bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rings of C2H in the Molecular Disks Orbiting TW Hya and V4046 Sgr
Authors: Kastner J. H. , Qi C. , Gorti U. , Hily-Blant P. , Oberg K. , Forveille T. , Andrews S. , Wilner D. 
Published: January 2016

AbstractWe have used the Submillimeter Array (SMA) to image, at ~1″ resolution, C2H(3−2) emission from the molecule-rich circumstellar disks orbiting the nearby, classical T Tauri star systems TW Hya and V4046 Sgr. The SMA imaging reveals that the C2H emission exhibits a ring-like morphology within each disk; the radius of the inner hole of the C2H ring within the V4046 Sgr disk (~70 AU) is somewhat larger than than of its counterpart within the TW Hya disk (~45 AU). We suggest that, in each case, the C2H emission likely traces irradiation of the tenuous surface layers of the outer disks by high-energy photons from the central stars.
The WISE Census of Young Stellar Objects in Canis Major
Authors: Fischer W. J. , Padgett D. L. , Stapelfeldt K. R. 
Published: January 2016

AbstractWhile searches for young stellar objects (YSOs) with the Spitzer Space Telescope focused on known molecular clouds, photometry from the Wide-field Infrared Survey Explorer (WISE) can be used to extend the search to the entire sky. As a precursor to more expansive searches, we present results for a 100 deg2 region centered on the Canis Major clouds.
Sensitive Identification of Nearby Debris Disks via Precise Calibration of WISE Data
Authors: Patel Rahul , Metchev Stanimir , Heinze Aren , Trollo Joe 
Published: January 2016

AbstractUsing data from the WISE All-Sky Survey, we have found >100 new infrared excess sources around main-sequence Hipparcos stars within 75 pc. Our empirical calibration of WISE photospheric colors and removal of non-trivial false-positive sources are responsible for the high confidence (>99.5%) of detections, while our corrections to saturated W1 and W2 photometry have for the first time allowed us to search for new infrared excess sources around bright field stars in WISE. The careful calibration and filtering of the WISE data have allowed us to probe excess fluxes down to roughly 8% of the photospheric emission at 22μm around saturated stars in WISE. We expect that the increased sensitivity of our survey will not only aid in understanding the evolution of debris disks, but will also benefit future studies using WISE.
The BANYAN All-Sky Survey for Brown Dwarf Members of Young Moving Groups
Authors: Gagné Jonathan , Lafrenière David , Doyon René , Faherty Jacqueline K. , Malo Lison , Cruz Kelle L. , Artigau Étienne , Burgasser Adam J. , Naud Marie-Eve , Bouchard Sandie , Gizis John E. , Albert Loïc 
Published: January 2016

AbstractWe describe in this work the BASS survey for brown dwarfs in young moving groups of the solar neighborhood, and summarize the results that it generated. These include the discovery of the 2MASS J01033563–5515561 (AB)b and 2MASS J02192210–3925225 B young companions near the deuterium-burning limit as well as 44 new low-mass stars and 69 new brown dwarfs with a spectroscopically confirmed low gravity. Among those, ~20 have estimated masses within the planetary regime, one is a new L4 γ bona fide member of AB Doradus, three are TW Hydrae candidates with later spectral types (L1–L4) than all of its previously known members and six are among the first contenders for low-gravity ≥ L5 β/γ brown dwarfs, reminiscent of WISEP J004701.06+680352.1, PSO J318.5338–22.8603 and VHS J125601.92–125723.9 b. Finally, we describe a future version of this survey, BASS-Ultracool, that will specifically target ≥ L5 candidate members of young moving groups. First experimentations in designing the survey have already led to the discovery of a new T dwarf bona fide member of AB Doradus, as well as the serendipitous discoveries of an L9 subdwarf and an L5 + T5 brown dwarf binary.
Determining the Ages of Nearby A-Stars with Long-Baseline Interferometry
Authors: Jones Jeremy , White R. J. , Boyajian T. , Schaefer G. , Baines E. , Ireland M. , Patience J. ,   The CHARA Team
Published: January 2016

AbstractWe determine the age of 7 stars in the Ursa Major moving group using a novel method that models the fundamental parameters of rapidly rotating A-stars based on interferometric observations and literature photometry and compares these parameters (namely, radius, luminosity, and rotation velocity) with evolution models that account for rotation. We find these stars to be coeval, thus providing an age estimate for the moving group and validating this technique. With this technique validated, we determine the age of the rapidly rotating, directly imaged planet host star, κ Andromedae.
The Isochronal Age Scale of Young Moving Groups in the Solar Neighbourhood
Authors: Bell Cameron P. M. , Mamajek Eric E. , Naylor Tim 
Published: January 2016

AbstractWe present a self-consistent, absolute isochronal age scale for young (≲ 200 Myr), nearby (≲ 100 pc) moving groups, which is consistent with recent lithium depletion boundary ages for both the β Pic and Tucana-Horologium moving groups. This age scale was derived using a set of semi-empirical pre-main-sequence model isochrones that incorporate an empirical colour-Teffrelation and bolometric corrections based on the observed colours of Pleiades members, with theoretical corrections for the dependence on logg. Absolute ages for young, nearby groups are vital as these regions play a crucial role in our understanding of the early evolution of low- and intermediate-mass stars, as well as providing ideal targets for direct imaging and other measurements of dusty debris discs, substellar objects and, of course, extrasolar planets.
What Do Young Brown Dwarfs Tell Us About Exoplanets?
Authors: Allers Katelyn N. , Liu Michael C. , Dupuy Trent J. 
Published: January 2016

AbstractIn recent years, all-sky surveys have uncovered a new and interesting population of young (≈10–200 Myr), nearby substellar objects. Many of these objects have inferred masses and temperatures that overlap those of directly imaged exoplanets. These young brown dwarfs provide valuable analogs to young, dusty exoplanets in a context where detailed spectroscopic observations across a broad range of wavelengths and at high S/N are possible. How do the temperatures inferred by atmospheric models and evolutionary models compare? Can we determine the formation mechanism of a young planetary-mass object? How well do we understand the role that disequilibrium chemistry and dust clouds play in the atmospheres of these objects? We review the successes and challenges in determining the fundamental properties (mass, log(g), effective temperature) of young substellar objects, both brown dwarfs and gas-giant exoplanets.
The Chemistry of Nearby Disks
Authors: Öberg Karin I. 
Published: January 2016

AbstractThe gas and dust rich disks around young stars are the formation sites of planets. Observations of molecular trace species have great potential as probes of the disk structures and volatile compositions that together regulate planet formation. The disk around young star TW Hya has become a template for disk molecular studies due to a combination of proximity, a simple face-on geometry and richness in volatiles. It is unclear, however, how typical the chemistry of the TW disk is. In this proceeding, we review lessons learnt from exploring the TW Hya disk chemistry, focusing on the CO snowline, and on deuterium fractionation chemistry. We compare these results with new ALMA observations toward more distant, younger disks. We find that while all disks have some chemical structures in common, there are also substantial differences between the disks, which may be due to different initial conditions, structural or chemical evolutionary stages, or a combination of all three.
T Tauri Disk Lifetime in the Lupus Association
Authors: Galli P. A. B. , Bertout C. , Teixeira R. , Ducourant C. 
Published: January 2016

AbstractIn a recent study, we derived individual distances for a sample of pre-main sequence stars that define the comoving association of young stars in the Lupus star-forming region. Here, we use these new distances to investigate the mass and age distributions of Lupus T Tauri stars and derive the average disk lifetime in the Lupus association based on an empirical disk model.
Protoplanetary Disk Evolution: Singles vs. Binaries
Authors: Daemgen Sebastian , Jayawardhana Ray , Petr-Gotzens Monika G. , Meyer Elliot 
Published: January 2016

AbstractBased on a large number of observations carried out in the last decade it appears that the fraction of stars with protoplanetary disks declines steadily between ~1 Myr and ~10 Myr. We do, however, know that the multiplicity fraction of star-forming regions can be as high as >50% and that multiples have reduced disk lifetimes on average. As a consequence, the observed roughly exponential disk decay can be fully attributed neither to single nor binary stars and its functional form may need revision. Observational evidence for a non-exponential decay has been provided by Kraus et al. (2012), who statistically correct previous disk frequency measurements for the presence of binaries and find agreement with models that feature a constantly high disk fraction up to ~3 Myr, followed by a rapid (≲2 Myr) decline.We present results from our high angular resolution observational program to study the fraction of protoplanetary disks of single and binary stars separately. We find that disk evolution timescales of stars bound in close binaries (<100 AU) are significantly reduced compared to wider binaries. The frequencies of accretors among single stars and wide binaries appear indistinguishable, and are found to be lower than predicted from planet forming disk models governed by viscous evolution and photoevaporation.
Effect of Prior Information on Bayesian Membership Calculations for Nearby Young Star Associations
Authors: Lee Jinhee , Song Inseok 
Published: January 2016

AbstractWe present a refined moving group membership diagnostics scheme based on Bayesian inference. Compared to the BANYAN II method, we improved the calculation by updating bona fide members of a moving group, field star treatment, and uniform spatial distribution of moving group members. Here, we present the detailed description of our method and the new results for Bayesian membership calculation. Comparison of our method with BANYAN II shows probability differences up to ~90%. We conclude that more cautious consideration is needed in moving group membership based on Bayesian inference.
Where the Wild Young M Dwarfs Are: the SUPERBLINK Proper Motion Survey and a Search for Low-mass Moving Group Candidates
Authors: Lépine Sébastien 
Published: January 2016

AbstractThe SUPERBLINK survey catalogs all stars brighter than R = 19 mag and with proper motions larger than 40 mas yr−1, down to a declination of −33○. The catalog inevitably includes a significant fraction of the presumed low-mass members of several nearby young moving groups (Beta Pic, AB Dor, Tuc-Hor, Argus), or low-mass escapees from the Hyades and Pleiades clusters. We discuss opportunities and challenges in identifying the missing M dwarf members of these moving groups. While rounding up the majority of the potential M dwarf members of these groups, such samples are significantly affected by co-moving field stars, both young and old, due to the heavy clumping of the local field population in velocity space.
Nearby Young Moving Groups: Statistical Methods and Challenges for Assigning Membership
Authors: Malo L. , Gagne J. , Doyon R. , Lafreniere D. , Artigau E. , Albert L. 
Published: January 2016

AbstractYoung associations, being sparsely populated and relatively close to the Sun, their members are found all over the sky. In the Solar Neighborhood, young moving groups are found within 100 pc with ages ranging from 5 to 120 Myr. While known members of these groups were identified mostly through the Hipparcos data, only the most massive members have been fully characterized so far, and defined the core members. In the last decades, several new candidate members have been identified, using different approaches. Based on the global properties of the core members (kinematics and over luminosity), those methods used several criteria to establish the membership, from qualitative manner to quantitive methods using reduced chi-squared or membership probability. A full confirmation of the membership for those numerous candidates requires radial velocity and parallax measurements to confirm their kinematics, age-dating indicator measurement to assess their youth and multiplicity follow-up to rule out binary objects. In this proceeding, we summarize a general recipe to assign membership, describe the numerous challenges for assigning membership, and end with a discussion on the appropriateness and reliability of the BANYAN I and II tools to assess membership.
LACEwING: Lessons from a New Moving Group Code
Authors: Riedel A. R. 
Published: January 2016

AbstractWith the recent accelerating rate of discoveries in the field of nearby young stars, the ability to identify new nearby young stars is as important as ever, and membership identification codes will continue to perform a vital role in scientific research. In the process of creating a new moving group membership identification code - LocAting Constituent mEmbers In Nearby Groups (LACEwING): we have compiled a few pointers relevant to astronomers trying to use codes like LACEwING to locate young stars.
HD141569A: Disk Dissipation Caught in Action
Authors: Péricaud J. , Di Folco E. , Dutrey A. , Augereau J.-C. , Piétu V. , Guilloteau S. 
Published: January 2016

AbstractDebris disks are usually thought to be gas-poor, the gas being dissipated by accretion or evaporation during the protoplanetary phase. HD141569A is a 5 Myr old star harboring a famous debris disk, with multiple rings and spiral features. I present here the first PdBI maps of the 12CO(2−1), 13CO(2−1) gas and dust emission at 1.3 mm in this disk. The analysis reveals there is still a large amount of (primordial) gas extending out to 250 AU, i.e. inside the rings observed in scattered light. HD141569A is thus a hybrid disk with a huge debris component, where dust has evolved and is produced by collisions, with a large remnant reservoir of gas.
Warm Debris Disks with WISE and HST
Authors: Padgett Deborah , Stapelfeldt Karl 
Published: January 2016

AbstractUsing 22 μm data from the Wide Field Infrared Survey Explorer (WISE), we have completed a sensitive all-sky survey for debris disks in Hipparcos and Tycho catalog stars within 120 pc. This warm excess emission traces material in the circumstellar region likely to host terrestrial planets. Several hundred previously unknown debris disk candidates were identified. We are currently performing follow-up observations to characterize the stars, companions, and circumstellar material in these systems with a variety of facilities including Keck, Herschel, and HST. Thirteen WISE debris disks have been observed to date using HST/STIS coronagraphy. Five of these disks have been detected in scattered light. One is a large and highly asymmetric edge-on disk which appears to be both warped and bifurcated.
Fourth Day of Creation: The Proto-history of Young Stars, Star Streams, and Exoplanets Near the Sun
Authors: Trimble Virginia 
Published: January 2016

AbstractItems of scientific knowledge at any moment in time have pre-histories when they were debated, doubted, or absolutely denied. The examples considered here are the admitted facts that star formation is an on-going process in the Milky Way, that there are young moving groups (the products of young star clusters in the process of dissolution and perhaps more complex processes), and that planets orbiting other stars are common. It is hard to imagine any of these ceasing to be part of core astronomical knowledge, but you are advised not to place large bets on this.
Low-gravity L Dwarfs Are Likely More Variable
Authors: Metchev Stanimir , Heinze Aren , Apai Daniel , Flateau Davin , Radigan Jacqueline , Burgasser Adam , Marley Mark , Artigau Étienne , Plavchan Peter , Goldman Bertrand 
Published: January 2016

AbstractIn the “Weather on Other Worlds” Spitzer Exploration Science program, we surveyed 44 nearby L3–T8 dwarfs for spot-induced rotational variability. Among single L3–L9.5 dwarfs, we found that 80% are variable at >0.2% in the 3–5 μm wavelength range, while 36% of T0–T8 were variable at >0.4%. Taking into account viewing angle and sensitivity considerations, both of these findings are consistent with spots being present on ~100% of L3–T8 dwarfs. Intriguingly, we find a tentative association (92% confidence) between low surface gravity and high-amplitude variability among L3–L5.5 dwarfs. Although we can not confirm whether lower gravity is also correlated with a higher incidence of variables, the result is promising for the characterization of directly imaged young extrasolar planets through variability.
Debris Disks in Nearby Young Moving Groups in the ALMA Era
Authors: Kóspál Á. , Moór A. 
Published: January 2016

AbstractMany members of nearby young moving groups exhibit infrared excess attributed to circumstellar debris dust, formed via erosion of planetesimals. With their proximity and well-dated ages, these groups are excellent laboratories for studying the early evolution of debris dust and of planetesimal belts. ALMA can spatially resolve the disk emission, revealing the location and extent of these belts, putting constraints on planetesimal evolution models, and allowing us to study planet-disk interactions. While the main trends of dust evolution in debris disks are well-known, there is almost no information on the evolution of gas. During the transition from protoplanetary to debris state, even the origin of gas is dubious. Here we review the exciting new results ALMA provided by observing young debris disks, and discuss possible future research directions.
Planetary Evaporation and the Dynamics of Planet Wind/Stellar Wind Bow Shocks
Authors: Frank A. , Lui B. , Carroll-Nellenback J. , Quillen A. C. , Blackman E. G. , Kasting J. , Dobbs-Dixon I. 
Published: January 2016

AbstractWe present initial results of a new campaign of simulations focusing on the interaction of planetary winds with stellar environments using Adaptive Mesh Refinement methods. We have confirmed the results of Stone & Proga (2009) that an azimuthal flow structure is created in the planetary wind due to day/night temperatures differences. We show that a backflow towards the planet will occur with a strength that depends on the escape parameter. When a stellar outflow is included, we see unstable bow waves forming through the outflow's interaction with the planetary wind.
Bone marrow-derived monocytes give rise to self-renewing and fully differentiated Kupffer cells
Authors: Scott Charlotte L. , Zheng Fang , De Baetselier Patrick , Martens Liesbet , Saeys Yvan , De Prijck Sofie , Lippens Saskia , Abels Chloé , Schoonooghe Steve , Raes Geert , Devoogdt Nick , Lambrecht Bart N. , Beschin Alain , Guilliams Martin 
Published: January 2016

AbstractSelf-renewing tissue-resident macrophages are thought to be exclusively derived from embryonic progenitors. However, whether circulating monocytes can also give rise to such macrophages has not been formally investigated. Here we use a new model of diphtheria toxin-mediated depletion of liver-resident Kupffer cells to generate niche availability and show that circulating monocytes engraft in the liver, gradually adopt the transcriptional profile of their depleted counterparts and become long-lived self-renewing cells. Underlining the physiological relevance of our findings, circulating monocytes also contribute to the expanding pool of macrophages in the liver shortly after birth, when macrophage niches become available during normal organ growth. Thus, like embryonic precursors, monocytes can and do give rise to self-renewing tissue-resident macrophages if the niche is available to them.
Restricting mutualistic partners to enforce trade reliance
Authors: Wyatt Gregory A. K. , Kiers E. Toby , Gardner Andy , West Stuart A. 
Published: January 2016

AbstractMutualisms are cooperative interactions between members of different species, often involving the trade of resources. Here, we suggest that otherwise-cooperative mutualists might be able to gain a benefit from actively restricting their partners’ ability to obtain resources directly, hampering the ability of the restricted partner to survive and/or reproduce without the help of the restricting mutualist. We show that (i) restriction can be favoured when it makes the resources of the restricting individual more valuable to their partner, and thus allows them to receive more favourable terms of trade; (ii) restriction maintains cooperation in conditions where cooperative behaviour would otherwise collapse; and (iii) restriction can lead to either an increase or decrease in a restricted individual’s fitness. We discuss the applicability of this scenario to mutualisms such as those between plants and mycorrhizal fungi. These results identify a novel conflict in mutualisms as well as several public goods dilemmas, but also demonstrate how conflict can help maintain cooperation.
Wavelength-tunable sources of entangled photons interfaced with atomic vapours
Authors: Trotta Rinaldo , Martín-Sánchez Javier , Wildmann Johannes S. , Piredda Giovanni , Reindl Marcus , Schimpf Christian , Zallo Eugenio , Stroj Sandra , Edlinger Johannes , Rastelli Armando 
Published: January 2016

AbstractThe prospect of using the quantum nature of light for secure communication keeps spurring the search and investigation of suitable sources of entangled photons. A single semiconductor quantum dot is one of the most attractive, as it can generate indistinguishable entangled photons deterministically and is compatible with current photonic-integration technologies. However, the lack of control over the energy of the entangled photons is hampering the exploitation of dissimilar quantum dots in protocols requiring the teleportation of quantum entanglement over remote locations. Here we introduce quantum dot-based sources of polarization-entangled photons whose energy can be tuned via three-directional strain engineering without degrading the degree of entanglement of the photon pairs. As a test-bench for quantum communication, we interface quantum dots with clouds of atomic vapours, and we demonstrate slow-entangled photons from a single quantum emitter. These results pave the way towards the implementation of hybrid quantum networks where entanglement is distributed among distant parties using optoelectronic devices.
Magnetic ground state of an individual Fe2+ ion in strained semiconductor nanostructure
Authors: Smoleński T. , Kazimierczuk T. , Kobak J. , Goryca M. , Golnik A. , Kossacki P. , Pacuski W. 
Published: January 2016

AbstractSingle impurities with nonzero spin and multiple ground states offer a degree of freedom that can be utilized to store the quantum information. However, Fe2+ dopant is known for having a single nondegenerate ground state in the bulk host semiconductors and thus is of little use for spintronic applications. Here we show that the well-established picture of Fe2+ spin configuration can be modified by subjecting the Fe2+ ion to high strain, for example, produced by lattice mismatched epitaxial nanostructures. Our analysis reveals that high strain induces qualitative change in the ion energy spectrum and results in nearly doubly degenerate ground state with spin projection Sz=±2. We provide an experimental proof of this concept using a new system: a strained epitaxial quantum dot containing individual Fe2+ ion. Magnetic character of the Fe2+ ground state in a CdSe/ZnSe dot is revealed in photoluminescence experiments by exploiting a coupling between a confined exciton and the single-iron impurity. We also demonstrate that the Fe2+ spin can be oriented by spin-polarized excitons, which opens a possibility of using it as an optically controllable two-level system free of nuclear spin fluctuations.