bluuebunny/crossref_metadata_2025_split huggingface dataset:
The kinematics of white dwarfs from the SDSS DR12
Authors: García–Berro E. , Skorobogatov G. , Torres S. , Anguiano B. , Rebassa-Mansergas A. 
Published: August 2018

AbstractWe use the Sloan Digital Sky Survey Data Release 12, which is the largest available white dwarf catalogue to date, to study the evolution of the kinematical properties of the population of white dwarfs of the Galactic disk. We derive masses, ages, photometric distances and radial velocities for all white dwarfs with hydrogen-rich atmospheres. For those stars for which proper motions from the USNO-B1 catalogue are available, the three-dimensional components of the velocity are obtained. This subset of the original sample comprises 20,247 stars, making it the largest sample of white dwarfs with measured three-dimensional velocities. The volume probed by our sample is large, allowing us to obtain relevant kinematical information. In particular, our sample extends from a Galactocentric radial distance RG = 7.8 to 9.3 kpc, and vertical distances from the Galactic plane ranging from Z = +0.5 to –0.5 kpc.
A population synthesis study of the local white dwarf population
Authors: Torres Santiago , Nutten Florian , Skorobogatov Georgy , García-Berro Enrique 
Published: August 2018

AbstractWhite dwarfs are natural cosmochronometers, and this allows us to use them to study relevant properties of the Galaxy, such as its age or its star formation rate history. Here we present a population synthesis study of the white dwarf population within 40 pc from the Sun, and compare the results of this study with the properties of the observed sample. We use a state-of-the-art population synthesis code based on Monte Carlo techniques that incorporates the most recent and reliable white dwarf cooling sequences, an accurate description of the Galactic neighborhood, and a realistic treatment of all the known observational biases.
APOGEE Chemical Anomalies discovered everywhere in the Milky Way: Giant stars with GC-like abundance patterns
Authors: Fernández-Trincado J. G. 
Published: August 2018

AbstractWe report the discovery by APOGEE of five mildly metal-poor ([Fe/H] &gt;−1) anomalous giant stars in the halo/disk/bulge Galaxy with abundances of C, N, and Al that are typically found in globular cluster stars (GCs, see e.g. Carretta et al. 2009a; Mészáros et al. 2015; Pancino et al. 2017; Schiavon et al. 2017a; Tang et al. 2017) and in the inner Galaxy (e.g., Schiavon et al. 2017b; Recio-Blanco et al. 2017) simultaneously with atypical abundances of Mg (Mg-poor: [Mg/Fe] &lt; 0) never before seen in Milky Way (MW) GCs, dwarf galaxies (see Hasselquist et al. 2017) neither in MW field stars. Additionally, four new moderately metal-poor ([Fe/H] &lt;−1) anomalous giant stars (i.e., N-rich, Al-rich and C-poor) with trustly GCs second-generation like chemical patterns were identified within the Galactic bulge, halo and disk field.
The barred inner Milky Way: dynamical models from surveys
Authors: Gerhard Ortwin 
Published: August 2018

AbstractThe Milky Way is a barred galaxy whose central bulge has a box/peanut shape and consists of multiple stellar populations with different orbit distributions. This review describes dynamical and chemo-dynamical equilibrium models for the Bulge, Bar, and inner Disk based on recent survey data. Some of the highlighted results include (i) stellar mass determinations for the different Galactic components, (ii) the need for a core in the dark matter distribution, (iii) a revised pattern speed putting corotation at ~6 kpc, (iv) the strongly barred distribution of the metal-rich stars, and (v) the radially varying dynamics of the metal-poor stars which is that of a thick disk-bar outside ~1 kpc, but changes into an inner centrally concentrated component with several possible origins. On-going and future surveys will refine this picture, making the Milky Way a unique case for studying how similar galaxies form and evolve.
The age and abundance structure of the stellar populations in the central sub-kpc of the Milky Way
Authors: Bensby T. , Feltzing S. , Gould A. , Yee J. C. , Johnson J. A. , Asplund M. , Meléndez J. , Lucatello S. , Howes L. M. 
Published: August 2018

AbstractThe four main findings about the age and abundance structure of the Milky Way bulge based on microlensed dwarf and subgiant stars are: (1) a wide metallicity distribution with distinct peaks at [Fe/H] = -1.09, -0.63, -0.20, +0.12, +0.41; (2) a high fraction of intermediate-age to young stars where at [Fe/H] &gt; 0 more than 35 % are younger than 8 Gyr, (3) several episodes of significant star formation in the bulge 3, 6, 8, and 11 Gyr ago; (4) the ‘knee’ in the α-element abundance trends of the sub-solar metallicity bulge appears to be located at a slightly higher [Fe/H] (about 0.05 to 0.1 dex) than in the local thick disk.
Cepheids as Swiss army knives for Milky Way archaeology
Authors: Lemasle B. , Kovtyukh V. , da Silva R. , Mor R. , Bono G. , Figueras F. , François P. , Inno L. , Magurno D. , Matsunaga N. , McWilliam A. , Robin A. C. 
Published: August 2018

AbstractCepheids are excellent stellar tracers: they are bright enough to be observed even at large distances; their distances can be accurately determined via period-luminosity relations; their spectra contain numerous lines that enable us to derive abundances for many α, iron-peak or neutron-capture elements. Classical Cepheids are yellow supergiants that trace the young populations (⩽ 300 Myr); Type II Cepheids are post Horizontal Branch, low-mass, Population II stars (⩾ 10 Gyr). Both can be used for many purposes in Milky Way archaeology.
Rediscovering the origins of the stellar halo with chemical tagging
Authors: Martell Sarah L 
Published: August 2018

AbstractThe Galactic halo has a complex assembly history, which can be seen in its wealth of kinematic and chemical substructure. Globular clusters lose stars through tidal interactions with the Galaxy and cluster evaporation processes, meaning that they are inevitably a source of halo stars. These “migrants” from globular clusters can be recognized in the halo field by the characteristic light element abundance anticorrelations that are commonly observed only in globular cluster stars, and the number of halo stars that can be chemically tagged to globular clusters can be used to place limits on the formation pathways of those clusters.
Structure in the Milky Way
Authors: Wenger Trey V. , Balser Dana S. , Anderson L. D. , Bania T. M. 
Published: August 2018

AbstractThe morphological and chemical structure of the Milky Way today is an important constraint on models of the formation and evolution of the Galaxy. We use H ii regions, the sites of recent massive star formation, to probe both the Galactic spiral structure and the Galactic metallicity structure. H ii regions are the brightest objects in the Galaxy at radio wavelengths and are detected across the entire Galactic disk. We derive the distances to H ii regions using parallax measurements or by deriving kinematic distances. Here we summarize ongoing work to assess the accuracy of kinematic distances and to complete the census of Galactic H ii regions in the Southern sky.
Detailed near-IR stellar abundances of red giants in the Inner Bulge and Galactic Center
Authors: Ryde N. , Rich R. M. , Thorsbro B. , Schultheis M. , Fritz T. K. , Origlia L. 
Published: August 2018

AbstractOwing to their extreme crowding and high and variable extinction, stars in the Galactic Bulge, within ±2° of the Galactic plane, and especially those in the Nuclear Star Cluster, have only rarely been targeted for an analyses of their detailed abundances. There is also some disagreement about the high end of the abundance scale for these stars. It is now possible to obtain high dispersion, high S/N spectra in the infrared K band (~2.0 − 2.4 µm) for these giants; we report our progress at Keck and VLT in using these spectra to infer the composition of this stellar population.
Constraining the Formation and Mass of the Milky Way Halo using Globular Cluster Orbits from HST Proper Motions
Authors: Sohn S. Tony , van der Marel Roeland P. , Deason Alis , Bellini Andrea , Besla Gurtina , Watkins Laura 
Published: August 2018

AbstractThe globular cluster (GC) system of the Milky Way (MW) provides important information on the MW’s present structure and past evolution. Full 3d motions, accessed through proper motions (PMs), are required to calculate accurate orbits of GCs in the MW halo. We present our HST program to create a PM database for 20 halo GCs. We demonstrate how the observed PMs of individual GCs can be used to study their origins, and we also describe how the PM measurements of our entire targets can be used to constrain the anisotropy profile. Finally, we describe how our PM results can be used for Gaia as an external check, and discuss prospects of PM measurements with HST and Gaia in the coming years.
Star formation history and dynamical evolution of the solar neighbourhood
Authors: Just Andreas , Sysoliatina Kseniia 
Published: August 2018

AbstractWe used our detailed analytic local disc model to compare predictions in number counts, colour distribuitons and kinematics with a data set extracted from a combination of TGAS and RAVE catalogues. We find generally a very good agreement with some deviations close to the Galactic plane.
The oldest stars of the bulge: new information on the ancient Galaxy
Authors: Cescutti Gabriele , Chiappini Cristina , Hirschi Raphael 
Published: August 2018

AbstractRecently the search for the oldest stars have started to focus on the Bulge region. The Galactic bulge hosts extremely old stars, with ages compatible with the ages of the oldest halo stars. The data coming from these recent observations present new chemical signatures and therefore provide complementary constraints to those already found in the halo. So, the study of the oldest bulge stars can improve dramatically the constraints on the nature of first stars and how they polluted the pristine ISM of our Galaxy. We present our first results regarding the light elements (CNO) and the neutron capture elements. Our findings in the oldest bulge stars support the scenario where the first stellar generations have been fast rotators.
Simulations of MW-mass galaxies in the cosmological context
Authors: Scannapieco Cecilia 
Published: August 2018

AbstractDuring the last three decades simulations of the formation of galaxies have made fantastic progress, overcoming problems such as the angular momentum catastrophe and producing galaxies that resemble disk-bulge systems similar to those observed. In this work, I discuss such progress focusing on the formation and evolution of disks in galaxies similar to our Milky Way, and on the effects of different feedback processes that affect galaxies through cosmic time.I also present the results of simulations that use constrained initial conditions of the Local Group, and discuss environmental effects that might play a role in the formation and evolution of our Galaxy.
Galactic Archeology with 4MOST
Authors: Feltzing S. , Bensby T. , Bergemann M. , Chiappini C. , Christlieb N. , Cioni M.-R. , Helmi A. , Irwin M. , Minchev I. , Starkenburg E. , de Jong R. 
Published: August 2018

Abstract4MOST is a new wide-field, high-multiplex spectroscopic survey facility for the VISTA telescope of ESO. Starting in 2022, 4MOST will deploy 2400 fibres in a 4.1 square degree field-of-view using a positioner based on the tilting spine principle. In this contribution we give an outline of the major science goals we wish to achieve with 4MOST in the area of Galactic Archeology. The 4MOST Galactic Archeology surveys have been designed to address long-standing and far-reaching problems in Galactic science. They are focused on four major themes: 1) Near-field cosmology tests, 2) Chemo-dynamical characterisation of the major Milky Way stellar components, 3) The Galactic Halo and beyond, and 4) Discovery and characterisation of extremely metal-poor stars. In addition to a top-level description of the Galactic surveys we provide information about how the community will be able to join 4MOST via a call for Public Spectroscopic Surveys that ESO will launch.
Stellar Populations of the Outer Milky-Way Halo
Authors: Santiago Baslio , Luque Elmer , Pieres Adriano , Queiroz Anna Bárbara 
Published: August 2018

AbstractThe stellar spheroidal components of the Milky-Way contain the oldest and most metal poor of its stars. Inevitably the processes governing the early stages of Galaxy evolution are imprinted upon them. According to the currently favoured hierarchical bottom-up scenario of galaxy formation, these components, specially the Galactic halo, are the repository of most of the mass built up from accretion events in those early stages. These events are still going on today, as attested by the long stellar streams associated to the Sagittarius dwarf galaxy and several other observed tidal substructure, whose geometry, extent, and kinematics are important constraints to reconstruct the MW gravitational potential and infer its total (visible + dark) mass. In addition, the remaining system of MW satellites is expected to be a fossil record of the much larger population of Galactic building blocks that once existed and got accreted. For all these reasons, it is crucial to unravel as much of this remaining population as possible, as well as the current stellar streams that orbit within the halo. The best bet to achieve this task is to carry out wide, deep, and multi-band photometric surveys that provide homogeneous stellar samples. In this contribution, we summarize the results of several years of work towards detecting and characterizing distant MW stellar systems, star clusters and dwarf spheroidals alike, with an emphasis on the analysis of data from the Dark Energy Survey (DES). We argue that most of the volume in distance, size and luminosity space, both in the Galaxy and in the Clouds, is still unprobed. We then discuss the perspectives of exploring this outer MW volume using the current surveys, as well as other current and future surveys, such as the Large Synoptic Survey Telescope (LSST).
The Large Synoptic Survey Telescope and Milky Way Science
Authors: Rich R. Michael 
Published: August 2018

AbstractThe Large Synoptic Survey Telescope (LSST) surveys have initially been optimized to omit the inner part of the Milky Way disk/bar from deep and cadence observations. However it is now clear that the LSST will be powerful for Galactic astronomy and may play a crucial role in continuing to extend the Gaia astrometric catalog until a future satellite, either optical or IR, carries on. LSST will provide metallicities and kinematics for the bulge, and will map halo structures to as distant as 450 kpc, nearly half the distance to the Andromeda galaxy. Thanks to the unprecedented calibration effort for its photometric system, and surprisingly good astrometry (transverse velocity measurements of 0.2 mas/yr at r=21; 1 mas/yr at r=24)LSST will provide photometric abundances and distance constraints for a billion or more Milky Way stars to distances of 450 kpc, and kinematics from proper motions to ~100 kpc. Single observation depths reach ~24 in theugrizybands, while depths at end of mission reach ~27. Although halo structures such as streams and dwarf galaxies are initially identified by the RR Lyrae and giants, their structure will be fleshed out by the 100× more abundant dwarfs that will be detected to 100 kpc (single observation) and ~300 kpc by end of mission. More complete mapping of stream structures may constrain the mass distribution of dark matter and perhaps confirm the interaction of dark matter halos and streams. I also describe the Blanco DECam Bulge Survey, a 200 deg2LSST pathfinder survey of the bulge inugrizyusing the Dark Energy Camera on the Blanco 4m telescope. The purpose of this article is to encourage active workers on the Milky Way and Local Volume to participate in the LSST project, in particular to urge that the Galactic Plane receive the same cadence and depth coverage as the rest of the extragalactic sky.
Rediscovering the Galactic outer disk with LAMOST data
Authors: Liu Chao , Xu Yan , Wang Haifeng , Wan Junchen 
Published: August 2018

AbstractFrom the derived stellar density profile using LAMOST giant stars, we find that the Galactic disk does not show truncation or break, but smoothly transit to the halo from 19 kpc. The scale length of the outer disk is only 1.6 ± 0.1 kpc, substantially smaller than previous results. This implies that the shapes of the inner and outer disk are different. Meanwhile, the disk flaring is not only found in older populations, but also in younger population. Moreover, the vertical oscillations of the disk are identified in a wide range or R from 8 to 14 kpc. We also find that the velocity dispersion profile as a function of the Galactocentric radius is flat with scale length of 26.3 ± 3.2 kpc. We confirm that the radial velocity profile in outer disk is significantly affected by asymmetric motion. The bar with either a slower or a faster pattern speed can induce the similar radial asymmetric motion.
The ages of (the oldest) stars
Authors: Catelan M. 
Published: August 2018

AbstractMuch progress has been achieved in the age-dating of old stellar systems, and even of individual stars in the field, in the more than sixty years since the evolution of low-mass stars was first correctly described. In this paper, I provide an overview of some of the main methods that have been used in this context, and discuss some of the issues that still affect the determination of accurate ages for the oldest stars.
When do people choose to be informed? Predictors of information-seeking in the choice of primary care provider in Sweden
Authors: Hoffstedt Caroline , Fredriksson Magnus , Lenhoff Håkan , Winblad Ulrika 
Published: August 2018

AbstractImproving the ability of patients to make informed choices of health care provider can give providers more incentive to compete based on quality. Still, it is not evident to what extent and when people search for information when choosing a provider. The aim of this study is to identify under what circumstances individuals seek information when choosing a primary care provider. Research to date has mostly focused on individuals’ demographic and socio-economic characteristics and the poor availability of information as barriers to information-seeking and use. Our results highlight the importance of taking individuals’ personal motivations and situational context into account when studying information-seeking behavior. Overall, these results suggest that not even individuals who are likely to search for information since they switched or considered switching primary care provider, do so to any greater extent. However, those motivated to change providers by internal factors such as dissatisfaction or a belief that other providers may provide superior services actively sought out information to a greater extent than those motivated by external factors such as the closure of their current provider, or by moving house. Gender, employment status, place of residence and education level was also significantly associated with information-seeking.
Alliance Formation in a Side-Taking Experiment
Authors: DeScioli Peter , Kimbrough Erik O. 
Published: August 2018

AbstractWe investigate in an economic experiment how people choose sides in disputes. In an eight-player side-taking game, two disputants at a time fight over an indivisible resource and other group members choose sides. The player with more supporters wins the resource, which is worth real money. Conflicts occur spontaneously between any two individuals in the group. Players choose sides by ranking their loyalties to everyone else in the group, and they automatically support the disputant they ranked higher. We manipulate participants’ information about other players’ loyalties and also their ability to communicate with public chat messages. We find that participants spontaneously and quickly formed alliances, and more information about loyalties caused more alliance-building. Without communication, we observe little evidence of bandwagon or egalitarian strategies, but with communication, some groups invented rank rotation schemes to equalize payoffs while choosing the same side to avoid fighting costs.
Propagation Characteristics of BSISO Indices
Authors: Wang Shuguang , Ma Ding , Sobel Adam H. , Tippett Michael K. 
Published: August 2018

AbstractThe spatial structure and propagation of tropical intraseasonal convection anomalies diagnosed with the outgoing longwave radiation‐based Madden‐Julian Oscillation index are examined in the boreal summer and winter seasons. It is shown that the outgoing longwave radiation‐based Madden‐Julian Oscillation index represents both northward and eastward propagation in summer and eastward propagation in winter in a manner consistent with Madden‐Julian Oscillation and Boreal Summer Intraseasonal Oscillation propagation as diagnosed in many previous studies. The outgoing longwave radiation‐based Madden‐Julian Oscillation index and three other widely used indices for tracking the Boreal Summer Intraseasonal Oscillation are then compared in their lag correlation structure over selected reference areas, cross‐correlation coefficients of the two principal component time series, and time‐dependent phase angle composites. The outgoing longwave radiation anomalies from these different indices propagate differently according to these diagnostics. One of them exhibits little propagation at all, even though one would expect good propagation based on composites of the phases separately. This illustrates the general point that while composites of individual phases, presented in a sequence, are generally taken to imply that the phases tend to occur in that sequence in time, that need not be the case. It is suggested that propagation characteristics are relevant to the application of the indices and that smoother propagation is desirable.
Differentially expressed genes related to major depressive disorder and antidepressant response: genome-wide gene expression analysis
Authors: Woo Hye In , Lim Shinn-Won , Myung Woojae , Kim Doh Kwan , Lee Soo-Youn 
Published: August 2018

AbstractTreatment response to antidepressants is limited and varies among patients with major depressive disorder (MDD). To discover genes and mechanisms related to the pathophysiology of MDD and antidepressant treatment response, we performed gene expression analyses using peripheral blood specimens from 38 MDD patients and 14 healthy individuals at baseline and at 6 weeks after the initiation of either selective serotonin reuptake inhibitor (SSRI) or mirtazapine treatment. The results were compared with results from public microarray data. Seven differentially expressed genes (DEGs) between MDD patients and controls were identified in our study and in the public microarray data: CD58, CXCL8, EGF, TARP, TNFSF4, ZNF583, and ZNF587. CXCL8 was among the top 10 downregulated genes in both studies. Eight genes related to SSRI responsiveness, including BTNL8, showed alterations in gene expression in MDD. The expression of the FCRL6 gene differed between SSRI responders and nonresponders and changed after SSRI treatment compared to baseline. In evaluating the response to mirtazapine, 21 DEGs were identified when comparing MDD patients and controls and responders and nonresponders. These findings suggest that the pathophysiology of MDD and treatment response to antidepressants are associated with a number of processes, including DNA damage and apoptosis, that can be induced by immune activation and inflammation.