar Population Tools

    CERN Document Server

    Brown, Thomas M; Zoccali, Manuela; Renzini, Alvio; Ferguson, Henry C; Anderson, Jay; Smith, Ed; Bond, Howard E; Minniti, Dante; Valenti, Jeff A; Casertano, Stefano; Livio, Mario; Panagia, Nino; VandenBerg, Don A; Valenti, Elena

    2008-01-01

    [Abridged] When WFC3 is installed on HST, the community will have powerful new tools for investigating resolved stellar populations. The WFC3 Galactic Bulge Treasury program will obtain deep imaging on 4 low-extinction fields. These non-proprietary data will enable a variety of science investigations not possible with previous data sets. To aid in planning for the use of these data and for future proposals, we provide an introduction to the program, its photometric system, and the associated calibration effort. The observing strategy is based upon a new 5-band photometric system spanning the UV, optical, and near-infrared. With these broad bands, one can construct reddening-free indices of Teff and [Fe/H]. Besides the 4 bulge fields, the program will target 6 fields in well-studied star clusters, spanning a wide range of [Fe/H]. The cluster data serve to calibrate the indices, provide population templates, and correct the transformation of isochrones into the WFC3 photometric system. The bulge data will shed ...

  1. Numerical analysis of ECT signals for bulge and dent type defect on SG tube

    International Nuclear Information System (INIS)

    Electromagnetic numerical analysis of Eddy current non-destructive testing signals for bulge and dent type defect on steam generator tube is presented. The bulge defect can be found near tube sheet and is mainly caused by explosive tube expansion. The dent defect can appear near tube support plate and is mainly caused by thermal expansion of the plate. The INCONEL600 tube which is adopted in Uljin-4 NPP in Korea is used as an analysis model. The Bobbin probe is used for obtaining the impedance signals. For the numerical analysis the electromagnetic governing equation for Eddy current problem is derived from Maxwell's equation, and by performing the finite element formulation 3-D finite element code with brick element is developed. For the interpretation of simulated results and comparison the numerical results with experimental ones, the numerically simulated signals are adjusted by using the ASME standard 100% through hole defect signal. To see the effect of the defect on the impedance signal, parametric case study is performed and the results are presented in this paper. Also the impedance signals of bulge and dent defect with additional volumetric defect is presented. The results in this paper can be helpful for the analysis and interpretation of the field impedance signals obtained during the examination of the steam generator in NPP. (orig.)

  2. Milky Way mass galaxies with X-shaped bulges are not rare in the local Universe

    CERN Document Server

    Laurikainen, E; Athanassoula, E; Bosma, A; Herrera-Endoqui, M

    2014-01-01

    Boxy/Peanut/X-shaped (B/P/X) bulges are studied using the 3.6 micron images from the Spitzer Survey of Stellar Structure in Galaxies (S4G), and the Ks-band images from the Near-IR S0 galaxy Survey (NIRS0S). They are compared with the properties of barlenses, defined as lens-like structures embedded in bars. Based on observations and recent simulation models we show evidence that barlenses are the more face-on counterparts of B/P/X-shaped bulges. Using unsharp masks 18 new X-shaped structures were identified, covering a large range of galaxy inclinations. The similar masses and red B-3.6 micron colors of the host galaxies, and the fact that the combined axial ratio distribution of the host galaxy disks is flat, supports the interpretation that barlenses and X-shapes are physically the same phenomenon. Our detailed 2D multi-component decompositions for 30 galaxies, fitting the barlens/X-shape with a separate component indicate very small or non-existent classical bulges. Taking into account that the structures ...

  3. Nonlinear Local Bending Response and Bulging Factors for Longitudinal and Circumferential Cracks in Pressurized Cylindrical Shells

    Science.gov (United States)

    Young, Richard D.; Rose, Cheryl A.; Starnes, James H., Jr.

    2000-01-01

    Results of a geometrically nonlinear finite element parametric study to determine curvature correction factors or bulging factors that account for increased stresses due to curvature for longitudinal and circumferential cracks in unstiffened pressurized cylindrical shells are presented. Geometric parameters varied in the study include the shell radius, the shell wall thickness, and the crack length. The major results are presented in the form of contour plots of the bulging factor as a function of two nondimensional parameters: the shell curvature parameter, lambda, which is a function of the shell geometry, Poisson's ratio, and the crack length; and a loading parameter, eta, which is a function of the shell geometry, material properties, and the applied internal pressure. These plots identify the ranges of the shell curvature and loading parameters for which the effects of geometric nonlinearity are significant. Simple empirical expressions for the bulging factor are then derived from the numerical results and shown to predict accurately the nonlinear response of shells with longitudinal and circumferential cracks. The numerical results are also compared with analytical solutions based on linear shallow shell theory for thin shells, and with some other semi-empirical solutions from the literature, and limitations on the use of these other expressions are suggested.

  4. The Battle of the Bulge: Decay of the Thin, False Cosmic String

    CERN Document Server

    Lee, Bum-Hoon; MacKenzie, Richard; Paranjape, M B; Yajnik, U A; Yeom, Dong-han

    2013-01-01

    We consider the decay of cosmic strings that are trapped in the false vacuum in a theory of scalar electrodynamics in 3+1 dimensions. We restrict our analysis to the case of thin-walled cosmic strings which occur when large magnetic flux trapped inside the string. Thus the string looks like a tube of fixed radius, at which it is classically stable. The core of the string contains magnetic flux in the true vacuum, while outside the string, separated by a thin wall, is the false vacuum. The string decays by tunnelling to a configuration which is represented by a bulge, where the region of true vacuum within, is ostensibly enlarged. The bulge can be described as the meeting, of a kink soliton anti-soliton pair, along the length of the string. It can be described as a bulge appearing in the initial string, starting from the string of small, classically stable radius, expanding to a fat string of large, classically unstable (to expansion) radius and then returning back to the string of small radius along its lengt...

  5. A close look at secular evolution: Boxy/peanut bulges reduce gas inflow to the central kiloparsec

    CERN Document Server

    Fragkoudi, F; Bosma, A

    2016-01-01

    In this letter we investigate the effect of boxy/peanut (b/p) bulges on bar-induced gas inflow to the central kiloparsec, which plays a crucial role on the evolution of disc galaxies. We carry out hydrodynamic gas response simulations in realistic barred galaxy potentials, including or not the geometry of a b/p bulge, to investigate the amount of gas inflow induced in the different models. We find that b/p bulges can reduce the gas inflow rate to the central kiloparsec by more than an order of magnitude, which leads to a reduction in the amount of gas available in the central regions. We also investigate the effect of the dark matter halo concentration on these results, and find that for maximal discs, the effect of b/p bulges on gas inflow remains significant. The reduced amount of gas reaching the central regions due to the presence of b/p bulges could have significant repercussions on the formation of discy- (pseudo-) bulges, on the amount of nuclear star formation and feedback, on the fuel reservoir for A...

  6. The Milky Way without X: An alternative interpretation of the double red clump in the Galactic bulge

    CERN Document Server

    Lee, Young-Wook; Chung, Chul

    2015-01-01

    The presence of two red clumps (RCs) in high latitude fields of the Milky Way bulge is interpreted as evidence for an X-shaped structure originated from the bar instability. Here we show, however, that this double RC phenomenon is more likely to be another manifestation of multiple populations observed in globular clusters (GCs) in the metal-rich regime. As in the bulge GC Terzan 5, the helium enhanced second generation stars (G2) in the classical bulge component of the Milky Way are placed on the bright RC, which is about 0.5 mag brighter than the normal RC originated from the first generation stars (G1), producing the observed double RC. In a composite bulge, where a classical bulge can coexist with a boxy pseudo bulge, our models can also reproduce key observations, such as the dependence of the double RC feature on metallicity and Galactic latitude and longitude. If confirmed by Gaia trigonometric parallax distances, this would indicate that the Milky Way bar is not sufficiently buckled to form the X-shap...

  7. THE NATURE OF GROWING BULGES WITHIN z < 1.3 GALAXY DISKS IN THE GOODS-N FIELD

    International Nuclear Information System (INIS)

    We analyze central surface brightness μ0, nuclear and global colors of intermediate redshift disk galaxies. On an apparent-diameter-limited sample of 398 galaxies from ACS/HST (Advanced Camera for Surveys in the Hubble Space Telescope) The Great Observatories Origins Deep Survey North (GOODS-N), we find 131 galaxies with bulges and 214 without. Up to z ∼ 0.8, blue, star-forming nuclei are found in galaxies with low μ0 only; all high-μ0 nuclei show red, passive colors, so that nuclear and global (U - B) colors strongly correlate with central surface brightness, as found in the local universe. At 0.8 < z < 1.3, a fraction of ∼27% of the high surface brightness nuclei show blue colors, and positive nuclear color gradients. The associated nuclear star formation must lead to bulge growth inside disks. Population modeling suggests that such blue bulges evolve into local pseudobulges rather than classical bulges. We do not find evidence for rejuvenation of classical bulges at the sampled z. High luminosity active galactic nuclei (AGNs) become common at 0.8 < z < 1.3, perhaps pointing to a role of AGNs in the growth or star formation truncation of bulges.

  8. Experimental thermodynamics experimental thermodynamics of non-reacting fluids

    CERN Document Server

    Neindre, B Le

    2013-01-01

    Experimental Thermodynamics, Volume II: Experimental Thermodynamics of Non-reacting Fluids focuses on experimental methods and procedures in the study of thermophysical properties of fluids. The selection first offers information on methods used in measuring thermodynamic properties and tests, including physical quantities and symbols for physical quantities, thermodynamic definitions, and definition of activities and related quantities. The text also describes reference materials for thermometric fixed points, temperature measurement under pressures, and pressure measurements. The publicatio

  9. Local equilibrium and the second law of thermodynamics for irreversible systems with thermodynamic inertia.

    Science.gov (United States)

    Glavatskiy, K S

    2015-10-28

    Validity of local equilibrium has been questioned for non-equilibrium systems which are characterized by delayed response. In particular, for systems with non-zero thermodynamic inertia, the assumption of local equilibrium leads to negative values of the entropy production, which is in contradiction with the second law of thermodynamics. In this paper, we address this question by suggesting a variational formulation of irreversible evolution of a system with non-zero thermodynamic inertia. We introduce the Lagrangian, which depends on the properties of the normal and the so-called "mirror-image" systems. We show that the standard evolution equations, in particular, the Maxwell-Cattaneo-Vernotte equation, can be derived from the variational procedure without going beyond the assumption of local equilibrium. We also argue that the second law of thermodynamics in non-equilibrium should be understood as a consequence of the variational procedure and the property of local equilibrium. For systems with instantaneous response this leads to the standard requirement of the local instantaneous entropy production being always positive. However, if a system is characterized by delayed response, the formulation of the second law of thermodynamics should be altered. In particular, the quantity, which is always positive, is not the instantaneous entropy production, but the entropy production averaged over a proper time interval. PMID:26520492

  10. Local equilibrium and the second law of thermodynamics for irreversible systems with thermodynamic inertia

    Energy Technology Data Exchange (ETDEWEB)

    Glavatskiy, K. S. [School of Chemical Engineering, The University of Queensland, St. Lucia QLD 4072 (Australia)

    2015-10-28

    Validity of local equilibrium has been questioned for non-equilibrium systems which are characterized by delayed response. In particular, for systems with non-zero thermodynamic inertia, the assumption of local equilibrium leads to negative values of the entropy production, which is in contradiction with the second law of thermodynamics. In this paper, we address this question by suggesting a variational formulation of irreversible evolution of a system with non-zero thermodynamic inertia. We introduce the Lagrangian, which depends on the properties of the normal and the so-called “mirror-image” systems. We show that the standard evolution equations, in particular, the Maxwell-Cattaneo-Vernotte equation, can be derived from the variational procedure without going beyond the assumption of local equilibrium. We also argue that the second law of thermodynamics in non-equilibrium should be understood as a consequence of the variational procedure and the property of local equilibrium. For systems with instantaneous response this leads to the standard requirement of the local instantaneous entropy production being always positive. However, if a system is characterized by delayed response, the formulation of the second law of thermodynamics should be altered. In particular, the quantity, which is always positive, is not the instantaneous entropy production, but the entropy production averaged over a proper time interval.

  11. Local equilibrium and the second law of thermodynamics for irreversible systems with thermodynamic inertia

    International Nuclear Information System (INIS)

    Validity of local equilibrium has been questioned for non-equilibrium systems which are characterized by delayed response. In particular, for systems with non-zero thermodynamic inertia, the assumption of local equilibrium leads to negative values of the entropy production, which is in contradiction with the second law of thermodynamics. In this paper, we address this question by suggesting a variational formulation of irreversible evolution of a system with non-zero thermodynamic inertia. We introduce the Lagrangian, which depends on the properties of the normal and the so-called “mirror-image” systems. We show that the standard evolution equations, in particular, the Maxwell-Cattaneo-Vernotte equation, can be derived from the variational procedure without going beyond the assumption of local equilibrium. We also argue that the second law of thermodynamics in non-equilibrium should be understood as a consequence of the variational procedure and the property of local equilibrium. For systems with instantaneous response this leads to the standard requirement of the local instantaneous entropy production being always positive. However, if a system is characterized by delayed response, the formulation of the second law of thermodynamics should be altered. In particular, the quantity, which is always positive, is not the instantaneous entropy production, but the entropy production averaged over a proper time interval

  12. Correct thermodynamic forces in Tsallis thermodynamics: connection with Hill nanothermodynamics

    International Nuclear Information System (INIS)

    The equivalence between Tsallis thermodynamics and Hill's nanothermodynamics is established. The correct thermodynamic forces in Tsallis thermodynamics are pointed out. Through this connection we also find a general expression for the entropic index q which we illustrate with two physical examples, allowing in both cases to relate q to the underlying dynamics of the Hamiltonian systems

  13. On Teaching Thermodynamics

    Science.gov (United States)

    Debbasch, F.

    2011-01-01

    The logical structure of classical thermodynamics is presented in a modern, geometrical manner. The first and second law receive clear, operatively oriented statements and the Gibbs free energy extremum principle is fully discussed. Applications relevant to chemistry, such as phase transitions, dilute solutions theory and, in particular, the law…

  14. Thermodynamics with Design Problems.

    Science.gov (United States)

    Cilento, E. V.; Sears, J. T.

    1983-01-01

    Discusses how basic thermodynamics concepts are integrated with design problems. Includes course goals, instructional strategies, and major advantages/disadvantages of the integrated design approach. Advantages include making subject more concrete, emphasizing interrelation of variables, and reinforcing concepts by use in design analysis; whereas…

  15. Thermodynamically Stable Pickering Emulsions

    NARCIS (Netherlands)

    Sacanna, S.; Kegel, W.K.; Philipse, A.P.

    2007-01-01

    We show that under appropriate conditions, mixtures of oil, water, and nanoparticles form thermodynamically stable oil-in-water emulsions with monodisperse droplet diameters in the range of 30–150 nm. This observation challenges current wisdom that so-called Pickering emulsions are at most metastabl

  16. Black hole thermodynamical entropy

    Energy Technology Data Exchange (ETDEWEB)

    Tsallis, Constantino [Centro Brasileiro de Pesquisas Fisicas and National Institute of Science and Technology for Complex Systems, Rio de Janeiro, RJ (Brazil); Santa Fe Institute, Santa Fe, NM (United States); Cirto, Leonardo J.L. [Centro Brasileiro de Pesquisas Fisicas and National Institute of Science and Technology for Complex Systems, Rio de Janeiro, RJ (Brazil)

    2013-07-15

    As early as 1902, Gibbs pointed out that systems whose partition function diverges, e.g. gravitation, lie outside the validity of the Boltzmann-Gibbs (BG) theory. Consistently, since the pioneering Bekenstein-Hawking results, physically meaningful evidence (e.g., the holographic principle) has accumulated that the BG entropy S{sub BG} of a (3+1) black hole is proportional to its area L{sup 2} (L being a characteristic linear length), and not to its volume L{sup 3}. Similarly it exists the area law, so named because, for a wide class of strongly quantum-entangled d-dimensional systems, S{sub BG} is proportional to lnL if d=1, and to L{sup d-1} if d>1, instead of being proportional to L{sup d} (d {>=} 1). These results violate the extensivity of the thermodynamical entropy of a d-dimensional system. This thermodynamical inconsistency disappears if we realize that the thermodynamical entropy of such nonstandard systems is not to be identified with the BG additive entropy but with appropriately generalized nonadditive entropies. Indeed, the celebrated usefulness of the BG entropy is founded on hypothesis such as relatively weak probabilistic correlations (and their connections to ergodicity, which by no means can be assumed as a general rule of nature). Here we introduce a generalized entropy which, for the Schwarzschild black hole and the area law, can solve the thermodynamic puzzle. (orig.)

  17. Focus on stochastic thermodynamics

    Science.gov (United States)

    Van den Broeck, Christian; Sasa, Shin-ichi; Seifert, Udo

    2016-02-01

    We introduce the thirty papers collected in this ‘focus on’ issue. The contributions explore conceptual issues within and around stochastic thermodynamics, use this framework for the theoretical modeling and experimental investigation of specific systems, and provide further perspectives on and for this active field.

  18. Thermodynamics and statistical mechanics

    CERN Document Server

    Landsberg, Peter T

    1990-01-01

    Exceptionally articulate treatment combines precise mathematical style with strong physical intuition. Wide range of applications includes negative temperatures, negative heat capacities, special and general relativistic effects, black hole thermodynamics, gravitational collapse, more. Over 100 problems with worked solutions. Advanced undergraduate, graduate level. Table of applications. Useful formulas and other data.

  19. Nonequilibrium thermodynamics of nucleation

    NARCIS (Netherlands)

    Schweizer, M.; Sagis, L.M.C.

    2014-01-01

    We present a novel approach to nucleation processes based on the GENERIC framework (general equation for the nonequilibrium reversible-irreversible coupling). Solely based on the GENERIC structure of time-evolution equations and thermodynamic consistency arguments of exchange processes between a met

  20. Thermodynamics of meat proteins

    NARCIS (Netherlands)

    Sman, van der R.G.M.

    2012-01-01

    We describe the water activity of meat, being a mixture of proteins, salts and water, by the Free-Volume-Flory–Huggins (FVFH) theory augmented with the equation. Earlier, the FVFH theory is successfully applied to describe the thermodynamics to glucose homopolymers like starch, dextrans and maltodex

  1. Details of the thermodynamical derivation of the Ginzburg-Landau equations

    International Nuclear Information System (INIS)

    We examine the procedure for the thermodynamical derivation of the Ginzburg-Landau equation for current, which is given unclear and contradictory interpretations in existing textbooks. We clarify all the steps of this procedure and find, as a consequence, a limitation on the validity range of the thermodynamic Ginzburg-Landau theory that has not previously been explicitly stated. We conclude that the thermodynamic theory is applicable only to a superconducting specimen that is not part of an external current-carrying loop

  2. Quantum Rényi relative entropies affirm universality of thermodynamics.

    Science.gov (United States)

    Misra, Avijit; Singh, Uttam; Bera, Manabendra Nath; Rajagopal, A K

    2015-10-01

    We formulate a complete theory of quantum thermodynamics in the Rényi entropic formalism exploiting the Rényi relative entropies, starting from the maximum entropy principle. In establishing the first and second laws of quantum thermodynamics, we have correctly identified accessible work and heat exchange in both equilibrium and nonequilibrium cases. The free energy (internal energy minus temperature times entropy) remains unaltered, when all the entities entering this relation are suitably defined. Exploiting Rényi relative entropies we have shown that this "form invariance" holds even beyond equilibrium and has profound operational significance in isothermal process. These results reduce to the Gibbs-von Neumann results when the Rényi entropic parameter α approaches 1. Moreover, it is shown that the universality of the Carnot statement of the second law is the consequence of the form invariance of the free energy, which is in turn the consequence of maximum entropy principle. Further, the Clausius inequality, which is the precursor to the Carnot statement, is also shown to hold based on the data processing inequalities for the traditional and sandwiched Rényi relative entropies. Thus, we find that the thermodynamics of nonequilibrium state and its deviation from equilibrium together determine the thermodynamic laws. This is another important manifestation of the concepts of information theory in thermodynamics when they are extended to the quantum realm. Our work is a substantial step towards formulating a complete theory of quantum thermodynamics and corresponding resource theory. PMID:26565222

  3. Thermodynamics for the practicing engineer

    CERN Document Server

    Theodore, Louis; Vanvliet, Timothy

    2009-01-01

    This book concentrates specifically on the applications of thermodynamics, rather than the theory. It addresses both technical and pragmatic problems in the field, and covers such topics as enthalpy effects, equilibrium thermodynamics, non-ideal thermodynamics and energy conversion applications. Providing the reader with a working knowledge of the principles of thermodynamics, as well as experience in their application, it stands alone as an easy-to-follow self-teaching aid to practical applications and contains worked examples.

  4. Choice of the thermodynamic variables

    International Nuclear Information System (INIS)

    Some basic ideas of thermodynamics and statistical mechanics, both at equilibrium and off equilibrium, are recalled. In particular, the selection of relevant variables which underlies any macroscopic description is discussed, together with the meaning of the various thermodynamic quantities, in order to set the thermodynamic approaches used in nuclear physics in a general prospect

  5. Thermodynamics in science of metals

    International Nuclear Information System (INIS)

    The main concepts of thermodynamic properties, as applied to chemical compounds, one-component systems and solutions, are given. Thermodynamic substantiation of phase diagrams is presented. Methods for the determination of thermodynamic activity, the value of which depends on the interaction between the system constituents, which, in their turn, are determined by binding energies and spatial location of the constituents mentioned, are described

  6. Kinetic equilibrium and relativistic thermodynamics

    OpenAIRE

    Ván P.

    2011-01-01

    Relativistic thermodynamics is treated from the point of view of kinetic theory. It is shown that the generalized J\\"uttner distribution suggested in [1] is compatible with kinetic equilibrium. The requirement of compatibility of kinetic and thermodynamic equilibrium reveals several generalizations of the Gibbs relation where the velocity field is an independent thermodynamic variable.

  7. Perspective on quantum thermodynamics

    Science.gov (United States)

    Millen, James; Xuereb, André

    2016-01-01

    Classical thermodynamics is unrivalled in its range of applications and relevance to everyday life. It enables a description of complex systems, made up of microscopic particles, in terms of a small number of macroscopic quantities, such as work and entropy. As systems get ever smaller, fluctuations of these quantities become increasingly relevant, prompting the development of stochastic thermodynamics. Recently we have seen a surge of interest in exploring the quantum regime, where the origin of fluctuations is quantum rather than thermal. Many questions, such as the role of entanglement and the emergence of thermalisation, lie wide open. Answering these questions may lead to the development of quantum heat engines and refrigerators, as well as to vitally needed simple descriptions of quantum many-body systems.

  8. Dynamically tunable transformation thermodynamics

    Science.gov (United States)

    García-Meca, Carlos; Barceló, Carlos

    2016-04-01

    Recently, the introduction of transformation thermodynamics has provided a way to design thermal media that alter the flow of heat according to any spatial deformation, enabling the construction of novel devices such as thermal cloaks or concentrators. However, in its current version, this technique only allows static deformations of space. Here, we develop a space–time theory of transformation thermodynamics that incorporates the possibility of performing time-varying deformations. This extra freedom greatly widens the range of achievable effects, providing an additional degree of control for heat management applications. As an example, we design a reconfigurable thermal cloak that can be opened and closed dynamically, therefore being able to gradually adjust the temperature distribution of a given region.

  9. Thermodynamics of Crystalline States

    CERN Document Server

    Fujimoto, Minoru

    2013-01-01

    Thermodynamics is a well-established discipline of physics for properties of matter in thermal equilibrium with the surroundings. Applying to crystals, however, the laws encounter undefined properties of crystal lattice, which therefore need to be determined for a clear and well-defined description of crystalline states. Thermodynamics of Crystalline States explores the roles played by order variables and dynamic lattices in crystals in a wholly new way. The book begins by clarifying basic concepts for stable crystals. Next, binary phase transitions are discussed to study collective motion of order variables, as described mostly as classical phenomena. New to this edition is the examination of magnetic crystals, where magnetic symmetry is essential for magnetic phase transitions. The multi-electron system is also discussed  theoretically, as a quantum-mechanical example, for superconductivity in metallic crystals. Throughout the book, the role played by the lattice is emphasized and studied in-depth. Thermod...

  10. A commentary on thermodynamics

    CERN Document Server

    Day, William Alan

    1988-01-01

    The aim of this book is to comment on, and clarify, the mathematical aspects of the theory of thermodynamics. The standard presentations of the subject are often beset by a number of obscurities associated with the words "state", "reversible", "irreversible", and "quasi-static". This book is written in the belief that such obscurities are best removed not by the formal axiomatization of thermodynamics, but by setting the theory in the wider context of a genuine field theory which incorporates the effects of heat conduction and intertia, and proving appropriate results about the governing differential equations of this field theory. Even in the simplest one-dimensional case it is a nontrivial task to carry through the details of this program, and many challenging problems remain open.

  11. Dynamically tunable transformation thermodynamics

    International Nuclear Information System (INIS)

    Recently, the introduction of transformation thermodynamics has provided a way to design thermal media that alter the flow of heat according to any spatial deformation, enabling the construction of novel devices such as thermal cloaks or concentrators. However, in its current version, this technique only allows static deformations of space. Here, we develop a space–time theory of transformation thermodynamics that incorporates the possibility of performing time-varying deformations. This extra freedom greatly widens the range of achievable effects, providing an additional degree of control for heat management applications. As an example, we design a reconfigurable thermal cloak that can be opened and closed dynamically, therefore being able to gradually adjust the temperature distribution of a given region. (paper)

  12. Thermodynamic Function of Life

    CERN Document Server

    Michaelian, K

    2009-01-01

    Darwinian Theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic, out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living component of the biosphere of greatest mass, the plants and cyanobacteria, are involved in the transpiration of vast amounts of water. Transpiration is part of the global water cycle, and it is this cycle that distinguishes Earth from its life barren neighboring planets, Venus and Mars. The water cycle, including the absorption of sunlight in the biosphere, is by far the greatest entropy producing process occurring on Earth. Life, from this perspective, can therefore be viewed as performing an important thermodynamic function; acting as a dynamic catalyst by aiding process such as the water cycle, hurricanes, and ocean and wind currents to produce entropy. The role of animals in this view is that of unwitting but dedicated servants ...

  13. Thermodynamics of nuclear transport

    Science.gov (United States)

    Wang, Ching-Hao; Mehta, Pankaj; Elbaum, Michael

    Molecular transport across the nuclear envelope is important for eukaryotes for gene expression and signaling. Experimental studies have revealed that nuclear transport is inherently a nonequilibrium process and actively consumes energy. In this work we present a thermodynamics theory of nuclear transport for a major class of nuclear transporters that are mediated by the small GTPase Ran. We identify the molecular elements responsible for powering nuclear transport, which we term the ``Ran battery'' and find that the efficiency of transport, measured by the cargo nuclear localization ratio, is limited by competition between cargo molecules and RanGTP to bind transport receptors, as well as the amount of NTF2 (i.e. RanGDP carrier) available to circulate the energy flow. This picture complements our current understanding of nuclear transport by providing a comprehensive thermodynamics framework to decipher the underlying biochemical machinery. Pm and CHW were supported by a Simons Investigator in the Mathematical Modeling in Living Systems grant (to PM).

  14. Contact symmetries and Hamiltonian thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bravetti, A., E-mail: bravetti@correo.nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de México, A.P. 70-543, 04510 Mexico D.F. (Mexico); Lopez-Monsalvo, C.S., E-mail: cesar.slm@correo.nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de México, A.P. 70-543, 04510 Mexico D.F. (Mexico); Nettel, F., E-mail: Francisco.Nettel@roma1.infn.it [Dipartimento di Fisica, Università di Roma La Sapienza, P.le Aldo Moro 5, I-00185 Rome (Italy)

    2015-10-15

    It has been shown that contact geometry is the proper framework underlying classical thermodynamics and that thermodynamic fluctuations are captured by an additional metric structure related to Fisher’s Information Matrix. In this work we analyse several unaddressed aspects about the application of contact and metric geometry to thermodynamics. We consider here the Thermodynamic Phase Space and start by investigating the role of gauge transformations and Legendre symmetries for metric contact manifolds and their significance in thermodynamics. Then we present a novel mathematical characterization of first order phase transitions as equilibrium processes on the Thermodynamic Phase Space for which the Legendre symmetry is broken. Moreover, we use contact Hamiltonian dynamics to represent thermodynamic processes in a way that resembles the classical Hamiltonian formulation of conservative mechanics and we show that the relevant Hamiltonian coincides with the irreversible entropy production along thermodynamic processes. Therefore, we use such property to give a geometric definition of thermodynamically admissible fluctuations according to the Second Law of thermodynamics. Finally, we show that the length of a curve describing a thermodynamic process measures its entropy production.

  15. Thermodynamics of lanthanum uranovanadate

    International Nuclear Information System (INIS)

    Temperature dependence of specific heat in the range of 80-300 K and absolute entropy of compound La(VUO6)·10H2O, as well as the standard functions of formation, i.e. enthalpy, entropy and Gibbs' function at 298.15 K, were determined by the methods of reaction and adiabatic vacuum calorimetry. Thermodynamic characteristics of dehydration, synthesis and dissolution of the compound were calculated

  16. Thermodynamics of firms' growth

    OpenAIRE

    Eduardo Zambrano; Alberto Hernando; Aurelio Fernandez-Bariviera; Ricardo Hernando; Angelo Plastino

    2015-01-01

    The distribution of firms' growth and firms' sizes is a topic under intense scrutiny. In this paper, we show that a thermodynamic model based on the maximum entropy principle, with dynamical prior information, can be constructed that adequately describes the dynamics and distribution of firms' growth. Our theoretical framework is tested against a comprehensive database of Spanish firms, which covers, to a very large extent, Spain's economic activity, with a total of 1 155 142 firms evolving a...

  17. Thermodynamic Origin of Life

    OpenAIRE

    K. Michaelian

    2009-01-01

    Understanding the thermodynamic function of life may shed light on its origin. Life, as are all irreversible processes, is contingent on entropy production. Entropy production is a measure of the rate of the tendency of Nature to explore available microstates. The most important irreversible process generating entropy in the biosphere, and thus facilitating this exploration, is the absorption and transformation of sunlight into heat. Here we hypothesize that life began, and persists today, as...

  18. Thermodynamic Function of Life

    OpenAIRE

    K. Michaelian

    2009-01-01

    Darwinian Theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic, out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living component of the biosphere of greatest mass, the plants and cyanobacteria, are involved in the transpiration of vast amounts of water. Transpiration is part of the global water cycle, and it is this cycle that disti...

  19. Thermodynamics of Dark Energy

    OpenAIRE

    Bilic, Neven

    2008-01-01

    Thermodynamic properties of dark energy are discussed assuming that dark energy is described in terms of a selfinteracting complex scalar. We first show that, under certain assumptions, selfinteracting complex scalar field theories are equivalent to purely kinetic k-essence models. Then we analyze the themal properties of k-essence and in particular we show that dark-energy in the phantom regime does not necessarily yield negative entropy.

  20. The discovery of thermodynamics

    Science.gov (United States)

    Weinberger, Peter

    2013-07-01

    Based on the idea that a scientific journal is also an "agora" (Greek: market place) for the exchange of ideas and scientific concepts, the history of thermodynamics between 1800 and 1910 as documented in the Philosophical Magazine Archives is uncovered. Famous scientists such as Joule, Thomson (Lord Kelvin), Clausius, Maxwell or Boltzmann shared this forum. Not always in the most friendly manner. It is interesting to find out, how difficult it was to describe in a scientific (mathematical) language a phenomenon like "heat", to see, how long it took to arrive at one of the fundamental principles in physics: entropy. Scientific progress started from the simple rule of Boyle and Mariotte dating from the late eighteenth century and arrived in the twentieth century with the concept of probabilities. Thermodynamics was the driving intellectual force behind the industrial revolution, behind the enormous social changes caused by this revolution. The history of thermodynamics is a fascinating story, which also gives insights into the mechanism that seem to govern science.

  1. Nonequilibrium thermodynamics of nucleation

    International Nuclear Information System (INIS)

    We present a novel approach to nucleation processes based on the GENERIC framework (general equation for the nonequilibrium reversible-irreversible coupling). Solely based on the GENERIC structure of time-evolution equations and thermodynamic consistency arguments of exchange processes between a metastable phase and a nucleating phase, we derive the fundamental dynamics for this phenomenon, based on continuous Fokker-Planck equations. We are readily able to treat non-isothermal nucleation even when the nucleating cores cannot be attributed intensive thermodynamic properties. In addition, we capture the dynamics of the time-dependent metastable phase being continuously expelled from the nucleating phase, and keep rigorous track of the volume corrections to the dynamics. Within our framework the definition of a thermodynamic nuclei temperature is manifest. For the special case of nucleation of a gas phase towards its vapor-liquid coexistence, we illustrate that our approach is capable of reproducing recent literature results obtained by more microscopic considerations for the suppression of the nucleation rate due to nonisothermal effects

  2. Nonequilibrium thermodynamics of nucleation.

    Science.gov (United States)

    Schweizer, M; Sagis, L M C

    2014-12-14

    We present a novel approach to nucleation processes based on the GENERIC framework (general equation for the nonequilibrium reversible-irreversible coupling). Solely based on the GENERIC structure of time-evolution equations and thermodynamic consistency arguments of exchange processes between a metastable phase and a nucleating phase, we derive the fundamental dynamics for this phenomenon, based on continuous Fokker-Planck equations. We are readily able to treat non-isothermal nucleation even when the nucleating cores cannot be attributed intensive thermodynamic properties. In addition, we capture the dynamics of the time-dependent metastable phase being continuously expelled from the nucleating phase, and keep rigorous track of the volume corrections to the dynamics. Within our framework the definition of a thermodynamic nuclei temperature is manifest. For the special case of nucleation of a gas phase towards its vapor-liquid coexistence, we illustrate that our approach is capable of reproducing recent literature results obtained by more microscopic considerations for the suppression of the nucleation rate due to nonisothermal effects. PMID:25494727

  3. Mapping the outer bulge with RRab stars from the VVV Survey

    Science.gov (United States)

    Gran, F.; Minniti, D.; Saito, R. K.; Zoccali, M.; Gonzalez, O. A.; Navarrete, C.; Catelan, M.; Contreras Ramos, R.; Elorrieta, F.; Eyheramendy, S.; Jordán, A.

    2016-07-01

    Context. The VISTA Variables in the Vía Láctea (VVV) is a near-IR time-domain survey of the Galactic bulge and southern plane. One of the main goals of this survey is to reveal the 3D structure of the Milky Way through their variable stars. In particular, enormous numbers of RR Lyrae stars have been discovered in the inner regions of the bulge (-8° ≲ b ≲ -1°) by optical surveys such as OGLE and MACHO, but leaving an unexplored window of more than ~47 sq deg (-10.0° ≲ ℓ ≲ + 10.7° and - 10.3° ≲ b ≲ -8.0°) observed by the VVV Survey. Aims: Our goal is to characterize the RR Lyrae stars in the outer bulge in terms of their periods, amplitudes, Fourier coefficients, and distances in order to evaluate the 3D structure of the bulge in this area. The distance distribution of RR Lyrae stars will be compared to that of red clump stars, which is known to trace a X-shaped structure, in order to determine whether these two different stellar populations share the same Galactic distribution. Methods: A search for RR Lyrae stars was performed in more than ~47 sq deg at low Galactic latitudes (-10.3° ≲ b ≲ -8.0°). In the procedure the χ2 value and analysis of variance (AoV) statistic methods were used to determine the variability and periodic features of the light curves, respectively. To prevent misclassifications, the analysis was performed only on the fundamental mode RR Lyrae stars (RRab) owing to similarities found in the near-IR light curve shapes of contact eclipsing binaries (W UMa) and first overtone RR Lyrae stars (RRc). On the other hand, the red clump stars of the same analyzed tiles were selected, and cuts in the color-magnitude diagram were applied and the maximum distance restricted to ~20 kpc in order to construct a similar catalog in terms of distances and covered area compared to the RR Lyrae stars. Results: We report the detection of more than 1000 RR Lyrae ab-type stars in the VVV Survey located in the outskirts of the Galactic bulge

  4. Chemical and kinematical properties of galactic bulge stars surrounding the stellar system Terzan 5

    International Nuclear Information System (INIS)

    As part of a study aimed at determining the kinematical and chemical properties of Terzan 5, we present the first characterization of the bulge stars surrounding this puzzling stellar system. We observed 615 targets located well beyond the tidal radius of Terzan 5 and found that their radial velocity distribution is well described by a Gaussian function peaked at (v rad) = +21.0 ± 4.6 km s–1 with dispersion σ v = 113.0 ± 2.7 km s–1. This is one of the few high-precision spectroscopic surveys of radial velocities for a large sample of bulge stars in such a low and positive latitude environment (b = +1.°7). We found no evidence of the peak at (v rad) ∼ +200 km s–1 found in Nidever et al. Strong contamination of many observed spectra by TiO bands prevented us from deriving the iron abundance for the entire spectroscopic sample, introducing a selection bias. The metallicity distribution was finally derived for a subsample of 112 stars in a magnitude range where the effect of the selection bias is negligible. The distribution is quite broad and roughly peaked at solar metallicity ([Fe/H] ≅ +0.05 dex) with a similar number of stars in the super-solar and in the sub-solar ranges. The population number ratios in different metallicity ranges agree well with those observed in other low-latitude bulge fields, suggesting (1) the possible presence of a plateau for |b| < 4° in the ratio between stars in the super-solar (0 < [Fe/H] <0.5 dex) and sub-solar (–0.5 < [Fe/H] <0 dex) metallicity ranges; (2) a severe drop in the metal-poor component ([Fe/H] <–0.5) as a function of Galactic latitude.

  5. Chemical and Kinematical Properties of Galactic Bulge Stars Surrounding the Stellar System Terzan 5

    Science.gov (United States)

    Massari, D.; Mucciarelli, A.; Ferraro, F. R.; Origlia, L.; Rich, R. M.; Lanzoni, B.; Dalessandro, E.; Ibata, R.; Lovisi, L.; Bellazzini, M.; Reitzel, D.

    2014-08-01

    As part of a study aimed at determining the kinematical and chemical properties of Terzan 5, we present the first characterization of the bulge stars surrounding this puzzling stellar system. We observed 615 targets located well beyond the tidal radius of Terzan 5 and found that their radial velocity distribution is well described by a Gaussian function peaked at langv radrang = +21.0 ± 4.6 km s-1 with dispersion σ v = 113.0 ± 2.7 km s-1. This is one of the few high-precision spectroscopic surveys of radial velocities for a large sample of bulge stars in such a low and positive latitude environment (b = +1.°7). We found no evidence of the peak at langv radrang ~ +200 km s-1 found in Nidever et al. Strong contamination of many observed spectra by TiO bands prevented us from deriving the iron abundance for the entire spectroscopic sample, introducing a selection bias. The metallicity distribution was finally derived for a subsample of 112 stars in a magnitude range where the effect of the selection bias is negligible. The distribution is quite broad and roughly peaked at solar metallicity ([Fe/H] sime +0.05 dex) with a similar number of stars in the super-solar and in the sub-solar ranges. The population number ratios in different metallicity ranges agree well with those observed in other low-latitude bulge fields, suggesting (1) the possible presence of a plateau for |b| Observatory, proposal numbers 087.D-0716(B), 087.D-0748(A), and 283.D-5027(A), and at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  6. CO J = 2-1 EMISSION FROM EVOLVED STARS IN THE GALACTIC BULGE

    International Nuclear Information System (INIS)

    We observe a sample of eight evolved stars in the Galactic bulge in the CO J = 2-1 line using the Submillimeter Array with angular resolution of 1''-4''. These stars have been detected previously at infrared wavelengths, and several of them have OH maser emission. We detect CO J = 2-1 emission from three of the sources in the sample: OH 359.943 +0.260, [SLO2003] A12, and [SLO2003] A51. We do not detect the remaining five stars in the sample because of heavy contamination from the galactic CO emission. Combining CO data with observations at infrared wavelengths constraining dust mass loss from these stars, we determine the gas-to-dust ratios of the Galactic bulge stars for which CO emission is detected. For OH 359.943 +0.260, we determine a gas mass-loss rate of 7.9 (±2.2) × 10–5 M ☉ yr–1 and a gas-to-dust ratio of 310 (±89). For [SLO2003] A12, we find a gas mass-loss rate of 5.4 (±2.8) × 10–5 M ☉ yr–1 and a gas-to-dust ratio of 220 (±110). For [SLO2003] A51, we find a gas mass-loss rate of 3.4 (±3.0) × 10–5 M ☉ yr–1 and a gas-to-dust ratio of 160 (±140), reflecting the low quality of our tentative detection of the CO J = 2-1 emission from A51. We find that the CO J = 2-1 detections of OH/IR stars in the Galactic bulge require lower average CO J = 2-1 backgrounds.

  7. Milky Way demographics with the VVV survey. I. The 84-million star colour-magnitude diagram of the Galactic bulge

    CERN Document Server

    Saito, R K; Dias, B; Hempel, M; Rejkuba, M; Alonso-Garcia, J; Barbuy, B; Catelan, M; Emerson, J P; Gonzalez, O A; Lucas, P W; Zoccali, M; 10.1051/0004-6361/201219448

    2012-01-01

    The Milky Way (MW) bulge is a fundamental Galactic component for understanding the formation and evolution of galaxies, in particular our own. The ESO Public Survey VISTA Variables in the Via Lactea is a deep near-IR survey mapping the Galactic bulge and southern plane. Data taken during 2010-11 covered 315 deg2 in the bulge area in the JHKs bands. We used VVV data for the whole bulge area as a single and homogeneous data set to build for the first time a single colour-magnitude diagram (CMD) for the entire Galactic bulge. Photometric data in the JHKs bands were combined to produce a single and huge data set containing 173.1M+ sources in the three bands. Selecting only the data points flagged as stellar, the total number of sources is 84.0M+. We built the largest CMDs published up to date, containing 173.1+ million sources for all data points, and more than 84.0 million sources accounting for the stellar sources only. The CMD has a complex shape, mostly owing to the complexity of the stellar population and th...

  8. Dissecting the Red Sequence: The Bulge and Disc Colours of Early-Type Galaxies in the Coma Cluster

    CERN Document Server

    Head, Jacob T C G; Hudson, Micheal J; Smith, Russel J

    2014-01-01

    We explore the internal structure of red sequence galaxies in the Coma cluster across a wide range of luminosities ($-17>M_g>-22$) and cluster-centric radii ($0bulge-disc decomposition of galaxies in deep Canada-France-Hawaii Telescope $u,g,i$ imaging using GALFIT. Rigorous filtering is applied to identify an analysis sample of 200 galaxies which are well described by an `archetypal' S0 structure (central bulge + outer disc). We consider internal bulge and/or disc colour gradients by allowing component sizes to vary between bands. Gradients are required for $30\\%$ of analysis sample galaxies. Bulge half-light radii are found to be uncorrelated with galaxy luminosity ($R_e \\sim 1$ kpc, $n\\sim2$) for all but the brightest galaxies ($M_g<-20.5$). The S0 discs are brighter (at fixed size, or smaller at fixed luminosity) than those of star-forming spirals. A similar colour-magnitude relation is found for both bulges and discs. The global red sequence for ...

  9. Structure and dynamics of galaxies with a low surface-brightness disc - II. Stellar populations of bulges

    CERN Document Server

    Morelli, L; Pizzella, A; Bontà, E Dalla; Coccato, L; Méndez-Abreu, J; Cesetti, M

    2012-01-01

    The radial profiles of the Hb, Mg, and Fe line-strength indices are presented for a sample of eight spiral galaxies with a low surface-brightness stellar disc and a bulge. The correlations between the central values of the line-strength indices and velocity dispersion are consistent to those known for early-type galaxies and bulges of high surface-brightness galaxies. The age, metallicity, and alpha/Fe enhancement of the stellar populations in the bulge-dominated region are obtained using stellar population models with variable element abundance ratios. Almost all the sample bulges are characterized by a young stellar population, on-going star formation, and a solar alpha/Fe enhancement. Their metallicity spans from high to sub-solar values. No significant gradient in age and alpha/Fe enhancement is measured, whereas only in a few cases a negative metallicity gradient is found. These properties suggest that a pure dissipative collapse is not able to explain formation of all the sample bulges and that other ph...

  10. Kinematics of the X-shaped Milky Way Bulge: Expectations from a Self-consistent N-body Model

    CERN Document Server

    Qin, Yujing; Li, Zhao-Yu; Mao, Shude; Smith, Martin C; Rich, R Michael; Kunder, Andrea; Liu, Chao

    2015-01-01

    We explore the kinematics (both the radial velocity and the proper motion) of the vertical X-shaped feature in the Milky Way with an N-body bar/bulge model. From the solar perspective, the distance distribution of particles is double-peaked in fields passing through the X-shape. The separation and amplitude ratio between the two peaks qualitatively match the observed trends towards the Galactic bulge. We confirm clear signatures of cylindrical rotation in the pattern of mean radial velocity across the bar/bulge region. We also find possible imprints of coherent orbital motion inside the bar structure in the radial velocity distribution along l=0 degree, where the near and far sides of the bar/bulge show excesses of approaching and receding particles. The coherent orbital motion is also reflected in the slight displacement of the zero-velocity-line in the mean radial velocity, and the displacement of the maximum/minimum in the mean longitudinal proper motion across the bulge region. We find some degree of anis...

  11. Tidal radii and destruction rates of globular clusters in the Milky Way due to bulge-bar and disk shocking

    International Nuclear Information System (INIS)

    We calculate orbits, tidal radii, and bulge-bar and disk shocking destruction rates for 63 globular clusters in our Galaxy. Orbits are integrated in both an axisymmetric and a nonaxisymmetric Galactic potential that includes a bar and a three-dimensional model for the spiral arms. With the use of a Monte Carlo scheme, we consider in our simulations observational uncertainties in the kinematical data of the clusters. In the analysis of destruction rates due to the bulge-bar, we consider the rigorous treatment of using the real Galactic cluster orbit instead of the usual linear trajectory employed in previous studies. We compare results in both treatments. We find that the theoretical tidal radius computed in the nonaxisymmetric Galactic potential compares better with the observed tidal radius than that obtained in the axisymmetric potential. In both Galactic potentials, bulge-shocking destruction rates computed with a linear trajectory of a cluster at its perigalacticons give a good approximation of the result obtained with the real trajectory of the cluster. Bulge-shocking destruction rates for clusters with perigalacticons in the inner Galactic region are smaller in the nonaxisymmetric potential than those in the axisymmetric potential. For the majority of clusters with high orbital eccentricities (e > 0.5), their total bulge+disk destruction rates are smaller in the nonaxisymmetric potential.

  12. Orientation-specific cis complementation by bulge- and loop-mutated human immunodeficiency virus type 1 TAR RNAs.

    Science.gov (United States)

    Braddock, M; Powell, R; Sutton, J; Kingsman, A J; Kingsman, S M

    1994-12-01

    Tat activates human immunodeficiency type 1 gene expression by binding to TAR RNA. TAR comprises a partially base paired stem and hexanucleotide loop with a tripyrimidine bulge in the upper stem. In vitro, Tat binds to the bulge and upper stem, with no requirement for the loop. However, in vivo, loop sequences are critical for activation, implying that a loop binding cellular factor may be involved in the activation pathway. Given that activation appears to be a two-component system comprising a Tat-bulge interaction and a cellular factor-loop interaction, we considered that it might be possible to spatially separate the two components and retain activation. We have constructed a series of double TAR elements comprising various combinations of mutated TAR structures. Defective TARs with nucleotide substitutions in either the bulge or the loop complemented each other to give wild-type activation. However, the complementation was orientation specific, requiring the intact Tat binding site to reside on the 5'-proximal TAR. These data suggest that provided the wild-type orientation of the bulge and loop elements is retained, there is no requirement for them to coexist on the same TAR structure. PMID:7966633

  13. Tidal radii and destruction rates of globular clusters in the Milky Way due to bulge-bar and disk shocking

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Edmundo; Pichardo, Bárbara [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70-264, 04510 México, D. F. (Mexico); Velázquez, Héctor [Observatorio Astronómico Nacional, Universidad Nacional Autónoma de México, Apdo. Postal 877, 22800 Ensenada (Mexico)

    2014-10-01

    We calculate orbits, tidal radii, and bulge-bar and disk shocking destruction rates for 63 globular clusters in our Galaxy. Orbits are integrated in both an axisymmetric and a nonaxisymmetric Galactic potential that includes a bar and a three-dimensional model for the spiral arms. With the use of a Monte Carlo scheme, we consider in our simulations observational uncertainties in the kinematical data of the clusters. In the analysis of destruction rates due to the bulge-bar, we consider the rigorous treatment of using the real Galactic cluster orbit instead of the usual linear trajectory employed in previous studies. We compare results in both treatments. We find that the theoretical tidal radius computed in the nonaxisymmetric Galactic potential compares better with the observed tidal radius than that obtained in the axisymmetric potential. In both Galactic potentials, bulge-shocking destruction rates computed with a linear trajectory of a cluster at its perigalacticons give a good approximation of the result obtained with the real trajectory of the cluster. Bulge-shocking destruction rates for clusters with perigalacticons in the inner Galactic region are smaller in the nonaxisymmetric potential than those in the axisymmetric potential. For the majority of clusters with high orbital eccentricities (e > 0.5), their total bulge+disk destruction rates are smaller in the nonaxisymmetric potential.

  14. Stochastic Correlation Model of Galactic Bulge Velocity Dispersions and Central Black Holes Masses

    OpenAIRE

    Dokuchaev, V. I.; Eroshenko, Yu. N.

    2002-01-01

    We consider the cosmological model in which a part of the Universe \\Omega_h\\sim 10^-5 is in the form of primordial black holes with mass \\sim 10^5M_\\odot. These primordial black holes would be centers for growing protogalaxies which experienced multiple mergers with ordinary galaxies. This process of galaxies formation is accompanied by the merging of central black holes in the galactic nuclei. It is shown that recently discovered correlations between the central black holes and bulges of gal...

  15. Bulge, Bubble, and Y: How a RNA Exonuclease Repairs DNA, in Detail

    OpenAIRE

    Yu-Yuan Hsiao; Woei-Horng Fang; Chia-Chia Lee; Yi-Ping Chen; Yuan, Hanna S.

    2014-01-01

    DNA repair mechanisms are essential for preservation of genome integrity. However, it is not clear how DNA are selected and processed at broken ends by exonucleases during repair pathways. Here we show that the DnaQ-like exonuclease RNase T is critical for Escherichia coli resistance to various DNA-damaging agents and UV radiation. RNase T specifically trims the 3' end of structured DNA, including bulge, bubble, and Y-structured DNA, and it can work with Endonuclease V to restore the deaminat...

  16. On the Black Hole - Bulge Mass Ratios in Narrow-Line Seyfert 1 Galaxies

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    We present estimated ratios of the central black hole mass to the bulgemass (Mbh/Mbulge) for 15 Narrow Line Seyfert 1 galaxies (NLS1s). It is found thatNLS1s apparently have lower mass ratios: the average mass ratio is about 1 × 10-4with a spread of 2, which is one order of magnitude lower than for Broad Line AGNsand quiescent galaxies. This lower value, as compared to that established essentiallyfor all other types of galaxies, can be accounted for by an underestimation of theblack hole masses and an overestimation of the bulge masses in the NLS1s.

  17. Bulge-Disk Decompositions and Structural Bimodality of Ursa Major Cluster Spiral Galaxies

    OpenAIRE

    McDonald, Michael; Courteau, Stephane; Tully, R. Brent

    2008-01-01

    We present bulge and disk (B/D) decompositions of existing K'-band surface brightness profiles for 65 Ursa Major cluster spiral galaxies. This improves upon the disk-only fits of Tully et al. (1996). The 1996 disk fits were used by Tully & Verheijen (1997) for their discovery of the bimodality of structural parameters in the UMa cluster galaxies. It is shown that our new 1D B/D decompositions yield disk structural parameters that differ only slightly from the basic fits of Tully et al. and ev...

  18. A Vertical Resonance Heating Model for X- or Peanut-Shaped Galactic Bulges

    OpenAIRE

    Quillen, Alice C.; Minchev, Ivan; Sharma, Sanjib; Qin, Yu-Jing; Di Matteo, Paola

    2013-01-01

    We explore a second order Hamiltonian vertical resonance model for X-shaped or peanut-shaped galactic bulges. The X-shape is caused by the 2:1 vertical Lindblad resonance with the bar, with two vertical oscillation periods per orbital period in the bar frame. We examine N-body simulations and find that due to the bar slowing down and disk thickening during bar buckling, the resonance and associated peanut-shape moves outward. The peanut-shape is consistent with the location of the vertical re...

  19. High resolution spectroscopic analysis of seven giants in the bulge globular cluster NGC 6723

    Science.gov (United States)

    Rojas-Arriagada, A.; Zoccali, M.; Vásquez, S.; Ripepi, V.; Musella, I.; Marconi, M.; Grado, A.; Limatola, L.

    2016-03-01

    Context. Globular clusters associated with the Galactic bulge are important tracers of stellar populations in the inner Galaxy. High resolution analysis of stars in these clusters allows us to characterize them in terms of kinematics, metallicity, and individual abundances, and to compare these fingerprints with those characterizing field populations. Aims: We present iron and element ratios for seven red giant stars in the globular cluster NGC 6723, based on high resolution spectroscopy. Methods: High resolution spectra (R ~ 48 000) of seven K giants belonging to NGC 6723 were obtained with the FEROS spectrograph at the MPG/ESO 2.2 m telescope. Photospheric parameters were derived from ~130 Fe i and Fe ii transitions. Abundance ratios were obtained from line-to-line spectrum synthesis calculations on clean selected features. Results: An intermediate metallicity of [Fe/H] = -0.98 ± 0.08 dex and a heliocentric radial velocity of vhel = -96.6 ± 1.3 km s-1 were found for NGC 6723. Alpha-element abundances present enhancements of [O/Fe] = 0.29 ± 0.18 dex, [Mg/Fe] = 0.23 ± 0.10 dex, [Si/Fe] = 0.36 ± 0.05 dex, and [Ca/Fe] = 0.30 ± 0.07 dex. Similar overabundance is found for the iron-peak Ti with [Ti/Fe] = 0.24 ± 0.09 dex. Odd-Z elements Na and Al present abundances of [Na/Fe] = 0.00 ± 0.21 dex and [Al/Fe] = 0.31 ± 0.21 dex, respectively. Finally, the s-element Ba is also enhanced by [Ba/Fe] = 0.22 ± 0.21 dex. Conclusions: The enhancement levels of NGC 6723 are comparable to those of other metal-intermediate bulge globular clusters. In turn, these enhancement levels are compatible with the abundance profiles displayed by bulge field stars at that metallicity. This hints at a possible similar chemical evolution with globular clusters and the metal-poor of the bulge going through an early prompt chemical enrichment.

  20. Variable stars towards the bulge of M31: the AGAPE catalogue

    OpenAIRE

    Ansari, R.; Auriere, M.; Baillon, P.; Bouquet, A.; Coupinot, G.; Coutures, Ch.; Ghesquiere, C.; Giraud-Heraud, Y.; Gillieron, D.; Gondolo, P.; Hecquet, J.; Kaplan, J; Kim, A.; Du, Y. Le; Melchior, A. L.

    2004-01-01

    We present the AGAPE astrometric and photometric catalogue of 1579 variable stars in a 14'x10' field centred on M31. This work is the first survey devoted to variable stars in the bulge of M31. The R magnitudes of the objects and the B-R colours suggest that our sample is dominated by red long-period variable stars (LPV), with a possible overlap with Cepheid-like type II stars. Twelve nova candidates are identified. Correlations with other catalogues suggest that 2 novae could be recurrent no...

  1. Battle of the bulge: Decay of the thin, false cosmic string

    Science.gov (United States)

    Lee, Bum-Hoon; Lee, Wonwoo; MacKenzie, Richard; Paranjape, M. B.; Yajnik, U. A.; Yeom, Dong-han

    2013-11-01

    We consider the decay of cosmic strings that are trapped in the false vacuum in a theory of scalar electrodynamics in 3+1 dimensions. This paper is the 3+1-dimensional generalization of the 2+1-dimensional decay of false vortices which we have recently completed . We restrict our analysis to the case of thin-walled cosmic strings which occur when large magnetic flux is trapped inside the string. Thus the string looks like a tube of fixed radius, at which it is classically stable. The core of the string contains magnetic flux in the true vacuum, while outside the string, separated by a thin wall, is the false vacuum. The string decays by tunneling to a configuration which is represented by a bulge, where the region of true vacuum within is ostensibly enlarged. The bulge can be described as the meeting of a kink soliton-antisoliton pair along the length of the string. It can be described as a bulge appearing in the initial string, starting from the string of small, classically stable radius, expanding to a fat string of large, classically unstable (to expansion) radius and then returning back to the string of small radius along its length. This configuration is the bounce point of a corresponding O(2) symmetric instanton, which we can determine numerically. Once the bulge appears it explodes in real time. The paired soliton and antisoliton recede from each other along the length of the string with a velocity that quickly approaches the speed of light, leaving behind a fat tube. At the same time the radius of the fat tube that is being formed expands (transversely) as it is no longer classically stable, converting false vacuum to the true vacuum with ever-diluting magnetic field within. The rate of this expansion is determined by the energy difference between the true vacuum and the false vacuum. Our analysis could be applied to a network of cosmic strings formed in the very early Universe or vortex lines in a superheated superconductor.

  2. New Planetary Nebulae in the Galactic Bulge region with l>0deg - II

    CERN Document Server

    Boumis, P; Xilouris, E M; Mavromatakis, F; Kapakos, E; Papamastorakis, J; Goudis, C D

    2006-01-01

    The presentation of new results from an [O III] 5007 A survey in a search for planetary nebulae (PNe) in the galactic bulge is continued. A total of 60 objects, including 19 new PNe, have been detected in the remaining 34 per cent of the survey area, while 41 objects are already known. Deep Halpha+[N II] CCD images as well as low resolution spectra have been acquired for these objects. Their spectral signatures suggest that the detected emission originates from photoionized nebulae. In addition, absolute line fluxes have been measured and the electron densities are given. Accurate optical positions and optical diameters are also determined.

  3. Structure of the Galactic Bulge: Is the Milky Way a Double-barred Galaxy?

    Science.gov (United States)

    Nishiyama, Shogo; Nagata, Tetsuya; IRSF/SIRIUS Team

    2006-12-01

    Using the data of the IRSF/SIRIUS infrared survey along the Galactic plane (| l | red clump stars changes continuously from KS ~ 13.5 (l = -10°) to KS ~ 12.3 (l = +10°), and this can be explained by the bar structure of the Galactic Bulge. However, the apparent magnitude changes by only ~ 0.1 mag over the central 8°, and this indicates that there is a distinct structure inside the primary bar. In the process of the distance derivation, we have used the infrared extinction law in the J, H, and KS bands toward the Galactic center newly determined from our survey.

  4. The Distance to the Galactic Center Derived From Infrared Photometry of Bulge Red Clump Stars

    OpenAIRE

    Nishiyama, Shogo; Nagata, Tetsuya; Sato, Shuji; Kato, Daisuke; Nagayama, Takahiro; Kusakabe, Nobuhiko; Matsunaga, Noriyuki; Naoi, Takahiro; Sugitani, Koji; Tamura, Motohide

    2006-01-01

    On the basis of the near infrared observations of bulge red clump stars near the Galactic center, we have determined the galactocentric distance to be R_0 = 7.52 +- 0.10 (stat) +- 0.35 (sys) kpc. We observed the red clump stars at |l| < 1.0 deg and 0.7 deg < |b| < 1.0 deg with the IRSF 1.4 m telescope and the SIRIUS camera in the H and Ks bands. After extinction and population corrections, we obtained (m - M)_0 = 14.38 +- 0.03 (stat) +- 0.10 (sys). The statistical error is dominated by the un...

  5. Sub-Saturn Planet MOA-2008-BLG-310Lb: Likely To Be In The Galactic Bulge

    OpenAIRE

    Janczak, Julia; Fukui, A; Dong, Subo; Monard, B.; Kozlowski, Szymon; Gould, A.; Beaulieu, J.P.; Kubas, Daniel; Marquette, J. B.; Sumi, T.; Bond, I. A.; Bennett, D.P.; Collaboration, the MOA; Collaboration, the MicroFUN; collaboration, the MiNDSTEp

    2009-01-01

    We report the detection of sub-Saturn-mass planet MOA-2008-BLG-310Lb and argue that it is the strongest candidate yet for a bulge planet. Deviations from the single-lens fit are smoothed out by finite-source effects and so are not immediately apparent from the light curve. Nevertheless, we find that a model in which the primary has a planetary companion is favored over the single-lens model by \\Delta\\chi^2 ~ 880 for an additional three degrees of freedom. Detailed analysis yields a planet/sta...

  6. Bulge-Disk Decomposition of 659 Spiral and Lenticular Galaxy Brightness Profiles

    OpenAIRE

    Baggett, W. E.; Baggett, S. M.; Anderson, K. S. J.

    1998-01-01

    We present one of the largest homogeneous sets of spiral and lenticular galaxy brightness profile decompositions completed to date. The 659 galaxies in our sample have been fitted with a deVaucouleurs' law for the bulge component and an inner-truncated exponential for the disk component. Of the 659 galaxies in the sample, 620 were successfully fit with the chosen fitting functions. The fits are generally well-defined, with more than 90% having RMS deviations from the observed profile of less ...

  7. Near-Infrared Properties of Metal-poor Globular Clusters in the Galactic Bulge Direction

    OpenAIRE

    Chun, S. -H.; Kim, J. -W.; Shin, I. -G.; Chung, C.; Lim, D. -W.; Park, J. -H.; Kim, H. -I.; Han, W.; Sohn, Y. -J.

    2010-01-01

    Aims. J, H, and K' images obtained from the near-infrared imager CFHTIR on the Canada-France-Hawaii Telescope are used to derive the morphological parameters of the red giant branch (RGB) in the near-infrared color-magnitude diagrams for 12 metal-poor globular clusters in the Galactic bulge direction. Using the compiled data set of the RGB parameters for the observed 12 clusters, in addition to the previously studied 5 clusters, we discuss the properties of the RGB morphology for the clusters...

  8. Characterization of Friction Stir Welded Tubes by Means of Tube Bulge Test

    International Nuclear Information System (INIS)

    Mechanical properties of friction stir welded joints are generally evaluated by means of conventional tensile test. This testing method might provide insufficient information because maximum strain obtained in tensile test before necking is small; moreover, the application of tensile test is limited when the joint path is not linear or even when the welds are executed on curved surfaces. Therefore, in some cases, it would be preferable to obtain the joints properties from other testing methods. Tube bulge test can be a valid solution for testing circumferential or longitudinal welds executed on tubular workpieces. The present work investigates the mechanical properties and the formability of friction stir welded tubes by means of tube bulge tests. The experimental campaign was performed on tubular specimens having a thickness of 3 mm and an external diameter of 40 mm, obtained starting from two semi-tubes longitudinally friction stir welded. The first step, regarding the fabrication of tubes, was performed combining a conventional forming process and friction stir welding. Sheets in Al-Mg-Si-Cu alloy AA6060 T6 were adopted for this purpose. Plates having a dimension of 225x60 mm were bent (with a bending axis parallel to the main dimension) in order to obtain semi-tubes. A particular care was devoted to the fabrication of forming devices (punch and die) in order to minimize the springback effects. Semi-tubes were then friction stir welded by means of a CNC machine tool. Some preliminary tests were carried out by varying the welding parameters, namely feed rate and rotational speed. A very simple tool having flat shoulder and cylindrical pin was used. The second step of the research was based on testing the welded tubes by means of tube bulge test. A specific equipment having axial actuators with a conical shape was adopted for this study. Some analyses were carried out on the tubes bulged up to a certain pressure level. In particular, the burst pressure and the

  9. Characterization of Friction Stir Welded Tubes by Means of Tube Bulge Test

    Science.gov (United States)

    D'Urso, G.; Longo, M.; Giardini, C.

    2011-05-01

    Mechanical properties of friction stir welded joints are generally evaluated by means of conventional tensile test. This testing method might provide insufficient information because maximum strain obtained in tensile test before necking is small; moreover, the application of tensile test is limited when the joint path is not linear or even when the welds are executed on curved surfaces. Therefore, in some cases, it would be preferable to obtain the joints properties from other testing methods. Tube bulge test can be a valid solution for testing circumferential or longitudinal welds executed on tubular workpieces. The present work investigates the mechanical properties and the formability of friction stir welded tubes by means of tube bulge tests. The experimental campaign was performed on tubular specimens having a thickness of 3 mm and an external diameter of 40 mm, obtained starting from two semi-tubes longitudinally friction stir welded. The first step, regarding the fabrication of tubes, was performed combining a conventional forming process and friction stir welding. Sheets in Al-Mg-Si-Cu alloy AA6060 T6 were adopted for this purpose. Plates having a dimension of 225×60 mm were bent (with a bending axis parallel to the main dimension) in order to obtain semi-tubes. A particular care was devoted to the fabrication of forming devices (punch and die) in order to minimize the springback effects. Semi-tubes were then friction stir welded by means of a CNC machine tool. Some preliminary tests were carried out by varying the welding parameters, namely feed rate and rotational speed. A very simple tool having flat shoulder and cylindrical pin was used. The second step of the research was based on testing the welded tubes by means of tube bulge test. A specific equipment having axial actuators with a conical shape was adopted for this study. Some analyses were carried out on the tubes bulged up to a certain pressure level. In particular, the burst pressure and the

  10. Reinforcing the link between the double red clump and the X-shaped bulge of the Milky Way

    Science.gov (United States)

    Gonzalez, O. A.; Zoccali, M.; Debattista, V. P.; Alonso-García, J.; Valenti, E.; Minniti, D.

    2015-11-01

    The finding of a double red clump in the luminosity function of the Milky Way bulge has been interpreted as evidence for an X-shaped structure. Recently, an alternative explanation has been suggested, where the double red clump is an effect of multiple stellar populations in a classical spheroid. In this Letter we provide an observational assessment of this scenario and show that it is not consistent with the behaviour of the red clump across different lines of sight, particularly at high distances from the Galactic plane. Instead, we confirm that the shape of the red clump magnitude distribution closely follows the distance distribution expected for an X-shaped bulge at critical Galactic latitudes. We also emphasize some key observational properties of the bulge red clump that should not be neglected in the search for alternative scenarios. Based on observations taken within the ESO VISTA Public Survey VVV, Programme ID 179.B-2002.

  11. What Do Statistics Reveal About the Black Hole versus the Bulge Mass Correlation and Co-evolution?

    CERN Document Server

    Peng, Chien Y

    2010-01-01

    Observational data show that the correlation between supermassive black holes (MBH) and galaxy bulge (Mbulge) masses follows a nearly linear trend, and that the correlation is strongest with the bulge rather than the total stellar mass (Mgal). With increasing redshift, the ratio Gamma=MBH/Mbulge relative to z=0 also seems to be larger for MBH >~ 10^{8.5} Msol. This study looks more closely at statistics to better understand the creation and observations of the MBH-Mbulge correlation. It is possible to show that if galaxy merging statistics can drive the correlation, minor mergers are responsible for causing a *convergence to linearity* most evident at high masses, whereas major mergers have a central limit convergence that more strongly *reduces the scatter*. This statistical reasoning is agnostic about galaxy morphology. Therefore, combining statistical prediction (more major mergers ==> tighter correlation) with observations (bulges = tightest correlation), would lead one to conclude that more major mergers...

  12. Reinforcing the link between the double red clump and the X-shaped bulge of the Milky Way

    CERN Document Server

    Gonzalez, O A; Debattista, Victor P; Alonso-García, J; Valenti, E; Minniti, D

    2015-01-01

    The finding of a double red clump in the luminosity function of the Milky Way bulge has been interpreted as evidence for an X-shaped structure. Recently, an alternative explanation has been suggested, where the double red clump is an effect of multiple stellar populations in a classical spheroid. In this letter we provide an observational assessment of this scenario and show that it is not consistent with the behaviour of the red clump across different lines of sight, particularly at high distances from the Galactic plane. Instead, we confirm that the shape of the red clump magnitude distribution closely follows the distance distribution expected for an X-shaped bulge at critical Galactic latitudes. We also emphasize some key observational properties of the bulge red clump that should not be neglected in the search for alternative scenarios.

  13. RNA Thermodynamic Structural Entropy.

    Directory of Open Access Journals (Sweden)

    Juan Antonio Garcia-Martin

    Full Text Available Conformational entropy for atomic-level, three dimensional biomolecules is known experimentally to play an important role in protein-ligand discrimination, yet reliable computation of entropy remains a difficult problem. Here we describe the first two accurate and efficient algorithms to compute the conformational entropy for RNA secondary structures, with respect to the Turner energy model, where free energy parameters are determined from UV absorption experiments. An algorithm to compute the derivational entropy for RNA secondary structures had previously been introduced, using stochastic context free grammars (SCFGs. However, the numerical value of derivational entropy depends heavily on the chosen context free grammar and on the training set used to estimate rule probabilities. Using data from the Rfam database, we determine that both of our thermodynamic methods, which agree in numerical value, are substantially faster than the SCFG method. Thermodynamic structural entropy is much smaller than derivational entropy, and the correlation between length-normalized thermodynamic entropy and derivational entropy is moderately weak to poor. In applications, we plot the structural entropy as a function of temperature for known thermoswitches, such as the repression of heat shock gene expression (ROSE element, we determine that the correlation between hammerhead ribozyme cleavage activity and total free energy is improved by including an additional free energy term arising from conformational entropy, and we plot the structural entropy of windows of the HIV-1 genome. Our software RNAentropy can compute structural entropy for any user-specified temperature, and supports both the Turner'99 and Turner'04 energy parameters. It follows that RNAentropy is state-of-the-art software to compute RNA secondary structure conformational entropy. Source code is available at https://github.com/clotelab/RNAentropy/; a full web server is available at http

  14. Time and Thermodynamics

    CERN Document Server

    Kirkland, Kyle

    2007-01-01

    Temperature is vital to the health and welfare of all living beings, and Earth's temperature varies considerably from place to place. Early humans could only live in warm areas such as the tropics. Although modern humans have the technology to keep their houses and offices warm even in cold environments, the growth and development of civilization has created unintentional effects. Cities are warmer than their surrounding regions, and on a global scale, Earth is experiencing rising temperatures. Thus, the science of thermodynamics offers an important tool to study these effects. "Time and

  15. Principles of thermodynamics

    CERN Document Server

    Kaufman, Myron

    2002-01-01

    Ideal for one- or two-semester courses that assume elementary knowledge of calculus, This text presents the fundamental concepts of thermodynamics and applies these to problems dealing with properties of materials, phase transformations, chemical reactions, solutions and surfaces. The author utilizes principles of statistical mechanics to illustrate key concepts from a microscopic perspective, as well as develop equations of kinetic theory. The book provides end-of-chapter question and problem sets, some using Mathcad™ and Mathematica™; a useful glossary containing important symbols, definitions, and units; and appendices covering multivariable calculus and valuable numerical methods.

  16. Thermodynamic Stability of Nanobubbles

    CERN Document Server

    Attard, Phil

    2015-01-01

    The observed stability of nanobubbles contradicts the well-known result in classical nucleation theory, that the critical radius is both microscopic and thermodynamically unstable. Here nanoscopic stability is shown to be the combined result of two non-classical mechanisms. It is shown that the surface tension decreases with increasing supersaturation, and that this gives a nanoscopic critical radius. Whilst neither a free spherical bubble nor a hemispherical bubble mobile on an hydrophobic surface are stable, it is shown that an immobilized hemispherical bubble with a pinned contact rim is stable and that the total entropy is a maximum at the critical radius.

  17. Thermodynamics of Fractal Universe

    OpenAIRE

    Sheykhi, Ahmad; Teimoori, Zeinab; Wang, Bin

    2012-01-01

    We investigate the thermodynamical properties of the apparent horizon in a fractal universe. We find that one can always rewrite the Friedmann equation of the fractal universe in the form of the entropy balance relation $ \\delta Q=T_h d{S_h}$, where $ \\delta Q $ and $ T_{h} $ are the energy flux and Unruh temperature seen by an accelerated observer just inside the apparent horizon. We find that the entropy $S_h$ consists two terms, the first one which obeys the usual area law and the second p...

  18. Stochastic thermodynamics of resetting

    Science.gov (United States)

    Fuchs, Jaco; Goldt, Sebastian; Seifert, Udo

    2016-03-01

    Stochastic dynamics with random resetting leads to a non-equilibrium steady state. Here, we consider the thermodynamics of resetting by deriving the first and second law for resetting processes far from equilibrium. We identify the contributions to the entropy production of the system which arise due to resetting and show that they correspond to the rate with which information is either erased or created. Using Landauer's principle, we derive a bound on the amount of work that is required to maintain a resetting process. We discuss different regimes of resetting, including a Maxwell demon scenario where heat is extracted from a bath at constant temperature.

  19. The Density of Dark Matter in the Galactic Bulge and Implications for Indirect Detection

    CERN Document Server

    Hooper, Dan

    2016-01-01

    A recent study, making use of the number of horizontal branch stars observed in infrared photometric surveys and kinematic measurements of M-giant stars from the BRAVA survey, combined with N-body simulations of stellar populations, has presented a new determination of the dark matter mass within the bulge-bar region of the Milky Way. That study constrains the total mass within the $\\pm 2.2 \\times \\pm 1.4 \\times \\pm 1.2$ kpc volume of the bulge-bar region to be ($1.84 \\pm 0.07) \\times 10^{10} \\, M_{\\odot}$, of which 9-30% is made up of dark matter. Here, we use this result to constrain the the Milky Way's dark matter density profile, and discuss the implications for indirect dark matter searches. Although uncertainties remain significant, these results favor dark matter distributions with a cusped density profile. For example, for a scale radius of 20 kpc and a local dark matter density of 0.4 GeV/cm$^3$, density profiles with an inner slope of 0.69 to 1.40 are favored, approximately centered around the stand...

  20. An X-ray Spectroscopic Study of the Hot Interstellar Medium Toward the Galactic Bulge

    CERN Document Server

    Hagihara, Toshishige; Mitsuda, Kazuhisa; Takei, Yoh; Sakai, Kazuhiro; Yao, Yangsen; Wang, Q Daniel; McCammon, Dan

    2011-01-01

    We present a detailed spectroscopic study of the hot gas toward the Galactic bulge along the 4U 1820-303 sight line by a combination analysis of emission and absorption spectra. In addition to the absorption lines of OVII Kalpha, OVII Kbeta, OVIII Kalpha and NeIX Kalpha by Chandra LTGS as shown by previous works, Suzaku detected clearly the emission lines of OVII, OVIII, NeIX and NeX from the vicinity. We used simplified plasma models with constant temperature and density. Evaluation of the background and foreground emission was performed carefully, including stellar X-ray contribution based on the recent X-ray observational results and stellar distribution simulator. If we assume that one plasma component exists in front of 4U1820-303 and the other one at the back, the obtained temperatures are T= 1.7 +/- 0.2 MK for the front-side plasma and T=3.9(+0.4-0.3) MK for the backside. This scheme is consistent with a hot and thick ISM disk as suggested by the extragalactic source observations and an X-ray bulge aro...

  1. An observer's view of simulated galaxies: disc-to-total ratios, bars, and (pseudo-)bulges

    CERN Document Server

    Scannapieco, Cecilia; Jonsson, Patrik; White, Simon D M

    2010-01-01

    We use cosmological hydrodynamical simulations of the formation of Milky Way mass galaxies to study the relative importance of the main stellar components, discs, bulges, and bars, at z=0. The main aim of this work is to understand if estimates of the structural parameters of these components determined from kinematics (as usually done in simulations) agree well with those obtained using a photometric bulge/disc/bar decomposition (as done in observations). To perform such a comparison, we produced synthetic observations of the simulation outputs with the Monte-Carlo radiative transfer code SUNRISE and used the BUDDA code to make 2D photometric decompositions of the resulting images. We find that the kinematic disc-to-total ratio (D/T) estimates are systematically and significantly lower than the photometric ones. While the maximum D/T ratios obtained with the former method are of the order of 0.2, they are typically >0.4, and can be as high as 0.7, according to the latter. The photometric decomposition shows ...

  2. Bulge-Disk Decompositions and Structural Bimodality of Ursa Major Cluster Spiral Galaxies

    CERN Document Server

    McDonald, Michael; Tully, R Brent

    2008-01-01

    We present bulge and disk (B/D) decompositions of existing K'-band surface brightness profiles for 65 Ursa Major cluster spiral galaxies. This improves upon the disk-only fits of Tully et al. (1996). The 1996 disk fits were used by Tully & Verheijen (1997) for their discovery of the bimodality of structural parameters in the UMa cluster galaxies. It is shown that our new 1D B/D decompositions yield disk structural parameters that differ only slightly from the basic fits of Tully et al. and evidence for structural bimodality of UMa galaxies is maintained. Our B/D software for the decomposition of 1D surface brightness profiles of galaxies uses a non-linear minimization scheme to recover the best fitting Sersic bulge and exponential disk while accounting for the possible presence of a compact nucleus and spiral arms and for the effects of seeing and disk truncations. In agreement with Tully & Verheijen, we find that the distribution of near-infrared disk central surface brightnesses is bimodal with an F...

  3. Bulge-disc decompositions and structural bimodality of Ursa Major cluster spiral galaxies

    Science.gov (United States)

    McDonald, Michael; Courteau, Stéphane; Tully, R. Brent

    2009-02-01

    We present bulge and disc (B/D) decompositions of existing K' surface brightness profiles for 65 Ursa Major (UMa) cluster spiral galaxies. This improves upon the disc-only fits of Tully et al. The 1996 disc fits were used by Tully & Verheijen for their discovery of the bimodality of structural parameters in the UMa cluster galaxies. It is shown that our new one-dimensional B/D decompositions yield disc structural parameters that differ only slightly from the basic fits of Tully et al. and evidence for structural bimodality of UMa galaxies is maintained. Our B/D software for the decomposition of one-dimensional surface brightness profiles of galaxies uses a non-linear minimization scheme to recover the best-fitting Sérsic bulge and the exponential disc while accounting for the possible presence of a compact nucleus and spiral arms and for the effects of seeing and disc truncations. In agreement with Tully & Verheijen, we find that the distribution of near-infrared disc central surface brightnesses is bimodal with an F-test confidence of 80 per cent. There is also strong evidence for a local minimum in the luminosity function at . A connection between the brightness bimodality and a dynamical bimodality, based on new HI linewidths, is identified. The B/D parameters are presented in Table 1.

  4. TR3 is preferentially expressed by bulge epithelial stem cells in human hair follicles

    Science.gov (United States)

    Xie, Lin; Yang, Ruifeng; Liu, Shujing; Lyle, Stephen; Cotsarelis, George; Xiang, Leihong; Zhang, Litao; Li, Bin; Wan, Miaojian; Xu, Xiaowei

    2016-01-01

    TR3 is an orphan member of the steroid/thyroid/retinoid nuclear receptor superfamily of transcription factors and it plays a pivotal role in regulating cell growth and apoptosis. The expression and function of TR3 in skin have not been well investigated. Using a cDNA expression assay, we discover that TR3 is significantly enriched in human telogen bulge compared with anagen bulb. Immunohistochemical staining confirms that TR3 is highly expressed in the bulge region of human hair follicles and it colocalizes with cytokeratin 15 (K15), an epithelial stem cell marker. To study the function of TR3 in the effect of androgens in keratinocytes, we treat HaCaT keratinocytes and primary human keratinocytes with dihydrotestosterone (DHT) and testosterone (T). The treated keratinocytes show a dose-dependent growth reduction to DHT and T. DHT increases the expression of TR3 in keratinocytes, associated with a concomitant increase of BAD and decrease of Bcl-2 expression. Knockdown TR3 expression by siRNA blocks the inhibitory effect of DHT on keratinocyte proliferation. Our results demonstrate that TR3 is localized to the stem cell compartment in the human hair follicles. Androgen increases TR3 expression in cultured keratinocytes. Our data suggest that TR3 mediates at least part of the inhibitory effect of androgens on keratinocytes. PMID:26707825

  5. High-resolution mapping of dust via extinction in the M31 bulge

    Science.gov (United States)

    Dong, Hui; Li, Zhiyuan; Wang, Q. D.; Lauer, Tod R.; Olsen, Knut A. G.; Saha, Abhijit; Dalcanton, Julianne J.; Groves, Brent A.

    2016-06-01

    We map the dust distribution in the central 180 arcsec (˜680 pc) region of the M31 bulge, based on HST WFC3 and ACS observations in ten bands from near-ultraviolet (2700 Å) to near-infrared (1.5 μm). This large wavelength coverage gives us great leverage to detect not only dense dusty clumps, but also diffuse dusty molecular gas. We fit a pixel-by-pixel spectral energy distributions to construct a high-dynamic-range extinction map with unparalleled angular resolution (˜0.5 arcsec, i.e. ˜2 pc) and sensitivity (the extinction uncertainty, δAV ˜ 0.05). In particular, the data allow to directly fit the fractions of starlight obscured by individual dusty clumps, and hence their radial distances in the bulge. Most of these clumps seem to be located in a thin plane, which is tilted with respect to the M31 disc and appears face-on. We convert the extinction map into a dust mass surface density map and compare it with that derived from the dust emission as observed by Herschel. The dust masses in these two maps are consistent with each other, except in the low-extinction regions, where the mass inferred from the extinction tends to be underestimated. Further, we use simulations to show that our method can be used to measure the masses of dusty clumps in Virgo cluster early-type galaxies to an accuracy within a factor of ˜2.

  6. GHOSTS | Bulges, Halos, and the Resolved Stellar Outskirts of Massive Disk Galaxies

    Science.gov (United States)

    de Jong, R. S.; Radburn-Smith, D. J.; Sick, J. N.

    2008-10-01

    In hierarchical galaxy formation the stellar halos of galaxies are formed by the accretion of minor satellites and therefore contain valuable information about the (early) assembly process of galaxies. Our GHOSTS survey measures the stellar envelope properties of 14 nearby disk galaxies by imaging their resolved stellar populations with HST/ACS and WFPC2. Most of the massive galaxies in the sample (V_{rot}>200 km s^{-1}) have very extended stellar envelopes with μ(r) ˜ r^{-2.5} power law profiles in the outer regions. For these massive galaxies there is some evidence that the stellar surface density of the profiles correlates with Hubble type and bulge-to-disk ratio, begging the question whether these envelopes are more related to bulges than to a Milky Way-type stellar halo. Smaller galaxies (V_{rot}˜100 km s^{-1}) have much smaller stellar envelopes, but depending on geometry, they could still be more luminous than expected from satellite remnants in hierarchical galaxy formation models. Alternatively, they could be created by disk heating through the bombardment of small dark matter sub-halos. We find that galaxies show varying amounts of halo substructure.

  7. GHOSTS | Bulges, Halos, and the Resolved Stellar Outskirts of Massive Disk Galaxies

    CERN Document Server

    de Jong, Roelof S; Sick, Jonathan N

    2007-01-01

    In hierarchical galaxy formation the stellar halos of galaxies are formed by the accretion of minor satellites and therefore contain valuable information about the (early) assembly process of galaxies. Our GHOSTS survey measures the stellar envelope properties of 14 nearby disk galaxies by imaging their resolved stellar populations with HST/ACS&WFPC2. Most of the massive galaxies in the sample (Vrot>200 km/s) have very extended stellar envelopes with mu(r) ~ r^{-2.5} power law profiles in the outer regions. For these massive galaxies there is some evidence that the stellar surface density of the profiles correlates with Hubble type and bulge-to-disk ratio, begging the question whether these envelopes are more related to bulges than to a Milky Way-type stellar halo. Smaller galaxies (Vrot 100 km/s) have much smaller stellar envelopes, but depending on geometry, they could still be more luminous than expected from satellite remnants in hierarchical galaxy formation models. Alternatively, they could be creat...

  8. THE BULGE RADIAL VELOCITY ASSAY (BRAVA). II. COMPLETE SAMPLE AND DATA RELEASE

    International Nuclear Information System (INIS)

    We present new radial velocity measurements from the Bulge Radial Velocity Assay, a large-scale spectroscopic survey of M-type giants in the Galactic bulge/bar region. The sample of ∼4500 new radial velocities, mostly in the region –10° < l < +10° and b ≈ –6°, more than doubles the existent published data set. Our new data extend our rotation curve and velocity dispersion profile to +20°, which is ∼2.8 kpc from the Galactic center. The new data confirm the cylindrical rotation observed at –6° and –8° and are an excellent fit to the Shen et al. N-body bar model. We measure the strength of the TiOε molecular band as a first step toward a metallicity ranking of the stellar sample, from which we confirm the presence of a vertical abundance gradient. Our survey finds no strong evidence of previously unknown kinematic streams. We also publish our complete catalog of radial velocities, photometry, TiO band strengths, and spectra, which is available at the Infrared Science Archive as well as at UCLA.

  9. On the kinematic separation of field and cluster stars across the bulge globular NGC 6528

    Energy Technology Data Exchange (ETDEWEB)

    Lagioia, E. P.; Bono, G.; Buonanno, R. [Dipartimento di Fisica, Università degli Studi di Roma-Tor Vergata, via della Ricerca Scientifica 1, I-00133 Roma (Italy); Milone, A. P. [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Stetson, P. B. [Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Prada Moroni, P. G. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); Dall' Ora, M. [INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy); Aparicio, A.; Monelli, M. [Instituto de Astrofìsica de Canarias, E-38200 La Laguna, Tenerife, Canary Islands (Spain); Calamida, A.; Ferraro, I.; Iannicola, G. [INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00044 Monte Porzio Catone (Italy); Gilmozzi, R. [European Southern Observatory, Karl-Schwarzschild-Straße 2, D-85748 Garching (Germany); Matsunaga, N. [Kiso Observatory, Institute of Astronomy, School of Science, The University of Tokyo, 10762-30, Mitake, Kiso-machi, Kiso-gun, 3 Nagano 97-0101 (Japan); Walker, A., E-mail: eplagioia@roma2.infn.it [Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena (Chile)

    2014-02-10

    We present deep and precise multi-band photometry of the Galactic bulge globular cluster NGC 6528. The current data set includes optical and near-infrared images collected with ACS/WFC, WFC3/UVIS, and WFC3/IR on board the Hubble Space Telescope. The images cover a time interval of almost 10 yr, and we have been able to carry out a proper-motion separation between cluster and field stars. We performed a detailed comparison in the m {sub F814W}, m {sub F606W} – m {sub F814W} color-magnitude diagram with two empirical calibrators observed in the same bands. We found that NGC 6528 is coeval with and more metal-rich than 47 Tuc. Moreover, it appears older and more metal-poor than the super-metal-rich open cluster NGC 6791. The current evidence is supported by several diagnostics (red horizontal branch, red giant branch bump, shape of the sub-giant branch, slope of the main sequence) that are minimally affected by uncertainties in reddening and distance. We fit the optical observations with theoretical isochrones based on a scaled-solar chemical mixture and found an age of 11 ± 1 Gyr and an iron abundance slightly above solar ([Fe/H] = +0.20). The iron abundance and the old cluster age further support the recent spectroscopic findings suggesting a rapid chemical enrichment of the Galactic bulge.

  10. The VST Photometric Halpha Survey of the Southern Galactic Plane and Bulge (VPHAS+)

    CERN Document Server

    Drew, J E; Greimel, R; Irwin, M J; Yoldas, A Kupcu; Lewis, J; Barentsen, G; Eisloeffel, J; Farnhill, H J; Martin, W E; Walsh, J R; Walton, N A; Mohr-Smith, M; Raddi, R; Sale, S E; Wright, N J; Groot, P; Barlow, M J; Corradi, R L M; Drake, J J; Fabregat, J; Frew, D J; Gaensicke, B T; Knigge, C; Mampaso, A; Morris, R A H; Naylor, T; Parker, Q A; Phillipps, S; Ruhland, C; Steeghs, D; Unruh, Y C; Vink, J S; Wesson, R; Zijlstra, A A

    2014-01-01

    The VST Photometric Halpha Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying the southern Milky Way in u, g, r, i and Halpha at 1 arcsec angular resolution. Its footprint spans the Galactic latitude range -5 < b < +5 at all longitudes south of the celestial equator. Extensions around the Galactic Centre to Galactic latitudes +/-10 bring in much of the Galactic Bulge. This ESO public survey, begun on 28th December 2011, reaches down to 20th magnitude (10-sigma) and will provide single-epoch digital optical photometry for around 300 million stars. The observing strategy and data pipelining is described, and an appraisal of the segmented narrowband Halpha filter in use is presented. Using model atmospheres and library spectra, we compute main-sequence (u - g), (g - r), (r - i) and (r - Halpha) stellar colours in the Vega system. We report on a preliminary validation of the photometry using test data obtained from two pointings overlapping the Sloan Digital Sky Survey. An example of the ...

  11. Looking for imprints of the first stellar generations in metal-poor bulge field stars

    CERN Document Server

    Siqueira-Mello, C; Barbuy, B; Freeman, K; Ness, M; Depagne, E; Cantelli, E; Pignatari, M; Hirschi, R; Frischknecht, U; Meynet, G; Maeder, A

    2016-01-01

    Context. Efforts to look for signatures of the first stars have concentrated on metal-poor halo objects. However, the low end of the bulge metallicity distribution has been shown to host some of the oldest objects in the Milky Way and hence this Galactic component potentially offers interesting targets to look at imprints of the first stellar generations. As a pilot project, we selected bulge field stars already identified in the ARGOS survey as having [Fe/H] ~ -1 and oversolar [alpha/Fe] ratios, and we used FLAMES-UVES to obtain detailed abundances of key elements that are believed to reveal imprints of the first stellar generations. Aims. The main purpose of this study is to analyse selected ARGOS stars using new high-resolution (R~45,000) and high-signal-to-noise (S/N >100) spectra. We aim to derive their stellar parameters and elemental ratios, in particular the abundances of C, N, the alpha-elements O, Mg, Si, Ca, and Ti, the odd-Z elements Na and Al, the neutron-capture s-process dominated elements Y, Z...

  12. Population synthesis of ultracompact X-ray binaries in the Galactic Bulge

    CERN Document Server

    van Haaften, L M; Voss, R; Toonen, S; Zwart, S F Portegies; Yungelson, L R; van der Sluys, M V

    2013-01-01

    [abridged] Aims. We model the number and properties of ultracompact X-ray binaries (UCXBs) in the Galactic Bulge. The objective is to learn about the formation of UCXBs and their evolution, such as the onset of mass transfer and late-time behavior. Methods. The binary population synthesis code SeBa and stellar evolutionary tracks are used to model the UCXB population. The luminosity behavior of UCXBs is predicted using long-term X-ray observations of the known UCXBs and the thermal-viscous disk instability model. Results. In our model, the majority of UCXBs initially have a helium burning star donor. In the absence of a mechanism that destroys old UCXBs, we predict (0.2 - 1.9) x 10^5 UCXBs in the Galactic Bulge, mostly at orbital periods longer than 60 min (a large number of long-period systems also follows from the observed short-period UCXB population). About 5 - 50 UCXBs should be brighter than 10^35 erg/s, mostly persistent sources with orbital periods shorter than 30 min and with degenerate helium and ca...

  13. From Discs to Bulges: effect of mergers on the morphology of galaxies

    CERN Document Server

    Kannan, Rahul; Fontanot, Fabio; Moster, Benjamin P; Karman, Wouter; Somerville, Rachel S

    2015-01-01

    We study the effect of mergers on the morphology of galaxies by means of the simulated merger tree approach first proposed by Moster et al. This method combines N-body cosmological simulations and semi-analytic techniques to extract realistic initial conditions for galaxy mergers. These are then evolved using high resolution hydrodynamical simulations, which include dark matter, stars, cold gas in the disc and hot gas in the halo. We show that the satellite mass accretion is not as effective as previously thought, as there is substantial stellar stripping before the final merger. The fraction of stellar disc mass transferred to the bulge is quite low, even in the case of a major merger, mainly due to the dispersion of part of the stellar disc mass into the halo. We confirm the findings of Hopkins et al., that a gas rich disc is able to survive major mergers more efficiently. The enhanced star formation associated with the merger is not localised to the bulge of galaxy, but a substantial fraction takes place i...

  14. Galaxy Bulge Formation: Interplay with Dark Matter Halo and Central Supermassive Black Hole

    CERN Document Server

    Xu, B X; Zhao, H S; Xu, Bing-Xiao; Wu, Xue-Bing; Zhao, HongSheng

    2007-01-01

    We present a simple scenario where the formation of galactic bulges was regulated by the dark halo gravity and regulated the growth of the central supermassive black hole. Assuming the angular momentum is low, we suggest that bulges form in a runaway collapse due to the "gravothermal" instability once the central gas density or pressure exceeds certain threshold (Xu & Zhao 2007). We emphasize that the threshold is nearly universal, set by the background NFW dark matter gravity $g_{DM} \\sim 1.2 \\times 10^{-8}{\\rm cm} {\\rm sec}^{-2}$ in the central cusps of halos. Unlike known thresholds for gradual formation of galaxy disks, we show that the universal "halo-regulated" star formation threshold for spheroids matches the very high star formation rate and star formation efficiency shown in high-redshift observations of central starburst regions. The starburst feedback also builds up a pressure shortly after the collapse. This large pressure could both act outward to halt further infall of gas from larger scale...

  15. High-Resolution Mapping of Dust via Extinction in the M31 Bulge

    CERN Document Server

    Dong, Hui; Wang, Q D; Lauer, Tod R; Olsen, Knut A G; Saha, Abhijit; Dalcanton, Julianne J; Groves, Brent A

    2016-01-01

    We map the dust distribution in the central 180" (~680 pc) region of the M31 bulge, based on HST/WFC3 and ACS observations in ten bands from near-ultraviolet (2700 A) to near-infrared (1.5 micron). This large wavelength coverage gives us great leverage to detect not only dense dusty clumps, but also diffuse dusty molecular gas. We fit a pixel-by-pixel spectral energy distributions to construct a high-dynamic-range extinction map with unparalleled angular resolution (~0.5" , i.e., ~2 pc) and sensitivity (the extinction uncertainty, \\delta A_V~0.05). In particular, the data allow to directly fit the fractions of starlight obscured by individual dusty clumps, and hence their radial distances in the bulge. Most of these clumps seem to be located in a thin plane, which is tilted with respect to the M31 disk and appears face-on. We convert the extinction map into a dust mass surface density map and compare it with that derived from the dust emission as observed by Herschel . The dust masses in these two maps are co...

  16. The Panchromatic Hubble Andromeda Treasury I: Bright UV Stars in the Bulge of M31

    CERN Document Server

    Rosenfield, Philip; Girardi, Léo; Dalcanton, Julianne J; Bressan, Alessandro; Lang, Dustin; Williams, Benjamin F; Guhathakurta, Puragra; Howley, Kirsten M; Lauer, Tod R; Bell, Eric F; Bianchi, Luciana; Caldwell, Nelson; Dolphin, Andrew; Dorman, Claire E; Gilbert, Karoline M; Kalirai, Jason; Larsen, Søren S; Olsen, Knut A G; Rix, Hans-Walter; Seth, Anil C; Skillman, Evan D; Weisz, Daniel R

    2012-01-01

    As part of the Panchromatic Hubble Andromeda Treasury (PHAT) multi-cycle program, we observed a 12' \\times 6.5' area of the bulge of M31 with the WFC3/UVIS filters F275W and F336W. From these data we have assembled a sample of \\sim4000 UV-bright, old stars, vastly larger than previously available. We use updated Padova stellar evolutionary tracks to classify these hot stars into three classes: Post-AGB stars (P-AGB), Post-Early AGB (PE-AGB) stars and AGB-manqu\\'e stars. P-AGB stars are the end result of the asymptotic giant branch (AGB) phase and are expected in a wide range of stellar populations, whereas PE-AGB and AGB-manqu\\'e (together referred to as the hot post-horizontal branch; HP-HB) stars are the result of insufficient envelope masses to allow a full AGB phase, and are expected to be particularly prominent at high helium or {\\alpha} abundances when the mass loss on the RGB is high. Our data support previous claims that most UV-bright sources in the bulge are likely hot (extreme) horizontal branch st...

  17. Novel scanning electron microscope bulge test technique integrated with loading function

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuanwei; Xie, Huimin, E-mail: liuzw@bit.edu.cn, E-mail: xiehm@mail.tsinghua.edu.cn [AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Liu, Zhanwei, E-mail: liuzw@bit.edu.cn, E-mail: xiehm@mail.tsinghua.edu.cn [School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2014-10-15

    Membranes and film-on-substrate structures are critical elements for some devices in electronics industry and for Micro Electro Mechanical Systems devices. These structures are normally at the scale of micrometer or even nanometer. Thus, the measurement for the mechanical property of these membranes poses a challenge over the conventional measurements at macro-scales. In this study, a novel bulge test method is presented for the evaluation of mechanical property of micro thin membranes. Three aspects are discussed in the study: (a) A novel bulge test with a Scanning Electron Microscope system realizing the function of loading and measuring simultaneously; (b) a simplified Digital Image Correlation method for a height measurement; and (c) an imaging distortion correction by the introduction of a scanning Moiré method. Combined with the above techniques, biaxial modulus as well as Young's modulus of the polyimide film can be determined. Besides, a standard tensile test is conducted as an auxiliary experiment to validate the feasibility of the proposed method.

  18. Variations of the selective extinction across the galactic bulge implications for the galactic bar

    CERN Document Server

    Wozniak, P R

    1995-01-01

    We propose a new method to investigate the coefficient of the selective extinction, based on two band photometry. This method uses red clump stars as a means to construct the reddening curve. We apply this method to the OGLE color-magnitude diagrams to investigate the variations of the selective extinction towards various parts of the Galactic bulge. We find that A_{_V}/E_{_{V-I}} coefficient is within the errors the same for l=\\pm 5\\deg OGLE fields. Therefore, the difference of \\sim 0.37\\;mag in the extinction adjusted apparent magnitude of the red clump stars in these fields (Stanek et al.~1994, 1995) cannot be assigned to a large-scale gradient of the selective extinction coefficient. This strengthens the implication of this difference as indicator of the presence of the bar in our Galaxy. However using present data we cannot entirely exclude the possibility of \\sim 0.2\\;mag/mag variations of the selective extinction coefficient on the large scales across the bulge.

  19. Deformation Characterization of Friction-Stir-Welded Tubes by Hydraulic Bulge Testing

    Science.gov (United States)

    Pang, Q.; Hu, Z. L.; Pan, X.; Zuo, X. Q.

    2014-10-01

    In this article, the large-diameter thin-walled aluminum alloy tubes were produced using a hybrid process combining friction-stir welding (FSW) and spinning. For this novel process, rolled aluminum alloy sheets with a thickness about 2-3 times the wall thickness of target tube, were FSW to form cylinders, and then the cylinders were subjected to spinning to get thin-walled aluminum alloy tubes. Both experimental and simulation study were conducted to investigate the deformation characterization of the FSW tube during hydraulic bulge testing, and the stress and strain states and thickness distribution of the FSW tube were investigated. It was found that the common defects of FSW tube can be significantly improved by specific welding devices. The ductility of the tube is considerably improved with nearly two times higher bulge ratio than as-spun tube after annealing treatment at 300°C. But the annealed tube still shows a high nonuniform wall thickness distribution due to the inhomogeneous deformation characteristics. With increasing deformation of the tube, the gap between the hoop and axial stress for the weld and base metal (BM) decreases. However, the hoop and axial stress of the weld are always greater than those of the BM at the same pressure.

  20. Stochastic non-circular motion and outflows driven by magnetic activity in the Galactic bulge region

    Science.gov (United States)

    Suzuki, Takeru K.; Fukui, Yasuo; Torii, Kazufumi; Machida, Mami; Matsumoto, Ryoji

    2015-12-01

    By performing a global magnetohydrodynamical simulation for the Milky Way with an axisymmetric gravitational potential, we propose that spatially dependent amplification of magnetic fields possibly explains the observed noncircular motion of the gas in the Galactic centre region. The radial distribution of the rotation frequency in the bulge region is not monotonic in general. The amplification of the magnetic field is enhanced in regions with stronger differential rotation, because magnetorotational instability and field-line stretching are more effective. The strength of the amplified magnetic field reaches ≳0.5 mG, and radial flows of the gas are excited by the inhomogeneous transport of angular momentum through turbulent magnetic field that is amplified in a spatially dependent manner. In addition, the magnetic pressure-gradient force also drives radial flows in a similar manner. As a result, the simulated position-velocity diagram exhibits a time-dependent asymmetric parallelogram-shape owing to the intermittency of the magnetic turbulence; the present model provides a viable alternative to the bar-potential-driven model for the parallelogram shape of the central molecular zone. This is a natural extension into the central few 100 pc of the magnetic activity, which is observed as molecular loops at radii from a few 100 pc to 1 kpc. Furthermore, the time-averaged net gas flow is directed outward, whereas the flows are highly time dependent, which we discuss from a viewpoint of the outflow from the bulge.

  1. Dynamics and thermodynamics of water

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Pradeep; Stanley, H Eugene [Center for Studies in Physics and Biology, Rockefeller University, New York, NY 10021 (United States); Franzese, Giancarlo [Departament de Fisica Fonamental, Universitat de Barcelona, Diagonal 647, Barcelona 08028 (Spain)], E-mail: pradeep.kumar@rockefeller.edu, E-mail: gfranzese@ub.edu, E-mail: hes@bu.edu

    2008-06-18

    On decreasing the temperature T, the correlation time {tau} of supercooled water displays a dynamic crossover from non-Arrhenius dynamics (with T-dependent activation energy) at high T to Arrhenius dynamics (with constant activation energy) at low T. Simulations for water models show that this crossover occurs at the locus of maximum isobaric specific heat in the pressure-temperature (P-T) plane. Results of simulations show also that at this locus there is a sharp change of local structure: more tetrahedral below the locus, and less tetrahedral above it. Furthermore, in water solutions with proteins or DNA, simulations show that in correspondence with this locus there is a crossover in the dynamics of the biomolecules, a phenomenon commonly known as the protein glass transition. To clarify the relation of the dynamic crossover with the thermodynamics of water, we study the dynamics of a cell model of water which can be tuned to exhibit: (1) a first-order phase transition line that separates the liquids of high and low densities at low temperatures; this phase transition line terminates at a liquid-liquid critical point (LLCP), from which departs the Widom line T{sub W}(P), i.e. the line of maximum isobaric specific heat in the P-T plane; (2) the singularity-free (SF) scenario, under which the system exhibits water-like anomalies but with no finite temperature liquid-liquid critical point. We find that the dynamic crossover is present in both the LLCP and the SF cases. Moreover, on the basis of the study of the probability p{sub B} of forming a bond, we propose and verify a relation between dynamics and thermodynamics that is able to show how the crossover is a consequence of a local relaxation process associated with breaking a bond and reorienting the molecule. We further find a distinct difference in pressure dependence of the dynamic crossover between the LLCP and SF scenarios, which may help in resolving which of the scenarios correctly explains the anomalous

  2. Dynamics and thermodynamics of water

    International Nuclear Information System (INIS)

    On decreasing the temperature T, the correlation time τ of supercooled water displays a dynamic crossover from non-Arrhenius dynamics (with T-dependent activation energy) at high T to Arrhenius dynamics (with constant activation energy) at low T. Simulations for water models show that this crossover occurs at the locus of maximum isobaric specific heat in the pressure-temperature (P-T) plane. Results of simulations show also that at this locus there is a sharp change of local structure: more tetrahedral below the locus, and less tetrahedral above it. Furthermore, in water solutions with proteins or DNA, simulations show that in correspondence with this locus there is a crossover in the dynamics of the biomolecules, a phenomenon commonly known as the protein glass transition. To clarify the relation of the dynamic crossover with the thermodynamics of water, we study the dynamics of a cell model of water which can be tuned to exhibit: (1) a first-order phase transition line that separates the liquids of high and low densities at low temperatures; this phase transition line terminates at a liquid-liquid critical point (LLCP), from which departs the Widom line TW(P), i.e. the line of maximum isobaric specific heat in the P-T plane; (2) the singularity-free (SF) scenario, under which the system exhibits water-like anomalies but with no finite temperature liquid-liquid critical point. We find that the dynamic crossover is present in both the LLCP and the SF cases. Moreover, on the basis of the study of the probability pB of forming a bond, we propose and verify a relation between dynamics and thermodynamics that is able to show how the crossover is a consequence of a local relaxation process associated with breaking a bond and reorienting the molecule. We further find a distinct difference in pressure dependence of the dynamic crossover between the LLCP and SF scenarios, which may help in resolving which of the scenarios correctly explains the anomalous behavior of

  3. Practical Chemical Thermodynamics for Geoscientists

    CERN Document Server

    Fegley, Jr, Bruce

    2012-01-01

    Practical Chemical Thermodynamics for Geoscientists covers classical chemical thermodynamics and focuses on applications to practical problems in the geosciences, environmental sciences, and planetary sciences. This book will provide a strong theoretical foundation for students, while also proving beneficial for earth and planetary scientists seeking a review of thermodynamic principles and their application to a specific problem. Strong theoretical foundation and emphasis on applicationsNumerous worked examples in each chapterBrief historical summaries and biographies of key thermodynamicist

  4. On thermodynamic and microscopic reversibility

    Energy Technology Data Exchange (ETDEWEB)

    Crooks, Gavin E.

    2011-07-12

    The word 'reversible' has two (apparently) distinct applications in statistical thermodynamics. A thermodynamically reversible process indicates an experimental protocol for which the entropy change is zero, whereas the principle of microscopic reversibility asserts that the probability of any trajectory of a system through phase space equals that of the time reversed trajectory. However, these two terms are actually synonymous: a thermodynamically reversible process is microscopically reversible, and vice versa.

  5. Thermodynamic Limit for Polydisperse Fluids

    OpenAIRE

    Banerjee, S.; Griffiths, R. B.; Widom, M.

    2000-01-01

    We examine the thermodynamic limit of fluids of hard core particles that are polydisperse in size and shape. In addition, particles may interact magnetically. Free energy of such systems is a random variable because it depends on the choice of particles. We prove that the thermodynamic limit exists with probability 1, and is independent of the choice of particles. Our proof applies to polydisperse hard-sphere fluids, colloids and ferrofluids. The existence of a thermodynamic limit implies sys...

  6. Gravitation, Thermodynamics, and Quantum Theory

    OpenAIRE

    Wald, Robert M.

    1999-01-01

    During the past 30 years, research in general relativity has brought to light strong hints of a very deep and fundamental relationship between gravitation, thermodynamics, and quantum theory. The most striking indication of such a relationship comes from black hole thermodynamics, where it appears that certain laws of black hole mechanics are, in fact, simply the ordinary laws of thermodynamics applied to a system containing a black hole. This article will review the present status of black h...

  7. The Black Hole Mass-Bulge Luminosity Relationship for Active Galactic Nuclei From Reverberation Mapping and Hubble Space Telescope Imaging

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Peterson, Bradley M.; Pogge, Richard W.;

    2009-01-01

    We investigate the relationship between black hole mass and bulge luminosity for active galactic nuclei (AGNs) with reverberation-based black hole mass measurements and bulge luminosities from two-dimensional decompositions of Hubble Space Telescope host galaxy images. We find that the slope...... of the relationship for AGNs is 0.76-0.85 with an uncertainty of ~0.1, somewhat shallower than the M BH vprop L 1.0±0.1 relationship that has been fit to nearby quiescent galaxies with dynamical black hole mass measurements. This difference is somewhat perplexing, as the AGN black hole masses include an overall...

  8. Molecular thermodynamics of nonideal fluids

    CERN Document Server

    Lee, Lloyd L

    2013-01-01

    Molecular Thermodynamics of Nonideal Fluids serves as an introductory presentation for engineers to the concepts and principles behind and the advances in molecular thermodynamics of nonideal fluids. The book covers related topics such as the laws of thermodynamics; entropy; its ensembles; the different properties of the ideal gas; and the structure of liquids. Also covered in the book are topics such as integral equation theories; theories for polar fluids; solution thermodynamics; and molecular dynamics. The text is recommended for engineers who would like to be familiarized with the concept

  9. Thermodynamics of Accelerating Black Holes

    CERN Document Server

    Appels, Michael; Kubiznak, David

    2016-01-01

    We address a long-standing problem of describing the thermodynamics of a charged accelerating black hole. We derive a standard first law of black hole thermodynamics, with the usual identification of entropy proportional to the area of the event horizon -- even though the event horizon contains a conical singularity. This result not only extends the applicability of black hole thermodynamics to realms previously not anticipated, it also opens a possibility for studying novel properties of an important class of exact radiative solutions of Einstein equations describing accelerated objects. We discuss the thermodynamic volume, stability and phase structure of these black holes.

  10. Experimental approaches to membrane thermodynamics

    DEFF Research Database (Denmark)

    Westh, Peter

    2009-01-01

    Thermodynamics describes a system on the macroscopic scale, yet it is becoming an important tool for the elucidation of many specific molecular aspects of membrane properties. In this note we discuss this application of thermodynamics, and give a number of examples on how thermodynamic measurements...... have contributed to the understanding of specific membrane phenomena. We mainly focus on non-specific interactions of bilayers and small molecules (water and solutes) in the surrounding solvent, and the changes in membrane properties they bring about. Differences between thermodynamic and...

  11. Charm Quark Thermodynamics

    International Nuclear Information System (INIS)

    Full text: Recently, the question of the charm quark contribution to the thermodynamics of the QGP has received some attention. In particular at the high temperatures that can be reached in heavy ion collisions at the LHC a better understanding the thermal contribution of charm to bulk thermodynamics will become relevant. Lattice QCD can provide an answer to this question, but fully dynamical, 4-flavor ensembles do not yet exist. The large charm quark mass also is expected to introduce additional cut-off effects. Nonetheless, as an exploratory study, we recently calculated the second-, fourth- and sixth-order susceptibilities for the charm quark in the partially quenched approximation using the p4 action. We found that our results were in good agreement with perturbative estimates for these quantities. We also studied correlations between charm and the lighter flavors. We compared these quantities to simple quasiparticle and resonance gas models. Lastly, we shall also comment on calculations of the charm's contribution to the pressure within the partially quenched approximation. (author)

  12. Dissipative work in thermodynamics

    International Nuclear Information System (INIS)

    This work explores the concept of dissipative work and shows that such a kind of work is an invariant non-negative quantity. This feature is then used to get a new insight into adiabatic irreversible processes; for instance, why the final temperature in any adiabatic irreversible process is always higher than that attained in a reversible process having the same initial state and equal final pressure or volume. Based on the concept of identical processes, numerical simulations of adiabatic irreversible compression and expansion were performed, enabling a better understanding of differences between configuration and dissipative work. The positive nature of the dissipative work was used to discuss the case where the dissipated energy ends up in the surroundings, while the invariance of such work under a system-surroundings interchange enabled the resulting modification in thermodynamical quantities to be determined. The ideas presented in this study are primarily intended for undergraduate students with a background in thermodynamics, but they may also be of interest to graduate students and teachers.

  13. Thermodynamic origin of life

    Directory of Open Access Journals (Sweden)

    K. Michaelian

    2010-03-01

    Full Text Available Understanding the thermodynamic function of life may shed light on its origin. Life, as are all irreversible processes, is contingent on entropy production. Entropy production is a measure of the rate of the tendency of Nature to explore available microstates. The most important irreversible process generating entropy in the biosphere and, thus, facilitating this exploration, is the absorption and transformation of sunlight into heat. Here we hypothesize that life began, and persists today, as a catalyst for the absorption and dissipation of sunlight on the surface of shallow seas. The resulting heat could then be efficiently harvested by other irreversible processes such as the water cycle, hurricanes, and ocean and wind currents. RNA and DNA are the most efficient of all known molecules for absorbing the intense ultraviolet light that penetrated the dense early atmosphere and are remarkably rapid in transforming this light into heat in the presence of liquid water. From this perspective, the origin and evolution of life, inseparable from water and the water cycle, can be understood as resulting from the natural thermodynamic imperative of increasing the entropy production of the Earth in its interaction with its solar environment. A mechanism is proposed for the reproduction of RNA and DNA without the need for enzymes, promoted instead through UV light dissipation and the ambient temperature conditions of prebiotic Earth.

  14. THERMODYNAMICS OF THE ACTINIDES

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, Burris B.

    1962-04-01

    Recent work on the thermodynamic properties of the transplutonium elements is presented and discussed in relation to trends in thermodynamic properties of the actinide series. Accurate values are given for room temperature lattice parameters of two crystallographic forms, (facecentred cubic) fcc and dhcp (double-hexagonal closepacked), of americium metal and for the coefficients of thermal expansion between 157 and 878 deg K (dhcp) and 295 to 633 deg K (fcc). The meiting point of the metal, and its magnetic susceptibility between 77 and 823 deg K are reported and the latter compared with theoretical values for the tripositive ion calculated from spectroscopic data. Similar data (crystallography, meiting point and magnetic susceptibility) are given for metallic curium. A value for the heat of formation of americium monoxide is reported in conjunction with crystallographic data on the monoxide and mononitride. A revision is made in the current value for the heat of formation of Am/O/sub 2/ and for the potential of the Am(III)-Am(IV) couple. The crystal structures and lattice parameters are reported for the trichloride, oxychloride and oxides of californium. (auth)

  15. Thermodynamics of geothermal fluids

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, P.S.Z.

    1981-03-01

    A model to predict the thermodynamic properties of geothermal brines, based on a minimum amount of experimental data on a few key systems, is tested. Volumetric properties of aqueous sodium chloride, taken from the literature, are represented by a parametric equation over the range 0 to 300{sup 0}C and 1 bar to 1 kbar. Density measurements at 20 bar needed to complete the volumetric description also are presented. The pressure dependence of activity and thermal properties, derived from the volumetric equation, can be used to complete an equation of state for sodium chloride solutions. A flow calorimeter, used to obtain heat capacity data at high temperatures and pressures, is described. Heat capacity measurements, from 30 to 200{sup 0}C and 1 bar to 200 bar, are used to derive values for the activity coefficient and other thermodynamic properties of sodium sulfate solutions as a function of temperature. Literature data on the solubility of gypsum in mixed electrolyte solutions have been used to evaluate model parameters for calculating gypsum solubility in seawater and natural brines. Predictions of strontium and barium sulfate solubility in seawater also are given.

  16. Thermodynamics of event horizons in (2+1)-dimensional gravity

    International Nuclear Information System (INIS)

    Although gravity in 2+1 dimensions is very different in nature from gravity in 3+1 dimensions, it is shown that the laws of thermodynamics for event horizons can be manifested also for (2+1)-dimensional gravity. The validity of the classical laws of horizon mechanics is verified in general and exemplified for the (2+1)-dimensional analogues of Reissner-Nordstroem and Schwarzschild--de Sitter spacetimes. We find that the entropy is given by 1/4L, where L is the length of the horizon. A consequence of having consistent thermodynamics is that the second law fixes the sign of Newton's constant to be positive

  17. "Diabetes Has Instant Consequences..."

    Science.gov (United States)

    ... please turn Javascript on. Feature: Diabetes Stories "Diabetes has instant consequences…" Past Issues / Fall 2009 Table of ... you want to chuck it all. But Diabetes has instant consequences. You learn to be responsible pretty ...

  18. CONSEQUENCES OF CORRUPTION

    OpenAIRE

    Drago, Kos

    2014-01-01

    In his paper Consequences of Corruption the author tries to find answers to the questions why corruption is considered to be harmful and whether it is possible to measure its consequences. The author manages to show that corruption has truly damaging effects, especially in the economic and social area and that some of the corruption effects (on investments, taxes, public expenditure, GDP growth, per capita GDP, school enrolment and life expectancy) can even be measured. Since there should not...

  19. Biochemical Thermodynamics under near Physiological Conditions

    Science.gov (United States)

    Mendez, Eduardo

    2008-01-01

    The recommendations for nomenclature and tables in Biochemical Thermodynamics approved by IUBMB and IUPAC in 1994 can be easily introduced after the chemical thermodynamic formalism. Substitution of the usual standard thermodynamic properties by the transformed ones in the thermodynamic equations, and the use of appropriate thermodynamic tables…

  20. Consequences of Accounting Standards

    Institute of Scientific and Technical Information of China (English)

    Cai Mingyue

    2009-01-01

    The first part of this article consists in attempting to highlight the importance of concerning about the economic consequences and introducing the foundation of economic consequence theory, proposing that the accounting standard is not only a kind of technical standard, it also has the economic consequences, so it becomes the object which all quarters special interest group gambles to get latent profit. After general characterization of the economic consequences in the second part, the article gives a description of the influences the change of accounting standards bring to the government, the ordinary investors and creditors, the auditors, and the enterprise, establishing a framework that how those groups react as the economic consequences in the third part. The fourth section compare technical theory and accounting standards theory, links the basic norms of accounting such as conservatism, relevance and reliability to the methods of escaping the harm of economic consequences, then proposes some specific methods in the formuhtion of accounting standard. Finally, the article utilizes the methods to settle the problems appearing in Chinese market.

  1. Thermodynamic solar plants

    International Nuclear Information System (INIS)

    The thermodynamic solar plants include all techniques aiming at converting the solar radiation into high temperature heat, and then at converting this heat into mechanical or electrical energy through a thermodynamic cycle connected to a power generator. The first step, capture of the solar radiation, requires the use of optical systems and, in most cases, the use of solar concentrators which allow to reach temperatures above 250 deg. C. The hybridization with another heat generation source (fossil or biomass) allows to increase the availability of the solar facilities. The heat is then converted into electricity using classical thermodynamic cycles with efficiencies ranging from 23% to 50%, and above in the case of combined cycles. The immediate efficiency of solar-electricity conversion is comprised between 20% and 30% depending on the technology implemented, and the investment costs are evaluated between 2800 euro/kWe (20-80 MWe plant with cylindro-parabolic collectors and Rankine cycle) and 4000 euro/KWe (40-200 MWe tower plant with combined cycles) but can reach 14000 euro/kWe in the case of a 10-25 kWe parabola-Stirling decentralized plant. The electricity cost ranges from 0.16 to 0.24 euro/kWhe for a big facility and is of about 0.30 euro/kWhe in the case of a parabola-Stirling plant (to be compared with 0.04 euro/kWe in the case of a nuclear power plant). The environmental impact of solar thermal electricity is lower than 20 kg CO2/MWhe and comparable to the impact of hydro or nuclear power (4 and 6 kg CO2/MWhe, respectively), but much lower than the impact of photovoltaic energy (100 kg CO2/MWhe) or coal combustion (900 kg CO2/MWhe). The time of return on energy (duration of plant operation to produce the energy needed for its fabrication) is of only 5 months and the lifetime of solar concentration facilities is estimated to 25-30 years. This article presents the state-of-the-art of solar plant technologies and their economic aspects (market penetration

  2. Thermodynamics from Car to Kitchen

    Science.gov (United States)

    Auty, Geoff

    2014-01-01

    The historical background to the laws of thermodynamics is explained using examples we can all observe in the world around us, focusing on motorised transport, refrigeration and solar heating. This is not to be considered as an academic article. The purpose is to improve understanding of thermodynamics rather than impart new knowledge, and for…

  3. Statistical Thermodynamics of Disperse Systems

    DEFF Research Database (Denmark)

    Shapiro, Alexander

    1996-01-01

    Principles of statistical physics are applied for the description of thermodynamic equilibrium in disperse systems. The cells of disperse systems are shown to possess a number of non-standard thermodynamic parameters. A random distribution of these parameters in the system is determined. On the...

  4. Thermodynamics of light and sound

    OpenAIRE

    Kremer, G. M.; Ingo Müller

    1991-01-01

    This paper presents a thermodynamic theory of light and sound. It demonstrates that extended thermodynamics permits the explicit calculation of the main part of the equations of balance of energy for photons and phonons. Wave speeds are calculated and the limiting cases of near-equilibrium and free streaming are discussed.

  5. The Thermodynamics of Black Holes

    Directory of Open Access Journals (Sweden)

    Wald Robert M.

    2001-01-01

    Full Text Available We review the present status of black hole thermodynamics. Our review includes discussion of classical black hole thermodynamics, Hawking radiation from black holes, the generalized second law, and the issue of entropy bounds. A brief survey also is given of approaches to the calculation of black hole entropy. We conclude with a discussion of some unresolved open issues.

  6. Thermodynamic study of selected monoterpenes

    Czech Academy of Sciences Publication Activity Database

    Štejfa, V.; Fulem, Michal; Růžička, K.; Červinka, C.; Rocha, M.A.A.; Santos, L.M.N.B.F.; Schröder, B.

    2013-01-01

    Roč. 60, MAY (2013), 117-125. ISSN 0021-9614 Institutional support: RVO:68378271 Keywords : monoterpenes * pinene * vapor pressure * heat capacity * vaporization and sublimation enthalpy * ideal-gas thermodynamic Subject RIV: BJ - Thermodynamics Impact factor: 2.423, year: 2013

  7. The Thermodynamics of Black Holes

    OpenAIRE

    Wald Robert M.

    1999-01-01

    We review the present status of black hole thermodynamics. Our review includes discussion of classical black hole thermodynamics, Hawking radiation from black holes, the generalized second law, and the issue of entropy bounds. A brief survey also is given of approaches to the calculation of black hole entropy. We conclude with a discussion of some unresolved open issues.

  8. THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. I. BRIGHT UV STARS IN THE BULGE OF M31

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfield, Philip; Johnson, L. Clifton; Dalcanton, Julianne J.; Williams, Benjamin F.; Gilbert, Karoline M. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Girardi, Leo [Osservatorio Astronomico di Padova-INAF, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Bressan, Alessandro [SISSA, Via Bonomea 265, 34136 Trieste (Italy); Lang, Dustin [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Guhathakurta, Puragra; Dorman, Claire E. [UCO/Lick Observatory and Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Howley, Kirsten M. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Lauer, Tod R.; Olsen, Knut A. G. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI 48109 (United States); Bianchi, Luciana [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Caldwell, Nelson [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street Cambridge, MA 02138 (United States); Dolphin, Andrew [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Kalirai, Jason [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Larsen, Soren S. [Astronomical Institute, University of Utrecht, Princetonplein 5, 3584 CC Utrecht (Netherlands); Rix, Hans-Walter [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); and others

    2012-08-20

    As part of the Panchromatic Hubble Andromeda Treasury multi-cycle program, we observed a 12' Multiplication-Sign 6.'5 area of the bulge of M31 with the WFC3/UVIS filters F275W and F336W. From these data we have assembled a sample of {approx}4000 UV-bright, old stars, vastly larger than previously available. We use updated Padova stellar evolutionary tracks to classify these hot stars into three classes: Post-AGB stars (P-AGB), Post-Early AGB (PE-AGB) stars, and AGB-manque stars. P-AGB stars are the end result of the asymptotic giant branch (AGB) phase and are expected in a wide range of stellar populations, whereas PE-AGB and AGB-manque (together referred to as the hot post-horizontal branch; HP-HB) stars are the result of insufficient envelope masses to allow a full AGB phase, and are expected to be particularly prominent at high helium or {alpha} abundances when the mass loss on the red giant branch is high. Our data support previous claims that most UV-bright sources in the bulge are likely hot (extreme) horizontal branch (EHB) stars and their progeny. We construct the first radial profiles of these stellar populations and show that they are highly centrally concentrated, even more so than the integrated UV or optical light. However, we find that this UV-bright population does not dominate the total UV luminosity at any radius, as we are detecting only the progeny of the EHB stars that are the likely source of the UV excess. We calculate that only a few percent of main-sequence stars in the central bulge can have gone through the HP-HB phase and that this percentage decreases strongly with distance from the center. We also find that the surface density of hot UV-bright stars has the same radial variation as that of low-mass X-ray binaries. We discuss age, metallicity, and abundance variations as possible explanations for the observed radial variation in the UV-bright population.

  9. THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. I. BRIGHT UV STARS IN THE BULGE OF M31

    International Nuclear Information System (INIS)

    As part of the Panchromatic Hubble Andromeda Treasury multi-cycle program, we observed a 12' × 6.'5 area of the bulge of M31 with the WFC3/UVIS filters F275W and F336W. From these data we have assembled a sample of ∼4000 UV-bright, old stars, vastly larger than previously available. We use updated Padova stellar evolutionary tracks to classify these hot stars into three classes: Post-AGB stars (P-AGB), Post-Early AGB (PE-AGB) stars, and AGB-manqué stars. P-AGB stars are the end result of the asymptotic giant branch (AGB) phase and are expected in a wide range of stellar populations, whereas PE-AGB and AGB-manqué (together referred to as the hot post-horizontal branch; HP-HB) stars are the result of insufficient envelope masses to allow a full AGB phase, and are expected to be particularly prominent at high helium or α abundances when the mass loss on the red giant branch is high. Our data support previous claims that most UV-bright sources in the bulge are likely hot (extreme) horizontal branch (EHB) stars and their progeny. We construct the first radial profiles of these stellar populations and show that they are highly centrally concentrated, even more so than the integrated UV or optical light. However, we find that this UV-bright population does not dominate the total UV luminosity at any radius, as we are detecting only the progeny of the EHB stars that are the likely source of the UV excess. We calculate that only a few percent of main-sequence stars in the central bulge can have gone through the HP-HB phase and that this percentage decreases strongly with distance from the center. We also find that the surface density of hot UV-bright stars has the same radial variation as that of low-mass X-ray binaries. We discuss age, metallicity, and abundance variations as possible explanations for the observed radial variation in the UV-bright population.

  10. Thermodynamics of Strong Interactions

    CERN Document Server

    Yukalov, V I

    1997-01-01

    The state of art in studying thermodynamic properties of hot and dense nuclear matter is reviewed with the special emphasis on the confinement-deconfinement transition between hadron matter and quark-gluon plasma. The most popular models used for describing deconfinement are analysed, including statistical bootstrap models, pure phase models, the model of clustered quarks, and the string-flip potential model. Predictions of these models are compared with the lattice numerical simulations. It is concluded that precursor fluctuation effects must be taken into account in order to get a realistic description of deconfinement transition. Deconfinement cannot be considered as a transition between pure hadron and quark-gluon phases. Quark-gluon plasma and hadron clusters are different quantum states of the same system, so that any statistical model pretending to treat nuclear matter under extreme conditions must incorporate the probability of these different channels.

  11. Thermodynamics of anisotropic branes

    CERN Document Server

    Ávila, Daniel; Patiño, Leonardo; Trancanelli, Diego

    2016-01-01

    We study the thermodynamics of flavor D7-branes embedded in an anisotropic black brane solution of type IIB supergravity. The flavor branes undergo a phase transition between a `Minkowski embedding', in which they lie outside of the horizon, and a `black hole embedding', in which they fall into the horizon. This transition depends on two independent dimensionless ratios, which are formed out of the black hole temperature, its anisotropy parameter, and the mass of the flavor degrees of freedom. It happens either at a critical temperature or at a critical anisotropy. A general lesson we learn from this analysis is that the anisotropy, in this particular realization, induces similar effects as the temperature. In particular, increasing the anisotropy bends the branes more and more into the horizon. Moreover, we observe that the transition becomes smoother for higher anisotropies.

  12. Thermodynamics and energy conversion

    CERN Document Server

    Struchtrup, Henning

    2014-01-01

    This textbook gives a thorough treatment of engineering thermodynamics with applications to classical and modern energy conversion devices.   Some emphasis lies on the description of irreversible processes, such as friction, heat transfer and mixing, and the evaluation of the related work losses. Better use of resources requires high efficiencies, therefore the reduction of irreversible losses should be seen as one of the main goals of a thermal engineer. This book provides the necessary tools.   Topics include: car and aircraft engines,  including Otto, Diesel and Atkinson cycles, by-pass turbofan engines, ramjet and scramjet;  steam and gas power plants, including advanced regenerative systems, solar tower, and compressed air energy storage; mixing and separation, including reverse osmosis, osmotic powerplants, and carbon sequestration; phase equilibrium and chemical equilibrium, distillation, chemical reactors, combustion processes, and fuel cells; the microscopic definition of entropy.    The book i...

  13. Thermodynamic Origin of Life

    CERN Document Server

    Michaelian, K

    2009-01-01

    Understanding the thermodynamic function of life may shed light on its origin. Out of equilibrium structuring in space and time is contingent on continuous entropy production. Entropy production is a measure of the rate of the natural tendency of Nature to explore all available microstates. The process producing the greatest amount of entropy in the biosphere is the absorption and transformation of sunlight, leading to the transpiration of water by plants and cyanobacteria. Here we hypothesize that life began, and exists today, as a dynamic catalyst for the absorption and transformation of sunlight into heat, which could then be efficiently harvested by the water cycle, hurricanes, and ocean and wind currents. RNA and DNA are the most efficient of all known molecules for absorbing the ultraviolet light that could have penetrated the dense early atmosphere, and are extremely rapid in transforming this light into heat that can be readily absorbed by liquid water. The origin and evolution of life was thus driven...

  14. Thermodynamics of Glass Melting

    Science.gov (United States)

    Conradt, Reinhard

    First, a model based on linear algebra is described by which the thermodynamic properties of industrial multi-component glasses and glass melts can be accurately predicted from their chemical composition. The model is applied to calculate the heat content of glass melts at high temperatures, the standard heat of formation of glasses from the elements, and the vapor pressures of individual oxides above the melt. An E-fiber glass composition is depicted as an example. Second, the role of individual raw materials in the melting process of E-glass is addressed, with a special focus on the decomposition kinetics and energetic situation of alkaline earth carriers. Finally, the heat of the batch-to-melt conversion is calculated. A simplified reaction path model comprising heat turnover, content of residual solid matter, and an approach to batch viscosity is outlined.

  15. Thermodynamics and cosmology

    International Nuclear Information System (INIS)

    A new type of cosmological history which includes large-scale entropy production is proposed. These cosmologies are based on a reinterpretation of the matter-energy stress tensor in Einsteins equations. This modifies the usual adiabatic energy conservation laws, thereby leading to a possible irreversible matter creation. This creation corresponds to an irreversible energy flow from the gravitational field to the created matter constituents. This new point of view results from the consideration of thermodynamics of open systems in the framework of cosmology. It appears that the usual initial singularity is structurally unstable with respect to irreversible matter creation. The corresponding cosmological history therefore starts from an instability of the vacuum rather than from a singularity. The universe evolves through an inflationary phase. This appears to be an attractor independent of the initial vacuum fluctuation

  16. Applied statistical thermodynamics

    CERN Document Server

    Lucas, Klaus

    1991-01-01

    The book guides the reader from the foundations of statisti- cal thermodynamics including the theory of intermolecular forces to modern computer-aided applications in chemical en- gineering and physical chemistry. The approach is new. The foundations of quantum and statistical mechanics are presen- ted in a simple way and their applications to the prediction of fluid phase behavior of real systems are demonstrated. A particular effort is made to introduce the reader to expli- cit formulations of intermolecular interaction models and to show how these models influence the properties of fluid sy- stems. The established methods of statistical mechanics - computer simulation, perturbation theory, and numerical in- tegration - are discussed in a style appropriate for newcom- ers and are extensively applied. Numerous worked examples illustrate how practical calculations should be carried out.

  17. A Hamiltonian approach to Thermodynamics

    CERN Document Server

    Baldiotti, M C; Molina, C

    2016-01-01

    In the present work we develop a strictly Hamiltonian approach to Thermodynamics. A thermodynamic description based on symplectic geometry is introduced, where all thermodynamic processes can be described within the framework of Analytic Mechanics. Our proposal is constructed ontop of a usual symplectic manifold, where phase space is even dimensional and one has well-defined Poisson brackets. The main idea is the introduction of an extended phase space where thermodynamic equations of state are realized as constraints. We are then able to apply the canonical transformation toolkit to thermodynamic problems. Throughout this development, Dirac's theory of constrained systems is extensively used. To illustrate the formalism, we consider paradigmatic examples, namely, the ideal, van der Waals and Clausius gases.

  18. Applied thermodynamics: A new frontier for biotechnology

    DEFF Research Database (Denmark)

    Mollerup, Jørgen

    2006-01-01

    The scientific career of one of the most outstanding scientists in molecular thermodynamics, Professor John M. Prausnitz at Berkeley, reflects the change in the agenda of molecular thermodynamics, from hydrocarbon chemistry to biotechnology. To make thermodynamics a frontier for biotechnology...

  19. Chemical evolution of the inner 2 degrees of the Milky Way bulge: [alpha/Fe] trends and metallicity gradients

    CERN Document Server

    Ryde, N; Grieco, V; Matteucci, F; Rich, R M; Uttenthaler, S

    2015-01-01

    The structure, formation, and evolution of the Milky Way bulge is a matter of debate. Important diagnostics for discriminating between bulge models include alpha-abundance trends with metallicity, and spatial abundance and metallicity gradients. Due to the severe optical extinction in the inner Bulge region, only a few detailed investigations have been performed of this region. Here we aim at investigating the inner 2 degrees by observing the [alpha/Fe] element trends versus metallicity, and by trying to derive the metallicity gradient. [alpha/Fe] and metallicities have been determined by spectral synthesis of 2 micron spectra observed with VLT/CRIRES of 28 M-giants, lying along the Southern minor axis at (l,b)=(0,0), (0,-1), and (0,-2). VLT/ISAAC spectra are used to determine the effective temperature of the stars. We present the first connection between the Galactic Center and the Bulge using similar stars, high spectral resolution, and analysis techniques. The [alpha/Fe] trends in all our 3 fields show a l...

  20. Theoretical reevaluations of black hole mass -- bulge mass relation - I. Influences of the seed black hole mass

    CERN Document Server

    Shirakata, Hikari; Okamoto, Takashi; Makiya, Ryu; Ishiyama, Tomoaki; Matsuoka, Yoshiki; Nagashima, Masahiro; Enoki, Motohiro; Oogi, Taira; Kobayashi, Masakazu A R

    2016-01-01

    We show influences of the mass of seed black holes on black hole mass -- bulge mass relation at z ~ 0 by using a semi-analytic model of galaxy formation combined with large cosmological N-body simulations. We constrain our model to reproduce observed properties of galaxies at z ~ 0. Similar to other semi-analytic models, we place a seed black hole immediately after a galaxy forms. When we set the seed black hole mass to 10^5 M_sun, we find that the model result becomes inconsistent with recent observational results of black hole mass -- bulge mass relation for dwarf galaxies. Namely, the model predicts that bulges with ~ 10^9 M_sun harbor black holes more massive than observed. On the other hand, when we employ seed black holes with 10^3 M_sun or randomly choose their masses in the range of 10^{3-5} M_sun, the black hole mass -- bulge mass relation obtained from these models are consistent with observational results including dispersions. We find that to obtain more stringent restrictions of the mass of seed ...