bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Simple Spectropolarimetric Temperature Diagnostic for Circumstellar Disks
Authors: Bjorkman Karen S. , Bjorkman Jon E. , Wood Kenneth 
Published: July 2016

AbstractWe describe a technique for estimating average temperatures of Be star disks from analysis of ultraviolet spectropolarimetry. The technique utilizes the fact that the spectrum of the scattered starlight is sensitive to the circumstellar opacity, and hence temperature, since the signature of the disk material is imprinted on the scattered light spectrum. Analysis of the polarization spectrum thus allows us to disentangle the relative contributions of the star and disk, and thereby obtain an estimate of the average disk opacity as a function of wavelength. Using an LTE line-blanketed model (containing about 106 spectral lines) for the opacity, we determine a theoretical opacity as a function of temperature. By comparing this to the opacity deduced from the spectropolarimetry, we can estimate the average disk temperature. For classical Be stars, the relative strengths of the Fe II and Fe III multiplets at around 2400Å and 1900Å, respectively, are a sensitive temperature diagnostic, so that the temperature estimate can be made within ±1000K. We demonstrate our technique with analysis of UV spectropolarimetry (from WUPPE) of the classical Be star ζ Tau, for which we infer an isothermal disk temperature of14000K.
Be Star Discs: Inflow or Outflow?
Authors: Porter John M. 
Published: July 2016

AbstractIt is assumed that the dynamics of Be star discs is dominated by the effects of viscous stresses. By examining angular momentum transport in discs, we show that many, if not all observed Be star discs should be accretion discs unless (i) the disc is acted upon by another agent (e.g. magnetic fields or the stellar radiation field), or (ii) the disc cools significantly as it flows outwards.
Searching for New Be/X–ray Binaries in the SMC: the case of 1SAXJ0103–7209, XTEJ0055–724, RXJ0052–7319, XTEJ0111–7317 and 2E0050–7247
Authors: Covino S. , Israel G.L. , Polcaro V.F. , Campana S. , Mereghetti S. , Stella L. 
Published: July 2016

AbstractWe obtained X–ray (ROSAT, BeppoSAX and ASCA) and optical observations of a sample of newly discovered X–ray pulsars. We here report on the discovery of the likely optical counterpart of five of them in the Small Magellanic Cloud: 1SAXJ0103–7209, XTEJ0055–724, RXJ0052–7319, XTEJ0111–7317 and 2E0050–7247.
Gas-Dynamical Modelling of Circumstellar Matter in β Lyr A
Authors: Bisikalo D. V. , Boyarchuk A. A. , Harmanec P. , Hadrava P. , Kuznetsov O. A. 
Published: July 2016

AbstractAvailable spectroscopic evidence of various circumstellar gaseous structures in the well-known binary β Lyr is confronted with the results of 3-D gas-dynamical simulations of mass transfer between the binary components, obtained for the currently best available basic physical properties of the system. It appears that the gas-dynamical model is capable to explain, at least qualitatively, the formation of all basic observed components of the circumstellar matter, including the jet-like structures, recently found from interferometry and polarimetry of the object.
Searching for New Be/X-ray Binaries in the Galactic Plane: the Case of GS 0834 – 43, 1WGA J1958.2+3232 and AXJ1820.5–1434
Authors: Israel G.L. , Covino S. , Polcaro V.F. , Campana S. , Mereghetti S. , Pizzella A. , Roche P. , Stella L. , Verrecchia F. 
Published: July 2016

AbstractOver the last year we obtained X-ray (ROSAT, BeppoSAX and ASCA) and optical (at ESO and at the Astronomical Observatory of Loiano) to infra-red (AAO) observations of a sample of newly discovered X-ray pulsars. Among this sample we discovered the likely optical counterpart of three of them located in the Galactic plane: GS 0834–43, 1WGA J1958.2+3232 and AX J1820.5–1434.
The Parkes Multibeam Pulsar Survey Data Release
Authors: Bell J.F. , Manchester R.N. , Crawford F. , Lyne A.G. , Camilo F. , Kaspi V.M. , Stairs I.H. , Morris D.J. , D’Amico N. , McKay N.P.F. , Kramer M. , Sheppard D.C. , Possenti A. 
Published: July 2016

AbstractThe Parkes multibeam pulsar survey which began in 1997 and is now about 50% complete. It has discovered more than 400 new pulsars so far, including a number of young, high magnetic field, and relativistic binary pulsars. Early results, descriptions of the survey and follow up timing programs can be found in papers by Lyne et al. (1999 MNRAS in press), Camilo et al. (this volume), and Manchester et al. (this volume). This paper describes the data release policy and how you can gain access to the raw data and details on the pulsars discovered.
Science with PuMa, the new Dutch PulsarMachine
Authors: Kouwenhoven M.L.A. , Stappers B.W. , Ramachandran R. , Voûte J.L.L. 
Published: July 2016

AbstractWe have built a pulsar machine (PuMa) for operation at the Westerbork Synthesis Radio Telescope. The combination of PuMa and WSRT is capable of many types of pulsar research. We show the coherent dedispersion capabilities and the flexible frequency resolution. We discuss pulsar searching and simultaneous multifrequency observations.
The Bologna submillisecond pulsar survey
Authors: D’Amico Nichi 
Published: July 2016

AbstractSince the discovery of the original millisecond pulsar, no pulsars with a shorter spin period (P&lt;1.56 ms) were found. However, according to the most popular equations of state, the theoretical limiting spin period of a neutron star can be much shorter. On the other hand, most of the large scale searches for millisecond pulsars carried out so far were strongly biased against the detection of ultrashort periodicities. In this paper we describe a new large scale pulsar survey with a minimum detectable period much shorter than previous searches.
A Search for Sub-millisecond Pulsations in Unidentified FIRST and NVSS Radio Sources
Authors: Crawford Fronefield , Kaspi Victoria M. , Bell Jon F. 
Published: July 2016

AbstractWe have searched 92 unidentified sources from the FIRST and NVSS radio catalogs for pulsations at 610 MHz. The selected sources are bright, have no identifications, are unresolved and have significant linear polarization. Our search was sensitive to sub-millisecond pulsations from pulsars with a large range of dispersion measures. We have detected no radio pulsations from these sources and conclude that they are unlikely to be a population of previously undetected pulsars.
Pulsar timing measurements with the 32-m TCfA radiotelescope
Authors: Lewandowski W. , Konacki M. , Redmerska M. , Feiler G. , Wolszczan A. 
Published: July 2016

Accurate, long-term timing measurements of pulsars provide a powerful method to study a variety of astrophysical phenomena. For “normal”, slow pulsars, the dominant factors that limit the timing precision are the intrinsic timing noise and single pulse “jitter” (e.g. Cordes 1993). In fact, because the pulse jitter surpasses radiometer noise for sufficiently strong pulsars and no further improvement of the timing precision can be achieved by increasing the antenna gain, the timing of such sources can be very efficiently conducted with suitably equipped medium-size radiotelescopes.We have been timing slow pulsars with the 32-m TCfA radiotelescope in Toruń, Poland, since July 1996, using a dual-channel, circular polarization L-band receiving system at frequencies around 1.7 GHz, and a 2 × 64 × 3 MHz channel pulsar backend, the Penn State Pulsar Machine - 2 (PSPM-2; for more details, see Konacki et al. 1999). Our gradually expanding source list currently includes 88 pulsars timed once a week with a millisecond precision using the observatory’s UTC-calibrated H-maser clock. Data analysis is routinely performed with the TEMPO software package. With a particularly dense, weekly sampling and a ≤1 ms timing precision, the TCfA program has a sensitivity to detect previously overlooked short period, low orbital inclination binaries, as well as very low-mass, planetary companions. In addition, it will be very useful in identifying and monitoring pulsar timing glitches and other forms of the timing noise.
Binary Eclipsing Millisecond Pulsars: A Decade of Timing
Authors: Nice David J. , Arzoumanian Zaven , Thorsett Stephen E. 
Published: July 2016

AbstractWe present results of long-term timing of eclipsing binaries PSR B1744–24A and PSR B1957+20 at Arecibo, the VLA, and Green Bank. Both pulsars exhibit irregularities in pulsar rotation and orbital motion. Increases and decreases of the orbital period of PSR B1957+20 are of order ΔPb/Pb∼ 10−7, varying on a time scale of a few years. Over a decade of observations, the orbital period of PSR B1744–24A has only decreased, with time scale |Pb/Ṗb| ∼ 200Myr. When the effects of orbital motion are removed from the timing data, long-term trends remain in the pulse phase residuals, with amplitudes of order 30 and 500μs, respectively, for B1957+20 and B1744–24A. Such large “timing noise” is not seen in other spun-up pulsars (isolated or binary), leading us to conclude that it is a consequence of mass flow in the system. Possible causes include variations in the rotation of the pulsars and movement of the binary systems along the line of sight (perhaps due to gravitational interactions with outflowing matter).
Pulsar timing noise spectra of pulsars 0834+06, 1237+25,1919+21, 2016+28 from 1978 – 1999 yrs. observations
Authors: Ilyasov Yu.P. , Potapov V.A. , Rodin A.E. 
Published: July 2016

AbstractThe long time series of observations of four pulsars made by the Pushchino Large Phased Array are analyzed to describe a pulsar timing noise. The analysis was made after making a standard fitting procedure.
The Noise Structure of Pulsar Clocks
Authors: Kundt Wolfgang 
Published: July 2016

AbstractPulse arrival times of pulsars have a high – though limited – degree of predictability: they show both discrete ‘glitches’, and continuous deviations from an analytic extrapolation of earlier data spans; they are ‘noisy’. This noise shows a strong dependence on a pulsar’s spindown age. Both types of noise can be understood as due to a loose coupling of the charged component of a pulsar’s moment of inertia to a neutral superfluid component, of relative moment of inertia usually below 1%, but reaching 10% in extreme cases. Differential spin ratesδΩ/Ω of the two components are ≲ 10−3, usually only ≲ 10−5.
Binary Pulsar Tests of General Relativity in the Presence of Low-Frequency Noise
Authors: Kopeikin Sergei M. , Potapov Vladimir A. 
Published: July 2016

AbstractThe influence of the low-frequency timing noise on the precision of measurements of the Keplerian and post-Keplerian orbital parameters in binary pulsars is studied. Fundamental limits on the accuracy of tests of alternative theories of gravity in the strong-field regime are established. The gravitational low-frequency timing noise formed by an ensemble of binary stars is briefly discussed.
Pulse Properties of a few Southern Pulsars at 150 MHz
Authors: Issur Nalini H. , Deshpande Avinash A. 
Published: July 2016

AbstractWe present 150 MHz observations of the bright millisecond pulsar J0437-4715, and pulsars J1453-6413 and J1752-2806, made with the Mauritius Radio Telescope (MRT). We use single-pulse sequences to derive some preliminary results on the pulse morphologies.
The Geometry Asymmetry of Mean Pulse Profile of Pulsar
Authors: Wu X.J. , Pan J. , Xu X.B. 
Published: July 2016

AbstractIn this paper, the effects of aberration, retardation and magnetic field sweep back, which are caused by pulsar’s rapid rotation, are estimated to see their influences on the pulse shape of pulsars and geometry asymmetry of the mean pulse profile. The width of mean pulse profile is modified only slightly, but the geometry asymmetry appears and will exhibit different behaviors at different cases. The pulsars of B1451-68 and J0437-4715 are analyzed as examples.
Limits on the optical magnitude of PSR 1821-24 in M28
Authors: Sutaria F. K. 
Published: July 2016

AbstractThe detection of a pulsed X-ray counterpart (RX J1824.2-2R52P) of the 3.05 ms pulsar PSR 1821-24, suggests the possibility of a part of the rotational energy loss of this high spindown rate pulsar being in the optical band. Archival HST data for M28 is used here to set upper limits on the optical V-band magnitude of PSR 1821-24. The optical limit extends the multiwavelength observations for this source and provides a constraint for theoretical models of pulsar emission.
ASCA and RXTE Upper Limits to Pulsed Emissions from PSR B1951+32
Authors: Chang Hsiang-Kuang , Guo Tz-Feng 
Published: July 2016

AbstractWe report upper limits to pulsed X-ray emissions from PSR B1951+32 in 0.5 - 250 keV based on observations of ASCA in 1993 and RXTE in 1996. Together with earlier ROSAT report, these upper limits strongly suggest a thermal pulsed component below about 1 keV. These upper limits also indicate a spectral bending occurring in 100 keV - 3 MeV, which favors an outer-magnetosphere origin for gamma-ray emissions from PSR B1951+32.
Timing and spectral Properties of PSR B1509–58 observed with BeppoSAX
Authors: Cusumano G. , Mineo T. , Nicastro L. , Massaro E. , Massaglia S. , Trussoni E. , Becker W. 
Published: July 2016

AbstractWe present some preliminary results of a BeppoSAX observation of the pulsar PSR B1509–58. We discuss in detail the spectrum energy distribution and show that the high energy data can be explained by a steepening continuum spectrum.
ASCA observations of Galactic rotation-powered pulsars
Authors: Pivovaroff M. J. , Kaspi V. M. , Gotthelf E. V. 
Published: July 2016

AbstractWe have examined several archivalASCAobservations of Galactic radio pulsars, including PSRs B1046–58 and B1610–50. X-ray emission is detected from PSR B1046–58 with a significance of ∼5σ. We find no evidence for pulsations. We argue that the emission is from a spatially unresolved synchrotron nebula powered by the pulsar. The location of the X-ray counterpart within the 95% position error ellipse of the gamma-ray source 3EG J1048–5840 strengthens the claim of Kaspi et al. (2000) that PSR B1046–58 emitϒ-rays. X-ray emission from PSR B1610–50 is not detected. We use the X-ray luminosity upper limit to constrain the pulsar’s velocity ≲ 200km s−1, arguing against an association with the nearby supernova remnant Kes 32. Our results for these radio pulsars contradict previous reports of detections of large (tens of arc minutes) associated synchrotron nebulae.
Applications of Ohm’s Law to the pulsar magnetosphere
Authors: Kunzl Thomas , Lesch Harald , Jessner Axel 
Published: July 2016

AbstractWe show that in the inner magnetosphere of a pulsar mildly relativistic particles can flow out steadily under two assumptions: i) all vacuum fields are completely shielded by copious amounts of particles drawn out by thermal and field emission (which is likely as shown in Jessneret al, 1999) ii) particles emitted from the neutron star surface have weakly relativistic energies (βϒ≈ 1). The results are consistent with the typical particle energies predicted in the radio emission model by Kunzlet al., 1999.
Beams in Magnetised Pair Plasmas
Authors: Rowe E. T. 
Published: July 2016

AbstractThe radiative instability was considered in the context of pulsar radio emission by Goldreich &amp; Keeley (1971) and rederived and extended by Asséo, Pellat, &amp; Sol (1983) and by Asséo (1995). Their results can be generalised and reproduced by replacing the thin cylindrical ring of charged particles by an infinitesimally thin current carrying sheet in either planar or cylindrical geometry, suggesting that the local ring geometry may not be essential for the instability. It may be useful to further investigate the generalised dispersion equation given below.
A Ray-Tracing Model of the Vela Magnetosphere
Authors: Hirano C. , Gwinn C. R. 
Published: July 2016

AbstractIn the relativistic plasma surrounding a pulsar, a subluminal ordinary-mode electromagnetic wave will propagate along a magnetic field line. After some distance, it can break free of the field line and escape the magnetosphere to reach an observer. We apply a simple model of pulsar radio emission based on this scenario to the case of the Vela pulsar and find it reproduces some qualitative characteristics of the observed Vela pulse profile.
Deconfinement signals from pulsar timing
Authors: Grigorian Hovik , Poghosyan Gevorg , Chubarian Edvard , Blaschke David 
Published: July 2016

AbstractThe occurence of a quark matter core in rotating compact stars has been investigated within general relativity as a function of both the rotational frequency and the total baryon number. We demonstrate that the deviation of the braking index fromn= 3 signals not only the occurence but also the size of a quark matter core in a pulsar. We suggest that in systems with mass accretion onto a rapidly rotating compact star a spin-down to spin-up transition might signal a deconfinement transition in its interior.
Magnetic field of pulsars with superconducting quark core
Authors: Blaschke David , Sedrakian David M. , Shahabasyan Karen M. 
Published: July 2016

AbstractWithin recent nonperturbative approaches to the effective quark interaction the diquark condensate forms a superconductor of second kind. Therefore the magnetic field will not be expelled from the superconducting quark core in accordance with observational data which indicate that life times of pulsar magnetic fields exceed 107years.
Recycling in progress: RXTE discovery of the first accretion-powered millisecond pulsar
Authors: van der Klis M. 
Published: July 2016

AbstractThe discovery is reported of the first accretion-powered millisecond pulsar, SAX J 1808.4–3658. This 2.5 millisecond pulsar has a magnetic field strength of 1–10108Gauss and has all the characteristics of the long-predicted millisecond radio pulsar progenitor, a neutron star in an X-ray binary system where the process of recycling is taking place at this time.
Low Frequency Radio Emission of Pulsar PSR J1907+0919 Associated with the Magnetar SGR1900+14
Authors: Shitov Yu. P. , Pugachev V. D. , Kutuzov S. M. 
Published: July 2016

AbstractThe soft gamma repeater SGR 1900+14 was observed in Pushchino observatory since 1988 December using BSA radio telescope operating at 111 MHz. We have detected the pulsed radio emission (Shitov 1999) with the same 5.16 s period that was reported earlier for this object (Hurley et al. 1998). The timing analysis has shown that this new radio pulsar PSR J1907+0919 associated with SGR 1900+14 has a superstrong magnetic field, which is 8.1 · 1014G, thereby confirming that it is a ”magnetar” (Duncan &amp; Thompson 1992; Kouveliotou et al. 1999). The dispersion measure of PSR J1907+0919 is 281.4(9)pc·cm−3which gives an estimate of the pulsar’s distance as about 5.8 kpc.
The Period of Organization of the International Latitude Service: 1889–1899
Authors: Proverbio E. 
Published: July 2016

Around 1880, and for some time after that, the possibility of revealing a variation in latitude as a consequence of a separation of the instantaneous rotation axis from the Earth’s axis of inertia gave rise to much perplexity due to the complexity of the problem and the existence of non-negligible and hard-to-find systematic errors in observations of a personal and instrumental nature. These errors also depended on effects of refraction and imprecise knowledge of star declinations.To this must be added the fact that the very idea that the rotational axis and the axis of inertia were distinct and in relative motions raised difficult problems of a physical and theoretical nature. At that time the idea of the Earth’s rigidity was still generally accepted and, even admitting the hypothesis of an Earth endowed with sufficient elasticity and plasticity, the theory of which had been partly examined by G.H. Darwin, it was then almost impossible, just as it still is today, to create a model of the movements of mass inside the Earth which could offer an explanation of possible aperiodic and secular variations. In reality, more than on the existence of periodic variations, the attention and interest of geodesists and astronomers was in those years focused on the problem of the existence or non-existence of secular variations in the Earth’s principal axis.
History of the International Polar Motion Service/International Latitude Service
Authors: Yokoyama Koichi , Manabe Seiji , Sakai Satoshi 
Published: July 2016

AbstractThe history of the International Latitude Service and the International Polar Motion Service is described, with an emphasis on the evolution of the international cooperation for monitoring the Earth’s rotation. Also given is a brief description of the history of the Japanese geodetic and astronomical activities, as well as the future prospects.
History of the Bureau International de l’Heure
Authors: Guinot B. 
Published: July 2016

AbstractAt the beginning of the 20th century, the development of radio time signals offered the possibility of unifying the measurements of Universal Time (UT). A new service, the Bureau International de l’Heure, hosted by the Paris Observatory, was entrusted with this task. The BIH began its operation in 1912, although its statutes were officially settled only in 1919. This paper recalls the activities of the BIH on time determination and various connected fields: Earth rotation, reference frames, atomic time. With the importance of atomic time and the emergence of new techniques for the measurement of Earth rotation, a new organization was required. It was prepared by the MERIT and COTES programs (1978) and by the bodies of the Metre Convention, with the active participation of the BIH. The BIH was dissolved at the end of 1987, its work being shared between the Bureau International des Poids et Mesures and the new International Earth Rotation Service.
E. P. Fedorov as President of Commission 19 of IAU During the Period of the Reorganization of ILS
Authors: Korsuń A.O. 
Published: July 2016

Evgeniy Pavlovich Fedorov (1909–1986) was President of Commission 19 of the IAU in 1955–1961. In this period the future of the ILS was discussed very actively and the plan for future study of the polar motion was elaborated. E. Fedorov was the organizer and the leader of these preparatory works.He was editor of the collection of papers “On the present state and the future of latitude investigations” (1960, Moscow). In this collection well-known scientists discussed their opinions on the state latitude observations and their improvement. Among them where: H. Spencer Jones, P. Melchior, T. Hattori, I. Fleckenstein, N. Sekiguchi, W. Munk, R. Vicente, A. Young, E. Fedorov, M. Torao, N. Stoyko. In that time Fedorov wrote on the problem of the ILS. The inception of the ILS was preceded by a period of thorough discussion of various aspects of latitude work. By the end of the 19th century polar motion had become a problem of vital importance in astronomy and geophysics. Many efforts were made at that time to find the best means for obtaining the most accurate polar coordinates. As a result a plan of international cooperation for the study of polar motion was worked out.
Determination of EOP from VLBI in IAA
Authors: Skurihkina E. 
Published: July 2016

AbstractResults of Earth orientation parameter (EOP) determinations from NEOS-A and CORE programs reduced using the package OCCAM version 3.5 at the Institute of Applied Astronomy of Russian Academy of Science (IAA) are presented. Results of EOP determination using different reference stations, relativistic models, the IERS Standards (1992) and IERS Conventions (1996) are also presented.