bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of radio sources with the virtual observatory tools: Results and problems
Authors: Zhelenkova O.P. 
Published: October 2014

AbstractRadio sources of the RCR catalogue, obtained from observational data of the “Cold” experiment, have been identified, almost completely, with optical objects. For this purpose, we used optical, infrared, and radio sky surveys as well as archive data from the VLA (NRAO) and the 6‐m telescope (SAO). According to spectroscopy and color index constraints, the identified sources are classified as galaxies and quasars; about 20 % of the sources remain unclassified because of being optically faint. We estimated radio luminosities of the sources and found that a majority (60%) of them belong to strong radio sources. Using ratios of FIRST and NVSS flux densities and angular sizes, we prepared a sample of steep spectrum compact sources. The existing infrastructure of the virtual observatory increases the effectiveness of astronomical studies like ours greatly. However, we still cannot consider the virtual observatory a completed project because it requires further development of services providing actualization of user data and better semantic compatibility of information. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
HARPS spectropolarimetry of Herbig Ae/Be stars
Authors: Hubrig S. , Ilyin I. , Schöller M. , Lo Curto G. 
Published: October 2014

AbstractOur knowledge of the presence and the strength of magnetic fields in intermediate‐mass pre‐main‐sequence stars remains very poor. We present new magnetic field measurements in six Herbig Ae/Be stars observed with HARPS in spectropolarimetric mode. We downloaded from the European Southern Observatory (ESO) archive the publically available HARPS spectra for six Herbig Ae/Be stars. Wavelength shifts between right‐ and left‐hand side circularly polarised spectra were interpreted in terms of a longitudinal magnetic field 〈Bz〉, using the moment technique introduced by Mathys. The application of the moment technique to the HARPS spectra allowed us in addition to study the presence of the crossover effect and quadratic magnetic fields. Our search for longitudinal magnetic fields resulted in first detections of weak magnetic fields in the Herbig Ae/Be stars HD 58647 and HD 98922. Further, we confirm the previous tentative detection of a weak magnetic field in HD 104237 by Donati et al. and confirm the previous detection of a magnetic field in the Herbig Ae star HD 190073. Surprisingly, the measured longitudinal magnetic field of HD 190073, 〈Bz〉 = 91 ± 18 G at a significance level of 5σ is not in agreement with the measurement results of Alecian et al. (2013), 〈Bz〉 = –10 ± 20 G, who applied the LSD method to exactly the same data. No crossover effect was detected for any star in the sample. Only for HD 98922 the crossover effect was found tobe close to 3σ with a measured value of –4228 ± 1443 km s–1 G. A quadratic magnetic field of the order of 10 kG was detected in HD 98922, and of ∼3.5 kG in HD 104237. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A photometric study of the nova‐like variable TT Arietis with the MOST satellite
Authors: Vogt N. , Chené A.‐N. , Moffat A.F.J. , Matthews J.M. , Kuschnig R. , Guenther D.B. , Rowe J.F. , Rucinski S.M. , Sasselov D. , Weiss W.W. 
Published: October 2014

AbstractVariability on all time scales between seconds and decades is typical for cataclysmic variables (CVs). One of the brightest and best studied CVs is TT Ari, a nova‐like variable which belongs to the VY Scl subclass, characterized by occasional low states in their light curves. It is also known as a permanent superhumper at high state, revealing “positive” (PS > P0) as well as “negative” (PS < P0) superhumps, where PS is the period of the superhump and P0 the orbital period. TT Ari was observed by the Canadian space telescope MOST for about 230 hours nearly continuously in 2007, with a time resolution of 48 seconds. Here we analyze these data, obtaining a dominant “negative” superhump signal with a period PS = 0.1331 days and a mean amplitude of 0.09 mag. Strong flickering with amplitudes up to 0.2 mag and peak‐to‐peak time scales of 15–20 minutes is superimposed on the periodic variations. We found no indications for significant quasi‐periodic oscillations with periods around 15 minutes, reported by other authors. We discuss the known superhump behaviour of TTAri during the last five decades and conclude that our period value is at the upper limit of all hitherto determined “negative” superhump periods of TTAri, before and after the MOST run. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characteristics of clockwise and counterclockwise spiral galaxies
Authors: Hoehn C. , Shamir L. 
Published: October 2014

AbstractWe compared measurements of 126 501 spiral galaxies to test whether the photometry of galaxies that rotate clockwise is different from the photometry of galaxies that rotate counterclockwise for the purpose of testing whether there is a link between photometry and spin direction of galaxies. The rotation directionality of the galaxies was determined by converting the galaxy image to its radial intensity plot, and then the galaxies in each 30° RA sector were separated into clockwise and counterclockwise rotating galaxies. The mean and standard deviation of SDSS DR7 photometric attributes of clockwise and counterclockwise rotating galaxies were then compared. The results show no significant difference between galaxies that rotate clockwise and galaxies that rotate counterclockwise. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FIES: The high‐resolution Fiber‐fed Echelle Spectrograph at the Nordic Optical Telescope
Authors: Telting J.H. , Avila G. , Buchhave L. , Frandsen S. , Gandolfi D. , Lindberg B. , Stempels H.C. , the NOT staff  , Prins S. 
Published: October 2014

AbstractFIES is a cross‐dispersed high‐resolution echelle spectrograph at the 2.56 m Nordic Optical Telescope (NOT), and was optimised for throughput and stability in 2006. The major 2006 upgrade involved the relocation of FIES to a stable environment and development of a fiber bundle that offers 3 different resolution modes, and made FIES an attractive tool for the user community of the NOT. Radial‐velocity stability is achieved through double‐chamber active temperature control. A dedicated data reduction tool, FIEStool, was developed. As a result of these upgrades, FIES is now one of the work‐horse instruments at the NOT. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Combining optical spectroscopy and interferometry
Authors: Kraus S. 
Published: October 2014

AbstractModern optical spectrographs and optical interferometers push the limits in the spectral and spatial regime, providing important new tools for the exploration of the Universe. In this contribution I outline the complementary nature of spectroscopic and interferometric observations and discuss different strategies for combining such data. Most remarkable, the latest generation of “spectro‐interferometric” instruments combine the milliarcsecond angular resolution achievable with interferometry with spectral capabilities, enabling direct constraints on the distribution, density, kinematics, and ionization structure of the gas component in protoplanetary disks. I will present some selected studies from the field of star‐ and planet formation and hot star research in order to illustrate these fundamentally new observational opportunities. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The sun‐as‐a‐star solar spectrum
Authors: Pevtsov A.A. , Bertello L. , Marble A.R. 
Published: October 2014

AbstractThe Sun is the only star for which individual surface features can be observed directly. For other stars, the properties of starspots, stellar rotation, stellar flares, etc, are derived indirectly via variation of star‐integrated spectral line profiles or their luminosity measurements. Solar disk‐integrated and disk‐resolved observations allow for investigations of the contribution of individual solar disk features to sun‐as‐a‐star spectra. Here, we provide a brief overview of three sun‐as‐a‐star programs, currently in operation, and describe recent improvements in observations and data reduction for the Integrated Sunlight Spectrometer (ISS), one of three instruments comprising the Synoptic Optical Long‐term Investigations of the Sun (SOLIS) system. Next, we discuss studies employing sun‐as‐a‐star observations (including Ca II K line as proxy for total unsigned magnetic flux and 2800 MHz radio flux) as well as the effects of flares on solar disk‐integrated spectra. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐resolution absorption spectroscopy of the circumgalactic medium of the Milky Way
Authors: Richter P. , Fox Aj. , Ben Bekhti N. , Murphy M. T. , Bomans D. , Frank S. 
Published: October 2014

AbstractIn this article we discuss the importance of high‐resolution absorption spectroscopy for our understanding of the distribution and physical nature of the gaseous circumgalactic medium (CGM) that surrounds the Milky Way. Observational and theoretical studies indicate a high complexity of the gas kinematics and an extreme multi‐phase nature of the CGM in low‐redshift galaxies. High‐precision absorption‐line measurements of the Milky Way's gas environment thus are essential to explore fundamental parameters of circumgalactic gas in the local Universe, such as mass, chemical composition, and spatial distribution. We shortly review important characteristics of the Milky Way's CGM and discuss recent results from our multi‐wavelength observations of the Magellanic Stream. Finally, we discuss the potential of studying the warm‐hot phase of the Milky Way's CGM by searching for extremely weak [Fe X] λ 6374.5 Å and [Fe XIV] λ 5302.9 Å absorption in optical QSO spectra. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plasma‐producing gaps in the global structure of the pulsar force‐free magnetosphere
Authors: Petrova S.A. 
Published: October 2014

AbstractThe pulsar high‐energy emission is usually associated with the magnetospheric gaps which are traditionally considered within the framework of the vacuum dipole model of the magnetosphere. Actually, the presence of an abundant plasma should modify the magnetospheric structure, and the context of a force‐free magnetosphere where the electromagnetic forces are balanced over most part of the volume is more appropriate. The gaps included into the structure of the force‐free magnetosphere should play an important role in sustaining and closing the pulsar current circuit. Here we examine the vacuum polar gap adjustment to the stationary force‐free magnetosphere in the presence of a closing current sheet. Our simplified model incorporates the regimes of the force‐free and vacuum monopole with the transition region amidst, where the bulk of pair plasma is formed and the poloidal force‐free current is closed. The analysis of the force and energy balance in the transition region shows that the current sheet cannot be regarded as infinitesimal and the closing process may be dissipation‐free. The implications of our results for the pulsar emission are outlined. In particular, the interpretation of a peculiar radio–X‐ray correlation in the pulsar PSR B0943+10 is suggested. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The stability of strong waves and its implications for pulsar wind shocks
Authors: Mochol I. , Kirk J. G. 
Published: October 2014

AbstractStrong waves can mediate a shock transition between a pulsar wind and its surroundings, playing the role of an extended precursor, in which the energy is effectively transferred from fields to non‐thermal particles. The damping of such precursors results in an essentially unmagnetized shock near the equator. In this context, we discuss the stability of strong waves and its implications for the properties of shocks. Those with stable precursors can exist in the winds of most of isolated pulsars, but the precursors may be unstable if the external pressure in the nebula is high, as in Vela‐like pulsars. Pulsar wind shocks in eccentric binary systems, such as B1259–63, can acquire precursors only at certain orbital phases, and this process should be accompanied by enhanced synchro‐Compton and inverse Compton emission from the precursor. The same scenario may be at work in the binary HESS J0632+057. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unifying neutron stars getting to GUNS
Authors: Igoshev A.P. , Popov S.B. , Turolla R. 
Published: October 2014

AbstractThe variety of the observational appearance of young isolated neutron stars must find an explanation in the framework of some unifying approach. Nowadays it is believed that such scenario must include magnetic field decay, the possibility of magnetic field emergence on a time scale of ≲104–105 yr, significant contribution of non‐dipolar fields, and appropriate initial parameter distributions. We present our results on the initial spin period distribution, and suggest that inconsistencies between distributions derived by different methods for samples with different average ages can uncover field decay or/and emerging field. We describe a new method to probe the magnetic field decay in normal pulsars. The method is a modified pulsar current approach, where we study pulsar flow along the line of increasing characteristic age for constant field. Our calculations, performed with this method, can be fitted with an exponential decay for ages in the range of 8×104– 3.5×105 yr with a time scale of ∼5×105 yr. We discuss several issues related to the unifying scenario. At first, we note that the dichotomy, among local thermally emitting neutron stars, between normal pulsars and the Magnificent Seven remains unexplained. Then we discuss the role of high‐mass X‐ray binaries in the unification of neutron star evolution. We note, that such systems allow to check evolutionary effects on a time scale longer than what can be probed with normal pulsars alone. We conclude with a brief discussion of the importance of discovering old neutron stars accreting from the interstellar medium. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
NuSTAR results and future plans for magnetar and rotation‐powered pulsar observations
Authors: An H. , Kaspi V.M. , Archibald R. , Bachetti M. , Bhalerao V. , Bellm E. C. , Beloborodov A. M. , Boggs S. E. , Chakrabarty D. , Christensen F. E. , Craig W. W. , Dufour F. , Forster K. , Gotthelf E. V. , Grefenstette B. W. , Hailey C. J. , Harrison F. A. , Hascoët R. , Kitaguchi T. , Kouveliotou Ch. , Madsen K. K. , Mori K. , Pivovaroff M. J. , Rana V. R. , Stern D. , Tendulkar S. , Tomsick J. A. , Vogel J. K. , Zhang W. W. , the NuSTAR Team  
Published: October 2014

AbstractThe Nuclear Spectroscopic Telescope Array (NuSTAR) is the first focusing hard X‐ray mission in orbit and operates in the 3–79 keV range. NuSTAR's sensitivity is roughly two orders of magnitude better than previous missions in this energy band thanks to its superb angular resolution. Since its launch in 2012 June, NuSTAR has performed excellently and observed many interesting sources including four magnetars, two rotation‐powered pulsars and the cataclysmic variable AE Aquarii. NuSTAR also discovered 3.76‐s pulsations from the transient source SGR J1745–29 recently found by Swift very close to the Galactic center, clearly identifying the source as a transient magnetar. For magnetar 1E 1841–045, we show that the spectrum is well fit by an absorbed blackbody plus broken power‐law model with a hard power‐law photon index of ∼ 1.3. This is consistent with previous results by INTEGRAL and RXTE. We also find an interesting double‐peaked pulse profile in the 25–35 keV band. For AE Aquarii, we show that the spectrum can be described by a multi‐temperature thermal model or a thermal plus non‐thermal model; a multi‐temperature thermal model without a non‐thermal component cannot be ruled out. Furthermore, we do not see a spiky pulse profile in the hard X‐ray band, as previously reported based on Suzaku observations. For other magnetars and rotation‐powered pulsars observed with NuSTAR, data analysis results will be soon available. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A classification scheme for magnetars
Authors: Göğüs E. 
Published: October 2014

AbstractWe investigate cumulative burst occurrence trends of five soft gamma repeaters (SGRs) and introduce an indicative mea‐sure for the duration of their outburst phases. We find a clear distinction between the durations of the active episodes of persistent and transient magnetars: The outburst episodes of the persistent sources are significantly longer (≲100 days) than those of transient sources (≲10 days). We also investigate burst‐induced changes in the radiative behavior of transient sources and suggest a mechanism for the constant flux trend seen in the early phases of the outburst of SGRs with low burst rates. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The properties of the progenitor, neutron star, and pulsar wind in the supernova remnant Kes 75
Authors: Gelfand J. D. , Slane P. O. , Temim T. 
Published: October 2014

AbstractBy studying composite supernova remnants (SNRs), remnants which contain a pulsar wind nebula (PWN), it is possible to estimate physical properties of the progenitor explosion, central neutron star, and its pulsar wind that are difficult to measure directly. This is best done by fitting the dynamical and broadband spectral properties of a PWN with an evolutionary model for a PWN inside an SNR. We apply such a model to the composite SNR Kes 75, whose associated pulsar PSR J1846‐0258 is thought to have an extremely strong surface magnetic field. If ∼3 M⊙ of mass was ejected in the supernova, our model suggests a normal or slightly subenergetic supernova in a low density environment. Additionally, for the measured pre‐outburst braking index of p = 2.65, our model prefers an age of ∼430 years and an initial spin period P0 ∼ 0.2 s. Lastly, the magnetization of the pulsar wind and energy spectrum of particles injected at the termination shock are similar to those observed from other PWNe powered by less magnetized neutron stars. While further study is needed to verify these results, they are nominally inconsistent with strong neutron star magnetic fields resulting from very fast initial rotation. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transmission profile of the Dutch Open Telescope Hα Lyot filter
Authors: Koza J. , Hammerschlag R. H. , Rybák J. , Gömöry P. , Kučera A. , Schwartz P. 
Published: October 2014

AbstractAccurate knowledge of the spectral transmission profile of a Lyot filter is important, in particular in comparing observations with simulated data. The paper summarizes available facts about the transmission profile of the Dutch Open Telescope (DOT) Hα Lyot filter pointing to a discrepancy between sidelobe‐free Gaussian‐like profile measured spectroscopically and signatures of possible leakage of parasitic continuum light in DOT Hα images. We compute wing‐to‐center intensity ratios resulting from convolutions of Gaussian and square of the sinc function with the Hα atlas profile and compare them with the ratios derived from observations of the quiet Sun chromosphere at disk center. We interpret discrepancies between the anticipated and observed ratios and the sharp limb visible in the DOT Hα image as an indication of possible leakage of parasitic continuum light. A method suggested here can be applied also to indirect testing of transmission profiles of other Lyot filters. We suggest two theoretical transmission profiles of the DOT Hα Lyot filter which should be considered as the best available approximations. Conclusive answer can only be given by spectroscopic re‐measurement of the filter. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determining the nature of orbits in a three‐dimensional galaxy model hosting a BL Lacertae object
Authors: Zotos E. E. 
Published: October 2014

AbstractA three‐dimensional dynamical model for a galaxy hosting a BL Lacertae object is constructed. The model consists of a logarithmic potential representing an elliptical host galaxy with a bulge of radius cb and a dense massive nucleus. Using numerical experiments, we try to distinguish between regular and chaotic motion in both 2D and 3D system. In particular, we investigate how the basic parameters of our model, such as the mass of the nucleus, the internal perturbation and the flattening parameters influence the amount and the degree of chaos. Interesting correlations are presented for both 2D and 3D dynamical models. Our numerical results are explained and supported using elementary theoretical arguments and analytical calculations. Of particular interest is the local integral of motion which have been found to exist in the vicinity of stable periodic points. The obtained numerical outcomes of the present research are linked and also compared with several data derived from observations. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homogenized Hertzsprung‐Russell diagram for the open cluster NGC 188
Authors: Malyuto V. , Zubarev S. , Shvelidze T. 
Published: October 2014

AbstractWe considered some selected published stellar catalogues with B – V and V values for the open cluster NGC 188 and estimated the errors from data comparisons. The results are used to homogenize the data by averaging with weights inversely proportional to the errors squared. A recent calibration by Casagrande et al. (2010) of B – V versus effective temperatures for F, G, and K dwarfs and subgiants is used to produce the homogenized effective temperatures for the cluster stars. A homogenized Hertzsprung‐Russell diagram (relationship between the effective temperatures and the absolute magnitudes) is presented and analysed. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wide‐Field Plate Archive of the University Observatory Jena
Authors: Poghosyan A.V. , Pfau W. , Tsvetkova K.P. , Mugrauer M. , Tsvetkov M.K. , Hambaryan V.V. , Neuhäuser R. , Kalaglarsky D.G. 
Published: October 2014

AbstractWe present the archive of the wide‐field plate observations obtained at the University Observatory Jena, which is stored at the Astrophysical Institute of the Friedrich Schiller University Jena. The archive contains plates taken in the period February 1963 to December 1982 with the 60/90/180‐cm Schmidt telescope of the university observatory. A computer‐readable version of the plate metadata catalogue (for 1257 plates), the logbooks, as well as the digitized Schmidt plates in low and high resolution are now accessible to the astronomical community.This paper describes the properties of the archive, as well as the processing procedure of all plates in detail. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Speckle observations with PISCO in Merate: XIII. Astrometric measurements of visual binaries in 2012, and new orbits for ADS 10786 BC, 12144, 12515, 16314 and 16539
Authors: Prieur J.‐L. , Scardia M. , Pansecchi L. , Argyle R.W. , Zanutta A. , Aristidi E. 
Published: October 2014

AbstractWe present relative astrometric measurements of visual binaries, made in 2012 with the speckle camera PISCO at the 102‐cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 355 new measurements of 344 visual binary stars, with angular separations in the range 0′.14–6′.9, and an average accuracy of 0.′02. The mean error on the position angles is 0°.5. Most of the position angles were determined without the usual 180° ambiguity with the application of triple‐correlation techniques and/or by inspection of the long integration files. We also present new revised orbits for ADS 10786 BC, 12144, 12515, 16314, and 16539, partly derived from PISCO observations. The corresponding estimated values for the masses of those systems are compatible with the spectral types. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)