324 research outputs found

    Researchers’ adoption of an institutional central fund for open-access article-processing charges: a case study using innovation diffusion theory

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    This article analyzes researchers’ adoption of an institutional central fund (or faculty publication fund) for open-access (OA) article-processing charges (APCs) to contribute to a wider understanding of take-up of OA journal publishing (“Gold” OA). Quantitative data, recording central fund usage at the University of Nottingham from 2006 to 2014, are analyzed alongside qualitative data from institutional documentation. The importance of the settings of U.K. national policy developments and international OA adoption trends are considered. Innovation Diffusion Theory (IDT) is used as an explanatory framework. It is shown that use of the central fund grew during the period from covering less than 1% of the University’s outputs to more than 12%. Health and Life Sciences disciplines made greatest use of the fund. Although highly variable, average APC prices rose during the period, with fully OA publishers setting lower average APCs. APCs were paid largely from internal funds, but external funding became increasingly important. Key factors in adoption are identified to be increasing awareness and changing perceptions of OA, communication, disciplinary differences, and adoption mandates. The study provides a detailed longitudinal analysis of one of the earliest central funds to be established globally with a theoretically informed explanatory model to inform future work on managing central funds and developing institutional and national OA policies

    Vsini-s for late-type stars from spectral synthesis in K-band region

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    We analyse medium-resolution spectra (R\sim 18000) of 19 late type dwarfs in order to determine vsini-s using synthetic rather than observational template spectra. For this purpose observational data around 2.2 μ\mum of stars with spectral classes from G8V to M9.5V were modelled. We find that the Na I (2.2062 and 2.2090 μ\mum) and 12^{12}CO 2-0 band features are modelled well enough to use for vsini determination without the need for a suitable observational template spectra. Within the limit of the resolution of our spectra, we use synthetic spectra templates to derive vsini values consistent with those derived in the optical regime using observed templates. We quantify the errors in our vsini determination due to incorrect choice of model parameters \Teff, log gg, vmicrov_{\rm micro}, [Fe/H] or FWHM and show that they are typically less than 10 per cent. We note that the spectral resolution of our data(\sim 16 km/s) limited this study to relatively fast rotators and that resolutions of 60000 will required to access most late-type dwarfs.Comment: 8 pages, 4 figures, 3 tables, accepted to the MNRA

    Identifying the ejected population from disintegrating multiple systems

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    Kinematic studies of the Hipparcos catalogue have revealed associations that are best explained as disintegrating multiple systems, presumably resulting from a dynamical encounter between single/multiple systems in the field (Li et al. 2009). In this work we explore the possibility that known ultra-cool dwarfs may be components of disintegrating multiple systems, and consider the implications for the properties of these objects. We will present here the methods/techniques that can be used to search for and identify disintegrating benchmark systems in three database/catalogues: Dwarf Archive, the Hipparcos Main Catalogue, and the Gliese-Jahrei{\ss} Catalogue. Placing distance constraints on objects with parallax or colour-magnitude information from spectrophotometry allowed us to identify common distance associations. Proper motion measurements allowed us to separate common proper motion multiples from our sample of disintegrating candidates. Moreover, proper motion and positional information allowed us to select candidate systems based on relative component positions that were tracked back and projected forward through time. Using this method we identified one candidate disintegrating quadruple association, and two candidate disintegrating binaries, all of them containing one ultra-cool dwarf.Comment: 5 pages, 1 figure, proceeding of The 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Su

    Benchmark ultra-cool dwarfs in widely separated binary systems

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    Ultra-cool dwarfs as wide companions to subgiants, giants, white dwarfs and main sequence stars can be very good benchmark objects, for which we can infer physical properties with minimal reference to theoretical models, through association with the primary stars. We have searched for benchmark ultra-cool dwarfs in widely separated binary systems using SDSS, UKIDSS, and 2MASS. We then estimate spectral types using SDSS spectroscopy and multi-band colors, place constraints on distance, and perform proper motions calculations for all candidates which have sufficient epoch baseline coverage. Analysis of the proper motion and distance constraints show that eight of our ultra-cool dwarfs are members of widely separated binary systems. Another L3.5 dwarf, SDSS 0832, is shown to be a companion to the bright K3 giant Eta Cancri. Such primaries can provide age and metallicity constraints for any companion objects, yielding excellent benchmark objects. This is the first wide ultra-cool dwarf + giant binary system identified.Comment: 4 pages, 3 figures, conference, "New Technologies for Probing the Diversity of Brown Dwarfs and Exoplanets", oral tal

    New, nearby bright southern ultracool dwarfs

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    We report the discovery of twenty-one hitherto unknown bright southern ultracool dwarfs with spectral types in the range M7 to L5.5, together with new observations of a further three late M dwarfs previously confirmed. Three more objects are already identified in the literature as high proper motion stars;we derive their spectral types for the first time. All objects were selected from the 2MASS All Sky and SuperCOSMOS point source databases on the basis of their optical/near-infrared colours, JJ-band magnitudes and proper motions. Low resolution (R \sim 1000) JHJH spectroscopy with the ESO/NTT SOFI spectrograph has confirmed the ultracool nature of 24 targets, out of a total of 25 candidates observed. Spectral types are derived by direct comparison with template objects and compared to results from H2_2O and FeH indices. We also report the discovery of one binary, as revealed by SOFI acquisition imaging; spectra were taken for both components. The spectral types of the two components are L2 and L4 and the distance \sim 19 pc. Spectroscopic distances and transverse velocities are derived for the sample. Two \sim L5 objects lie only \sim 10 pc distant. Such nearby objects are excellent targets for further study to derive their parallaxes and to search for fainter, later companions with AO and/or methane imaging.Comment: 11 pages, 10 figures, accepted to MNRA

    Preprints and scholarly communication : an exploratory qualitative study of adoption, practices, drivers and barriers

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    Background: Since 2013, there has been a dramatic increase in the number of preprint servers. Little is known about the position of researchers, funders, research performing organisations and other stakeholders with respect to this fast-paced landscape. In this article, we explore the perceived benefits and challenges of preprint posting, alongside issues including infrastructure and financial sustainability. We also discuss the definition of a ‘preprint’ in different communities, and the impact this has on uptake. Methods: This study is based on 38 semi-structured interviews of key stakeholders, based on a purposive heterogeneous sampling approach and undertaken between October 2018 and January 2019. Interviewees were primarily drawn from biology, chemistry and psychology, where use of preprints is growing. Interviews were recorded, transcribed and subjected to thematic analysis to identify trends. Interview questions were designed based on Innovation Diffusion Theory, which was also used to interpret our results. Results: Participants were conscious of the rising prominence of preprints and cited early and fast dissemination as their most appealing feature. Preprints were also considered to enable broader access to scientific literature and increased opportunities for informal commenting. The main concerns related to the lack of quality assurance and the ‘Ingelfinger rule’. We identified trust as an essential factor in preprint posting, and highlight the enabling role of Twitter in showcasing preprints. Conclusions: The preprints landscape is evolving fast, and disciplinary communities are at different stages in the innovation diffusion process. The landscape is characterised by experimentation, which leads to the conclusion that a one-size-fits-all approach to preprints is not feasible. Cooperation and active engagement between the stakeholders involved will play an important role going forward. We share questions for the further development of the preprints landscape, with the most important being whether preprint posting will develop as a publisher- or researcher-centric practice

    Towards a competitive and sustainable OA market in Europe - A study of the open access market and policy environment

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    Deliverable 5.3 of OpenAIRE WP5: FP7 Post Grant Gold Open Access Pilot. This deliverable consists of a study and an annex - and it will be supplemented by a roadmap in May 2017. This study considers the economic factors contributing to the current state of the open-access publishing market, and evaluates the potential for European policymakers to enhance market competition and sustainability in parallel to increasing access. It was commissioned within the scope of the OpenAIRE FP7 Post-Grant Open Access Pilot, and it will be accompanied by a Roadmap document developed with inputs from an expert workshop to be held in The Hague on 20 April 2017. In accordance with the project brief, the study aims to: Explore the current status of the OA publishing market Analyse existing OA publishing business models Evaluate how different national and international policies are complementing each other as a means to achieve a transition to OA Evaluate the impact of the Framework Programme 7 Post-grant OA pilot and its implications for future similar initiatives and the transition to OA. Provide a roadmap leading to a sustainable and competitive market The transition to open access concerns all kinds of academic research outputs, including monographs, journal articles, and data. This study focuses on open access to peer-reviewed research articles, which constitute the bulk of the market and the primary mechanism through which research is disseminated across disciplinary communities and beyond. This report is supplemented by an Annex containing a mid-term evaluation of the FP7 Post-Grant Open Access Pilot.This report will be accompanied by a Roadmap document developed with inputs from an expert workshop to be held in The Hague on 20 April 201

    Primeval very low-mass stars and brown dwarfs - VI. Population properties of metal-poor degenerate brown dwarfs

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    © 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.We presented 15 new T dwarfs that were selected from UKIRT Infrared Deep Sky Survey, Visible and Infrared Survey Telescope for Astronomy, and Wide-field Infrared Survey Explorer surveys, and confirmed with optical to near infrared spectra obtained with the Very Large Telescope and the Gran Telescopio Canarias. One of these new T dwarfs is mildly metal-poor with slightly suppressed KK-band flux. We presented a new X-shooter spectrum of a known benchmark sdT5.5 subdwarf, HIP 73786B. To better understand observational properties of brown dwarfs, we discussed transition zones (mass ranges) with low-rate hydrogen, lithium, and deuterium burning in brown dwarf population. The hydrogen burning transition zone is also the substellar transition zone that separates very low-mass stars, transitional, and degenerate brown dwarfs. Transitional brown dwarfs have been discussed in previous works of the Primeval series. Degenerate brown dwarfs without hydrogen fusion are the majority of brown dwarfs. Metal-poor degenerate brown dwarfs of the Galactic thick disc and halo have become T5+ subdwarfs. We selected 41 T5+ subdwarfs from the literature by their suppressed KK-band flux. We studied the spectral-type - colour correlations, spectral-type - absolute magnitude correlations, colour-colour plots, and HR diagrams of T5+ subdwarfs, in comparison to these of L-T dwarfs and L subdwarfs. We discussed the T5+ subdwarf discovery capability of deep sky surveys in the 2020s.Peer reviewe

    Binary frequency of planet-host stars at wide separations: A new brown dwarf companion to a planet-host star

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    The aim of the project is to improve our knowledge on the multiplicity of planet-host stars at wide physical separations. We cross-matched approximately 6200 square degree area of the Southern sky imaged by the Visible Infrared Survey Telescope for Astronomy (VISTA) Hemisphere Survey (VHS) with the Two Micron All Sky Survey (2MASS) to look for wide common proper motion companions to known planet-host stars. We complemented our astrometric search with photometric criteria. We confirmed spectroscopically the co-moving nature of seven sources out of 16 companion candidates and discarded eight, while the remaining one stays as a candidate. Among these new wide companions to planet-host stars, we discovered a T4.5 dwarf companion at 6.3 arcmin (~9000 au) from HIP70849, a K7V star which hosts a 9 Jupiter mass planet with an eccentric orbit. We also report two new stellar M dwarf companions to one G and one metal-rich K star. We infer stellar and substellar binary frequencies for our complete sample of 37 targets of 5.4+/-3.8% and 2.7+/-2.7% (1 sigma confidence level), respectively, for projected physical separations larger than ~60-160 au assuming the range of distances of planet-host stars (24-75 pc). These values are comparable to the frequencies of non planet-host stars. We find that the period-eccentricity trend holds with a lack of multiple systems with planets at large eccentricities (e > 0.2) for periods less than 40 days. However, the lack of planets more massive than 2.5 Jupiter masses and short periods (<40 days) orbiting single stars is not so obvious due to recent discoveries by ground-based transit surveys and space missions.Comment: Accepted for publication in A&A, 13 pages, 5 figures, 3 tables, optical spectra will be available at CDS Strasbour
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