bluuebunny/crossref_metadata_2025_split huggingface dataset:
A 3-D look into the atmosphere?
Authors: Wade G. A. , Mashonkina L. , Ryabchikova T. , Krticka J. , Silvester J. , Kochukhov O. , Sousa J. C. , Nomura T. , Wahlgren G. M. , Gruberbauer M. , Hubrig S. , Briquet M. , Yüce K. , Drake N. , Nunez N. , Gray R. O. , Ziznovsky J. , Cowley C. , Shavrina A. , Dworetsky M. , Pintado O. , Polosukhina N. , Cidale L. 
Published: October 2010

AbstractThe atmospheres of chemically peculiar stars can be highly structured in both the horizontal and vertical dimensions. While most prevalent in the magnetic stars, these structures can also exist in non-magnetic stars. In addition to providing an important window to understanding the physical processes at play in these complex atmospheres, they can also be exploited to study stellar pulsations. This article reviews contributions to the session “A 3D look into the atmosphere” of the Joint Discussion “Progress in understanding the physics of Ap and related stars”. It is divided into 3 sections: “Magnetic field and surface structures”, “Pulsations in the atmospheres of roAp stars/inversions”, and “Spectral synthesis/atmospheric models”.
CP and related phenomena in the context of Stellar Evolution
Authors: Braithwaite J. , Akgün T. , Alecian E. , Kholtygin A. F. , Landstreet J. D. , Mathis S. , Michaud G. , Portnoy J. , Alecian G. , Bychkov V. D. , Bychkova L. V. , Drake N. , Fabrika S. N. , Reisenegger A. , Steinitz R. , Vick M. 
Published: October 2010

AbstractWe review the interaction in intermediate and high mass stars between their evolution and magnetic and chemical properties. We describe the theory of Ap-star ‘fossil’ fields, before touching on the expected secular diffusive processes which give rise to evolution of the field. We then present recent results from a spectropolarimetric survey of Herbig Ae/Be stars, showing that magnetic fields of the kind seen on the main-sequence already exist during the pre-main sequence phase, in agreement with fossil field theory, and that the origin of the slow rotation of Ap/Bp stars also lies early in the pre-main sequence evolution; we also present results confirming a lack of stars with fields below a few hundred gauss. We then seek which macroscopic motions compete with atomic diffusion in determining the surface abundances of AmFm stars. While turbulent transport and mass loss, in competition with atomic diffusion, are both able to explain observed surface abundances, the interior abundance distribution is different enough to potentially lead to a test using asterosismology. Finally we review progress on the turbulence-driving and mixing processes in stellar radiative zones.
Joint Discussion 5 Modelling the Milky Way in the Era of Gaia
Authors: Binney James J. 
Published: October 2010

AbstractThe body of photometric and astrometric data on stars in the Galaxy has been growing very fast in recent years (Hipparcos/Tycho, OGLE-3, 2-Mass, DENIS, UCAC2, SDSS, RAVE, Pan Starrs, Hermes, . . .) and in two years ESA will launch the Gaia satellite, which will measure astrometric data of unprecedented precision for a billion stars. On account of our position within the Galaxy and the complex observational biases that are built into most catalogues, dynamical models of the Galaxy are a prerequisite full exploitation of these catalogues. On account of the enormous detail in which we can observe the Galaxy, models of great sophistication are required. Moreover, in addition to models we require algorithms for observing them with the same errors and biases as occur in real observational programs, and statistical algorithms for determining the extent to which a model is compatible with a given body of data.JD5 reviewed the status of our knowledge of the Galaxy, the different ways in which we could model the Galaxy, and what will be required to extract our science goals from the data that will be on hand when the Gaia Catalogue becomes available.
Structure and evolution of the Milky Way: the interstellar medium perspective
Authors: Boulanger François 
Published: October 2010

AbstractThe Herschel and Planck satellites have started imaging the sky at far-IR to mm wavelengths with an unprecedented combination of sky and spectral coverage, angular resolution, and sensitivity, thus opening the last window of the electromagnetic spectrum on the Galaxy. Dedicated observing programs on Herschel and the Planck all-sky survey will provide the first complete view at cold dust across the Galaxy, opening new perspectives on the structure and dynamical evolution of the Milky Way relevant to Gaia. The analysis and modelling of these observations will contribute to our understanding of two key questions: how do stars form from interstellar matter? how are the interstellar medium and the magnetic field dynamically coupled? The comparison with Gaia observations will contribute to build a 3D model of the Galactic extinction taking into account dust evolution between ISM components
How to build a 3D extinction model of the Galaxy
Authors: Lépine J. R. D. , Amôres E. B. 
Published: October 2010

AbstractWe show that anomalous extinction (deviations from the traditionally adopted RV = AV/E(B − V) = 3.1 introduces large uncertainties in the distances of stars, for distances larger than 1-2 kpc. We argue that for such distances and for directions close to the galactic plane, the use of extinction models based on the gas distribution in the Galaxy is safer, for the moment, than the use of extinction maps.
Implementation of the IAU 2000 definition of UT1 in astronomy
Authors: Capitaine Nicole , Wallace Patrick T. 
Published: October 2010

AbstractWe recall the concepts and nomenclature associated with the IAU 2000 definition of UT1 as function of the Earth rotation angle (ERA). We comment on the complications that arise when UT1 is regarded as both an angle and a time scale. We review the IAU 2006 expressions for the position of the celestial intermediate origin (CIO) and the equation of the origins, and the associated CIO and equinox based procedures for the celestial-to-terrestrial transformation.
Impact of Geophysical Fluids on UT1
Authors: Gross Richard S. 
Published: October 2010

AbstractGeophysical fluids have a major impact on the Earth's rotation. Tidal variations within the oceans are the predominant cause of subdaily length-of-day (lod) variations while those within the solid body of the Earth are a major source of longer period variations; tidal dissipation within the solid Earth and oceans cause a secular change in lod. Fluctuations of the atmospheric winds are the predominant cause of nontidal lod variations on sub-decadal time scales while decadal variations are caused by interactions between the fluid core and mantle.
Short-term tidal variations in UT1: compliance between modelling and observation
Authors: Englich Sigrid , Schuh Harald , Weber Robert 
Published: October 2010

AbstractThe Earth rotation rate and consequently universal time (UT1) and length of day (LOD) are periodically affected by solid Earth tides and oceanic tides. Solid Earth tides induce changes with periods from around 5 days to 18.6 years, with the largest amplitudes occurring at fortnightly, monthly, semi-annual and annual periods, and at 18.6 years. The principal variations caused by oceanic tides have diurnal and semi-diurnal periods. For the investigation of the tidal effects with periods of up to 35 days, UT1 series are estimated from VLBI observation data of the time interval 1984–2008. The amplitudes and phases of the terms of interest are calculated and the results for diurnal and sub-diurnal periods are compared and evaluated with tidal variations derived from a GNSS-based LOD time series of 8 months. The observed tidal signals are finally compared to the predicted tidal variations according to recent geophysical models.
Time Ephemeris and General Relativistic Scale Factor
Authors: Fukushima Toshio 
Published: October 2010

AbstractTime ephemeris is the location-independent part of the transformation formula relating two time coordinates such as TCB and TCG (Fukushima 2009). It is computed from the corresponding (space) ephemerides providing the relative motion of two spatial coordinate origins such as the motion of geocenter relative to the solar system barycenter. The time ephemerides are inevitably needed in conducting precise four dimensional coordinate transformations among various spacetime coordinate systems such as the GCRS and BCRS (Soffel et al. 2003). Also, by means of the time average operation, they are used in determining the information on scale conversion between the pair of coordinate systems, especially the difference of the general relativistic scale factor from unity such as LC. In 1995, we presented the first numerically-integrated time ephemeris, TE245, from JPL's planetary ephemeris DE245 (Fukushima 1995). It gave an estimate of LC as 1.4808268457(10) × 10−8, which was incorrect by around 2 × 10−16. This was caused by taking the wrong sign of the post-Newtonian contribution in the final summation. Four years later, we updated TE245 to TE405 associated with DE405 (Irwin and Fukushima 1999). This time the renewed vale of LC is 1.48082686741(200) × 10−8 Another four years later, by using a precise technique of time average, we improved the estimate of Newtonian part of LC for TE405 as 1.4808268559(6) × 10−8 (Harada and Fukushima 2003). This leads to the value of LC as LC = 1.48082686732(110) × 10−8. If we combine this with the constant defining the mean rate of TCG-TT, LG = 6.969290134 × 10−10 (IAU 2001), we estimate the numerical value of another general relativistic scale factor LB = 1.55051976763(110) × 10−8, which has the meaning of the mean rate of TCB-TT. The main reasons of the uncertainties are the truncation effect in time average and the uncertainty of asteroids' perturbation. As a compact realization of the time ephemeris, we prepared HF2002, a Fortran routine to compute approximate harmonic series of TE405 with the RMS error of 0.446 ns for the period 1600 to 2200 (Harada and Fukushima 2003). It is included in the IERS Convention 2003 (McCarthy and Petit 2003) and available from the IERS web site; http://tai.bipm.org/iers/conv2003/conv2003_c10.html.
Atomic time scales TAI and TT(BIPM): present performances and prospects
Authors: Petit Gérard 
Published: October 2010

AbstractWe review the stability and accuracy achieved by the reference atomic time scales TAI and TT(BIPM). We show that they presently are at the level of a few 10−16in relative value, based on the performance of primary standards, of the ensemble time scale and of the time transfer techniques. We consider how the 1 × 10−16value could be reached or superseded and which are the present limitations to attain this goal.
Impact of new frequency standards on the international time scales
Authors: Arias E. Felicitas , Panfilo Gianna 
Published: October 2010

AbstractThe reference time scales maintained at the International Bureau of Weights and Measures (BIPM) are constructed with data from industrial clocks and primary frequency standards operated in national metrology laboratories and observatories world-wide distributed. Clocks are compared making use of techniques of time transfer between remote sites. The algorithm of calculation relies on clock weighting and clock frequency prediction. We briefly present hereafter the influence of some clocks on the scales, as well as the possibilities for improvement.
VLBI Measurements for Frequency Transfer
Authors: Takiguchi Hiroshi , Koyama Yasuhiro , Ichikawa Ryuichi , Gotoh Tadahiro , Ishii Atsutoshi , Hobiger Thomas , Hosokawa Mizuhiko 
Published: October 2010

AbstractWe carried out the intercomparison experiments between VLBI, GPS and DMTD to show the VLBI can measure the right time difference. We produced the artificial change using by line stretcher. At the artificial change part, VLBI and DMTD show good agreement, less than 10ps. The quantity and sense of VLBI results match well with DMTD results. Consequently, the geodetic VLBI technique can measure the right time difference.
Search for ultra-long gravitational waves in pulsars' rotational parameters
Authors: Pshirkov Maxim S. 
Published: October 2010

AbstractA method is suggested to explore the gravitational wave background (GWB) in the frequency range from 10−12 to 10−8 Hz. That method is based on the precise measurements of pulsars' rotational parameters: the influence of the gravitational waves (GW) in the range will affect them and therefore some conclusions about energy density of the GWB can be made using analysis of the derivatives of pulsars' rotational frequency. The calculated values of the second derivative from a number of pulsars limit the density of GWB Ωgw as follows: Ωgwh2 < 10−6. Also, the time series of the frequency ν of different pulsars in pulsar array can be cross-correlated pairwise in the same manner as in anomalous residuals analysis thus providing the possibility of GWB detection in ultra-low frequency range.
QPO-jet relation in X-ray binaries
Authors: Belloni Tomaso M. 
Published: October 2010

AbstractIn the past years, a clear picture of the evolution of outbursts of black-hole X-ray binaries has emerged. While the X-ray properties can be classified into our distinct states, based on spectral and timing properties, the observations in the radio band have shown strong links between accretion and ejection properties. Here I briefly outline the association between X-ray timing and jet properties.
Are jets rotating at the launching?
Authors: Soker Noam 
Published: October 2010

AbstractI argue that the Doppler shift asymmetries observed in some young stellar object (YSO) jets result from the interaction of the jets with the circumstellar gas, rather than from jets' rotation. The jets do rotate, but at a velocity much below claimed values. During the meeting I carefully examined new claims, and found problems with the claimed jets' rotation. I will challenge any future observation that will claim to detect jet rotation in YSOs that requires the jets (and not a wind) to be launched from radii much larger than the accreting stellar radius. I conclude that the most likely jets' launching mechanism involves a very efficient dynamo in the inner part of the accretion disk, with a jets' launching mechanism that is similar to solar flares (coronal mass ejection).
High Resolution 3D Relativistic MHD Simulations of Jets
Authors: Ferrari A. , Mignone A. , Rossi P. , Bodo G. , Massaglia S. 
Published: October 2010

AbstractWe performed high-resolution three dimensional numerical simulations of relativistic MHD jets carrying an initially toroidal magnetic field responsible for the process of jet acceleration and collimation. We find that in the 3D case the toroidal field gives rise to strong current driven kink instabilities leading to jet wiggling. However, it appears to be able to maintain an highly relativistic spine along its full length.
Variable jets from young stars
Authors: Raga A. C. , Cantó J. , Esquivel A. , Rodríguez-González A. , Velázquez P. F. 
Published: October 2010

AbstractIn this paper we discuss the fact that the observed “accelerations” (i. e., higher velocities at larger distances from the source) observed along some Herbig-Haro (HH) jets directly imply that the ejection velocity has to be time-dependent. Even though discussed in the early literature of the subject, this is an often forgotten fact.
Radio and Millimeter Observations of YSOs
Authors: Rodríguez Luis F. 
Published: October 2010

AbstractThe growth of a forming star takes place by accretion from the surrounding dense medium, facilitated by a circumstellar disk. But at the same time the forming system produces collimated outflows of gas that remove excess angular momentum and magnetic flux. A key question in the field is whether we can extend the disk/jet model to stars of the largest masses or if other ingredients are present. In this note, I review recent observations from the Very Large Array and the Submillimeter Array, of IRAS 16547-4247, a massive young stellar object that exhibits evidence for both a disk and an outflow.
Hyperfine structure radio lines from hot ISM in elliptical galaxies
Authors: Docenko Dmitrijs , Sunyaev Rashid A. 
Published: October 2010

AbstractHyperfine structure (HFS) line of 14N VII ion with rest frequency of ν = 53.04 GHz should be detectable from the interstellar medium in some of the densest and coolest cores of elliptical galaxies at redshifts exceeding 0.15 or so.
Cool gas in brightest cluster galaxies
Authors: Oonk J. B. R. , Jaffe W. , Bremer M. N. , Hatch N. 
Published: October 2010

AbstractGas in galaxy clusters requires re-heating. We study the re-heating of the cool gas phases. Ionized and molecular gas is traced out to 20 kpc and found to be strongly coupled. The observed line emission may in part be explained by excitation due to hot, young stars.
A multi-instrument comparison of the hot ISM in elliptical galaxies
Authors: Bregman Joel N. 
Published: October 2010

AbstractConsistent metallicities are now obtained in X-ray bright galaxies, using the Chandra ACIS and XMM PN, MOS and RGS detectors. With two temperature models, the Fe metallicity of the gas is typically solar, similar to Mg, Si, and S, but the O abundance is about half solar. These values are in conflict with models, which predict a metallicity 3-5 times higher and a Fe to O ratio near unity. This suggests that a significant fraction of metals are not becoming mixed into the hot galactic atmosphere.
Abundance ratios in stars vs. hot gas in elliptical galaxies
Authors: Pipino Antonio 
Published: October 2010

AbstractI present predictions from a chemical evolution model for a self-consistent study of optical (i.e., stellar) and X-ray (i.e., gas) properties of present-day elliptical galaxies. Detailed cooling and heating processes in the interstellar medium are taken into account and allow a reliable modelling of the SN-driven galactic wind. The model simultaneously reproduces the mass-metallicity, colour-magnitude, LX - LB and LX - T relations, and the observed trend of [Mg/Fe] with σ. The "iron discrepancy" can be solved by taking into account the dust presence.
Fossil groups of galaxies: Are they groups? Are they fossils?
Authors: Dupke Renato de Alencar , Miller Eric , de Oliveira Claudia Mendes , Sodre Laerte , Rykoff Eli , de Oliveira Raimundo Lopes , Proctor Rob 
Published: October 2010

AbstractFossil groups present a puzzle to current theories of structure formation. Despite the low number of bright galaxies, their high velocity dispersions and high TX indicate cluster-like potential wells. Measured concentration parameters seem very high indicating early formation epochs in contradiction with the observed lack of large and well defined cooling cores. There are very few fossil groups with good quality X-ray data and their idiosyncrasies may enhance these apparent contradictions. The standard explanation for their formation suggests that bright galaxies within half the virial radii of these systems were wiped out by cannibalism forming the central galaxy. Since dry mergers, typically invoked to explain the formation of the central galaxies, are not expected to change the IGM energetics significantly, thus not preventing the formation of cooling cores, we investigate the scenario where recent gaseous (wet) mergers formed the central galaxy injecting energy and changing the chemistry of the IGM in fossil groups. We show a test for this scenario using fossil groups with enough X-ray flux in the Chandra X-ray Observatory archive by looking at individual metal abundance ratio distributions near the core. Secondary SN II powered winds would tend to erase the dominance of SN IA ejecta in the core of these systems and would help to erase previously existing cold cores. Strong SN II-powered galactic winds resulting from galaxy merging would be trapped by their deep potential wells reducing the central enhancement of SN Ia/SN II iron mass fraction ratio. The results indicate that there is a decrement in the ratio of SN Ia to SN II iron mass fraction in the central regions of the systems analyzed, varying from 99±1% in the outer regions to 85±2% within the cooling radius (Figure 1) and would inject enough energy into the IGM preventing central gas cooling. The results are consistent with a scenario of later formation epoch for fossil groups, as they are defined, when compared to galaxy clusters and normal groups.
A large X-ray sample of fossil groups
Authors: Miller Eric D. , Rykoff Eli , Dupke Renato de Alencar , de Oliveira Claudia Mendes , McKay Timothy , Koester Benjamin 
Published: October 2010

AbstractWe present Chandra snapshot observations of the first large X-ray sample of optically identified fossil groups. For 9 of 14 candidate groups, we are able to determine the X-ray luminosity and temperature, which span a range typical of large ellipticals to rich groups of galaxies. We discuss these initial results in the context of group IGM and central galaxy ISM evolution, and we also describe plans for a deep X-ray follow-up program.
AGN feedback in numerical simulations
Authors: Ciotti Luca 
Published: October 2010

AbstractThe passively evolving stellar population in elliptical galaxies (Es) provides a continuous source of fuel for accretion on the central supermassive black hole (SMBH), which is 1) extended over the entire galaxy life (but declining with cosmic time), 2) linearly proportional to the stellar mass of the host spheroid, 3) summing up to a total gas mass that is > 100 times larger than the currently observed SMBH masses, 4) available independently of merging events. The main results of numerical simulations of Es with central SMBH, in which a physically based implementation of radiative and mechanical feedback effects is considered, are presented.
Constraints on turbulent pressure in the X-ray halos of giant elliptical galaxies from resonant scattering
Authors: Werner Norbert , Zhuravleva Irina , Churazov Eugene , Simionescu Aurora , Allen Steve W. , Forman William , Jones Christine , Kaastra Jelle 
Published: October 2010

AbstractThe dense cores of X-ray emitting gaseous halos of large elliptical galaxies with temperatures below about 0.8 keV show two prominent Fe XVII emission features, which provide a sensitive diagnostic tool to measure the effects of resonant scattering. We present here high-resolution spectra of five bright nearby elliptical galaxies, obtained with the Reflection Grating Spectrometers (RGS) on the XMM-Newton satellite. The spectra for the cores of four of the galaxies show the Fe XVII line at 15.01 Angstrom being suppressed by resonant scattering. The data for NGC 4636 in particular allow the effects of resonant scattering to be studied in detail. Using deprojected density and temperature profiles for this galaxy obtained with the Chandra satellite, we model the radial intensity profiles of the strongest resonance lines, accounting for the effects of resonant scattering, for different values of the characteristic turbulent velocity. Comparing the model to the data, we find that the isotropic turbulent velocities on spatial scales smaller than about 1 kpc are less than 100 km/s and the turbulent pressure support in the galaxy core is smaller than 5% of the thermal pressure at the 90% confidence level, and less than 20% at 99% confidence. Neglecting the effects of resonant scattering in spectral fitting of the inner 2 kpc core of NGC 4636 will lead to underestimates of the chemical abundances of Fe and O by about 10-20%.
The effects of coupling variations on BBN
Authors: Olive Keith A. 
Published: October 2010

AbstractThe effect of variations of the fundamental nuclear parameters on big-bang nucleosynthesis are modeled and discussed in detail taking into account the interrelations between the fundamental parameters arising in unified theories. Considering only 4He, strong constraints on the variation of the neutron lifetime, neutron-proton mass difference are set. We show that a variation of the deuterium binding energy is able to reconcile the 7Li abundance deduced from the WMAP analysis with its spectroscopically determined value while maintaining concordance with D and 4He.