bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Physical Mechanism for the Generation of Extended Stellar Atmospheres
Authors: Hillendahl R. W. 
Published: June 2019

AbstractA physical mechanism that can result in the generation of extended expanding atmospheres is discussed. The process involves the unloading of stellar material following the arrival of a shock wave at the edge of the star. The basic principles are developed from a discussion of a simplified case that has been studied in the laboratory; they are then applied to the atmosphere of a star. A radiation-hydrodynamics computation of a model cepheid is then used to obtain quantitative atmospheric profiles. The computed continuum and spectral lines during the unloading process are then examined. A discussion of the possibility that the unloading process occurs in stars other than cepheids suggests the existence of a shock visibility factor associated with ionization or dissociation in the region behind the shock front and leads to a possible alternate interpretation of the variable star instability strips in the H-R diagram.
Disentangling X-Ray Reprocessing Sites in EXO 0748-676
Authors: Hynes R. I. , Haswell C. A. , Robinson E. L. , Horne K. , O'Brien K. , Charles P. A. , King A. R. , Rolfe D. J. 
Published: June 2019

AbstractWe present first results from a coordinated multiwavelength study of the neutron star low-mass X-ray binary EXO 0748 676. Fast UV, X-ray, and optical data were obtained including both spectral and timing information. We discuss how this study allows us to probe the temperature distribution within the binary and hence the geometry and efficiency of X-ray irradiation.
The Optical Counterpart of SAX J1808.4-3658 in Quiescence: Evidence of an Active Radio Pulsar?
Authors: Burderi L. , Di Salvo T. , D'Antona F. , Robba N. R. , Testa V. 
Published: June 2019

AbstractThe optical counterpart of the binary millisecond X-ray pulsar SAX J 1808.4-3658 during quiescence was detected at V = 21.5 mag, inconsistent with intrinsic emission from the fain companion star. We propose that the optical emission from this system during quiescence is due to the irradiation of the companion star and a remnant accretion disk by the rotational energy released by the fast spinning neutron star, switched on, as magneto-dipole rotator (radio pulsar). In this scenario the companion behaves as a bolometer, reprocessing in optical part of the power emitted by the pulsar. The reprocessed fraction depends only on known binary parameters. Thus the blackbody temperature of the companion can be predicted and compared with the observations. Our computations indicate that the observed optical magnitudes are fully consistent with this hypothesis. In this case the observed optical luminosity may be the first evidence that a radio pulsar is active in this system in quiescence.
The η Carinae Like Fell-Rich Spectrum of FBS0022-021
Authors: Zharikov S. , Tovmassian G. , Costero R. 
Published: June 2019

AbstractWe report results of Echelle and B&Ch spectroscopic observations of the emission-line object FBS 0022-021 that were obtained at SPM Observatory, Mexico. We analyze the emission-line spectra along with available optical and IR data. The Fell-rich spectrum of the object closely resembles that of the peculiar binary system η car. The discussion of the physical conditions leading to such spectrum and the nature of this peculiar object are presented.
Compact Binaries in Globular Clusters
Authors: Ivanova Natalia , Rasio Frederic A. 
Published: June 2019

AbstractIn dense stellar systems the frequent dynamical interactions between stars play a crucial role in the formation and evolution of compact binaries. We study these processes using a novel approach combining a state-of-the- art binary population synthesis code with a simple treatment of dynamical interactions in dense star cluster cores. Here we focus on the dynamical and evolutionary processes leading to the formation of compact binaries containing white dwarfs in dense globular clusters. We demonstrate that dynamics can increase by factors ~ 2 – 100 the production rates of interesting binaries such as cataclysmic variables, “nonflickerers” (He white dwarfs with a heavier dark companion), merging white dwarf binaries with total masses above the Chandrasekhar limit, and white dwarf binaries emitting gravitational waves in the LISA band.
Close Binary White Dwarfs and Supernovae la
Authors: Napiwotzki R. , Karl C. , Nelemans G. , Yungelson L. , Christlieb N. , Drechsel H. , Heber U. , Homeier D. , Leibundgut B. , Koester D. , Marsh T. R. , Moehler S. , Pauli E.-M. , Reimers D. , Renzini A. 
Published: June 2019

AbstractWe report on the current status of radial velocity surveys for white dwarf binaries (double degenerates DDs) including SPY (ESO Supernovae la progenitor survey) recently carried out at the VLT. A large sample of DD will allow us to put strong constraints on the phases of close binary evolution of the progenitor systems and to perform an observational test of the DD scenario for Supernovae of type Ia.
Long-Term Evolution of (Short) Gamma-Ray Burst Central Engines
Authors: Lee William H. 
Published: June 2019

AbstractCosmological gamma ray bursts (GRBs) possibly originate from accretion disks around stellar mass black holes. These could be formed after the merger of a double neutron star or black hole-neutron star binary. The dynamical evolution of the disk is important if one wishes to relate characteristic timescales with the observed duration and variability. We show here the results of such a set of calculations, relevant for short GRBs.
Warped Accretion Disks and Longterm X-Ray Periodicities
Authors: Clarkson W. I. , Charles P. A. , Laycock S. , Coe M. J. , Wilson-Hodge C. , Tout M. D. 
Published: June 2019

AbstractA significant number of X-ray binaries are now known to exhibit long-term periodicities on timescales of ~10 - 100 days. Several physical mechanisms have been proposed that give rise to such periodicities, one of which is radiation-driven warping and precession of the accretion disk. Recent theoretical work predicts the stability to disk warping as a, function of the mass ratio, binary radius, viscosity and accretion efficiency. We investigate the stability of the superorbital periodicities in the neutron star X-ray binaries Cyg X-2, LMC X-4, SMC X-l and Her X-l, and thereby confront stability predictions with observation. We find that the period and nature of the superorbital variations in these sources is consistent with the predictions of warping theory.
XMM Observations of Polars from the SDSS
Authors: Szkody Paula , Homer Lee , Chen Bing , Henden Arne , Schmidt Gary 
Published: June 2019

AbstractWe condueted XMM observations of 5 faint Polars discovered by the Sloan Digital Sky Survey. The X-ray fluxes and spectra show a variety of shock regimes. The lowest accretor has X-ray properties consistent with an origin on the secondary star. The light curves of all systems show large variability, with one showing a deep eclipse, and with some evidence for orbital-related variations in 2 others.
Replaying the 2001 Outburst of WZ SGE
Authors: Steeghs D. 
Published: June 2019

AbstractI present the key results of extensive optical spectroscopy obtained during the first three weeks of the 2001 super-outburst of WZ Sge. A sequence of Doppler maps of the accretion flow in various lines was constructed, and used to create real-time movies of WZ Sge as it evolved through the outburst. Main results include the detection of two-armed spiral asymmetries in the disk, emission from the irradiated donor star and an extended stream of emission around day 19 of the outburst that bears the hallmarks of a mass-transfer burst event.
On the Classification of Magnetic Cataclysmic Variables
Authors: Mason Paul A. 
Published: June 2019

AbstractThe classification scheme for Magnetic Cataclysmic Variables (MCVs) is addressed. When only ten or twenty MCVs had been discovered their classification was simple and based on direct observational properties. Now that the number of MCVs exceeds one hundred, the method of classification needs updating. One important consideration is the possibility that binaries might physically change their classification. For example will intermediate polars become polars as they evolve to shorter orbital periods? Or does a polar become an intermediate polar when synchronism is broken due to a nova?
V445 Puppis, A First Identified Helium Nova
Authors: Kato Mariko , Hachisu Izumi 
Published: June 2019

AbstractThe 2001 outburst, of V445 Puppis is an unique object, that shows absence of hydrogen, enrichment of helium and carbon, slow decay of the light curve with a small amplitude. We have calculated theoretical light curves of helium novae to confirm that V445 Pup is the first example of helium nova. From the light curve fitting we conclude that the white dwarf is very massive ≥ 1.33M⊙.
Discovery of the 2001 Outburst of WZ Sagittae
Authors: Ohshima T. 
Published: June 2019

I found WZ Sagittae at mvis = 9.7 in the rising phase of the historical outburst on 2001 July 23. This article vividly reports the very exciting situation at the discovery.WZ Sge is one of the most famous cataclysmic variables (CVs), and forms the WZ Sge sub-class with several other enigmatic SU UMa-type dwarf novae. The unusual characteristics of the WZ Sge stars are rare superoutbursts, large amplitudes, and no (or only few) normal outbursts. As to WZ Sge itself, the outburst cycle is over 10000 days in average. The outburst amplitude is 8 magnitude. Its magnitude is around 15th in quiescence.
Photometric Periodicities in Magellanic Cloud Be/Neutron Star Binaries
Authors: Schmidtke P. C. , Cowley A. P. , Levenson Lance , Sweet Katie 
Published: June 2019

We are investigating the photometric properties of Be/neutron star systems in the Magellanic Clouds using V, R, and I data from the MACHO and OGLE-II surveys. Here we give results for 6 systems, 4 of which are X-ray pulsars.The long-term light curves for each of these systems were searched for periodic variations. We first pre-whitened the data by fitting an appropriate polynomial to “flatten” lengthy portions of the light curves. We then used the method described by Home & Baliunas (1986) to find periodicities in the relative magnitudes.
Long-Term Variability in the Quiescent X-Ray Transient V404 CYG
Authors: Zurita C. , Casares J. , Charles P. A. , Hynes R. I. , Pavlenko E. P. , Shahbaz T. 
Published: June 2019

We present the results of optical and infrared photometry of the quiescent X-ray transient V404 Cyg during the period 1992-2003.It is largely known that the Soft X-ray Transient (SXT) V404 Cyg exhibits short-term (sub-orbital) variations during quiescence (see eg. Pavlenko et al. 1996). It seems that fast variability during quiescence is not a peculiarity of V404 Cyg but a fingerprint of quiescent SXTs, irrespective of the nature of the compact object (Zurita, Casares & Shahbaz, 2003). Although these variations seem to originate in the accretion disc, the underlaying physical mechanism is not yet understood. Since V404 Cyg is the brightest SXT, and hence accessible with 1-m type telescopes, we embarked on a study of the fast variability over the period 1992-2003.
New Clues on the Model of YY Her After Two Seasons
Authors: Hric L. , Gális R. , Dobrotka A. , Śimon V. , Petrík K. , Niarchos P. , Velić Z. , Gazeas K. , Šmelcer L. , Hájek P. , Sobotka P. , Koss K. , Brát L. , Lomoz F. 
Published: June 2019

During two observational seasons of international campaign of YY Her we secured photometric data which covered the primary as well as the secondary minima and revealed unexpected outburst activity of this system.YY Her belongs to the classical symbiotic binaries with nova-like outbursts. Recently Mikolajewska et al. (2002) explained the light variability of YY Her by combining the ellipsoidal changes and sinusoidal variations of the nebular continuum and line emission. In 2001 (Hric et al. 2001) we discovered in the binary system YY Her the presence of the secondary minimum that was indicated, however, by only three photometric observations from one observatory.
Dramatic Spectral Evolution of WZ Sge during the 2001 Superoutburst
Authors: Nogami D. , Iijima T. 
Published: June 2019

We spectroscopically observed WZ SGE in 11 nights during the 2001 superoutburst. The feature of the spectra dramatically varied from at the outburst maximum through during the rebrightening phase.WZ SGE is the prototypical star of WZ SGE-type stars, a small class of SU UMa-type dwarf novae. WZ SGE stars have unusual characteristics of quite large outburst amplitudes up to ~8 mag, extraordinary long recurrence cycles of the outbursts (≥10 years), no (or only a few) normal outbursts.
Peculiar Abundances in CV Secondary Stars: Revising their Evolutionary History?
Authors: Harrison Thomas E. , Howell Steve B. , Johnson Joni J. , Osborne Heather L. , Homeier Derek 
Published: June 2019

We have recently completed an infrared (K-band) spectroscopic survey of two dozen cataclysmic variables. The systems range in orbital period from Рorb = 1-35 hr (EF Eri), to Рorb = 11.0 hr (V442 Cen). We detect the secondary star in every system.Nearly all of the CVs in which we can clearly see the secondary have weak CO features. Most show evidence for enhanced levels of 13CO. In addition, we see apparent enhancements and/or deficits of such species as sodium, calcium, titanium, magnesium, silicon, and iron. In addition, we find a few lines that we have been unable to identify (such as the strong feature we call “cataclysmicum” at 2.2767 μm seen in the spectrum of EF Eri, and two other very short period CVs).
Analysis of Ulysses Dust Measurements within the Asteroid Belt
Authors: Mann I. , Wilck M. , Grün E. 
Published: June 2019

AbstractResults of Ulysses impact measurements are compared to Zodiacal cloud models. We discuss the influence of radiation pressure forces on particles of different size and composition and show its relevance for the understanding of impact measurements, and give an upper estimate for the dust density in an IRAS dust band.
Trapping of Dust Particles into Internal Resonances with the Inner Planets
Authors: Gomes Rodney S. 
Published: June 2019

AbstractTrapping of dust particles into external resonances with the inner planets is a quite relevant phenomenon, which induces the formation of rings of dust around the planets' orbits, there being observational evidence of the Earth's resonant ring (Dermott et al., 1994). On the other hand, notwithstanding it is a less probable event, capture into internal resonance (diverging orbits) is predicted in numerical integrations of dust particles' orbits subject to Poynting-Robertson drag with one or two disturbing planets. Average theories, which give a good explanation for resonance trapping when the orbits are converging, do not allow capture for diverging orbits. Close approaches with the perturbing planet disallow the application of average theories, and numerical examples show that resonance trapping for internal resonances must have a chaotic origin. As expected from analytical theories, for the case of one disturbing planet, the particle's eccentricity decreases continually after capture and resonance is eventually broken. When two disturbing planets are present, however, there is not necessarily a decrease of the eccentricity, but it may increase, decrease or oscillate, although escape from resonance always occurs anyway.
The Evolution of Meteoroid Streams
Authors: Williams I.P. 
Published: June 2019

AbstractThe existence of meteoroid streams is indicated by the regular appearance of coherent meteor activity at specified times during the year. Since it is the interaction of the meteoroid with the atmosphere that is detected, the meteoroid has to be greater than about 100 micrometers in radius. Observation of these interactions gives information on individual meteoroids as well as collective phenomena. It is generally agreed that streams form through the ejection of dust particles from the surfaces of comets and asteroids at speeds considerably lower than the orbital speed. The subsequent motion of these particles is affected by gravitational perturbations from the planets and the effects of solar radiation forces. This review is intended to present an overview of the development of the subject and of our current state of knowledge.
The Formation and Evolution of the Perseid Meteoroid Stream
Authors: Harris Nathan W. 
Published: June 2019

AbstractThe orbital evolution of two modelled ‘Perseid’ meteoroid streams is investigated using direct numerical integration techniques. We conclude that, in the absence of significant meteoroid velocity determination errors, the observed meteoroid orbital semi-major axis distribution is a direct consequence of the cometary ejection process and not due to subsequent orbital evolution. A high ejection-velocity (~ 0.6 km s-1) model stream succeeds in reproducing the observations. Conclusions are made concerning how the orbital stability of Earth-orbit-intersecting Perseid metecroids varies with initial orbital semi-major axis.
Dynamic and Probabilistic Relation between Meteoroids and their Parent Bodies
Authors: Adolfsson Lars G. , Gustafson Bo Å. S. 
Published: June 2019

AbstractWe estimate the probability that specific meteoroids were produced by a specific parent body and obtain the ejection velocity and several other conditions of the ejection as a by-product. The duration of cometary activity leading to a meteor stream, or the epoch of a collision can be estimated from the ejection times of meteoroids in the same stream. The level of activity of a comet or probability of asteroid collisions can be estimated from the part of the orbit where ejection took place. We show that Phaethon ejected Geminid meteoroids over at least 3000 years lasting to as recently as ≈ AD 1600. Ejections are predominantly in the direction of the sun, i.e., from Phaethon's day side, and give insights into the ejection process which is suggestive of cometary activity. Our calculations account for the uncertainty in the observational data and include the effects of planetary perturbations, radiation pressure, Poynting-Robertson light drag and solar wind corpuscular drag.
Modelling the Ejection of Meteoroids from Comets
Authors: Jones J. , Brown P. 
Published: June 2019

AbstractWe have reworked Whipple's (1951) theory of the ejection of meteoroids from comets to include the effects of cooling by the sublimation of the cometary ice and the adiabatic expansion of the escaping gases. We consider only those particles moving significantly slower than the gas speed and find that the inclusion of these effects does not yield results much different from Whipple's theory. We have extended the theory to include the case of an active area in the form of a spherical cap and have shown how the characteristics of the ejection process change when the cap is in the form of a pit or a depression. We present a empirical formulae which should be useful to modellers of meteor stream evolution.
Recent near Earth satellite flux data: contributions in the definition of the interplanetary flux at 1 AU heliocentric distance
Authors: McDonnell J. A. M. , Gardner D. J. , McBride N. 
Published: June 2019

AbstractRecently analysed hypervelocity impact data from retrieved satellites are summarised. Analyses of perforation data show that mean densities are low (around 1.5-2 g/cm3), impact velocities are consistent with radar meteor observations and that high aspect ratio particles are not found. Mean data, for Fmax > 30 μm agrees well with the Grün et al. Interplanetary flux model, though there is evidence of a strong bias towards the Earth apex of motion direction. For Fmax < 30 μm the data at LDEF's altitude is dominated by space debris.
Microparticle Impacts Observed on the Hubble Space Telescope Solar Array
Authors: Berthoud Lucinda , Paul Klaus 
Published: June 2019

AbstractThe recent recovery of the Hubble Space Telescope (HST) Solar-Array-1 offers a unique opportunity to improve our knowledge of the low Earth orbit (LEO) particle environment. The data from HST surfaces is particularly interesting for the meteoroid and debris community, as the Telescope was in orbit at an altitude of approximately 614 km and there has been no data from such a high orbit before.
Mars Dust Counter on Board ISAS PLANET-B
Authors: Igenbergs Eduard , Sasaki Sho , Färber Georg , Fischer Franz , Münzenmayer Ralf , Fujiwara Akira , Iglseder Heinrich , Glasmachers Albrecht , Grün Eberhard , Mukai Tadashi , Nogami Ken-ichi , Ohashi Hideo , Schwehm Gerhard , Svedhem Håkan , Yamakoshi Kazuo 
Published: June 2019

AbstractPLANET-B is an ISAS spacecraft which will investigate the upper atmosphere and the surroundings of Mars between 1999 and 2001 To clarify the presence and characteristics of the Martian dust ring/torus, an impact ionization dust detector will be on board PLANET-B The detector (PLANET B Mars Dust Counter), which is an improved version of the Munich Dust Counters of HITEN and BREMSAT, will weigh only 630g with an aperture area 140cm2. The detectable mass range will be between 10-16g and more than 10-6g and the velocity range will be from 1km/s to more than 70km/s. Since PLANET-B executes retrograde elliptic orbits close to the zodiacal plane, our detector can investigate the spatial distribution of prograde dust particles from Phobos and Deimos with relative encounter velocity as large as or higher than 1km/s. PLANET-B MDC shall also measure the dust environment around the Earth and interplanetary and possibly interstellar dust particles.
Dust Near the Sun
Authors: Mann I. 
Published: June 2019

AbstractYielding the inner continuation of the interplanetary dust cloud, the dust at about 0.3 AU and closer to the Sun is studied under observing conditions different from those of the Zodiacal light. The F-coronal brightness indicates its optical particle properties as well as its overall spatial distribution. The present knowledge is based on visible and near infrared F-coronal observations and may be improved from data of the SOHO satellite in the near future. Some dynamical effects become particulary important for sub-μm particles in the solar vicinity. However, these particles seem to have only a small effect on the observable corona brightness, but are more accessible to in-situ experiments.
Dust Particles Near The Sun
Authors: Shestakova L. I. , Tambovtseva L. V. 
Published: June 2019

AbstractThe orbital motion of interplanetary dust grains in the sublimation zone near the Sun has been considered for graphite and silicate. Calculations showed that dust grains with initial radii s = 0.5 - 5 μm can form regions of enhanced concentration. The inner corona is slightly enriched with particles s = 0.3 - 0.6 μm due to the departure of the evaporated grains onto highly elliptic orbits. However, they may be not recognized due to their small contribution to the total brightness along the line-of-sight compared with the background of the more typical Zodiacal particles. The astrosilicate dust grains do not form zones of enhanced concentration. Finally, particles with initial radii from 0.3 to 4 μm leave the Solar system and become β-meteoroids.
Composition and Optical Properties of Cometary Dust
Authors: Hanner Martha S. 
Published: June 2019

AbstractComet dust consists primarily of silicate and carbonaceous material. The carbonaceous material is not yet well-characterized. The 3.36 μm emission feature arises primarily from gas phase molecules, while a small feature at 3.29 μm may be due to aromatic hydrocarbons in the grains. Olivine, a high temperature condensate, is present in some comets. Polarization and albedo maps have shown that the coma is not uniform; an inner halo of large particles may be present.