bluuebunny/crossref_metadata_2025_split huggingface dataset:
First stars and reionization: Spinstars
Authors: Chiappini C. 
Published: October 2014

AbstractSoon after the Big Bang, the appearance of the first stellar generations (hereafter, first stars) drastically changed the course of the history of the Universe by enriching the primordial gas with elements heavier than helium (referred to as metals) through both stellar winds and supernova explosions. High‐resolution hydrodynamical simulations of the formation of the first stars suggest these objects to have formed in dark matter mini‐halos, and to have played a key role in the formation of the first galaxies. Today these stars are (most likely) long dead, and even though next generation facilities will push the observational frontier to extremely high redshifts, with the aim of discovering the first galaxies, the first stars will still lie beyond reach. Thus, the only way to constrain our theoretical understanding of the formation of the first stars is to search for their imprints left in the oldest, still surviving, stars in our own backyard: the Milky Way and its satellites. Which imprints are we looking for, and where can we find them? We address these questions in the present review. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Abundance analysis of the γ Doradus–δ Scuti hybrid metallic line (Am) star HD 8801
Authors: Neuteufel R. , Weiss W. , Handler G. 
Published: October 2014

AbstractLow frequency oscillation, typical for γ Doradus g‐mode type stellar core sensitive pulsation, as well as higher frequency δ Scuti type pulsation typical for p ‐modes, sensitive to the envelope, make HD 8801 a remarkable hybrid pulsator with the potential to probe a stellar structure over a wide range of radius. In addition HD 8801 is a rare pulsating metallic line (Am) star. We determined the astro‐physical fundamental parameters to locate HD 8801 in the H‐R diagram. We analyzed the element abundances, paying close attention to the errors involved, and confirm the nature of HD 8801 as a metallic line (Am) star. We also determined an upper limit on the magnetic field strength. Our abundance analysis is based on classical techniques, but uses for the final step a model atmosphere calculated with the abundances determined by us. We also discuss spectropolarimetric observations obtained for HD 8801. This object is remarkable in several respects. It is a nonmagnetic metallic line (Am) star, pulsating simultaneously in p‐ and g‐modes, but also shows oscillations with periods in between these two domains, whose excitation requires explanation. Overall, the pulsational incidence in unevolved classical Am stars is believed to be quite low; HD 8801 does not conform to this picture. Finally, about 75 % of Am stars are located in short‐period binaries, but there is no evidence that HD 8801 has a companion. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kinematics of nearby OB3 stars with interstellar Ca II line distances
Authors: Bobylev V.V. , Bajkova A.T. 
Published: October 2014

AbstractWe tested distances derived from the equivalent widths of interstellar Ca II spectral lines by Megier et al. (2009). To this end, we used a sample of nearby 126 young OB3 stars (r < 1 kpc) with known proper motions and line‐of‐site velocities. We shown that these stars are closely associated with the Gould Belt structure. The bulk of the sample (about 100 stars) shows the same kinematics as the sample of distant OB3 stars. Their galactocentric radial velocities agree well with the following spiral density wave parameters: the amplitude of radial perturbations fR ≈ 12 km s–1, wavelength λ ≈ 2.3 kpc, and phase of the Sun in spiral wave χ⊙ ≈ –90°. However, we revealed 20 stars with absolutely unusual kinematical features. Their galactocentric radial velocities show a wave shifted by ≈180° with respect to the wave found from the entire sample. The superposition of two spiral patterns seems to be a likely explanation. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gravitational stability and mass estimation of stellar disks
Authors: Saburova A.S. , Zasov A.V. 
Published: October 2014

AbstractWe estimate masses of galaxy disks using the marginal gravitational stability criterion and compare them with the photometric disk‐mass evaluations. The comparison reveals that stellar disks of most spiral galaxies we have considered cannot be substantially overheated (at least within several radial scale lengths) and are therefore unlikely to have experienced a significant merging event in their history. However, for a substantial part of S0‐type galaxies, their stellar velocity dispersion is well in excess of the gravitational stability threshold suggesting a major merger event in the past. For four low‐surface‐brightness galaxies, we find the disk masses corresponding to the marginal stability condition to be significantly higher than one may expect from their brightness. Either their disks are dynamically overheated, or they contain a large amount of non‐luminous matter. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stabilization of generalized polytropes
Authors: Polyachenko E.V. , Polyachenko V.L. , Shukhman I.G. 
Published: October 2014

AbstractStabilization of classical generalized polytropic models is studied. We discuss some contradictions found in the literature: on the one hand, calculations of the growth rates in the framework of linear stability theory and N‐body simulations show that these systems are stable if the velocity anisotropy parameter of the stellar distribution is lower than some finite positive value. On the other hand, instability is shown to persist up to the isotropic limit (zero anisotropy parameter). We demonstrate that stabilization of generalized polytropic models cannot be adequately described by approximate equations derived for nearly radial orbits. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On some fundamental concepts of galactic dynamics
Authors: Ossipkov L.P. 
Published: October 2014

AbstractWe discuss the following fundamental concepts of galactic dynamics: (a) regular (smoothed) and irregular (random) forces, (b) truncation of the impact parameter, (c) the invariance of the Maxwellian velocity distribution, and (d) the Jeans theorem. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Equilibrium figures with polar rings
Authors: Kondratyev B.P. 
Published: October 2014

AbstractWe study the dynamics of a spheroidal galaxy with a gravitating polar ring whose plane is perpendicular to the equator. We consider this problem in the tidal approximation and derive a closed set of equations, which we reduce to a seventh‐order differential equation. We solve the resulting equation to find that perturbations from the polar ring deform the spheroid into a non‐stationary rotating triaxial ellipsoid with linear internal velocity field. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cepheids and RR Lyrae type variables
Authors: Berdnikov L.N. , Dambis A.K. , Kniazev Vorname 
Published: October 2014

AbstractCurrent status and development prospects of Cepheid and RR Lyrae‐type variable‐star studies (photometry, radial velocity measurements, galactic structure and kinematics, and distance‐scale refinement) at the Sternberg Astronomical Institute are reported. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The LYRA photometric system and the catalog of photometric reference standard stars
Authors: Zakharov A.I. , Mironov A.V. , Nikolaev F.N. , Prokhorov M.E. , Tuchin M.S. 
Published: October 2014

AbstractThe 10‐color photometric system for the Russian space photometric experiment LYRA is described. It is shown that the system is effective for the determination of interstellar extinction, separation of supergiants, and evaluation of metallicity. The creation of a large grid of high‐precision photometric standards is one of the most important tasks of the LYRA experiment. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Expected characteristics of data from the LYRA mission
Authors: Zakharov A.I. , Mironov A.V. , Prokhorov M.E. , Nikolaev F.N. , Tuchin M.S. , Biryukov A.V. 
Published: October 2014

AbstractThe purpose of the LYRA mission is a multi‐color all‐sky survey of objects from 3m to 16m from the International Space Station, to result in a high‐precision photometric catalog (Zakharov et al. 2013b). The expected error of the catalog will be 0.001–0.003m for stars brighter than 12m and 0.01m for the stars down to 16m. The estimated duration of the survey is about 5 years. This paper describes the characteristics of data to be received in the course of the LYRA experiment for future users. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Classification of stars with WBVR photometry
Authors: Sichevskiy S.G. , Mironov A.V. , Malkov O.Yu. 
Published: October 2014

AbstractWe present a method of obtaining the most reliable stellar spectral type based on multi‐color photometry. The method also allows us to estimate color excess EB—V and distance to the star. Approbation of the method using bright stars with known spectral classification and WBVR photometry permits to estimate its reliability. Stellar spectra models from Pickles (1998) library and Fluks et al. (1994) interstellar extinction law were used in the application of the method. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiwavelength studies of Markarian galaxies
Authors: Mickaelian A.M. , Abrahamyan H.V. , Paronyan G.M. , Harutyunyan G.S. 
Published: October 2014

AbstractMarkarian galaxies are the result of the First Byurakan Survey (FBS) conducted in 1965–1980 by B.E. Markarian et al. The sample consists of 1515 UV‐excess galaxies containing many active galaxies, both AGN and starburst (SB) galaxies that are interesting from the point of view of galaxy evolution and multiwavelength studies. Several catalogs of Markarian galaxies have been published; however, multiwavelength (MW) data were not provided and matched for more efficient investigations. Moreover, SDSS spectra now give possibility for better classification by activity types, and we have accomplished fine classification obtaining new types and subtypes for most of the objects. We have cross‐correlated the Markarian catalogue with all available large‐area MW catalogues at various wavelengths, from X‐ray to radio: ROSAT BSC and FSC, GALEX, APM, MAPS, USNO B1.0, GSC 2.3.2, SDSS, 2MASS PSC and ESC, WISE, AKARI‐IRC, IRAS PSC, FSC, and SSSC, AKARI‐FIS, GB6, NVSS, FIRST, SUMSS, WENSS, and 7C providing 35 photometric data‐points, as well as the Digitized FBS (DFBS, http://byurakan.phys.uniroma1.it/) and Hamburg Quasar Survey (HQS) low‐dispersion spectra. The Armenian Virtual Observatory (ArVO, http://www.aras.am/Arvo/arvo.htm) services have been used for crosscorrelations and extraction of DFBS spectra; MW SEDs have been built using the IVOA tools, and MW classification has been accomplished. Diagrams with MW flux ratios have been built to reveal objects with extreme characteristics. The classifications have been matched with these flux ratios. A MW catalog of Markarian galaxies has been compiled. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Re‐determining the parameters of the Galactic spiral density wave from data on masers with trigonometric parallaxes
Authors: Bajkova A.T. , Bobylev V.V. 
Published: October 2014

AbstractThe parameters of the Galactic spiral wave are re‐determined using a modified periodogram (spectral) analysis of the galactocentric radial velocities of 58 masers with known trigonometric parallaxes, proper motions, and line‐of‐site velocities. The masers span a wide range of galactocentric distances, 3 < R < 14 kpc, which, combined with a large scatter of position angles θ of these objects in the Galactic plane required an accurate account of logarithmic dependence of spiral‐wave perturbations on both the galactocentric distance and position angle. A periodic signal was detected corresponding to a spiral density wave with wavelength of λ = 2.4 ± 0.4 kpc, peak velocity of wave perturbations of fR = 7.5 ± 1.5 km s–1, phase of the Sun of χ⊙ = –160 ± 15°, and pitch angle of –5.5 ± 1°. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Eclipsing variables: Catalogue and classification
Authors: Avvakumova E.A. , Malkov O.Yu. , Kniazev A.Yu. 
Published: October 2014

AbstractA new version of the Catalogue of Eclipsing Variables is presented. The catalogue contains parameters and morphological types of light curves for some 7200 stars. Spectral classification is also given when available. Recently published information about classification of 1352 systems is also included in the catalogue. Thus, the catalogue represents the largest list of eclipsing binaries classified from observations. The analysis of stellar parameter distributions of catalogued eclipsing systems has been performed, and an algorithm of eclipsing‐variable classification has been developed. Classification of some systems is troublesome or contradictory due to lack of modern observational data or their possible rare evolutionary class. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PAOLO: A Polarimeter Add‐On for the LRS Optics at a Nasmyth focus of the TNG
Authors: Covino S. , Molinari E. , Bruno P. , Cecconi M. , Conconi P. , D'Avanzo P. , di Fabrizio L. , Fugazza D. , Giarrusso M. , Giro E. , Leone F. , Lorenzi V. , Scuderi S. 
Published: October 2014

AbstractWe describe a new polarimetric facility available at the Istituto Nazionale di AstroFisica / Telescopio Nazionale Galileo at La Palma, Canary islands. This facility, PAOLO (Polarimetric Add‐On for the LRS Optics), is located at a Nasmyth focus of an alt‐az telescope and requires a specific modeling in order to remove the time‐ and pointing position‐dependent instrumental polarization. We also describe the opto‐mechanical structure of the instrument and its calibration and present early examples of applications. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability of the Kepler‐36 two‐planet system
Authors: Nagy I. , Ágas M. 
Published: October 2014

AbstractIn this paper we study the dynamics of the Kepler‐36 exoplanetary system. The two planets are engaged in the mean‐motion resonance of 6:7. The dynamical stability of this system has been studied by numerical methods using a Lie‐integrator and calculating the Lyapunov characteristic indicator (LCI) and maximum eccentricity (ME). We studied the stability of the system, the stability of another planet, and the stability of satellites belonging to the known planets. The possibility of trojans were also studied using the massless approximation. The tidal perturbations were neglected although they can become significant in some cases. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Symbiotic stars with spectral indication of bipolar ejection and stellar wind
Authors: Tomov N.A. , Tomova M.T. , Bisikalo D.V. 
Published: October 2014

AbstractFour out of a total of five symbiotic systems whose optical spectral lines contain satellite components indicating collimated ejection have an additional absorption of P Cyg type with different velocity. These systems are Z And, Hen 3‐1341, StHα 190, and BF Cyg. It is shown that the line profiles of every of these systems can be interpreted in the framework of a model of a collimated stellar wind from the hot compact component proposed initially to interpret the line profiles of Z And, observed during its last active phase after 2000. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The outbursts of the comet 29P/Schwassmann‐Wachmann 1: A new approach to the old problem
Authors: Gronkowski P. 
Published: October 2014

AbstractAs far as outbursts activity is concerned, the 29P/Schwassmann‐Wachmann 1 is the exceptional comet. This Centaur object shows quasi‐regular flares with periodicities of 50 days (Trigo‐Rodriguez et al. 2010). In the introductory part of the presented paper the most well‐known hypotheses which try to explain this cometary behaviour are reviewed. The second, actual part of this paper presents the new model for the outburst activity of this comet. The model is based on the idea of Ipatov (2012), according to which there are large cavities below a considerable fraction of the comet's surface containing material under high gas pressure. In favourite conditions the surface layers over the cavities are thrown away and the interior of these cavities is exposed. Consequently, an outburst of the comet's brightness may be observed. The main characteristics of an outburst of this comet, the brightness jump, is calculated. Numerical simulations were carried out for wide range of possible cometary parameters. The obtained results are in good agreement with the observations. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XMM‐Newton publication statistics
Authors: Ness J.‐U. , Parmar A.N. , Valencic L.A. , Smith R. , Loiseau N. , Salama A. , Ehle M. , Schartel N. 
Published: October 2014

AbstractWe assessed the scientific productivity of XMM‐Newton by examining XMM‐Newton publications and data usage statistics. We analyse 3272 refereed papers, published until the end of 2012, that directly use XMM‐Newton data. The SAO/NASA Astrophysics Data System (ADS) was used to provide additional information on each paper including the number of citations. For each paper, the XMM‐Newton observation identifiers and instruments used to provide the scientific results were determined. The identifiers were used to access the XMM‐Newton Science Archive (XSA) to provide detailed information on the observations themselves and on the original proposals. The information obtained from these sources was then combined to allow the scientific productivity of the mission to be assessed. Since around three years after the launch of XMM‐Newton there have been around 300 refereed papers per year that directly use XMM‐Newton data. After more than 13 years in operation, this rate shows no evidence that it is decreasing. Since 2002, around 100 scientists per year become lead authors for the first time on a refereed paper which directly uses XMM‐Newton data. Each refereed XMM‐Newton paper receives around four citations per year in the first few years with a long‐term citation rate of three citations per year, more than five years after publication. About half of the articles citing XMM‐Newton articles are not primarily X‐ray observational papers. The distribution of elapsed time between observations taken under the Guest Observer programme and first article peaks at 2 years with a possible second peak at 3.25 years. Observations taken under the Target of Opportunity programme are published significantly faster, after one year on average. The fraction of science time taken until the end of 2009 that has been used in at least one article is ∼90%. Most observations were used more than once, yielding on average a factor of two in usage on available observing time per year. About 20 % of all slew observations have been used in publications. The scientific productivity of XMM‐Newton measured by the publication rate, number of new authors and citation rate, remains extremely high with no evidence that it is decreasing after more than 13 years of operations.
The Subaru Telescope High Dispersion Spectrograph (HDS)
Authors: Aoki W. 
Published: October 2014

AbstractThe High Dispersion Spectrograph (HDS) is the échelle spectrograph for an open‐use instrument of the Subaru Telescope. The current status of the instrument is reviewed. The new image slicers that significantly improve the efficiency of observations with very high resolving power have been installed in the past three years. Brief overview of recent science results is given on studies of early generations of stars and extra‐solar planets. An upgrade plan and future prospects of this instrument are discussed. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
ESPRESSO: The next European exoplanet hunter
Authors: Pepe F. , Molaro P. , Cristiani S. , Rebolo R. , Santos N.C. , Dekker H. , Mégevand D. , Zerbi F.M. , Cabral A. , Di Marcantonio P. , Abreu M. , Affolter M. , Aliverti M. , Allende Prieto C. , Amate M. , Avila G. , Baldini V. , Bristow P. , Broeg C. , Cirami R. , Coelho J. , Conconi P. , Coretti I. , Cupani G. , D'Odorico V. , De Caprio V. , Delabre B. , Dorn R. , Figueira P. , Fragoso A. , Galeotta S. , Genolet L. , Gomes R. , González Hernández J.I. , Hughes I. , Iwert O. , Kerber F. , Landoni M. , Lizon J.‐L. , Lovis C. , Maire C. , Mannetta M. , Martins C. , Monteiro M. , Oliveira A. , Poretti E. , Rasilla J.L. , Riva M. , Santana Tschudi S. , Santos P. , Sosnowska D. , Sousa S. , Spanó P. , Tenegi F. , Toso G. , Vanzella E. , Viel M. , Zapatero Osorio M.R. 
Published: October 2014

AbstractThe acronym ESPRESSO stems for Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations; this instrument will be the next VLT high resolution spectrograph. The spectrograph will be installed at the Combined‐Coudé Laboratory of the VLT and linked to the four 8.2 m Unit Telescopes (UT) through four optical Coudé trains. ESPRESSO will combine efficiency and extreme spectroscopic precision. ESPRESSO is foreseen to achieve a gain of two magnitudes with respect to its predecessor HARPS, and to improve the instrumental radial‐velocity precision to reach the 10 cm s–1 level. It can be operated either with a single UT or with up to four UTs, enabling an additional gain in the latter mode. The incoherent combination of four telescopes and the extreme precision requirements called for many innovative design solutions while ensuring the technical heritage of the successful HARPS experience. ESPRESSO will allow to explore new frontiers in most domains of astro‐physics that require precision and sensitivity. The main scientific drivers are the search and characterization of rocky exoplanets in the habitable zone of quiet, nearby G to M‐dwarfs and the analysis of the variability of fundamental physical constants. The project passed the final design review in May 2013 and entered the manufacturing phase. ESPRESSO will be installed at the Paranal Observatory in 2016 and its operation is planned to start by the end of the same year. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)