bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adaptive Optics Observations of Exoplanets, Brown Dwarfs, and Binary Stars
Authors: Hinkley Sasha 
Published: April 2012

AbstractThe current direct observations of brown dwarfs and exoplanets have been obtained using instruments not specifically designed for overcoming the large contrast ratio between the host star and any wide-separation faint companions. However, we are about to witness the birth of several new dedicated observing platforms specifically geared towards high contrast imaging of these objects. The Gemini Planet Imager, VLT-SPHERE, Subaru HiCIAO, and Project 1640 at the Palomar 5m telescope will return images of numerous exoplanets and brown dwarfs over hundreds of observing nights in the next five years. Along with diffraction-limited coronagraphs and high-order adaptive optics, these instruments also will return spectral and polarimetric information on any discovered targets, giving clues to their atmospheric compositions and characteristics. Such spectral characterization will be key to forming a detailed theory of comparative exoplanetary science which will be widely applicable to both exoplanets and brown dwarfs. Further, the prevalence of aperture masking interferometry in the field of high contrast imaging is also allowing observers to sense massive, young planets at solar system scales (~3–30 AU)— separations out of reach to conventional direct imaging techniques. Such observations can provide snapshots at the earliest phases of planet formation—information essential for constraining formation mechanisms as well as evolutionary models of planetary mass companions. As a demonstration of the power of this technique, I briefly review recent aperture masking observations of the HR 8799 system. Moreover, all of the aforementioned techniques are already extremely adept at detecting low-mass stellar companions to their target stars, and I present some recent highlights.
Modelling of an Eclipsing RS CVn Binary: V405 And
Authors: Vida Krisztián , Oláh Katalin , Kővári Zsolt 
Published: April 2012

AbstractV405 And is an ultrafast-rotating (Prot ≈ 0.46 days) eclipsing binary. The system consists of a primary star with radiative core and convective envelope, and a fully convective secondary. Theories have shown that stellar structure can depend on magnetic activity, i.e., magnetically active M-dwarfs should have larger radii. Earlier light curve modelling of V405 And indeed showed this behaviour: we found that the radius of the primary is significantly larger than the theoretically predicted value for inactive main sequence stars (the discrepancy is the largest of all known objects), while the secondary fits well to the mass-radius relation. By modelling our recently obtained light curves, which show significant changes of the spotted surface of the primary, we can find further proof for this phenomenon.
Doppler Tomography in 2D and 3D of the X-ray Binary Cyg X-1 for June 2007
Authors: Sharova O. I. , Agafonov M. I. , Karitskaya E. A. , Bochkarev N. G. , Zharikov S. V. , Butenko G. Z. , Bondar A. V. 
Published: April 2012

AbstractThe 2D and 3D Doppler tomograms of X-ray binary system Cyg X-1 (V1357 Cyg) were reconstructed from spectral data for the line HeII 4686Å obtained with 2-m telescope of the Peak Terskol Observatory (Russia) and 2.1-m telescope of the Mexican National Observatory in June, 2007. Information about gas motions outside the orbital plane, using all of the three velocity components Vx, Vy, Vz, was obtained for the first time. The tomographic reconstruction was carried out for the system inclination angle of 45°. The equal resolution (50 × 50 × 50 km/s) is realized in this case, in the orbital plane (Vx, Vy) and also in the perpendicular direction Vz. The checkout tomograms were realized also for the inclination angle of 40° because of the angle uncertainty. Two versions of the result showed no qualitative discrepancy. Details of the structures revealed by the 3D Doppler tomogram were analyzed.
PTPS Candidate Exoplanet Host Star Radii Determination with CHARA Array
Authors: Zieliński Paweł , Vaňko Martin , Baines Ellyn , Niedzielski Andrzej , Wolszczan Aleksander 
Published: April 2012

AbstractWe propose to measure the radii of the Penn State - Toruń Planet Search (PTPS) exoplanet host star candidates using the CHARA Array. Stellar radii estimated from spectroscopic analysis are usually inaccurate due to indirect nature of the method and strong evolutionary model dependency. Also, the so-called degeneracy of stellar evolutionary tracks due to convergence of many tracks in the giant branch decreases the precision of such estimates. However, the radius of a star is a critical parameter for the calculation of stellar luminosity and mass, which are often not well known especially for giants. With well determined effective temperature (from spectroscopy) and radius, the luminosity may be calculated precisely. In turn also stellar mass may be estimated much more precisely. Therefore, direct radii measurements increase precision in the determination of planetary candidates masses and the surface temperatures of the planets.
The MUNI Photometric Archive
Authors: Chrastina Marek , Zejda Miloslav , Mikulášek Zdeněk 
Published: April 2012

AbstractIn the 1990s of the last century, CCD cameras became more reachable. Due to many advantages of CCD cameras, astronomers began using them as the primary detector for photometry of stellar objects. A typical observatory, which operates one telescope at a time, obtained 0.5 TB of raw data during two decades, that means one million about 500 kB-sized files. There are several observatories in the Czech Republic and Slovakia (taking into account all scientific, public as well as private ones). A rough estimate of the total amount of this photometric data is 10 TB, which could be a very interesting source of observational data. Unfortunately, these data are not available online. These data are stored in observatory archives in arbitrary format. Often it is not even possible to find requested data. We have decided to change this state by establishing a common archive of raw photometric data, which would be available online together with tools for searching, listing etc. We already defined the data format, file and directory structure of our archive. We developed sophisticated tools for archive maintenance as well. Our goal is to provide data storage with simple and straightforward access and we are ready to interconnect with the VO right after the IVOA Photometry Data Model will be released.
Stellar to Substellar Model Atmospheres
Authors: Allard France , Homeier Derek , Freytag Bernd 
Published: April 2012

AbstractThe spectral transition from Very Low Mass stars (VLMs) to brown dwarfs (BDs) and planetary mass objects (Planemos) requires model atmospheres that can treat line, molecule, and dust-cloud formation with completeness and accuracy. One of the essential problems is the determination of the surface velocity field throughout the main sequence down to the BD and planemo mass regimes. We present local 2D and 3D radiation hydrodynamic simulations using the CO5BOLD code with binned Phoenix gas opacities, forsterite dust formation (and opacities) and rotation. The resulting velocity field vs depth and Teff has been used in the general purpose model atmosphere code Phoenix, adapted in static 1D spherical symmetry for these cool atmospheres. The result is a better understanding of the spectral transition from the stellar to substellar regimes. However, problems remain in reproducing the colors of the dustiest brown dwarfs. The global properties of rotation can change the averaged spectral properties of these objects. Our project for the period 2011-2015 is therefore to develop scaled down global 3D simulations of convection, cloud formation and rotation thanks to funding by the Agence Nationale de la Recherche in France.
Chemical History of Algol and its Components
Authors: Kolbas V. , Pavlovski K. , Southworth J. , Lee C.-U. , Lee J. W. , Kim S.-L. , Kim H.-I. 
Published: April 2012

AbstractWe present a new observational project to study the hierarchical triple stellar system Algol, concentrating on the semidetached eclipsing binary at the heart of the system. Over 140 high-resolution and high-S/N spectra have been secured, of which 80 are from FIES at the Nordic Optical Telescope, La Palma, and the remainder were obtained with BOES at the Bohyunsan Optical Astronomy Observatory in Korea. All three components were successfully detected by the method of spectral disentangling, which yields the individual spectra of the three stars and also high-quality spectroscopic elements for both the inner and outer orbits. We present a detailed abundance study for the mass-accreting component in the inner orbit, which holds information on the history of mass transfer in the close inner binary system. We also reveal the atmospheric parameters and chemical composition of the tertiary component in the outer orbit.
Applying the Steepest Descent Method with BINSYN on RY Per Photometry
Authors: Sudar D. , Božić H. , Ruždjak D. 
Published: April 2012

AbstractRecent studies of the Algol-type binary RY Per presented strong evidence that there is an accretion disk around the primary in the system. We used new UBV photometry from Hvar Observatory and the BINSYN software package in order to determine the basic parameters of the disk. The search for the best parameter set was performed with a fully automated steepest descent method. The resulting disk is large and visible at all orbital phases. Somewhat surprising is the large mass transfer rate which should be tied with, currently unreported, secular period changes.
Quantitative Spectroscopy of Close Binary Stars
Authors: Pavlovski K. , Southworth J. 
Published: April 2012

AbstractThe method of spectral disentangling has now created the opportunity for studying the chemical composition in previously inaccessible components of binary and multiple stars. This in turn makes it possible to trace their chemical evolution, a vital aspect in understanding the evolution of stellar systems. We review different ways to reconstruct individual spectra from eclipsing and non-eclipsing systems, and then concentrate on some recent applications to detached binaries with high-mass and intermediate-mass stars, and Algol-type mass-transfer systems.
The Broadening Functions Technique
Authors: Rucinski Slavek M. 
Published: April 2012

AbstractEssential assumptions and features of the Broadening Function (BF) technique are presented. A distinction between BF determination and the BF concept and utilization is made. The BF's can be determined in various ways. The approach based on linear deconvolution involving stellar templates, as used during the DDO program (1999 – 2008) is described, but the LSD technique would also give excellent results. The BF concept to prove and/or verify photometric light-curve solutions has so far been very limited to only a few W UMa-type binaries, with AW UMa giving particularly unexpected results.
Constrained Genetic Disentangling of Close Binary Spectra
Authors: Kolbas V. , Pavlovski K. 
Published: April 2012

AbstractThe spectral disentangling technique makes possible separation of individual component spectra in binary or multiple systems, and determination of the orbital elements in a self-consistent way. Since its introduction, a number of variants of their basic idea have been implemented. We present yet another ‘direct’ approach using optimization by genetic algorithm. Starting with an initial random flux distribution representing individual spectra, genetic optimization returns both individual component spectra and an optimal set of orbital parameters only constrained by time-series of the observed composite spectra of the binary system. Benchmark tests on V453 Cyg, which is an eclipsing binary with total eclipse, as well as tests on the artificial time-series spectra, have proven that ‘constrained genetic disentangling’ is performing correctly and efficiently, albeit with high demand on CPU time. Since genetic optimization can be easily parallelized, we expect our second release to run on cluster in a less time-consuming way.
T Tauri Binaries in Orion: Evidence for Accelerated and Synchronized Disk Evolution
Authors: Daemgen Sebastian , Petr-Gotzens Monika G. , Correia Serge 
Published: April 2012

AbstractIn order to trace the role of binarity for disk evolution and hence planet formation, we started the currently largest spatially resolved near-infrared photometric and spectroscopic study of the inner dust and accretion disks of the individual components of 27 visual, 100–400 AU binaries in the Orion Nebula Cluster (ONC). We study the frequency of Brackett-γ (2.165μm) emitters to assess the frequency of accretion disk-bearing stars among the binaries of the ONC: only 34±9% of the binary components show signs of accretion and, hence, the presence of gaseous inner disks—less than the fraction of gas accretion disks among single stars of the ONC of ~50%. Additionally, we find a significant difference between binaries above and below 200 AU separation: no close systems with only one accreting component are found. The results suggest shortened disk lifetimes as well as synchronized disk evolution.
The AstraLux Binary M Dwarfs Survey
Authors: Bergfors Carolina , Brandner Wolfgang , Hippler Stefan , Henning Thomas , Janson Markus , Hormuth Felix 
Published: April 2012

AbstractBinary/multiple properties provide clues to the formation of stars. In the AstraLux binary survey, we use the Lucky Imaging technique to search for companions to a large sample of young, nearby M dwarfs. We present results from observations of the first sub-sample, consisting of 124 M dwarfs in the southern sky.
New Approach for Solution of the Planet Transit Problem
Authors: Kjurkchieva Diana P. , Dimitrov Dinko P. 
Published: April 2012

AbstractWe propose a new approach for a solution of the planet transit problem that is based on numerical calculation of integrals. The paper presents our method for the case of linear limb-darkening law and orbital inclination i = 90°, and illustrates the work of the code PTS written on the basis of our approach.
Searching for the Signatures of Terrestrial Planets in “Hot” Analogs
Authors: González Hernández J. I. , Delgado Mena E. , Israelian G. , Sousa S. G. , Santos N. C. , Udry S. 
Published: April 2012

AbstractThe Sun has been suggested to have a slightly low refractory-to-volatile abundance ratio when compared with field solar twins. This result may be interpreted as due to the fact that the refractory elements were trapped in rocky planets at the formation of the Solar System.A detailed and differential chemical abundance study was already performed in order to investigate this hypothesis in solar analogs with and without detected planets using high-resolution and high-S/N HARPS and UVES spectra of a relatively large sample of solar analogs with and without planets. We obtained very similar behaviours for both samples of stars with and without planets, even for two stars with super-Earth-like planets, which may indicate that this solar trend may not be related to the presence of terrestrial planets.The depletion signature should be imprinted once the convection zone reaches the current size. This suggests that stars hotter than the Sun should show this effect enhanced, due to their narrower convective zone. However, to avoid non-LTE, 3D, and other effects, we need to identify “hot” analogs with a Teff ~ 6100 K, to perform a differential analysis.Here, we present the preliminary results of our analysis using HARPS and UVES high-resolution and high-S/N spectra of a sample of ~ 60 “hot”analogs with and without planets, trying to search for some “hot” reference analogs.
Calibrating Ultracool Atmospheres with Benchmark Companions from WISE+2MASS
Authors: Gomes Joana I. , Pinfield David , Day-Jones Avril , Jones Hugh , Burningham Ben , Marocco Federico , Zhang ZengHuan , van Spaandonk Lieke 
Published: April 2012

AbstractThe complexities of ultracool atmospheres are best confronted by observations of ultracool dwarfs (UCDs) with well known physical properties (luminosity, mass, Teff, log(g), [M/H]), so-called “benchmark objects.” We present two discoveries from a new WISE+2MASS search for benchmark wide companions to Hipparcos and Gliese stars. This survey combination provides a powerful tool to confirm new companions using color-magnitude and common proper motion selections, and also yield full NIR-MIR measurements of the ultracool emission. These primary companions are providing important constraints on the age and composition of the benchmark brown dwarf, and the new discoveries add to our growing population of benchmarks that is providing crucial tests of ultracool physics.
NSVS 01031772 Cam: A New Low-Mass Triple?
Authors: Wolf M. , Zasche P. , Hornoch K. , Chrastina M. , Janík J. , Zejda M. 
Published: April 2012

AbstractWe present a photometric study of the newly discovered low-mass eclipsing binary NSVS 01031772 Cam based on observations obtained at Ondřejov observatory from 2007 – 2011.
CCD Photometric Study of the Puzzling W UMa-type Binary TZ Boo
Authors: Christopoulou P.-E. , Papageorgiou A. , Chrysopoulos I. 
Published: April 2012

AbstractThe puzzling W-UMa type binary TZ Boo has been monitored at the University of Patras, Observatory from March to July 2010. Photometric solutions were determined through an analysis of the complete BVRI light curves with PHOEBE (Wilson-Devinney code) and published spectroscopic data. This low mass ratio binary turns out to be a deep overcontact system with f = 52.5% of A-subtype. A conservative spot model has been applied to fit the particular features of light curves. Based on our 7 new light minimum times and all others compiled from the literature over 70 years, we studied the orbital period from the O-C curve.
Modeling Fluid Flow Effects in Close Binary and Protoplanetary Systems
Authors: Montgomery M. M. 
Published: April 2012

AbstractAccretion disks around some white dwarfs in Cataclysmic Variables are thought to tilt around the line of nodes by the lift force acting at the disk's center of pressure. We investigate whether protoplanetary disks can also experience disk tilt. We find that lift may be possible by an asymmetric, net uni-directional, in-falling gas/dust stream overflowing a bluff body (e.g., Class I sources) or inner annuli of young Class II sources if gas/dust is still in-falling and the aspect ratio and disk surface area are large enough. However, inner disks of Class II sources LkCa 15, UX Tau A, and Rox 44 are not large enough, and therefore disk tilt is not likely.
Arguing Global Environmental Constitutionalism
Authors: Kotzé Louis J. 
Published: April 2012

AbstractThe current global environmental law and governance regime has been designed primarily to attend to the worsening ecological crisis. Evidence, however, suggests that the regime is far from achieving its goal and it is failing in its efforts to solve what people perceive to be pervasive global environmental problems. There is little doubt that this regime is in need of urgent reforms and/or re-situation in a decidedly different paradigm. This article proposes that global constitutionalism, while no panacea, could contribute to these paradigm-shifting reforms by providing a new perspective through which to view the current deficient global environmental law and governance regime and, in real terms, ameliorating some of the deficiencies of the regime through a normative process of constitutionalization.
P‐V‐T equation of state of MgSiO3 perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle
Authors: Tange Yoshinori , Kuwayama Yasuhiro , Irifune Tetsuo , Funakoshi Ken‐ichi , Ohishi Yasuo 
Published: April 2012

In situ P‐V‐T measurements of MgSiO3 perovskite were carried out up to 110 GPa and 2500 K, using a sintered‐diamond multianvil apparatus and a laser‐heated diamond anvil cell together with synchrotron radiation. The P‐V‐T data sets obtained by multianvil experiments (28–63 GPa and 300–1500 K) and diamond anvil cell experiments (52–108 GPa and 300, 1500–2430 K) are consistent with each other. The equation of state of MgSiO3 perovskite was subsequently represented by a Mie‐Grüneisen‐Debye model, using the equation of state of MgO as reference for pressure determination. In this study, we provide mutually consistent and precise P‐V‐T equations of state of MgSiO3 perovskite and MgO applicable to the bottom of the Earth's lower mantle. These P‐V‐T equations of state and derivative thermodynamic and elastic properties are essential for mineralogy of the lower mantle as a comprehensive reference.
Climatology 2011: An MLS and sonde derived ozone climatology for satellite retrieval algorithms
Authors: McPeters Richard D. , Labow Gordon J. 
Published: April 2012

The ozone climatology used as the a priori for the version 8 Solar Backscatter Ultraviolet (SBUV) retrieval algorithms has been updated. The climatology was formed by combining data from Aura MLS (2004–2010) with data from balloon sondes (1988–2010). The Microwave Limb Sounder (MLS) instrument on Aura has excellent latitude coverage and measures ozone daily from the upper troposphere to the lower mesosphere. The new climatology consists of monthly average ozone profiles for ten degree latitude zones covering pressure altitudes from 0 to 65 km. Ozone below 8 km (below 12 km at high latitudes) is based on balloons sondes, while ozone above 16 km (21 km at high latitudes) is based on MLS measurements. Sonde and MLS data are blended in the transition region. Ozone accuracy in the upper troposphere is greatly improved because of the near uniform coverage by Aura MLS, while the addition of a large number of balloon sonde measurements improves the accuracy in the lower troposphere, in the tropics and southern hemisphere in particular. The addition of MLS data also improves the accuracy of the climatology in the upper stratosphere and lower mesosphere. The revised climatology has been used for the latest reprocessing of SBUV and TOMS satellite ozone data.
Bending stress and dissipation in subducted lithosphere
Authors: Buffett B. A. , Becker T. W. 
Published: April 2012

Oceanic lithosphere undergoes permanent deformation during subduction once the stresses exceed the elastic limit. Departures from elastic behavior occur by brittle failure in the shallow lithosphere and by a combination of low‐ and high‐temperature creep at greater depths. We combine laboratory‐based rheological models with estimates of slab shape from earthquake hypocenters to quantify the bending stress and dissipation in subduction zones. The peak stress occurs at the depth of the brittle‐ductile transition, which is controlled mainly by lithospheric age. Integrals of the stress over the thickness of the plate are used to evaluate the resistive bending force and the bending moment. A representative value for the resistive force on old oceanic lithosphere is 3 × 1012 N m−1, which is comparable in magnitude to ridge push but opposite in direction. Both the bending force and moment are remarkably insensitive to the rate of subduction. In fact, the bending moment can be approximated using a simple power law rheology and a stress exponent of n ≈ 14. Such a large exponent implies that the lithosphere behaves like a perfectly plastic solid. For most subduction zones the bending moment saturates along the entire plate. As a consequence, the bending stress does not influence the development of curvature during subduction. This behavior may explain why the curvature of subducted lithosphere is nearly independent of age.