bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulsations in hot supergiants
Authors: Godart Melanie , Grotsch-Noels Arlette , Dupret Marc-Antoine 
Published: February 2014

AbstractMassive stars are the cosmic engines that shape and drive our Universe. Many issues such as their formation, their stability and the mass loss effects, are far from being completely understood. Recent ground-based and space observations have shown pulsations in massive MS and post-MS stars, such as acoustic and gravity modes excited by the κ-mechanism and even solar-like oscillations. Theoretical studies emphasized the presence of strange modes in massive models, and recent theoretical analyses have shown that hot supergiants can pulsate in oscillatory convective modes. We review the instability domains of massive stars as well as their excitation mechanisms and present the latest results.
Stochastically excited oscillations in the upper main sequence
Authors: Antoci Victoria 
Published: February 2014

AbstractConvective envelopes in stars on the main sequence are usually connected only with stars of spectral types F5 or later. However, observations as well as theory indicate that the convective outer layers in hotter stars, despite being shallow, are still effective and turbulent enough to stochastically excite oscillations. Because of the low amplitudes, exploring stochastically excited pulsations became possible only with space missions such as Kepler and CoRoT. Here I review the recent results and discuss among others, pulsators such as δ Scuti, γ Doradus, roAp, β Cephei, Slowly Pulsating B and Be stars, all in the context of solar-like oscillations.
Energy of solar-like oscillations in red giants
Authors: Grosjean Mathieu , Dupret Marc-Antoine , Belkacem Kevin , Montalbán Josefina , Samadi Reza 
Published: February 2014

AbstractCoRoT and Kepler observations of red giants reveal a large variety of spectra of nonradial solar-like oscillations. So far, we understood pretty well the link between the global properties of the star (radius, mass, evolutionary state) and the properties of the oscillation spectrum (Δν, νmax, period spacing). We are interested here in the theoretical predictions of two other components of a power spectrum, the mode linewidths and heights. The study of the energy of the oscillations is of great importance to predict the peak parameters in the power spectrum. We will discuss circumstances under which mixed modes are detectable for red-giant stellar models from 1 to 2 M⊙, with emphasis on the effect of the evolutionary status of the star along the red-giant branch on theoretical power spectra.
3D simulations of internal gravity waves in solar-like stars
Authors: Alvan Lucie , Brun Allan Sacha , Mathis Stéphane 
Published: February 2014

AbstractWe perform numerical simulations of the whole Sun using the 3D anelastic spherical harmonic (ASH) code. In such models, the radiative and convective zones are non-linearly coupled and in the radiative interior a wave-like pattern is observed. For the first time, we are thus able to model in 3D the excitation and propagation of internal gravity waves (IGWs) in a solar-like star's radiative zone. We compare the properties of our waves to theoretical predictions and results of oscillation calculations. The obtained good agreement allows us to validate the consistency of our approach and to study the characteristics of IGWs. We find that a wave's spectrum is excited up to radial order n=58. This spectrum evolves with depth and time; we show that the lifetime of the highest-frequency modes must be greater than 550 days. We also test the sensitivity of waves to rotation and are able to retrieve the rotation rate to within 5% error by measuring the frequency splitting.
Corotation resonances for gravity waves and their impact on angular momentum transport in stellar interiors
Authors: Alvan Lucie , Mathis Stéphane , Decressin Thibaut 
Published: February 2014

AbstractGravity waves, which propagate in radiation zones, can extract or deposit angular momentum by radiative and viscous damping. Another process, poorly explored in stellar physics, concerns their direct interaction with the differential rotation and the related turbulence. In this work, we thus study their corotation resonances, also called critical layers, that occur where the Doppler-shifted frequency of the wave approaches zero. First, we study the adiabatic and non-adiabatic propagation of gravity waves near critical layers. Next, we derive the induced transport of angular momentum. Finally, we use the dynamical stellar evolution code STAREVOL to apply the results to the case of a solar-like star. The results depend on the value of the Richardson number at the critical layer. In the first stable case, the wave is damped. In the other unstable and turbulent case, the wave can be reflected and transmitted by the critical layer with a coefficient larger than one: the critical layer acts as a secondary source of excitation for gravity waves. These new results can have a strong impact on our understanding of angular momentum transport processes in stellar interiors along stellar evolution where strong gradients of angular velocity can develop.
Precise and accurate interpolated stellar oscillation frequencies on the main sequence
Authors: Ball Warrick H. , Schou Jesper , Gizon Laurent , Marques João P. C. 
Published: February 2014

AbstractHigh-quality data from space-based observatories present an opportunity to fit stellar models to observations of individually-identified oscillation frequencies, not just the large and small frequency separations. But such fits require the evaluation of a large number of accurate stellar models, which remains expensive. Here, we show that global-mode oscillation frequencies interpolated in a grid of stellar models are precise and accurate, at least in the neighbourhood of a solar model.
Variability of M giant stars based on Kepler photometry: general characteristics
Authors: Bányai E. , Kiss L. L. 
Published: February 2014

AbstractOur study based on the continuous, high-precision observations covering more than three years provided by the Kepler mission reveals a new systematic effect in the data, a possible transition region between solar-like and Mira-like oscillations, and gives an overview of M giant variability on a wide range of time-scales (hours to years).
Helio- and asteroseismology shedding light on “new physics”
Authors: Biesiada Marek 
Published: February 2014

AbstractLinkages between astronomy and physics have always been intimately close and mutually stimulating. Most often it was physics that served astronomy with its explanatory power. Today, however, we are increasingly witnessing the reverse: astrophysical considerations are being used to constrain new physics and moreover they are more efficient than laboratory experiments. This contribution reviews the ways helio- and white dwarf asteroseismology – branches in which Wojtek Dziembowski played a prominent role – are used for this purpose.
The IPoP method to measure Cepheid distances
Authors: Breitfelder J. , Mérand A. , Kervella P. , Gallenne A. 
Published: February 2014

AbstractCepheids are one of the most famous standard candles used to calibrate the Galactic distance scale. However, it is fundamental to develop and test independent tools to measure their distances, in order to reach a better calibration of their period-luminosity (P-L) relationship. We present here the first results obtained with the Integrated Parallax of Pulsation (IPoP) method, an extension of the classical Baade-Wesselink method that derives the distance by making a global modelisation of all the available data. With this method we aim to reach a 2% accuracy on distance measurements.Cepheid masses are also an essential key for our comprehension of those objects. We briefly present an original approach to derive observational constraint on Cepheid masses. Unfortunately, it does not lead to promising results.
Multicolour photometry of pulsating stars in the Galactic Bulge fields
Authors: Bruś Przemysław , Kołaczkowski Zbigniew 
Published: February 2014

AbstractWe present a study of photometric properties of very crowded stellar fields toward the Galactic Bulge. We performed a search for pulsating stars among thousands of variable stars from the OGLE-II survey supplementing the variability study with photometric measurements in four Johnson-Cousins UBVIC passbands. Using these data, we analysed the properties of objects located at different distances and, whenever possible, classified them.
What asteroseismology can teach us about low-mass core helium burning models
Authors: Constantino Thomas N. , Campbell Simon W. , Lattanzio John C. 
Published: February 2014

AbstractStandard models of low-mass core helium burning stars typically give an asymptotic l=1 g-mode period spacing well below that inferred from observed mixed modes. We find that most physical uncertainties, such as mixing beyond the fully convective core, are not significant enough to be responsible for such a discrepancy. The solution to the problem may lie in a deviation of structure away from its canonical form, such as a more massive H-exhausted core, which we briefly explore here.
Asteroseismology with the new opacity bump at log T ≈ 5.06
Authors: Cugier H. 
Published: February 2014

AbstractAlthough the κ mechanism of pulsations is known for early-type stars, opacities and the equation of state are still uncertain. Stellar models calculated for the OP data implemented with the new Kurucz opacities at log T < 5.2 were investigated for different chemical compositions of elements. The additional metallic opacity bump at log T ≈ 5.06 that occurs in the Kurucz data changes markedly the oscillation spectra of unstable modes. Basic properties of the new opacity bump and examples of seismic models are shown. B-type stars observed in the Galaxy, LMC and SMC were considered. The problem was studied using Dziembowski's computing codes for linear, non-adiabatic and non-radial oscillations.
Spectroscopic and photometric study of two B-type pulsators in eclipsing systems
Authors: Drobek Dominik , Pigulski Andrzej 
Published: February 2014

AbstractPulsating stars in eclipsing binary systems play an important role in asteroseismology. The combination of their spectroscopic and photometric orbital solutions can be used to determine, or at least to constrain, the masses and radii of components. To successfully perform any seismic modelling of a star, one has to identify at least some of the detected modes, which requires precise time-series photometric and spectroscopic observations. This work presents a progress report on the analysis of two β Cephei-type stars in eclipsing binaries: HD 101794 (V916 Cen) and HD 167003 (V4386 Sgr).
An interferometric view on binarity and circumstellar envelopes of Cepheids
Authors: Gallenne A. , Kervella P. , Mérand A. , Monnier J. D. , Breitfleder J. , Pietrzyński G. , Gieren W. 
Published: February 2014

AbstractOptical interferometry is the only technique giving access to milli-arcsecond (mas) resolution at infrared wavelengths. For Cepheids, this is a powerful and unique tool to detect the orbiting companions and the circumstellar envelopes (CSE). CSEs are interesting because they might be used to trace the Cepheid evolution history, and more particularly they could impact the distance scale. Cepheids belonging to binary systems offer an unique opportunity to make progress in resolving the Cepheid mass discrepancy. The combination of spectroscopic and interferometric measurements will allow us to derive the orbital elements, distances, and dynamical masses. Here we focus on recent results using 2- to 6-telescopes beam combiners for the Cepheids X Sgr, T Mon and V1334 Cyg.
Searching for pulsations in Kepler eclipsing binary stars
Authors: Gaulme Patrick , Guzik Joyce A. 
Published: February 2014

AbstractEclipsing binaries can in principle provide additional constraints to facilitate asteroseismology of one or more pulsating components. We have identified 94 possible eclipsing binary systems in a sample of over 1800 stars observed in long cadence as part of the Kepler Guest Observer Program to search for γ Doradus and δ Scuti star candidates. We show the results of a procedure to fold the light curve to identify the potential binary period, subtract a fit to the binary light curve, and perform a Fourier analysis on the residuals to search for pulsation frequencies that may arise in one or both of the stellar components. From this sample, we have found a large variety of light curve types; about a dozen stars show frequencies consistent with δ Sct or γ Dor pulsations, or light curve features possibly produced by stellar activity (rotating spots). For several stars, the folded candidate ‘binary’ light curve resembles more closely that of an RR Lyr, Cepheid, or high-amplitude δ Sct star. We show highlights of our results and discuss the potential for asteroseismology of the most interesting objects.
LIMBO: A time-series Lucky Imaging survey of variability in Galactic globular clusters
Authors: Kains N. , Bramich D. M. , Jaimes R. Figuera , Skottfelt J. 
Published: February 2014

AbstractWe present a large observing project monitoring globular clusters (GC) over long time baselines, which will lead to a complete census of variable stars in those clusters down to several magnitudes below the horizontal branch (HB). The use of Lucky Imaging (LI) will allow us to obtain high-precision photometry for even faint objects, and long-term monitoring will also mean that observations are sensitive to detecting other slow transient phenomena, such as gravitational microlensing, the primary aim of this project.
Global Astrophysical Telescope System — telescope No. 2
Authors: Kamiński Krzysztof , Baranowski Roman , Fagas Monika , Borczyk Wojciech , Dimitrov Wojciech , Polińska Magdalena 
Published: February 2014

AbstractWe present the new, second spectroscopic telescope of Poznań Astronomical Observatory. The telescope allows automatic simultaneous spectroscopic and photometric observations and is scheduled to begin operation from Arizona in autumn 2013. Together with the telescope located in Borowiec, Poland, it will constitute a perfect instrument for nearly continuous spectroscopic observations of variable stars. With both instruments operational, the Global Astrophysical Telescope System will be established.
The Large Magellanic Cloud Cepheids: effects of helium content variations
Authors: Marconi Marcella , Carini Roberta , Brocato Enzo , Raimondo Gabriella 
Published: February 2014

AbstractAn extended set of evolutionary and pulsational models has been computed for two chemical compositions representative of classical Cepheids in the Large Magellanic Cloud. The comparison between the standard and He enhanced theoretical predictions is analysed and the implications for interpreting current observations and for defining the Cepheid based distance scale are discussed.
Spectroscopic survey of Kepler stars: high-resolution observations of A- and F-type stars
Authors: Niemczura E. , Smalley B. , Murphy S. , Catanzaro G. , Uytterhoeven K. , Drobek D. , Briquet M. , De Cat P. , Marcos-Arenal P. , Pápics P. I. , Gameiro J. F. S. 
Published: February 2014

AbstractBasic stellar parameters such as effective temperature, surface gravity, chemical composition, and projected rotational velocity, are important to classify stars and are crucial for successful asteroseismic modelling. However, the Kepler space data do not provide such information. Therefore, ground-based spectral and multi-colour observations of Kepler asteroseismic targets are necessary to complement the space data. For this purpose, in coordination with the KASC ground-based observational Working Groups, high-resolution spectroscopic data for more than 500 B, A, F and G-type stars were collected.
Order and chaos in hydrodynamic BL Her models
Authors: Smolec Radosław , Moskalik Paweł 
Published: February 2014

AbstractMany dynamical systems of different complexity, e.g. 1D logistic map, the Lorentz equations, or real phenomena, like turbulent convection, show chaotic behaviour. Despite huge differences, the dynamical scenarios for these systems are strikingly similar: chaotic bands are born through the series of period doubling bifurcations and merge through interior crises. Within chaotic bands periodic windows are born through the tangent bifurcations, preceded by the intermittent behaviour. We demonstrate such behaviour in models of pulsating stars.
Analysis of strange-mode instability with time-dependent convection in hot massive stars
Authors: Sonoi Takafumi , Shibahashi Hiromoto 
Published: February 2014

AbstractWe carry out nonadiabatic analysis of strange-modes in hot massive stars with time-dependent convection (TDC) for the first time. Although convective luminosity in envelopes of hot massive stars is not as dominative as in stars near the red edge of the classical Cepheid instability strip in the Hertzsprung-Russell (H-R) diagram, we have found that the strange-mode instability can be affected by the treatment of convection. However, existence of the instability around and over the Humphreys-Davidson (H-D) limit is independent of the treatment. This implies that the strange-mode instability could be responsible for the lack of observed stars over the H-D limit regardless of uncertainties on convection theories.
The fast rotating δ Scuti pulsator V376 Per: Frequency analysis and mode identification
Authors: Themessl Nathalie , Fritz Veronique , Breger Michel , Karrer Sabine , Castanheira Barbara G. 
Published: February 2014

AbstractOur simultaneous analysis of ground-based photometric and high-resolution spectroscopic data of the δ Scuti star V376 Per revealed eight individual frequencies from 82 nights of two-color photometry and six frequencies from the line-profile variations using 769 stellar spectra. Additionally, we identified the corresponding pulsation modes and derived reliable estimates of the line profile and pulsation mode parameters.
Pulsations in the late-type B supergiant star HD 202850
Authors: Tomić Sanja , Kraus Michaela , Oksala Mary 
Published: February 2014

AbstractHD 202850 is a late B-type supergiant. It is known that photospheric lines of such stars vary. Due to macroturbulence the lines are much wider than expected. Macroturbulence has been linked to stellar pulsations. It has been reported that there are several B supergiants that undergo pulsations. In our previous work, we detected a pulsational period of 1.59 hours in this object from data taken with the Ondřejov 2-m telescope. We continued to investigate this object and we took several time series with the DAO 1.2-m telescope. Our new data suggest that there may be some additional pulsational periods in this star. We present our new results in this poster.
Antarctica photometric survey using PDM13
Authors: Zalian Cyrus , Chadid Merieme 
Published: February 2014

AbstractPDM13 is a new graphic interface program dedicated to frequency domain analysis based on the Phase Dispersion Minimization technique (PDM, Stellingwerf 2012). In this paper, we will present the different algorithms running in PDM13, including the Auto-Segmentation, the Gauss-Newton and the PDM algorithms. More details on this triptych are available in our recent paper (Zalian et al., submitted). Their aim is to offer a simple and powerful way to extract frequency. Amongst the numerous improvements offered by the program, we will particularly focus on the reduction of aliases and the ability to look directly for multiple-period phenomena and the Blazhko effect. After that, we will show the first results from PDM13 using the Antarctica photometric survey.
Molecular phylogeny of Myriapoda provides insights into evolutionary patterns of the mode in post-embryonic development
Authors: Miyazawa Hideyuki , Ueda Chiaki , Yahata Kensuke , Su Zhi-Hui 
Published: February 2014

AbstractMyriapoda, a subphylum of Arthropoda, comprises four classes, Chilopoda, Diplopoda, Pauropoda and Symphyla. While recent molecular evidence has shown that Myriapoda is monophyletic, the internal phylogeny, which is pivotal for understanding the evolutionary history of myriapods, remains unresolved. Here we report the results of phylogenetic analyses and estimations of divergence time and ancestral state of myriapods. Phylogenetic analyses were performed based on three nuclear protein-coding genes determined from 19 myriapods representing the four classes (17 orders) and 11 outgroup species. The results revealed that Symphyla whose phylogenetic position has long been debated is the sister lineage to all other myriapods and that the interordinal relationships within classes were consistent with traditional classifications. Ancestral state estimation based on the tree topology suggests that myriapods evolved from an ancestral state that was characterized by a hemianamorphic mode of post-embryonic development and had a relatively low number of body segments and legs.
Heart rate response and fitness effects of various types of physical education for 8‐ to 9‐year‐old schoolchildren
Authors: Bendiksen Mads , Williams Craig A. , Hornstrup Therese , Clausen Helle , Kloppenborg Jesper , Shumikhin Dmitriy , Brito João , Horton Joshua , Barene Svein , Jackman Sarah R. , Krustrup Peter 
Published: February 2014

AbstractThe present study investigated the heart rate (HR) response to various types of physical education (PE) activities for 8‐ to 9‐year‐olds (five school classes, n = 93) and the fitness effects of a short‐term PE training programme (three of the five classes, n = 59) with high compared to low‐to‐moderate aerobic intensity. HR was recorded during small‐sided indoor soccer (SO), basketball (BB), unihockey (UH), circuit training (CT), walking (W) and Nintendo Wii Boxing (NWB) and Nintendo Wii Tennis (NWT). Maximal HR (HRmax) and physical fitness was determined by the Yo‐Yo Intermittent Recovery Level 1 Children's test (YYIR1C) test. Following cluster randomisation, three classes were tested before and after 6 wks with 2 × 30 min/wk SO and UH lessons [high‐intensity (HI), 2 classes, n = 39] or low‐to‐moderate intensity PE lessons (CON, 1 class, n = 20). Average HR in SO (76 ± 1% HRmax), BA (77 ± 1% HRmax) and UH (74 ± 1% HRmax) was higher (P < 0.05) than in CT (62 ± 1% HRmax), W (57 ± 1% HRmax), NWB (65 ± 2% HRmax) and NWT (57 ± 1% HRmax). Time with HR > 80% and 90% HRmax, respectively, was higher (P < 0.05) in SO (42 ± 4 and 12 ± 2%), BB (41 ± 5 and 13 ± 3%) and UH (34 ± 3 and 9 ± 2%) than in CT, W and NW (0–5%), with time >80% HRmax being higher (P < 0.05) in SO than UH. After 6 wk, YYIR1C performance was increased (P < 0.05) by 22% in HI (673 ± 57 to 821 ± 71 m), but unaltered in CON (674 ± 88 to 568 ± 81 m). HR 2 min into YYIR1C was lowered (P < 0.05) in HI after 6 wks (92.4 ± 0.8 to 89.1 ± 0.9% HRmax), but not in CON. In conclusion, ball games elicited high aerobic loading for young schoolchildren and a short‐term, low‐volume ball game PE‐intervention improved physical fitness. Traditional PE sessions had no effects on intermittent exercise performance.
An APN model for Arrhythmic beat classification
Authors: Chiang Hsiu-Sen , Shih Dong-Her , Lin Binshan , Shih Ming-Hung 
Published: February 2014

Motivation: Changes in the normal rhythm of a human heart may result in different cardiac arrhythmias, which may be immediately fatal or cause irreparable damage to the heart sustained over long periods of time. Therefore, the ability to automatically identify arrhythmias from ECG recordings is important for clinical diagnosis and treatment. In this article, classification by using associative Petri net (APN) for personalized ECG-arrhythmia-pattern identification is proposed for the first time in literature.
Results: A rule-based classification model and reasoning algorithm of APN are created for ECG arrhythmias classification. The performance evaluation using MIT-BIH arrhythmia database shows that our approach compares well with other reported studies.
Contact: shihdh@yuntech.edu.tw