Science.gov

Sample records for gaia universe model

  1. The Explosive Universe with Gaia

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Łukasz; Hodgkin, Simon T.; Blagorodnova, Nadejda; Belokurov, Vasily

    2014-01-01

    The Gaia mission will observe the entire sky for 5 years providing ultra-precise astrometric, photometric and spectroscopic measurements for a billion stars in the Galaxy. Hence, naturally, Gaia becomes an all-sky multi-epoch photometric survey, which will monitor and detect variability with millimag precision as well as new transient sources such as supernovae, novae, microlensing events, tidal disruption events, asteroids, among others. Gaia data-flow allows for quick detections of anomalies within 24-48h after the observation. Such near-real-time survey will be able to detect about 6000 supernovae brighter than 19 mag up to redshifts of Z 0.15. The on-board low-resolution (R 100) spectrograph will allow for early and robust classification of transients and minimise the false-alert rate, even providing the estimates on redshift for supernovae. Gaia will also offer a unique possibility for detecting astrometric shifts in microlensing events, which, combined with Gaia's and ground-based photometry, will provide unique mass measurements of lenses, constrains on the dark matter content in the Milky Way and possible detections of free floating black holes. Alerts from Gaia will be publicly available soon after the detection is verified and tested. First alerts are expected early in 2014 and those will be used for ground-based verification. All facilities are invited to join the verification and the follow-up effort. Alerts will be published on a web page, via Skyalert.org and via emailing list. Each alert will contain coordinates, Gaia light curve and low-resolution spectra, classification and cross-matching results. More information on the Gaia Science Alerts can be found here: http://www.ast.cam.ac.uk/ioa/wikis/gsawgwiki/ The full version of the poster is available here: http://www.ast.cam.ac.uk/ioa/wikis/gsawgwiki/images/1/13/GaiaAlertsPosterIAUS298.pdf

  2. An entropic model of Gaia.

    PubMed

    Arthur, R; Nicholson, A

    2017-10-07

    We modify the Tangled Nature Model of Christensen et. al. (2002) so that the agents affect the carrying capacity. This leads to a model of species-environment co-evolution where the system tends to have a larger carrying capacity with life than without. We discuss the model as an example of an entropic hierarchy and some implications for Gaia theory. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Modelling radiation damage to ESA's Gaia satellite CCDs

    NASA Astrophysics Data System (ADS)

    Seabroke, George; Holland, Andrew; Cropper, Mark

    2008-07-01

    The Gaia satellite is a high-precision astrometry, photometry and spectroscopic ESA cornerstone mission, currently scheduled for launch in late 2011. Its primary science drivers are the composition, formation and evolution of the Galaxy. Gaia will not achieve its scientific requirements without detailed calibration and correction for radiation damage. Microscopic models of Gaia's CCDs are being developed to simulate the effect of radiation damage, charge trapping, which causes charge transfer inefficiency. The key to calculating the probability of a photoelectron being captured by a trap is the 3D electron density within each CCD pixel. However, this has not been physically modelled for Gaia CCD pixels. In this paper, the first of a series, we motivate the need for such specialised 3D device modelling and outline how its future results will fit into Gaia's overall radiation calibration strategy.

  4. Gaia: automated quality assessment of protein structure models.

    PubMed

    Kota, Pradeep; Ding, Feng; Ramachandran, Srinivas; Dokholyan, Nikolay V

    2011-08-15

    Increasing use of structural modeling for understanding structure-function relationships in proteins has led to the need to ensure that the protein models being used are of acceptable quality. Quality of a given protein structure can be assessed by comparing various intrinsic structural properties of the protein to those observed in high-resolution protein structures. In this study, we present tools to compare a given structure to high-resolution crystal structures. We assess packing by calculating the total void volume, the percentage of unsatisfied hydrogen bonds, the number of steric clashes and the scaling of the accessible surface area. We assess covalent geometry by determining bond lengths, angles, dihedrals and rotamers. The statistical parameters for the above measures, obtained from high-resolution crystal structures enable us to provide a quality-score that points to specific areas where a given protein structural model needs improvement. We provide these tools that appraise protein structures in the form of a web server Gaia (http://chiron.dokhlab.org). Gaia evaluates the packing and covalent geometry of a given protein structure and provides quantitative comparison of the given structure to high-resolution crystal structures. dokh@unc.edu Supplementary data are available at Bioinformatics online.

  5. Gaia DR2 documentation

    NASA Astrophysics Data System (ADS)

    van Leeuwen, F.; de Bruijne, J. H. J.; Arenou, F.; Bakker, J.; Blomme, R.; Busso, G.; Cacciari, C.; Castañeda, J.; Cellino, A.; Clotet, M.; Comoretto, G.; Eyer, L.; González-Núñez, J.; Guy, L.; Hambly, N.; Hobbs, D.; van Leeuwen, M.; Luri, X.; Manteiga, M.; Pourbaix, D.; Roegiers, T.; Salgado, J.; Sartoretti, P.; Tanga, P.; Ulla, A.; Utrilla Molina, E.; Abreu, A.; Altmann, M.; Andrae, R.; Antoja, T.; Audard, M.; Babusiaux, C.; Bailer-Jones, C. A. L.; Barache, C.; Bastian, U.; Beck, M.; Berthier, J.; Bianchi, L.; Biermann, M.; Bombrun, A.; Bossini, D.; Breddels, M.; Brown, A. G. A.; Busonero, D.; Butkevich, A.; Cantat-Gaudin, T.; Carrasco, J. M.; Cheek, N.; Clementini, G.; Creevey, O.; Crowley, C.; David, M.; Davidson, M.; De Angeli, F.; De Ridder, J.; Delbò, M.; Dell'Oro, A.; Diakité, S.; Distefano, E.; Drimmel, R.; Durán, J.; Evans, D. W.; Fabricius, C.; Fabrizio, M.; Fernández-Hernández, J.; Findeisen, K.; Fleitas, J.; Fouesneau, M.; Galluccio, L.; Gracia-Abril, G.; Guerra, R.; Gutiérrez-Sánchez, R.; Helmi, A.; Hernandez, J.; Holl, B.; Hutton, A.; Jean-Antoine-Piccolo, A.; Jevardat de Fombelle, G.; Joliet, E.; Jordi, C.; Juhász, Á.; Klioner, S.; Löffler, W.; Lammers, U.; Lanzafame, A.; Lebzelter, T.; Leclerc, N.; Lecoeur-Taïbi, I.; Lindegren, L.; Marinoni, S.; Marrese, P. M.; Mary, N.; Massari, D.; Messineo, R.; Michalik, D.; Mignard, F.; Molinaro, R.; Molnár, L.; Montegriffo, P.; Mora, A.; Mowlavi, N.; Muinonen, K.; Muraveva, T.; Nienartowicz, K.; Ordenovic, C.; Pancino, E.; Panem, C.; Pauwels, T.; Petit, J.; Plachy, E.; Portell, J.; Racero, E.; Regibo, S.; Reylé, C.; Rimoldini, L.; Ripepi, V.; Riva, A.; Robichon, N.; Robin, A.; Roelens, M.; Romero-Gómez, M.; Sarro, L.; Seabroke, G.; Segovia, J. C.; Siddiqui, H.; Smart, R.; Smith, K.; Sordo, R.; Soria, S.; Spoto, F.; Stephenson, C.; Turon, C.; Vallenari, A.; Veljanoski, J.; Voutsinas, S.

    2018-04-01

    The second Gaia data release, Gaia DR2, encompasses astrometry, photometry, radial velocities, astrophysical parameters (stellar effective temperature, extinction, reddening, radius, and luminosity), and variability information plus astrometry and photometry for a sample of pre-selected bodies in the solar system. The data collected during the first 22 months of the nominal, five-year mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC), resulting into this second data release. A summary of the release properties is provided in Gaia Collaboration et al. (2018b). The overall scientific validation of the data is described in Arenou et al. (2018). Background information on the mission and the spacecraft can be found in Gaia Collaboration et al. (2016), with a more detailed presentation of the Radial Velocity Spectrometer (RVS) in Cropper et al. (2018). In addition, Gaia DR2 is accompanied by various, dedicated papers that describe the processing and validation of the various data products. Four more Gaia Collaboration papers present a glimpse of the scientific richness of the data. In addition to this set of refereed publications, this documentation provides a detailed, complete overview of the processing and validation of the Gaia DR2 data. Gaia data, from both Gaia DR1 and Gaia DR2, can be retrieved from the Gaia archive, which is accessible from https://archives.esac.esa.int/gaia. The archive also provides various tutorials on data access and data queries plus an integrated data model (i.e., description of the various fields in the data tables). In addition, Luri et al. (2018) provide concrete advice on how to deal with Gaia astrometry, with recommendations on how best to estimate distances from parallaxes. The Gaia archive features an enhanced visualisation service which can be used for quick initial explorations of the entire Gaia DR2 data set. Pre-computed cross matches between Gaia DR2 and a selected set of large surveys are

  6. Modelling electron distributions within ESA's Gaia satellite CCD pixels to mitigate radiation damage

    NASA Astrophysics Data System (ADS)

    Seabroke, G. M.; Holland, A. D.; Burt, D.; Robbins, M. S.

    2009-08-01

    The Gaia satellite is a high-precision astrometry, photometry and spectroscopic ESA cornerstone mission, currently scheduled for launch in 2012. Its primary science drivers are the composition, formation and evolution of the Galaxy. Gaia will achieve its unprecedented positional accuracy requirements with detailed calibration and correction for radiation damage. At L2, protons cause displacement damage in the silicon of CCDs. The resulting traps capture and emit electrons from passing charge packets in the CCD pixel, distorting the image PSF and biasing its centroid. Microscopic models of Gaia's CCDs are being developed to simulate this effect. The key to calculating the probability of an electron being captured by a trap is the 3D electron density within each CCD pixel. However, this has not been physically modelled for the Gaia CCD pixels. In Seabroke, Holland & Cropper (2008), the first paper of this series, we motivated the need for such specialised 3D device modelling and outlined how its future results will fit into Gaia's overall radiation calibration strategy. In this paper, the second of the series, we present our first results using Silvaco's physics-based, engineering software: the ATLAS device simulation framework. Inputting a doping profile, pixel geometry and materials into ATLAS and comparing the results to other simulations reveals that ATLAS has a free parameter, fixed oxide charge, that needs to be calibrated. ATLAS is successfully benchmarked against other simulations and measurements of a test device, identifying how to use it to model Gaia pixels and highlighting the affect of different doping approximations.

  7. Gaia challenging performances verification: combination of spacecraft models and test results

    NASA Astrophysics Data System (ADS)

    Ecale, Eric; Faye, Frédéric; Chassat, François

    2016-08-01

    To achieve the ambitious scientific objectives of the Gaia mission, extremely stringent performance requirements have been given to the spacecraft contractor (Airbus Defence and Space). For a set of those key-performance requirements (e.g. end-of-mission parallax, maximum detectable magnitude, maximum sky density or attitude control system stability), this paper describes how they are engineered during the whole spacecraft development process, with a focus on the end-to-end performance verification. As far as possible, performances are usually verified by end-to-end tests onground (i.e. before launch). However, the challenging Gaia requirements are not verifiable by such a strategy, principally because no test facility exists to reproduce the expected flight conditions. The Gaia performance verification strategy is therefore based on a mix between analyses (based on spacecraft models) and tests (used to directly feed the models or to correlate them). Emphasis is placed on how to maximize the test contribution to performance verification while keeping the test feasible within an affordable effort. In particular, the paper highlights the contribution of the Gaia Payload Module Thermal Vacuum test to the performance verification before launch. Eventually, an overview of the in-flight payload calibration and in-flight performance verification is provided.

  8. Ultraviolet Light Curves of Gaia16apd in Superluminous Supernova Models

    NASA Astrophysics Data System (ADS)

    Tolstov, Alexey; Zhiglo, Andrey; Nomoto, Ken'ichi; Sorokina, Elena; Kozyreva, Alexandra; Blinnikov, Sergei

    2017-08-01

    Observations of Gaia16apd revealed extremely luminous ultraviolet emission among superluminous supernovae (SLSNe). Using radiation hydrodynamics simulations, we perform a comparison of UV light curves, color temperatures, and photospheric velocities between the most popular SLSN models: pair-instability supernova, magnetar, and interaction with circumstellar medium. We find that the interaction model is the most promising to explain the extreme UV luminosity of Gaia16apd. The differences in late-time UV emission and in color evolution found between the models can be used to link an observed SLSN event to the most appropriate model. Observations at UV wavelengths can be used to clarify the nature of SLSNe and more attention should be paid to them in future follow-up observations.

  9. Ultraviolet Light Curves of Gaia16apd in Superluminous Supernova Models

    SciTech Connect

    Tolstov, Alexey; Zhiglo, Andrey; Nomoto, Ken’ichi

    2017-08-10

    Observations of Gaia16apd revealed extremely luminous ultraviolet emission among superluminous supernovae (SLSNe). Using radiation hydrodynamics simulations, we perform a comparison of UV light curves, color temperatures, and photospheric velocities between the most popular SLSN models: pair-instability supernova, magnetar, and interaction with circumstellar medium. We find that the interaction model is the most promising to explain the extreme UV luminosity of Gaia16apd. The differences in late-time UV emission and in color evolution found between the models can be used to link an observed SLSN event to the most appropriate model. Observations at UV wavelengths can be used to clarify the naturemore » of SLSNe and more attention should be paid to them in future follow-up observations.« less

  10. Gaian bottlenecks and planetary habitability maintained by evolving model biospheres: the ExoGaia model

    NASA Astrophysics Data System (ADS)

    Nicholson, Arwen E.; Wilkinson, David M.; Williams, Hywel T. P.; Lenton, Timothy M.

    2018-06-01

    The search for habitable exoplanets inspires the question - how do habitable planets form? Planet habitability models traditionally focus on abiotic processes and neglect a biotic response to changing conditions on an inhabited planet. The Gaia hypothesis postulates that life influences the Earth's feedback mechanisms to form a self-regulating system, and hence that life can maintain habitable conditions on its host planet. If life has a strong influence, it will have a role in determining a planet's habitability over time. We present the ExoGaia model - a model of simple `planets' host to evolving microbial biospheres. Microbes interact with their host planet via consumption and excretion of atmospheric chemicals. Model planets orbit a `star' that provides incoming radiation, and atmospheric chemicals have either an albedo or a heat-trapping property. Planetary temperatures can therefore be altered by microbes via their metabolisms. We seed multiple model planets with life while their atmospheres are still forming and find that the microbial biospheres are, under suitable conditions, generally able to prevent the host planets from reaching inhospitable temperatures, as would happen on a lifeless planet. We find that the underlying geochemistry plays a strong role in determining long-term habitability prospects of a planet. We find five distinct classes of model planets, including clear examples of `Gaian bottlenecks' - a phenomenon whereby life either rapidly goes extinct leaving an inhospitable planet or survives indefinitely maintaining planetary habitability. These results suggest that life might play a crucial role in determining the long-term habitability of planets.

  11. Gaia archive

    NASA Astrophysics Data System (ADS)

    Hypki, Arkadiusz; Brown, Anthony

    2016-06-01

    The Gaia archive is being designed and implemented by the DPAC Consortium. The purpose of the archive is to maximize the scientific exploitation of the Gaia data by the astronomical community. Thus, it is crucial to gather and discuss with the community the features of the Gaia archive as much as possible. It is especially important from the point of view of the GENIUS project to gather the feedback and potential use cases for the archive. This paper presents very briefly the general ideas behind the Gaia archive and presents which tools are already provided to the community.

  12. Gaia DR2 documentation Chapter 7: Variability

    NASA Astrophysics Data System (ADS)

    Eyer, L.; Guy, L.; Distefano, E.; Clementini, G.; Mowlavi, N.; Rimoldini, L.; Roelens, M.; Audard, M.; Holl, B.; Lanzafame, A.; Lebzelter, T.; Lecoeur-Taïbi, I.; Molnár, L.; Ripepi, V.; Sarro, L.; Jevardat de Fombelle, G.; Nienartowicz, K.; De Ridder, J.; Juhász, Á.; Molinaro, R.; Plachy, E.; Regibo, S.

    2018-04-01

    This chapter of the Gaia DR2 documentation describes the models and methods used on the 22 months of data to produce the Gaia variable star results for Gaia DR2. The variability processing and analysis was based mostly on the calibrated G and integrated BP and RP photometry. The variability analysis approach to the Gaia data has been described in Eyer et al. (2017), and the Gaia DR2 results are presented in Holl et al. (2018). Detailed methods on specific topics will be published in a number of separate articles. Variability behaviour in the colour magnitude diagram is presented in Gaia Collaboration et al. (2018c).

  13. Asteroid science by Gaia

    NASA Astrophysics Data System (ADS)

    Muinonen, Karri; Cellino, Alberto; Dell Oro, Aldo; Tanga, Paolo; Delbo, Marco; Mignard, Francois; Thuillot, William; Berthier, Jerome; Carry, Benoit; Hestroffer, Daniel; Granvik, Mikael; Fedorets, Grigori

    2016-07-01

    some tests and validations of the processing of the asteroid observations. Overall, our findings are consistent with the expectations from the performances of Gaia and of the subsequent data reduction. As to the long-term processing of Gaia data, we expect to derive masses, sizes, average densities, spin properties, reflectance spectra, albedos, as well as new taxonomic classifications for large numbers of asteroids. In this review, we will describe the prospects for Gaia photometry and spectrophotometry. We will describe inverse methods for sparse photometric data using the so-called Lommel-Seeliger ellipsoids. We will further describe the modeling of Gaia spectra for the compositional studies of asteroids, as well as the prospects for a new Gaia asteroid taxonomy. Gaia data will open a new era in asteroid science, allowing us to answer fundamental questions concerning, for example, the interrelation between asteroid internal structure and surface properties.

  14. GAIA modeling of electrodynamics in the lower ionosphere during a severe solar flare event

    NASA Astrophysics Data System (ADS)

    Matsumura, M.; Shiokawa, K.; Shinagawa, H.; Jin, H.; Fujiwara, H.; Miyoshi, Y.; Otsuka, Y.

    2016-12-01

    Recent studies indicated that the ionospheric F-region disturbances due to solar flare irradiance are controlled not only by photoionization but also by electrodynamical changes of the ionosphere [Liu et al., 2007; Qian et al., 2012]. The electric field changes during solar flare events occur mainly in the E-region due to the X-ray flux enhancement, and in the equatorial counter electrojet regions the eastward electric field turns into westward below 107-km altitude [Manju and Viswanathan, 2005]. The TIME-GCM model has been used to investigate the flare-related electrodynamics of the ionosphere [Qian et al., 2012]. However, the model did not consider the flare effects at altitudes below 97 km due to the ionospheric lower boundary of the model. On the other hand, the GAIA model [Jin et al., 2011] can simulate electron density variations and electrodynamics around and below 100 km because the model does not have the limitation of the lower boundary. We have improved the GAIA model to incorporate the Flare Irradiance Spectral Model (FISM) [Chamberlin et al., 2007; 2008] to understand the global response of the whole ionosphere including E and D regions to the solar flares. We have performed a simulation for the X17 flare event of October 28, 2003, and have showed that soft X-ray considerably enhances conductivity even at an altitude of 80 km. We will report its effect on the ionospheric electric field and the equatorial electrojet currents.

  15. Red clump stars and Gaia: calibration of the standard candle using a hierarchical probabilistic model

    NASA Astrophysics Data System (ADS)

    Hawkins, Keith; Leistedt, Boris; Bovy, Jo; Hogg, David W.

    2017-10-01

    Distances to individual stars in our own Galaxy are critical in order to piece together the nature of its velocity and spatial structure. Core helium burning red clump (RC) stars have similar luminosities, are abundant throughout the Galaxy and thus constitute good standard candles. We build a hierarchical probabilistic model to quantify the quality of RC stars as standard candles using parallax measurements from the first Gaia data release. A unique aspect of our methodology is to fully account for (and marginalize over) parallax, photometry and dust correction uncertainties, which lead to more robust results than standard approaches. We determine the absolute magnitude and intrinsic dispersion of the RC in 2MASS bands J, H, Ks, Gaia G band and WISE bands W1, W2, W3 and W4. We find that the absolute magnitude of the RC is -1.61 ± 0.01 (in Ks), +0.44 ± 0.01 (in G), -0.93 ± 0.01 (in J), -1.46 ± 0.01 (in H), -1.68 ± 0.02 (in W1), -1.69 ± 0.02 (in W2), -1.67 ± 0.02 (in W3) and -1.76 ± 0.01 mag (in W4). The mean intrinsic dispersion is ˜0.17 ± 0.03 mag across all bands (yielding a typical distance precision of ˜8 per cent). Thus RC stars are reliable and precise standard candles. In addition, we have also re-calibrated the zero-point of the absolute magnitude of the RC in each band, which provides a benchmark for future studies to estimate distances to RC stars. Finally, the parallax error shrinkage in the hierarchical model outlined in this work can be used to obtain more precise parallaxes than Gaia for the most distant RC stars across the Galaxy.

  16. High-speed photometry of Gaia14aae: an eclipsing AM CVn that challenges formation models

    NASA Astrophysics Data System (ADS)

    Green, M. J.; Marsh, T. R.; Steeghs, D. T. H.; Kupfer, T.; Ashley, R. P.; Bloemen, S.; Breedt, E.; Campbell, H. C.; Chakpor, A.; Copperwheat, C. M.; Dhillon, V. S.; Hallinan, G.; Hardy, L. K.; Hermes, J. J.; Kerry, P.; Littlefair, S. P.; Milburn, J.; Parsons, S. G.; Prasert, N.; van Roestel, J.; Sahman, D. I.; Singh, N.

    2018-05-01

    AM CVn-type systems are ultracompact, hydrogen-deficient accreting binaries with degenerate or semidegenerate donors. The evolutionary history of these systems can be explored by constraining the properties of their donor stars. We present high-speed photometry of Gaia14aae, an AM CVn with a binary period of 49. 7 min and the first AM CVn in which the central white dwarf is fully eclipsed by the donor star. Modelling of the light curves of this system allows for the most precise measurement to date of the donor mass of an AM CVn, and relies only on geometric and well-tested physical assumptions. We find a mass ratio q = M2/M1 = 0.0287 ± 0.0020 and masses M1 = 0.87 ± 0.02 M⊙ and M2 = 0.0250 ± 0.0013 M⊙. We compare these properties to the three proposed channels for AM CVn formation. Our measured donor mass and radius do not fit with the contraction that is predicted for AM CVn donors descended from white dwarfs or helium stars at long orbital periods. The donor properties we measure fall in a region of parameter space in which systems evolved from hydrogen-dominated cataclysmic variables are expected, but such systems should show spectroscopic hydrogen, which is not seen in Gaia14aae. The evolutionary history of this system is therefore not clear. We consider a helium-burning star or an evolved cataclysmic variable to be the most likely progenitors, but both models require additional processes and/or fine-tuning to fit the data. Additionally, we calculate an updated ephemeris which corrects for an anomalous time measurement in the previously published ephemeris.

  17. ENSO effects on MLT diurnal tides: A 21 year reanalysis data-driven GAIA model simulation

    NASA Astrophysics Data System (ADS)

    Liu, Huixin; Sun, Yang-Yi; Miyoshi, Yasunobu; Jin, Hidekatsu

    2017-05-01

    Tidal responses to El Niño-Southern Oscillation (ENSO) in the mesosphere and lower thermosphere (MLT) are investigated for the first time using reanalysis data-driven simulations covering 21 years. The simulation is carried out with the Ground-to-topside Atmosphere-Ionosphere model for Aeronomy (GAIA) during 1996-2016, which covers nine ENSO events. ENSO impacts on diurnal tides at 100 km altitude are analyzed and cross-compared among temperature (T), zonal wind (U), and meridional wind (V), which reveals the following salient features: (1) Tidal response can differ significantly among T, U, and V in terms of magnitude and latitudinal structure, making detection of ENSO effects sensitive to the parameter used and the location of a ground station; (2) the nonmigrating DE3 tide in T and U shows a prominent hemisphere asymmetric response to La Niña, with an increase between 0° and 30°N and a decrease between 30° and 0°S. In contrast, DE3 in V exhibits no significant response; (3) the migrating DW1 enhances during El Niño in equatorial regions for T and U but in off-equatorial regions for V. As the first ENSO study based on reanalysis-driven simulations, GAIA's full set of tidal responses in T, U, and V provides us with a necessary global context to better understand and cross-compare observations during ENSO events. Comparisons with observations during the 1997-98 El Niño and 2010-11 La Niña reveal good agreement in both magnitude and timing. Comparisons with "free-run" WACCM simulations (T) show consistent results in nonmigrating tides DE2 and DE3 but differences in the migrating DW1 tide.

  18. Darwinizing Gaia.

    PubMed

    Doolittle, W Ford

    2017-12-07

    The Gaia hypothesis of James Lovelock was co-developed with and vigorously promoted by Lynn Margulis, but most mainstream Darwinists scorned and still do not accept the notion. They cannot imagine selection for global stability being realized at the level of the individuals or species that make up the biosphere. Here I suggest that we look at the biogeochemical cycles and other homeostatic processes that might confer stability - rather than the taxa (mostly microbial) that implement them - as the relevant units of selection. By thus focusing our attentions on the "song", not the "singers", a Darwinized Gaia might be developed. Our understanding of evolution by natural selection would however need to be stretched to accommodate differential persistence as well as differential reproduction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. The Magnetar Model of the Superluminous Supernova GAIA16apd and the Explosion Jet Feedback Mechanism

    SciTech Connect

    Soker, Noam, E-mail: soker@physics.technion.ac.il

    Under the assumption that jets explode core collapse supernovae (CCSNe) in a negative jet feedback mechanism (JFM), this paper shows that rapidly rotating neutron stars are likely to be formed when the explosion is very energetic. Under the assumption that an accretion disk or an accretion belt around the just-formed neutron star launch jets and that the accreted gas spins-up the just-formed neutron star, I derive a crude relation between the energy that is stored in the spinning neutron star and the explosion energy. This relation is ( E {sub NS-spin}/ E {sub exp}) ≈ E {sub exp}/10{sup 52} erg;more » It shows that within the frame of the JFM explosion model of CCSNe, spinning neutron stars, such as magnetars, might have significant energy in super-energetic explosions. The existence of magnetars, if confirmed, such as in the recent super-energetic supernova GAIA16apd, further supports the call for a paradigm shift from neutrino-driven to jet-driven CCSN mechanisms.« less

  20. The Magnetar Model of the Superluminous Supernova GAIA16apd and the Explosion Jet Feedback Mechanism

    NASA Astrophysics Data System (ADS)

    Soker, Noam

    2017-04-01

    Under the assumption that jets explode core collapse supernovae (CCSNe) in a negative jet feedback mechanism (JFM), this paper shows that rapidly rotating neutron stars are likely to be formed when the explosion is very energetic. Under the assumption that an accretion disk or an accretion belt around the just-formed neutron star launch jets and that the accreted gas spins-up the just-formed neutron star, I derive a crude relation between the energy that is stored in the spinning neutron star and the explosion energy. This relation is (E NS-spin/E exp) ≈ E exp/1052 erg; It shows that within the frame of the JFM explosion model of CCSNe, spinning neutron stars, such as magnetars, might have significant energy in super-energetic explosions. The existence of magnetars, if confirmed, such as in the recent super-energetic supernova GAIA16apd, further supports the call for a paradigm shift from neutrino-driven to jet-driven CCSN mechanisms.

  1. GAIA - a generalizable, extensible structure for integrating games, models and social networking to support decision makers

    NASA Astrophysics Data System (ADS)

    Paxton, L. J.; Schaefer, R. K.; Nix, M.; Fountain, G. H.; Weiss, M.; Swartz, W. H.; Parker, C. L.; MacDonald, L.; Ihde, A. G.; Simpkins, S.; GAIA Team

    2011-12-01

    In this paper we describe the application of a proven methodology for modeling the complex social and economic interactions embodied in real-world decision making to water scarcity and water resources. We have developed a generalizable, extensible facility we call "GAIA" - Global Assimilation of Information for Action - and applied it to different problem sets. We describe the use of the "Green Country Model" and other gaming/simulation tools to address the impacts of climate and climate disruption issues at the intersection of science, economics, policy, and society. There is a long history in the Defense community of using what are known as strategic simulations or "wargames" to model the complex interactions between the environment, people, resources, infrastructure and the economy in a competitive environment. We describe in this paper, work that we have done on understanding how this heritage can be repurposed to help us explore how the complex interplay between climate disruption and our socio/political and economic structures will affect our future. Our focus here is on a fundamental and growing issue - water and water availability. We consider water and the role of "virtual water" in the system. Various "actors" are included in the simulations. While these simulations cannot definitively predict what will happen, they do illuminate non-linear feedbacks between, for example, treaty agreement, the environment, the economy, and the government. These simulations can be focused on the global, regional, or local environment. We note that these simulations are not "zero sum" games - there need not be a winner and a loser. They are, however, competitive influence games: they represent the tools that a nation, state, faction or group has at its disposal to influence policy (diplomacy), finances, industry (economy), infrastructure, information, etc to achieve their particular goals. As in the real world the problem is competitive - not everyone shares the same

  2. The Gaia mission status

    NASA Astrophysics Data System (ADS)

    Prusti, T.

    2018-04-01

    Gaia is an ESA cornerstone mission conducting a full sky survey over its 5 year operational period. Gaia performs astrometric, photometric and spectroscopic measurements. The data processing is entrusted to scientists and engineers who have formed the Gaia Data Processing and Analysis Consortium (DPAC). The photometric science alerts started in 2014. The first intermediate data release (Gaia DR1) took place 14 September 2016 and it has been extensively used by the community. Gaia DR2 is scheduled for April 2018. Gaia is expected to be able to continue observations roughly for another 5 years after the nominal phase. The procedure to grant funding for the extension period has been initiated. In case funding is granted, the total operational time of Gaia may be 10 years.

  3. Thermography During Thermal Test of the Gaia Deployable Sunshield Assembly Qualification Model in the ESTEC Large Space Simulator

    NASA Astrophysics Data System (ADS)

    Simpson, R.; Broussely, M.; Edwards, G.; Robinson, D.; Cozzani, A.; Casarosa, G.

    2012-07-01

    The National Physical Laboratory (NPL) and The European Space Research and Technology Centre (ESTEC) have performed for the first time successful surface temperature measurements using infrared thermal imaging in the ESTEC Large Space Simulator (LSS) under vacuum and with the Sun Simulator (SUSI) switched on during thermal qualification tests of the GAIA Deployable Sunshield Assembly (DSA). The thermal imager temperature measurements, with radiosity model corrections, show good agreement with thermocouple readings on well characterised regions of the spacecraft. In addition, the thermal imaging measurements identified potentially misleading thermocouple temperature readings and provided qualitative real-time observations of the thermal and spatial evolution of surface structure changes and heat dissipation during hot test loadings, which may yield additional thermal and physical measurement information through further research.

  4. The Gaia mission

    NASA Astrophysics Data System (ADS)

    Gaia Collaboration; Prusti, T.; de Bruijne, J. H. J.; Brown, A. G. A.; Vallenari, A.; Babusiaux, C.; Bailer-Jones, C. A. L.; Bastian, U.; Biermann, M.; Evans, D. W.; Eyer, L.; Jansen, F.; Jordi, C.; Klioner, S. A.; Lammers, U.; Lindegren, L.; Luri, X.; Mignard, F.; Milligan, D. J.; Panem, C.; Poinsignon, V.; Pourbaix, D.; Randich, S.; Sarri, G.; Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette, V.; van Leeuwen, F.; Walton, N. A.; Aerts, C.; Arenou, F.; Cropper, M.; Drimmel, R.; Høg, E.; Katz, D.; Lattanzi, M. G.; O'Mullane, W.; Grebel, E. K.; Holland, A. D.; Huc, C.; Passot, X.; Bramante, L.; Cacciari, C.; Castañeda, J.; Chaoul, L.; Cheek, N.; De Angeli, F.; Fabricius, C.; Guerra, R.; Hernández, J.; Jean-Antoine-Piccolo, A.; Masana, E.; Messineo, R.; Mowlavi, N.; Nienartowicz, K.; Ordóñez-Blanco, D.; Panuzzo, P.; Portell, J.; Richards, P. J.; Riello, M.; Seabroke, G. M.; Tanga, P.; Thévenin, F.; Torra, J.; Els, S. G.; Gracia-Abril, G.; Comoretto, G.; Garcia-Reinaldos, M.; Lock, T.; Mercier, E.; Altmann, M.; Andrae, R.; Astraatmadja, T. L.; Bellas-Velidis, I.; Benson, K.; Berthier, J.; Blomme, R.; Busso, G.; Carry, B.; Cellino, A.; Clementini, G.; Cowell, S.; Creevey, O.; Cuypers, J.; Davidson, M.; De Ridder, J.; de Torres, A.; Delchambre, L.; Dell'Oro, A.; Ducourant, C.; Frémat, Y.; García-Torres, M.; Gosset, E.; Halbwachs, J.-L.; Hambly, N. C.; Harrison, D. L.; Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle, H. E.; Hutton, A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn, A. J.; Lanzafame, A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.; Osinde, J.; Pancino, E.; Pauwels, T.; Petit, J.-M.; Recio-Blanco, A.; Robin, A. C.; Sarro, L. M.; Siopis, C.; Smith, M.; Smith, K. W.; Sozzetti, A.; Thuillot, W.; van Reeven, W.; Viala, Y.; Abbas, U.; Abreu Aramburu, A.; Accart, S.; Aguado, J. J.; Allan, P. M.; Allasia, W.; Altavilla, G.; Álvarez, M. A.; Alves, J.; Anderson, R. I.; Andrei, A. H.; Anglada Varela, E.; Antiche, E.; Antoja, T.; Antón, S.; Arcay, B.; Atzei, A.; Ayache, L.; Bach, N.; Baker, S. G.; Balaguer-Núñez, L.; Barache, C.; Barata, C.; Barbier, A.; Barblan, F.; Baroni, M.; Barrado y Navascués, D.; Barros, M.; Barstow, M. A.; Becciani, U.; Bellazzini, M.; Bellei, G.; Bello García, A.; Belokurov, V.; Bendjoya, P.; Berihuete, A.; Bianchi, L.; Bienaymé, O.; Billebaud, F.; Blagorodnova, N.; Blanco-Cuaresma, S.; Boch, T.; Bombrun, A.; Borrachero, R.; Bouquillon, S.; Bourda, G.; Bouy, H.; Bragaglia, A.; Breddels, M. A.; Brouillet, N.; Brüsemeister, T.; Bucciarelli, B.; Budnik, F.; Burgess, P.; Burgon, R.; Burlacu, A.; Busonero, D.; Buzzi, R.; Caffau, E.; Cambras, J.; Campbell, H.; Cancelliere, R.; Cantat-Gaudin, T.; Carlucci, T.; Carrasco, J. M.; Castellani, M.; Charlot, P.; Charnas, J.; Charvet, P.; Chassat, F.; Chiavassa, A.; Clotet, M.; Cocozza, G.; Collins, R. S.; Collins, P.; Costigan, G.; Crifo, F.; Cross, N. J. G.; Crosta, M.; Crowley, C.; Dafonte, C.; Damerdji, Y.; Dapergolas, A.; David, P.; David, M.; De Cat, P.; de Felice, F.; de Laverny, P.; De Luise, F.; De March, R.; de Martino, D.; de Souza, R.; Debosscher, J.; del Pozo, E.; Delbo, M.; Delgado, A.; Delgado, H. E.; di Marco, F.; Di Matteo, P.; Diakite, S.; Distefano, E.; Dolding, C.; Dos Anjos, S.; Drazinos, P.; Durán, J.; Dzigan, Y.; Ecale, E.; Edvardsson, B.; Enke, H.; Erdmann, M.; Escolar, D.; Espina, M.; Evans, N. W.; Eynard Bontemps, G.; Fabre, C.; Fabrizio, M.; Faigler, S.; Falcão, A. J.; Farràs Casas, M.; Faye, F.; Federici, L.; Fedorets, G.; Fernández-Hernández, J.; Fernique, P.; Fienga, A.; Figueras, F.; Filippi, F.; Findeisen, K.; Fonti, A.; Fouesneau, M.; Fraile, E.; Fraser, M.; Fuchs, J.; Furnell, R.; Gai, M.; Galleti, S.; Galluccio, L.; Garabato, D.; García-Sedano, F.; Garé, P.; Garofalo, A.; Garralda, N.; Gavras, P.; Gerssen, J.; Geyer, R.; Gilmore, G.; Girona, S.; Giuffrida, G.; Gomes, M.; González-Marcos, A.; González-Núñez, J.; González-Vidal, J. J.; Granvik, M.; Guerrier, A.; Guillout, P.; Guiraud, J.; Gúrpide, A.; Gutiérrez-Sánchez, R.; Guy, L. P.; Haigron, R.; Hatzidimitriou, D.; Haywood, M.; Heiter, U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.; Holland, G.; Hunt, J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat de Fombelle, G.; Jofré, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.; Karampelas, A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas, E.; Koposov, S. E.; Kordopatis, G.; Koubsky, P.; Kowalczyk, A.; Krone-Martins, A.; Kudryashova, M.; Kull, I.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza, A. F.; Lavigne, J.-B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter, T.; Leccia, S.; Leclerc, N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt, H.; Leroux, F.; Liao, S.; Licata, E.; Lindstrøm, H. E. P.; Lister, T. A.; Livanou, E.; Lobel, A.; Löffler, W.; López, M.; Lopez-Lozano, A.; Lorenz, D.; Loureiro, T.; MacDonald, I.; Magalhães Fernandes, T.; Managau, S.; Mann, R. G.; Mantelet, G.; Marchal, O.; Marchant, J. M.; Marconi, M.; Marie, J.; Marinoni, S.; Marrese, P. M.; Marschalkó, G.; Marshall, D. J.; Martín-Fleitas, J. M.; Martino, M.; Mary, N.; Matijevič, G.; Mazeh, T.; McMillan, P. J.; Messina, S.; Mestre, A.; Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina, D.; Molinaro, R.; Molinaro, M.; Molnár, L.; Moniez, M.; Montegriffo, P.; Monteiro, D.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.; Morley, T.; Morris, D.; Mulone, A. F.; Muraveva, T.; Musella, I.; Narbonne, J.; Nelemans, G.; Nicastro, L.; Noval, L.; Ordénovic, C.; Ordieres-Meré, J.; Osborne, P.; Pagani, C.; Pagano, I.; Pailler, F.; Palacin, H.; Palaversa, L.; Parsons, P.; Paulsen, T.; Pecoraro, M.; Pedrosa, R.; Pentikäinen, H.; Pereira, J.; Pichon, B.; Piersimoni, A. M.; Pineau, F.-X.; Plachy, E.; Plum, G.; Poujoulet, E.; Prša, A.; Pulone, L.; Ragaini, S.; Rago, S.; Rambaux, N.; Ramos-Lerate, M.; Ranalli, P.; Rauw, G.; Read, A.; Regibo, S.; Renk, F.; Reylé, C.; Ribeiro, R. A.; Rimoldini, L.; Ripepi, V.; Riva, A.; Rixon, G.; Roelens, M.; Romero-Gómez, M.; Rowell, N.; Royer, F.; Rudolph, A.; Ruiz-Dern, L.; Sadowski, G.; Sagristà Sellés, T.; Sahlmann, J.; Salgado, J.; Salguero, E.; Sarasso, M.; Savietto, H.; Schnorhk, A.; Schultheis, M.; Sciacca, E.; Segol, M.; Segovia, J. C.; Segransan, D.; Serpell, E.; Shih, I.-C.; Smareglia, R.; Smart, R. L.; Smith, C.; Solano, E.; Solitro, F.; Sordo, R.; Soria Nieto, S.; Souchay, J.; Spagna, A.; Spoto, F.; Stampa, U.; Steele, I. A.; Steidelmüller, H.; Stephenson, C. A.; Stoev, H.; Suess, F. F.; Süveges, M.; Surdej, J.; Szabados, L.; Szegedi-Elek, E.; Tapiador, D.; Taris, F.; Tauran, G.; Taylor, M. B.; Teixeira, R.; Terrett, D.; Tingley, B.; Trager, S. C.; Turon, C.; Ulla, A.; Utrilla, E.; Valentini, G.; van Elteren, A.; Van Hemelryck, E.; van Leeuwen, M.; Varadi, M.; Vecchiato, A.; Veljanoski, J.; Via, T.; Vicente, D.; Vogt, S.; Voss, H.; Votruba, V.; Voutsinas, S.; Walmsley, G.; Weiler, M.; Weingrill, K.; Werner, D.; Wevers, T.; Whitehead, G.; Wyrzykowski, Ł.; Yoldas, A.; Žerjal, M.; Zucker, S.; Zurbach, C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende Prieto, C.; Amorim, A.; Anglada-Escudé, G.; Arsenijevic, V.; Azaz, S.; Balm, P.; Beck, M.; Bernstein, H.-H.; Bigot, L.; Bijaoui, A.; Blasco, C.; Bonfigli, M.; Bono, G.; Boudreault, S.; Bressan, A.; Brown, S.; Brunet, P.-M.; Bunclark, P.; Buonanno, R.; Butkevich, A. G.; Carret, C.; Carrion, C.; Chemin, L.; Chéreau, F.; Corcione, L.; Darmigny, E.; de Boer, K. S.; de Teodoro, P.; de Zeeuw, P. T.; Delle Luche, C.; Domingues, C. D.; Dubath, P.; Fodor, F.; Frézouls, B.; Fries, A.; Fustes, D.; Fyfe, D.; Gallardo, E.; Gallegos, J.; Gardiol, D.; Gebran, M.; Gomboc, A.; Gómez, A.; Grux, E.; Gueguen, A.; Heyrovsky, A.; Hoar, J.; Iannicola, G.; Isasi Parache, Y.; Janotto, A.-M.; Joliet, E.; Jonckheere, A.; Keil, R.; Kim, D.-W.; Klagyivik, P.; Klar, J.; Knude, J.; Kochukhov, O.; Kolka, I.; Kos, J.; Kutka, A.; Lainey, V.; LeBouquin, D.; Liu, C.; Loreggia, D.; Makarov, V. V.; Marseille, M. G.; Martayan, C.; Martinez-Rubi, O.; Massart, B.; Meynadier, F.; Mignot, S.; Munari, U.; Nguyen, A.-T.; Nordlander, T.; Ocvirk, P.; O'Flaherty, K. S.; Olias Sanz, A.; Ortiz, P.; Osorio, J.; Oszkiewicz, D.; Ouzounis, A.; Palmer, M.; Park, P.; Pasquato, E.; Peltzer, C.; Peralta, J.; Péturaud, F.; Pieniluoma, T.; Pigozzi, E.; Poels, J.; Prat, G.; Prod'homme, T.; Raison, F.; Rebordao, J. M.; Risquez, D.; Rocca-Volmerange, B.; Rosen, S.; Ruiz-Fuertes, M. I.; Russo, F.; Sembay, S.; Serraller Vizcaino, I.; Short, A.; Siebert, A.; Silva, H.; Sinachopoulos, D.; Slezak, E.; Soffel, M.; Sosnowska, D.; Straižys, V.; ter Linden, M.; Terrell, D.; Theil, S.; Tiede, C.; Troisi, L.; Tsalmantza, P.; Tur, D.; Vaccari, M.; Vachier, F.; Valles, P.; Van Hamme, W.; Veltz, L.; Virtanen, J.; Wallut, J.-M.; Wichmann, R.; Wilkinson, M. I.; Ziaeepour, H.; Zschocke, S.

    2016-11-01

    Gaia is a cornerstone mission in the science programme of the EuropeanSpace Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page. http://www.cosmos.esa.int/gaia

  5. Stellar clusters in the Gaia era

    NASA Astrophysics Data System (ADS)

    Bragaglia, Angela

    2018-04-01

    Stellar clusters are important for astrophysics in many ways, for instance as optimal tracers of the Galactic populations to which they belong or as one of the best test bench for stellar evolutionary models. Gaia DR1, with TGAS, is just skimming the wealth of exquisite information we are expecting from the more advanced catalogues, but already offers good opportunities and indicates the vast potentialities. Gaia results can be efficiently complemented by ground-based data, in particular by large spectroscopic and photometric surveys. Examples of some scientific results of the Gaia-ESO survey are presented, as a teaser for what will be possible once advanced Gaia releases and ground-based data will be combined.

  6. VizieR Online Data Catalog: Gaia photometry for white dwarfs (Carrasco+, 2014)

    NASA Astrophysics Data System (ADS)

    Carrasco, J. M.; Catalan, S.; Jordi, C.; Tremblay, P.-E.; Napiwotzki, R.; Luri, X.; Robin, A. C.; Kowalski, P. M.

    2014-03-01

    The Gaia space mission, through its 5-6 years survey of the whole sky up to magnitude V=20-25, will drastically increase the sample of known white dwarfs allowing to address new science questions. In this paper we provide a characterisation of Gaia photometry for the case of white dwarfs to better prepare for the analysis of the scientific output of the mission including relationships among colours involving Gaia magnitudes (white light G, blue GBP, red GRP and GRVS passbands) and colours from other commonly used photometric systems (Johnson-Cousins, SDSS and 2MASS). We also present numbers of white dwarfs predicted by the Gaia Universe Model Snapshot and compare them with an alternative simulation calibrated with the local white dwarfs sample. In these online tables we provide the values used to fit the relationships in the paper, especially useful for those cases where the deviation from the established relationships is large. The most recent Gaia transmission curves and three different compositions for white dwarfs were considered here (pure hydrogen, pure helium and mixed composition with H/He=0.1). (3 data files).

  7. Global response of the ionosphere to atmospheric tides forced from below: Comparison between COSMIC measurements and simulations by atmosphere-ionosphere coupled model GAIA

    NASA Astrophysics Data System (ADS)

    Pancheva, D.; Miyoshi, Y.; Mukhtarov, P.; Jin, H.; Shinagawa, H.; Fujiwara, H.

    2012-07-01

    This paper for the first time presents a detailed comparison between simulated and observed global electron density responses to different atmospheric tides forced from below. The recently developed Earth's whole atmospheric model from the troposphere to the ionosphere, called GAIA, has been used for the simulation of the electron density tidal responses. They have been compared with the extracted from the COSMIC electron density data tidal responses for the period of time October 2007 to March 2009. Particular attention has been paid to the nonmigrating DE3/DE2 and migrating DW1, SW2 and TW3 electron density responses. The GAIA model reproduced quite well the COSMIC DE3/DE2 responses. Both simulations and observations revealed three altitude regions of enhanced electron density responses: (1) an upper level response, above 300 km height, apparently shaped mainly by the “fountain effect” (2) a response located near altitudes of ˜200-270 km, and (3) a lower thermospheric response situated near 120-150 km height. A possible mechanism is suggested for explaining the two lower level responses. For the first time the GAIA model simulations supported the observational evidence found in the COSMIC measurements that the ionospheric WN4 (WN3) longitude structure is not generated only by the DE3 (DE2) tide as it has been often assumed. As regards the comparison of the migrating DW1, SW2 and TW3 responses the obtained results clearly demonstrate that the GAIA model reproduce very well of the SW2 and TW3 COSMIC electron density responses. The only main discrepancy is seen in the migrating DW1 response; the observation does not support the splitting of the simulated response at both sides of the equator. This is due mainly to the difference between the SABER and GAIA SW2 tide in the lower thermosphere as it turned out that the DW1 electron density response strongly depends on the mean features of the lower thermospheric SW2 tide.

  8. GAIA virtual observatory - development and practices

    NASA Astrophysics Data System (ADS)

    Syrjäsuo, Mikko; Marple, Steve

    2010-05-01

    The Global Auroral Imaging Access, or GAIA, is a virtual observatory providing quick access to summary data from satellite and ground-based instruments that remote sense auroral precipitation (http://gaia-vxo.org). This web-based service facilitates locating data relevant to particular events by simultaneously displaying summary images from various data sets around the world. At the moment, there are GAIA server nodes in Canada, Finland, Norway and the UK. The development is an international effort and the software and metadata are freely available. The GAIA system is based on a relational database which is queried by a dedicated software suite that also creates the graphical end-user interface if such is needed. Most commonly, the virtual observatory is used interactively by using a web browser: the user provides the date and the type of data of interest. As the summary data from multiple instruments are displayed simultaneously, the user can conveniently explore the recorded data. The virtual observatory provides essentially instant access to the images originating from all major auroral instrument networks including THEMIS, NORSTAR, GLORIA and MIRACLE. The scientific, educational and outreach use is limited by creativity rather than access. The first version of the GAIA was developed at the University of Calgary (Alberta, Canada) in 2004-2005. This proof-of-concept included mainly THEMIS and MIRACLE data, which comprised of millions of summary plots and thumbnail images. However, it was soon realised that a complete re-design was necessary to increase flexibility. In the presentation, we will discuss the early history and motivation of GAIA as well as how the development continued towards the current version. The emphasis will be on practical problems and their solutions. Relevant design choices will also be highlighted.

  9. Overall properties of the Gaia DR1 reference frame

    NASA Astrophysics Data System (ADS)

    Liu, N.; Zhu, Z.; Liu, J.-C.; Ding, C.-Y.

    2017-03-01

    Aims: The first Gaia data release (Gaia DR1) provides 2191 ICRF2 sources with their positions in the auxiliary quasar solution and five astrometric parameters - positions, parallaxes, and proper motions - for stars in common between the Tycho-2 catalogue and Gaia in the joint Tycho-Gaia astrometric solution (TGAS). We aim to analyze the overall properties of Gaia DR1 reference frame. Methods: We compare quasar positions of the auxiliary quasar solution with ICRF2 sources using different samples and evaluate the influence on the Gaia DR1 reference frame owing to the Galactic aberration effect over the J2000.0-J2015.0 period. Then we estimate the global rotation between TGAS with Tycho-2 proper motion systems to investigate the property of the Gaia DR1 reference frame. Finally, the Galactic kinematics analysis using the K-M giant proper motions is performed to understand the property of Gaia DR1 reference frame. Results: The positional comparison between the auxiliary quasar solution and ICRF2 shows negligible orientation and validates the declination bias of -0.1mas in Gaia quasar positions with respect to ICRF2. Galactic aberration effect is thought to cause an offset 0.01mas of the Z axis direction of Gaia DR1 reference frame. The global rotation between TGAS and Tycho-2 proper motion systems, obtained by different samples, shows a much smaller value than the claimed value 0.24mas yr-1. For the Galactic kinematics analysis of the TGAS K-M giants, we find possible non-zero Galactic rotation components beyond the classical Oort constants: the rigid part ωYG = -0.38±0.15mas yr-1 and the differential part ω^primeYG = -0.29±0.19mas yr-1 around the YG axis of Galactic coordinates, which indicates possible residual rotation in Gaia DR1 reference frame or problems in the current Galactic kinematical model. Conclusions: The Gaia DR1 reference frame is well aligned to ICRF2, and the possible influence of the Galactic aberration effect should be taken into consideration

  10. The Gaia-ESO Survey: Separating disk chemical substructures with cluster models. Evidence of a separate evolution in the metal-poor thin disk

    NASA Astrophysics Data System (ADS)

    Rojas-Arriagada, A.; Recio-Blanco, A.; de Laverny, P.; Schultheis, M.; Guiglion, G.; Mikolaitis, Š.; Kordopatis, G.; Hill, V.; Gilmore, G.; Randich, S.; Alfaro, E. J.; Bensby, T.; Koposov, S. E.; Costado, M. T.; Franciosini, E.; Hourihane, A.; Jofré, P.; Lardo, C.; Lewis, J.; Lind, K.; Magrini, L.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Worley, C. C.; Zaggia, S.; Chiappini, C.

    2016-02-01

    Context. Recent spectroscopic surveys have begun to explore the Galactic disk system on the basis of large data samples, with spatial distributions sampling regions well outside the solar neighborhood. In this way, they provide valuable information for testing spatial and temporal variations of disk structure kinematics and chemical evolution. Aims: The main purposes of this study are to demonstrate the usefulness of a rigorous mathematical approach to separate substructures of a stellar sample in the abundance-metallicity plane, and provide new evidence with which to characterize the nature of the metal-poor end of the thin disk sequence. Methods: We used a Gaussian mixture model algorithm to separate in the [Mg/Fe] vs. [Fe/H] plane a clean disk star subsample (essentially at RGC< 10 kpc) from the Gaia-ESO survey (GES) internal data release 2 (iDR2). We aim at decomposing it into data groups highlighting number density and/or slope variations in the abundance-metallicity plane. An independent sample of disk red clump stars from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) was used to cross-check the identified features. Results: We find that the sample is separated into five groups associated with major Galactic components; the metal-rich end of the halo, the thick disk, and three subgroups for the thin disk sequence. This is confirmed with the sample of red clump stars from APOGEE. The three thin disk groups served to explore this sequence in more detail. The two metal-intermediate and metal-rich groups of the thin disk decomposition ([Fe/H] > -0.25 dex) highlight a change in the slope at solar metallicity. This holds true at different radial regions of the Milky Way. The distribution of Galactocentric radial distances of the metal-poor part of the thin disk ([Fe/H] < -0.25 dex) is shifted to larger distances than those of the more metal-rich parts. Moreover, the metal-poor part of the thin disk presents indications of a scale height

  11. Gaia DR2 documentation Chapter 1: Introduction

    NASA Astrophysics Data System (ADS)

    de Bruijne, J. H. J.; Abreu, A.; Brown, A. G. A.; Castañeda, J.; Cheek, N.; Crowley, C.; De Angeli, F.; Drimmel, R.; Fabricius, C.; Fleitas, J.; Gracia-Abril, G.; Guerra, R.; Hutton, A.; Messineo, R.; Mora, A.; Nienartowicz, K.; Panem, C.; Siddiqui, H.

    2018-04-01

    This chapter of the Gaia DR2 documentation describes the Gaia mission, the Gaia spacecraft, and the organisation of the Gaia Data Processing and Analysis Consortium (DPAC), which is responsible for the processing and analysis of the Gaia data. Furthermore, various properties of the data release are summarised, including statistical properties, object statistics, completeness, selection and filtering criteria, and limitations of the data.

  12. New statements on the Gaia theory.

    PubMed

    Lovelock, J E

    1995-09-01

    Gaia is the name the ancient Greeks gave to their goddess of the Earth and is the root of words like geography and geology. Gaia is also a straightforward scientific theory about the Earth and the organisms that inhabit it. Gaia theory is testable and has a proper mathematical basis in a set of closely coupled differential equations. We do not yet know if it is a good explanation of the way our planet works; the evidence is only partially gathered. Its main value at this stage is to provide a different way to look at the Earth. In science, Gaia theory has already led to significant discoveries but just as important it forces us to question whether the good of humankind is the only thing that matters. The true value of the journeys into space was to reveal the Earth as a live planet. They made us realise for the first time that humanism is not enough. The view from space teaches that we are part of a greater entity, the Earth, and that our survival and its good health are inextricably entwined. Perhaps in time we can expand our view to encompass the larger systems of the galaxy and the Universe. Now the Earth needs our full attention.

  13. VizieR Online Data Catalog: Parameters and IR excesses of Gaia DR1 stars (McDonald+, 2017)

    NASA Astrophysics Data System (ADS)

    McDonald, I.; Zijlstra, A. A.; Watson, R. A.

    2017-08-01

    Spectral energy distribution fits are presented for stars from the Tycho-Gaia Astrometric Solution (TGAS) from Gaia Data Release 1. Hipparcos-Gaia stars are presented in a separate table. Effective temperatures, bolometric luminosities, and infrared excesses are presented (alongside other parameters pertinent to the model fits), plus the source photometry used. (3 data files).

  14. Astrometric exoplanet detection with Gaia

    SciTech Connect

    Perryman, Michael; Hartman, Joel; Bakos, Gáspár Á.

    2014-12-10

    We provide a revised assessment of the number of exoplanets that should be discovered by Gaia astrometry, extending previous studies to a broader range of spectral types, distances, and magnitudes. Our assessment is based on a large representative sample of host stars from the TRILEGAL Galaxy population synthesis model, recent estimates of the exoplanet frequency distributions as a function of stellar type, and detailed simulation of the Gaia observations using the updated instrument performance and scanning law. We use two approaches to estimate detectable planetary systems: one based on the signal-to-noise ratio of the astrometric signature per field crossing, easilymore » reproducible and allowing comparisons with previous estimates, and a new and more robust metric based on orbit fitting to the simulated satellite data. With some plausible assumptions on planet occurrences, we find that some 21,000 (±6000) high-mass (∼1-15M {sub J}) long-period planets should be discovered out to distances of ∼500 pc for the nominal 5 yr mission (including at least 1000-1500 around M dwarfs out to 100 pc), rising to some 70,000 (±20, 000) for a 10 yr mission. We indicate some of the expected features of this exoplanet population, amongst them ∼25-50 intermediate-period (P ∼ 2-3 yr) transiting systems.« less

  15. The Gaia-ESO Survey: dynamical models of flattened, rotating globular clusters

    NASA Astrophysics Data System (ADS)

    Jeffreson, S. M. R.; Sanders, J. L.; Evans, N. W.; Williams, A. A.; Gilmore, G. F.; Bayo, A.; Bragaglia, A.; Casey, A. R.; Flaccomio, E.; Franciosini, E.; Hourihane, A.; Jackson, R. J.; Jeffries, R. D.; Jofré, P.; Koposov, S.; Lardo, C.; Lewis, J.; Magrini, L.; Morbidelli, L.; Pancino, E.; Randich, S.; Sacco, G. G.; Worley, C. C.; Zaggia, S.

    2017-08-01

    We present a family of self-consistent axisymmetric rotating globular cluster models which are fitted to spectroscopic data for NGC 362, NGC 1851, NGC 2808, NGC 4372, NGC 5927 and NGC 6752 to provide constraints on their physical and kinematic properties, including their rotation signals. They are constructed by flattening Modified Plummer profiles, which have the same asymptotic behaviour as classical Plummer models, but can provide better fits to young clusters due to a slower turnover in the density profile. The models are in dynamical equilibrium as they depend solely on the action variables. We employ a fully Bayesian scheme to investigate the uncertainty in our model parameters (including mass-to-light ratios and inclination angles) and evaluate the Bayesian evidence ratio for rotating to non-rotating models. We find convincing levels of rotation only in NGC 2808. In the other clusters, there is just a hint of rotation (in particular, NGC 4372 and NGC 5927), as the data quality does not allow us to draw strong conclusions. Where rotation is present, we find that it is confined to the central regions, within radii of R ≤ 2rh. As part of this work, we have developed a novel q-Gaussian basis expansion of the line-of-sight velocity distributions, from which general models can be constructed via interpolation on the basis coefficients.

  16. From Hipparcos to Gaia

    NASA Astrophysics Data System (ADS)

    Eyer, L.; Dubath, P.; Saesen, S.; Evans, D. W.; Wyrzykowski, L.; Hodgkin, S.; Mowlavi, N.

    2012-04-01

    The measurement of the positions, distances, motions and luminosities of stars represents the foundations of modern astronomical knowledge. Launched at the end of the eighties, the ESA Hipparcos satellite was the first space mission dedicated to such measurements. Hipparcos improved position accuracies by a factor of 100 compared to typical ground-based results and provided astrometric and photometric multi-epoch observations of 118,000 stars over the entire sky. The impact of Hipparcos on astrophysics has been extremely valuable and diverse. Building on this important European success, the ESA Gaia cornerstone mission promises an even more impressive advance. Compared to Hipparcos, it will bring a gain of a factor 50 to 100 in position accuracy and of a factor of 10,000 in star number, collecting photometric, spectrophotometric and spectroscopic data for one billion celestial objects. During its 5-year flight, Gaia will measure objects repeatedly, up to a few hundred times, providing an unprecedented database to study the variability of all types of celestial objects. Gaia will bring outstanding contributions, directly or indirectly, to most fields of research in astrophysics, such as the study of our Galaxy and of its stellar constituents, and the search for planets outside the solar system.

  17. Application of time transfer functions to Gaia's global astrometry. Validation on DPAC simulated Gaia-like observations

    NASA Astrophysics Data System (ADS)

    Bertone, Stefano; Vecchiato, Alberto; Bucciarelli, Beatrice; Crosta, Mariateresa; Lattanzi, Mario G.; Bianchi, Luca; Angonin, Marie-Christine; Le Poncin-Lafitte, Christophe

    2017-12-01

    Context. A key objective of the ESA Gaia satellite is the realization of a quasi-inertial reference frame at visual wavelengths by means of global astrometric techniques. This requires accurate mathematical and numerical modeling of relativistic light propagation, as well as double-blind-like procedures for the internal validation of the results, before they are released to the scientific community at large. Aims: We aim to specialize the time transfer functions (TTF) formalism to the case of the Gaia observer and prove its applicability to the task of global sphere reconstruction (GSR), in anticipation of its inclusion in the GSR system, already featuring the Relativistic Astrometric MODel (RAMOD) suite, as an additional semi-external validation of the forthcoming Gaia baseline astrometric solutions. Methods: We extended the current GSR framework and software infrastructure (GSR2) to include TTF relativistic observation equations compatible with Gaia's operations. We used simulated data generated by the Gaia Data Processing and Analysis Consortium (DPAC) to obtain different least-squares estimations of the full (five-parameter) stellar spheres and gauge results. These were compared to analogous solutions obtained with the current RAMOD model in GSR2 (RAMOD@GSR2) and to the catalog generated with the Gaia RElativistic Model (GREM), the model baselined for Gaia and used to generate the DPAC synthetic data. Results: Linearized least-squares TTF solutions are based on spheres of about 132 000 primary stars uniformly distributed on the sky and simulated observations spanning the entire 5 yr range of Gaia's nominal operational lifetime. The statistical properties of the results compare well with those of GREM. Finally, comparisons to RAMOD@GSR2 solutions confirmed the known lower accuracy of that model and allowed us to establish firm limits on the quality of the linearization point outside of which an iteration for non-linearity is required for its proper convergence

  18. Gaia DR2 documentation Chapter 3: Astrometry

    NASA Astrophysics Data System (ADS)

    Hobbs, D.; Lindegren, L.; Bastian, U.; Klioner, S.; Butkevich, A.; Stephenson, C.; Hernandez, J.; Lammers, U.; Bombrun, A.; Mignard, F.; Altmann, M.; Davidson, M.; de Bruijne, J. H. J.; Fernández-Hernández, J.; Siddiqui, H.; Utrilla Molina, E.

    2018-04-01

    This chapter of the Gaia DR2 documentation describes the models and processing steps used for the astrometric core solution, namely, the Astrometric Global Iterative Solution (AGIS). The inputs to this solution rely heavily on the basic observables (or astrometric elementaries) which have been pre-processed and discussed in Chapter 2, the results of which were published in Fabricius et al. (2016). The models consist of reference systems and time scales; assumed linear stellar motion and relativistic light deflection; in addition to fundamental constants and the transformation of coordinate systems. Higher level inputs such as: planetary and solar system ephemeris; Gaia tracking and orbit information; initial quasar catalogues and BAM data are all needed for the processing described here. The astrometric calibration models are outlined followed by the details processing steps which give AGIS its name. We also present a basic quality assessment and validation of the scientific results (for details, see Lindegren et al. 2018).

  19. Modelling University Governance

    ERIC Educational Resources Information Center

    Trakman, Leon

    2008-01-01

    Twentieth century governance models used in public universities are subject to increasing doubt across the English-speaking world. Governments question if public universities are being efficiently governed; if their boards of trustees are adequately fulfilling their trust obligations towards multiple stakeholders; and if collegial models of…

  20. The Gaia-ESO Survey: open clusters in Gaia-DR1 . A way forward to stellar age calibration

    NASA Astrophysics Data System (ADS)

    Randich, S.; Tognelli, E.; Jackson, R.; Jeffries, R. D.; Degl'Innocenti, S.; Pancino, E.; Re Fiorentin, P.; Spagna, A.; Sacco, G.; Bragaglia, A.; Magrini, L.; Prada Moroni, P. G.; Alfaro, E.; Franciosini, E.; Morbidelli, L.; Roccatagliata, V.; Bouy, H.; Bravi, L.; Jiménez-Esteban, F. M.; Jordi, C.; Zari, E.; Tautvaišiene, G.; Drazdauskas, A.; Mikolaitis, S.; Gilmore, G.; Feltzing, S.; Vallenari, A.; Bensby, T.; Koposov, S.; Korn, A.; Lanzafame, A.; Smiljanic, R.; Bayo, A.; Carraro, G.; Costado, M. T.; Heiter, U.; Hourihane, A.; Jofré, P.; Lewis, J.; Monaco, L.; Prisinzano, L.; Sbordone, L.; Sousa, S. G.; Worley, C. C.; Zaggia, S.

    2018-05-01

    Context. Determination and calibration of the ages of stars, which heavily rely on stellar evolutionary models, are very challenging, while representing a crucial aspect in many astrophysical areas. Aims: We describe the methodologies that, taking advantage of Gaia-DR1 and the Gaia-ESO Survey data, enable the comparison of observed open star cluster sequences with stellar evolutionary models. The final, long-term goal is the exploitation of open clusters as age calibrators. Methods: We perform a homogeneous analysis of eight open clusters using the Gaia-DR1 TGAS catalogue for bright members and information from the Gaia-ESO Survey for fainter stars. Cluster membership probabilities for the Gaia-ESO Survey targets are derived based on several spectroscopic tracers. The Gaia-ESO Survey also provides the cluster chemical composition. We obtain cluster parallaxes using two methods. The first one relies on the astrometric selection of a sample of bona fide members, while the other one fits the parallax distribution of a larger sample of TGAS sources. Ages and reddening values are recovered through a Bayesian analysis using the 2MASS magnitudes and three sets of standard models. Lithium depletion boundary (LDB) ages are also determined using literature observations and the same models employed for the Bayesian analysis. Results: For all but one cluster, parallaxes derived by us agree with those presented in Gaia Collaboration (2017, A&A, 601, A19), while a discrepancy is found for NGC 2516; we provide evidence supporting our own determination. Inferred cluster ages are robust against models and are generally consistent with literature values. Conclusions: The systematic parallax errors inherent in the Gaia DR1 data presently limit the precision of our results. Nevertheless, we have been able to place these eight clusters onto the same age scale for the first time, with good agreement between isochronal and LDB ages where there is overlap. Our approach appears promising

  1. A Gaia DR2 Mock Stellar Catalog

    NASA Astrophysics Data System (ADS)

    Rybizki, Jan; Demleitner, Markus; Fouesneau, Morgan; Bailer-Jones, Coryn; Rix, Hans-Walter; Andrae, René

    2018-07-01

    We present a mock catalog of Milky Way stars, matching in volume and depth the content of the Gaia data release 2 (GDR2). We generated our catalog using Galaxia, a tool to sample stars from a Besançon Galactic model, together with a realistic 3D dust extinction map. The catalog mimics the complete GDR2 data model and contains most of the entries in the Gaia source catalog: five-parameter astrometry, three-band photometry, radial velocities, stellar parameters, and associated scaled nominal uncertainty estimates. In addition, we supplemented the catalog with extinctions and photometry for non-Gaia bands. This catalog can be used to prepare GDR2 queries in a realistic runtime environment, and it can serve as a Galactic model against which to compare the actual GDR2 data in the space of observables. The catalog is hosted through the virtual observatory GAVO’s Heidelberg data center (http://dc.g-vo.org/tableinfo/gdr2mock.main) service, and thus can be queried using ADQL as for GDR2 data.

  2. BINARY ASTROMETRIC MICROLENSING WITH GAIA

    SciTech Connect

    Sajadian, Sedighe, E-mail: sajadian@ipm.ir; Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran

    2015-04-15

    We investigate whether or not Gaia can specify the binary fractions of massive stellar populations in the Galactic disk through astrometric microlensing. Furthermore, we study whether or not some information about their mass distributions can be inferred via this method. In this regard, we simulate the binary astrometric microlensing events due to massive stellar populations according to the Gaia observing strategy by considering (i) stellar-mass black holes, (ii) neutron stars, (iii) white dwarfs, and (iv) main-sequence stars as microlenses. The Gaia efficiency for detecting the binary signatures in binary astrometric microlensing events is ∼10%–20%. By calculating the optical depth duemore » to the mentioned stellar populations, the numbers of the binary astrometric microlensing events being observed with Gaia with detectable binary signatures, for the binary fraction of about 0.1, are estimated to be 6, 11, 77, and 1316, respectively. Consequently, Gaia can potentially specify the binary fractions of these massive stellar populations. However, the binary fraction of black holes measured with this method has a large uncertainty owing to a low number of the estimated events. Knowing the binary fractions in massive stellar populations helps with studying the gravitational waves. Moreover, we investigate the number of massive microlenses for which Gaia specifies masses through astrometric microlensing of single lenses toward the Galactic bulge. The resulting efficiencies of measuring the mass of mentioned populations are 9.8%, 2.9%, 1.2%, and 0.8%, respectively. The numbers of their astrometric microlensing events being observed in the Gaia era in which the lens mass can be inferred with the relative error less than 0.5 toward the Galactic bulge are estimated as 45, 34, 76, and 786, respectively. Hence, Gaia potentially gives us some information about the mass distribution of these massive stellar populations.« less

  3. Gaiaverse: the Gaia's outreach portal

    NASA Astrophysics Data System (ADS)

    Masana, E.

    2017-03-01

    Gaiaverse (http://gaiaverse.eu) is a dissemination portal on the ESA Gaia's mission developed within the GENIUS project, an European project funded by the European Commission to boost the impact of the next European breakthrough in astrophysics, the Gaia astrometric mission. The portal was opened in July 2015. Gaiaverse is administrated by the Universitat de Barcelona (UB) and the Consorci de Serveis Universitaris de Catalunya (CSUC).

  4. The Gaia scientific exploitation networks

    NASA Astrophysics Data System (ADS)

    Figueras, F.; Jordi, C.

    2015-05-01

    On July 2014 the Gaia satellite, placed at L2 since January 2014, finished their commissioning phase and started collecting high accurate scientific data. New and more realistic estimations of the astrometric, photometric and spectroscopic accuracy expected after five years mission operation (2014-2019) have been recently published in the Gaia Science Performance Web page. Here we present the coordination efforts and the activities being conducted through the two GREAT (Gaia Research for European Astronomy Training) European Networks, the GREAT-ESF, a programme supported by the European Science Foundation (2010-2015), and the GREAT-ITN network, from the European Union's Seventh Framework Programme (2011-2015). The main research theme of these networks is to unravel the origin and history of our home galaxy. Emphasis is placed on the research projects being conducted by the Spanish Researchers through these networks, well coordinated by the Red Española de Explotación Científica de Gaia (REG network, with more than 140 participants). Members of the REG play an important role on the collection of complementary spectroscopic data from ground based telescopes, on the development of new tools for an optimal scientific exploitation of Gaia data and on the preparation task to create the Gaia archive.

  5. Le premier ciel de Gaia

    NASA Astrophysics Data System (ADS)

    Turon, Catherine; Arenou, Frederic

    2016-11-01

    On 14 September 2016, the first data release of the ESA's Gaia mission has been published. Based on raw data collected between 25 July 2014 and 16 Septembre 2015, i.e. only over the first 14 months of mission, this first "Gaia sky" includes the accurate positions and Gaia magnitudes of more than a billion objects: it is already the largest all-sky survey to date even though the incomplete scanning of some areas of the sky is reflected by some artefacts that will gradually fade out as more data are collected. In addition, for a subset of two million stars in common between Gaia and the Hipparcos and Tycho-2 catalogues, positions, parallaxes and proper motions have been obtained with an accuracy 3 times better than those of Hipparcos and for 20 times more stars. Finally, light curves of about 3200 RR Lyrae and Cepheid variable stars have been obtained from the repeated observations of the Ecliptic Poles made during the first month of Gaia operations. A first glance at the quality of the data is presented here, as well as some remarks about the use of this very preliminary Gaia catalogue.

  6. VizieR Online Data Catalog: Wide binaries in Tycho-Gaia: search method (Andrews+, 2017)

    NASA Astrophysics Data System (ADS)

    Andrews, J. J.; Chaname, J.; Agueros, M. A.

    2017-11-01

    Our catalogue of wide binaries identified in the Tycho-Gaia Astrometric Solution catalogue. The Gaia source IDs, Tycho IDs, astrometry, posterior probabilities for both the log-flat prior and power-law prior models, and angular separation are presented. (1 data file).

  7. GAIA payload module mechanical development

    NASA Astrophysics Data System (ADS)

    Touzeau, S.; Sein, E.; Lebranchu, C.

    2017-11-01

    Gaia is the European Space Agency's cornerstone mission for global space astrometry. Its goal is to make the largest, most precise three-dimensional map of our Galaxy by surveying an unprecedented number of stars. This paper gives an overview of the mechanical system engineering and verification of the payload module. This development includes several technical challenges. First of all, the very high stability performance as required for the mission is a key driver for the design, which incurs a high degree of stability. This is achieved through the extensive use of Silicon Carbide (Boostec® SiC) for both structures and mirrors, a high mechanical and thermal decoupling between payload and service modules, and the use of high-performance engineering tools. Compliance of payload mass and volume with launcher capability is another key challenge, as well as the development and manufacturing of the 3.2-meter diameter toroidal primary structure. The spacecraft mechanical verification follows an innovative approach, with direct testing on the flight model, without any dedicated structural model.

  8. The First Data from Gaia

    NASA Astrophysics Data System (ADS)

    Fabricius, C.; Torra, J.

    2018-01-01

    The Gaia astrometric satellite is in its science operational phase since July 2014. At an average rate of 50 million observations per day, Gaia scans the full sky once every six months. The first data release (Gaia DR1), issued in September 2016, contains astrometric and photometric results for more than 1 billion stars brighter than magnitude 21 based on observations acquired during the first 14 months of operations. For more than two million stars brighter than 11.5 mag, positions, parallaxes, and proper motions have been obtained to HIPPARCOS-type precision through a combination with the earlier HIPPARCOS and Tycho-2 positions. For the remaining stars, positions at epoch J2015.0 have been obtained by essentially neglecting their proper motions and parallaxes. Positions and proper motions are in the ICRF radio/ VLBI frame. We give an overview of the current status of the mission, the astrometric challenges, the Data Processing and Analysis Consortium operations, the validation processes, the contents of Gaia DR1, and the prospects for the coming releases. We emphasise that although Gaia DR1 data are based on provisional and incomplete calibrations of the instrument, the results represent a huge improvement in the available fundamental stellar data, and discuss some of the first results.

  9. The Gaia hybrid catalog: a leverage to find Galactic structures

    NASA Astrophysics Data System (ADS)

    Fouesneau, M.; Bailer-Jones, C. A. L.

    2014-07-01

    of the WISE filters, one can select the Oxygen-rich Asymptotic Giant Branch (AGBs) stars to find spatial substructures with particular interstellar medium properties. Breaking through the distance-extinction degeneracies will also help finding large scale structures in the disk such as streams or spiral arms, especially when combined with age or metallicity selections for instance. Second, we presented one aspect of the hybrid catalogs dedicated to support the analysis of star clusters. Star clusters are not only calibrators of stellar evolution models but also references to study star formation in general. We presented one future outcome of the hybrid catalogs, in which we provide for known star clusters, an assessment of stellar memberships based on a combination of phase-space, and colormagnitude distribution fitting. In this application, the assumption that a cluster is a "simple" population provides a significant advantage when deriving individual star properties. Eventually one can imagine this application can be extended to stellar streams. Hybrid catalogs are meant to be provided along with the Gaia data releases, and will offer a tremendous source of validation for the Gaia Data Processing.

  10. Chaotic universe model.

    PubMed

    Aydiner, Ekrem

    2018-01-15

    In this study, we consider nonlinear interactions between components such as dark energy, dark matter, matter and radiation in the framework of the Friedman-Robertson-Walker space-time and propose a simple interaction model based on the time evolution of the densities of these components. By using this model we show that these interactions can be given by Lotka-Volterra type equations. We numerically solve these coupling equations and show that interaction dynamics between dark energy-dark matter-matter or dark energy-dark matter-matter-radiation has a strange attractor for 0 > w de  >-1, w dm  ≥ 0, w m  ≥ 0 and w r  ≥ 0 values. These strange attractors with the positive Lyapunov exponent clearly show that chaotic dynamics appears in the time evolution of the densities. These results provide that the time evolution of the universe is chaotic. The present model may have potential to solve some of the cosmological problems such as the singularity, cosmic coincidence, big crunch, big rip, horizon, oscillation, the emergence of the galaxies, matter distribution and large-scale organization of the universe. The model also connects between dynamics of the competing species in biological systems and dynamics of the time evolution of the universe and offers a new perspective and a new different scenario for the universe evolution.

  11. Revealing Black Holes with Gaia

    NASA Astrophysics Data System (ADS)

    Breivik, Katelyn; Chatterjee, Sourav; Larson, Shane L.

    2017-11-01

    We estimate the population of black holes with luminous stellar companions (BH-LCs) in the Milky Way (MW) observable by Gaia. We evolve a realistic distribution of BH-LC progenitors from zero-age to the current epoch taking into account relevant physics, including binary stellar evolution, BH-formation physics, and star formation rate, in order to estimate the BH-LC population in the MW today. We predict that Gaia will discover between 3800 and 12,000 BH-LCs by the end of its 5 {years} mission, depending on BH natal kick strength and observability constraints. We find that the overall yield, and distributions of eccentricities and masses of observed BH-LCs, can provide important constraints on the strength of BH natal kicks. Gaia-detected BH-LCs are expected to have very different orbital properties compared to those detectable via radio, X-ray, or gravitational-wave observations.

  12. UTM: Universal Transit Modeller

    NASA Astrophysics Data System (ADS)

    Deeg, Hans J.

    2014-12-01

    The Universal Transit Modeller (UTM) is a light-curve simulator for all kinds of transiting or eclipsing configurations between arbitrary numbers of several types of objects, which may be stars, planets, planetary moons, and planetary rings. A separate fitting program, UFIT (Universal Fitter) is part of the UTM distribution and may be used to derive best fits to light-curves for any set of continuously variable parameters. UTM/UFIT is written in IDL code and its source is released in the public domain under the GNU General Public License.

  13. Galactic Surveys in the Gaia Era

    NASA Astrophysics Data System (ADS)

    Wyse, Rosemary F. G.

    2018-04-01

    The final astrometric data from the Gaia mission will transform our view of the stellar content of the Galaxy, particularly when complemented with spectroscopic surveys providing stellar parameters, line-of-sight kinematics and elemental abundances. Analyses with Gaia DR1 are already demonstrating the insight gained and the promise of what is to come with future Gaia releases. I present a brief overview of results and puzzles from recent Galactic Archaeology surveys for context, focusing on the Galactic discs.

  14. The Tycho-Gaia Astrometric Solution

    NASA Astrophysics Data System (ADS)

    Lindegren, Lennart

    2018-04-01

    Gaia DR1 is based on the first 14 months of Gaia's observations. This is not long enough to reliably disentangle the parallax effect from proper motion. For most sources, therefore, only positions and magnitudes are given. Parallaxes and proper motions were nevertheless obtained for about two million of the brighter stars through the Tycho-Gaia astrometric solution (TGAS), combining the Gaia observations with the much earlier Hipparcos and Tycho-2 positions. In this review I focus on some important characteristics and limitations of TGAS, in particular the reference frame, astrometric uncertainties, correlations, and systematic errors.

  15. VizieR Online Data Catalog: Gaia DR1 (Gaia Collaboration, 2016)

    NASA Astrophysics Data System (ADS)

    Gaia Collaboration

    2016-06-01

    Gaia DR1 is based on observations collected between 25 July 2014 and 16 September 2015. Gaia DR1 contains positions (RA,DE) and G magnitudes for all sources with acceptable formal standard errors on positions. Positions and individual uncertainties are computed using a generic prior and Bayes' rule (detailed description in "Gaia astrometry for stars with too few observations. A Bayesian approach", Michalik et al., 2015A&A...583A..68M). The five-parameter astrometric solution - positions, parallaxes, and proper motions - for stars in common between the Tycho-2 Catalogue and Gaia is contained in Gaia DR1. This part of Gaia DR1 is based on the Tycho-Gaia Astrometric Solution (paper with detailed description (Michalik et al., 2015A&A...574A.115M); paper describing theory and background (Michalik et al., 2014A&A...571A..85M); paper describing quasar extension (Michalik & Lindegren, 2016A&A...586A..26M)). At the beginning of the routine phase, for a period of 4 weeks, a special scanning mode repeatedly covering the ecliptic poles on every spin was executed for calibration purposes. Photometric data of selected RR Lyrae and Cepheid variable stars based on these high-cadence measurements are contained in Gaia DR1. Positions (RA,DE) and G magnitudes for 2152 ICRF quasars (F. Mignard et al., 2016, A&A, in press.). The Gaia Archive DR1 data is available at archives.esac.esa.int/gaia. Tgas and Gaia Sources can be downloaded as VOTables, FITS or CSV at http://cdn.gea.esac.esa.int/Gaia/ If you use public Gaia DR1 data in your paper, please take note of our guide on how to acknowledge and cite Gaia DR1: http://gaia.esac.esa.int/documentation/GDR1/Miscellaneous/\\ seccreditandcitationinstructions.html (9 data files).

  16. Space Astrometry Science with Gaia

    NASA Astrophysics Data System (ADS)

    Mignard, Francois

    2009-05-01

    The European Space Agency has formally approved in spring 2006 the overall funding of its next space astrometry mission Gaia scheduled for a launch in spring 2012. The mission will create an extraordinarily precise three-dimensional map of about one billion stars throughout our Galaxy and beyond from repeated astrometric and photometric observations over about five years. End-of-mission expected accuracies in wide angle astrometry fall in the 7-25 muas range for start brighter than 15 mag and sub-mas at the faint end (20 mag). The science covered by Gaia is broad and extends from galactic and stellar astrophysics to solar systems dynamics and physics and the construction of an inertial frame in the visible with extragalactic sources. Fundamental physics with general relativity testing will also be a major product of the mission. In the presentation I will overview the Gaia science case, stressing more specifically the astrometric side of the expected results and provide few hints on the overall organisation of the data analysis entrusted to the Data Processing and Analysis Consortium (DPAC).

  17. Spotting stellar activity cycles in Gaia astrometry

    NASA Astrophysics Data System (ADS)

    Morris, Brett M.; Agol, Eric; Davenport, James R. A.; Hawley, Suzanne L.

    2018-06-01

    Astrometry from Gaia will measure the positions of stellar photometric centroids to unprecedented precision. We show that the precision of Gaia astrometry is sufficient to detect starspot-induced centroid jitter for nearby stars in the Tycho-Gaia Astrometric Solution (TGAS) sample with magnetic activity similar to the young G-star KIC 7174505 or the active M4 dwarf GJ 1243, but is insufficient to measure centroid jitter for stars with Sun-like spot distributions. We simulate Gaia observations of stars with 10 year activity cycles to search for evidence of activity cycles, and find that Gaia astrometry alone likely cannot detect activity cycles for stars in the TGAS sample, even if they have spot distributions like KIC 7174505. We review the activity of the nearby low-mass stars in the TGAS sample for which we anticipate significant detections of spot-induced jitter.

  18. Pulsating star research and the Gaia revolution

    NASA Astrophysics Data System (ADS)

    Eyer, Laurent; Clementini, Gisella; Guy, Leanne P.; Rimoldini, Lorenzo; Glass, Florian; Audard, Marc; Holl, Berry; Charnas, Jonathan; Cuypers, Jan; Ridder, Joris De; Evans, Dafydd W.; de Fombelle, Gregory Jevardat; Lanzafame, Alessandro; Lecoeur-Taibi, Isabelle; Mowlavi, Nami; Nienartowicz, Krzysztof; Riello, Marco; Ripepi, Vincenzo; Sarro, Luis; Süveges, Maria

    2017-09-01

    In this article we present an overview of the ESA Gaia mission and of the unprecedented impact that Gaia will have on the field of variable star research. We summarise the contents and impact of the first Gaia data release on the description of variability phenomena, with particular emphasis on pulsating star research. The Tycho-Gaia astrometric solution, although limited to 2.1 million stars, has been used in many studies related to pulsating stars. Furthermore a set of 3,194 Cepheids and RR Lyrae stars with their times series have been released. Finally we present the plans for the ongoing study of variable phenomena with Gaia and highlight some of the possible impacts of the second data release on variable, and specifically, pulsating stars.

  19. Near-Earth Asteroids Astrometry with Gaia

    NASA Astrophysics Data System (ADS)

    Bancelin, D.; Hestroffer, D.; Thuillot, W.

    2011-05-01

    Potentially Hazardous Asteroids (PHAs) are Near-Earth Asteroids caraterised by a Minimum Orbital Intersection Distance (MOID) with Earth less to 0.05 A.U and an absolute magnitude H<22. Those objects have sometimes a so significant close approach with Earth that they can be put on a chaotic orbit. This kind of orbit is very sensitive for exemple to the initial conditions, to the planetary theory used (for instance JPL's model versus IMCCE's model) or even to the numerical integrator used (Lie Series, Bulirsch-Stoer or Radau). New observations (optical, radar, flyby or satellite mission) can improve those orbits and reduce the uncertainties on the Keplerian elements.The Gaia mission is an astrometric mission that will be launched in 2012 and will observe a large number of Solar System Objects down to magnitude V≤20. During the 5-year mission, Gaia will continuously scan the sky with a specific strategy: objects will be observed from two lines of sight separated with a constant basic angle. Five constants already fixed determinate the nominal scanning law of Gaia: The inertial spin rate (1°/min) that describe the rotation of the spacecraft around an axis perpendicular to those of the two fields of view, the solar-aspect angle (45°) that is the angle between the Sun and the spacecraft rotation axis, the precession period (63.12 days) which is the precession of the spin axis around the Sun-Earth direction. Two other constants are still free parameters: the initial spin phase, and the initial precession angle that will be fixed at the start of the nominal science operations. These latter are constraint by scientific outcome (e.g. possibility of performing test of fundamental physics) together with operational requirements (downlink to Earth windows). Several sets of observations of specific NEOs will hence be provided according to the initial precession angle. The purpose here is to study the statistical impact of the initial precession angle on the error

  20. Gaia: Mapping the Milky Way: The Scientific Promise of Gaia DR2

    NASA Astrophysics Data System (ADS)

    Walton, Nicholas; ESA Gaia, Data Processing and Analysis Consortium (DPAC)

    2018-06-01

    The ESA Gaia mission will release its first major all sky astrometric catalogue (Gaia DR2), of more than 1.3 billion stars in our Galaxy, on 25 April 2018.This presentation will provide an overview of the Gaia mission, focussing on the significant scientific potential of the Gaia DR2 release. This is based on 22 months of input data and allows for a full Gaia stand alone astrometric solution, including parallaxes and proper motions, of over 1.3 billion sources. The astrometric uncertainties in Gaia DR2 will be at the level of tens of micro-arcsec for sources G<15.The Gaia DR2 release provides not only high precision full five parameter astrometry, but also a complete photometric catalogue of the sources on an all sky homogeneous photometric system in the Gaia G band and broad bands G_BP and G_RP. The release will include median radial velocities for more than six million stars (brighter that G_RVS = 12) together with a set of astrophysical parameters (including stellar temperatures) for some 150 million stars. Finally the Gaia DR2 release will include a set of additional data products including the light curves of more than half a million variable stars, and the positions of more than thirteen thousand objects in our Solar System.Together with the Gaia DR2 data products and associated release documentation, a small number of performance verification papers, using Gaia DR2 data only to provide new insights into a number of key areas of Gaia science, will be published in a special edition of A&A. These will provide demonstrations of the scientific potential of the Gaia DR2 catalogue, and also highlight some of the issues and limitations involved in the use of the Gaia DR2 data.The Gaia mission and Gaia Data Releases are made possible through the dedication and expertise of the community scientists and engineers involved in the design, construction, and operation of Gaia (led by ESA) and the collaboration of some 450 scientists and software engineers responsible for

  1. The Gaia Astrometric Survey of Nearby M Dwarfs: A Treasure Trove for Exoplanet Astrophysics

    NASA Astrophysics Data System (ADS)

    Sozzetti, Alessandro; Giacobbe, P.; Lattanzi, M. G.; Micela, G.; Tinetti, G.

    2011-09-01

    Cool, nearby M dwarfs within a few tens of parsecs from the Sun are becoming the focus of dedicated experiments in the realm of exoplanets astrophysics. This is due to the shift in theoretical paradigms in light of new observations, and to the improved understanding of the observational opportunities for planet detection and characterization provided by this sample. Gaia, in its all-sky survey, will deliver precision astrometry for a magnitude-limited (V=20) sample of M dwarfs, providing an inventory of cool nearby stars with a much higher degree of completeness (particularly for late sub-types) with respect to currently available catalogs. We gauge the Gaia potential for precision astrometry of exoplanets orbiting a sample of already known dM stars within 30 pc from the Sun, carefully selected based on cross-correlation among catalogs in the literature (e.g., Lepine, PMSU). We express Gaia sensitivity thresholds as a function of system parameters and in view of the latest mission profile, including the most up-to-date astrometric error model. The simulations also provide insight on the capability of high-precision astrometry to reconstruct the underlying orbital elements and mass distributions of the generated companions. These results will help in evaluating the complete expected Gaia planet population around late-type stars. We investigate the synergy between the Gaia data on nearby M dwarfs and other ground-based and space-borne programs for planet detection and characterization, with a particular focus on: a) the improvements in the determination of transiting planet parameters thanks to the exquisitely precise stellar distances determined by Gaia; b) the betterment in orbit modeling when Gaia astrometry and precision radial-velocities are available for the same targets; and c) the ability of Gaia to carefully predict the ephemerides of (transiting and non-transiting) planets around M stars, for spectroscopic characterization of their atmospheres with

  2. Gaia FGK benchmark stars: Metallicity

    NASA Astrophysics Data System (ADS)

    Jofré, P.; Heiter, U.; Soubiran, C.; Blanco-Cuaresma, S.; Worley, C. C.; Pancino, E.; Cantat-Gaudin, T.; Magrini, L.; Bergemann, M.; González Hernández, J. I.; Hill, V.; Lardo, C.; de Laverny, P.; Lind, K.; Masseron, T.; Montes, D.; Mucciarelli, A.; Nordlander, T.; Recio Blanco, A.; Sobeck, J.; Sordo, R.; Sousa, S. G.; Tabernero, H.; Vallenari, A.; Van Eck, S.

    2014-04-01

    Context. To calibrate automatic pipelines that determine atmospheric parameters of stars, one needs a sample of stars, or "benchmark stars", with well-defined parameters to be used as a reference. Aims: We provide detailed documentation of the iron abundance determination of the 34 FGK-type benchmark stars that are selected to be the pillars for calibration of the one billion Gaia stars. They cover a wide range of temperatures, surface gravities, and metallicities. Methods: Up to seven different methods were used to analyze an observed spectral library of high resolutions and high signal-to-noise ratios. The metallicity was determined by assuming a value of effective temperature and surface gravity obtained from fundamental relations; that is, these parameters were known a priori and independently from the spectra. Results: We present a set of metallicity values obtained in a homogeneous way for our sample of benchmark stars. In addition to this value, we provide detailed documentation of the associated uncertainties. Finally, we report a value of the metallicity of the cool giant ψ Phe for the first time. Based on NARVAL and HARPS data obtained within the Gaia DPAC (Data Processing and Analysis Consortium) and coordinated by the GBOG (Ground-Based Observations for Gaia) working group and on data retrieved from the ESO-ADP database.Tables 6-76 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/564/A133

  3. Galaxy simulations in the Gaia era

    NASA Astrophysics Data System (ADS)

    Minchev, Ivan

    2018-04-01

    We live in an age where an enormous amount of astrometric, photometric, asteroseismic, and spectroscopic data of Milky Way stars are being acquired, many orders of magnitude larger than about a decade ago. Thanks to the Gaia astrometric mission and followup ground-based spectroscopic surveys in the next 5-10 years about 10-20 Million stars will have accurate 6D kinematics and chemical composition measurements. KEPLER-2, PLATO, and TESS will provide asteroseismic ages for a good fraction of those. In this article we outline some outstanding problems concerning the formation and evolution of the Milky Way and argue that, due to the complexity of physical processes involved in the formation of disk galaxies, numerical simulations in the cosmological context are needed for the interpretation of Milky Way observations. We also discuss in some detail the formation of the Milky Way thick disk, chemodynamical models, and the effects of radial migration.

  4. Gaia I: the Mission - the adventure begins

    NASA Astrophysics Data System (ADS)

    Altmann, M.

    2015-10-01

    The ESA Gaia satellite mission, launched on Dec. 19, 2013, will undoubtedly leave a profound impact on Galactic dynamics, revolutionising many aspects of the trade. Nine months later, with the commissioning phase over and the regular five year measuring phase of Gaia starting, it is time to give an overview of the mission, what to expect after the potential of the spacecraft has been fully assessed in situ. Moreover this paper will give a brief description of the mission as a whole, to be followed by a second contribution by Figueras (2015) focussing on Gaia science.

  5. Transient astronomy with the Gaia satellite.

    PubMed

    Hodgkin, Simon T; Wyrzykowski, Łukasz; Blagorodnova, Nadejda; Koposov, Sergey

    2013-06-13

    Gaia is a cornerstone European Space Agency astrometry space mission and a successor to the Hipparcos mission. Gaia will observe the whole sky for 5 years, providing a serendipitous opportunity for the discovery of large numbers of transient and anomalous events, e.g. supernovae, novae and microlensing events, gamma-ray burst afterglows, fallback supernovae, as well as theoretical or unexpected phenomena. In this paper, we discuss our preparations to use Gaia to search for transients at optical wavelengths, and briefly describe the early detection, classification and prompt publication of anomalous sources.

  6. University Macro Analytic Simulation Model.

    ERIC Educational Resources Information Center

    Baron, Robert; Gulko, Warren

    The University Macro Analytic Simulation System (UMASS) has been designed as a forecasting tool to help university administrators budgeting decisions. Alternative budgeting strategies can be tested on a computer model and then an operational alternative can be selected on the basis of the most desirable projected outcome. UMASS uses readily…

  7. Short arc orbit determination and Gaia alerts

    NASA Astrophysics Data System (ADS)

    Spoto, Federica; Tanga, Paolo; Del Vigna, Alessio; Carry, Benoit; Thuillot, William; David, Pedro; Mignard, Francois; Milani, Andrea; Tommei, Giacomo

    2017-10-01

    Since October 2016, the short term (ST) processing of Solar System Objects (SSOs) by Gaia is up and running, and it has produced almost 600 alerts. A crucial point in the chain is the possibility of performing a short arc orbit determination as soon as the object has been detected, which allows the follow up of the object from the ground.The method we present has been recentely developed for two mainreasons: 1) search for imminent impactors within the NEO - Confirmation Page(imminent impactors are asteroids that could impact the Earth infew days from their discovery) 2) validation of the SSO-ST Gaia pipeline.We show some good confirmations on objects that could have been discovered by Gaia, and some properties of the Gaia astrometry for the short term.

  8. Gaia: from proposal to GDR1

    NASA Astrophysics Data System (ADS)

    Gilmore, Gerard

    2018-04-01

    In this concluding article I recall the early history of the Gaia mission, showing that the original science case and expectations of wide community interest in Gaia data have been met. The quarter-century long partnership involving some 1,000 scientists, engineers and managers in industry and academia is delivering a large, high-quality and unique data set which will underpin astrophysics across many sub-fields for years to come.

  9. The Black Hole Universe Model

    NASA Astrophysics Data System (ADS)

    Zhang, Tianxi

    2014-06-01

    The black hole universe model is a multiverse model of cosmology recently developed by the speaker. According to this new model, our universe is a fully grown extremely supermassive black hole, which originated from a hot star-like black hole with several solar masses, and gradually grew up from a supermassive black hole with million to billion solar masses to the present state with trillion-trillion solar masses by accreting ambient matter or merging with other black holes. The entire space is structured with infinite layers or universes hierarchically. The innermost three layers include the universe that we live, the inside star-like and supermassive black holes called child universes, and the outside space called mother universe. The outermost layer is infinite in mass, radius, and entropy without an edge and limits to zero for both the matter density and absolute temperature. All layers are governed by the same physics and tend to expand physically in one direction (outward or the direction of increasing entropy). The expansion of a black hole universe decreases its density and temperature but does not alter the laws of physics. The black hole universe evolves iteratively and endlessly without a beginning. When one universe expands out, a new similar one is formed from inside star-like and supermassive black holes. In each of iterations, elements are resynthesized, matter is reconfigurated, and the universe is renewed rather than a simple repeat. The black hole universe is consistent with the Mach principle, observations, and Einsteinian general relativity. It has only one postulate but is able to explain all phenomena occurred in the universe with well-developed physics. The black hole universe does not need dark energy for acceleration and an inflation epoch for flatness, and thus has a devastating impact on the big bang model. In this talk, I will present how this new cosmological model explains the various aspects of the universe, including the origin

  10. Surveying Nearby M dwarfs with Gaia: A Treasure Trove for Exoplanet Astrophysics

    NASA Astrophysics Data System (ADS)

    Sozzetti, A.; Tinetti, G.; Lattanzi, M. G.; Micela, G.; Morbidelli, R.; Giacobbe, P.

    2011-10-01

    Cool, nearby M dwarfs within a few tens of parsecs from the Sun are today becoming the focus of dedicated experiments in the realm of exoplanets astrophysics. This is due to the shift in theoretical paradigms in light of new observations, and thanks to the improved understanding of the observational opportunities for planet detection and characterization provided by this sample. Gaia, in its all-sky survey, will deliver precision astrometry for a magnitude-limited (V=20) sample of M dwarfs in the vicinity of the Sun, providing an inventory of cool nearby stars with a much higher degree of completeness (particularly for late sub-types) with respect to currently available catalogs. We gauge the Gaia potential for precision astrometry of exoplanets orbiting a sample of actual M stars within 30 pc from the Sun. The stellar reservoir is carefully selected based on cross-correlation among catalogs in the literature (e.g., Lepine, PMSU).We express Gaia sensitivity thresholds as a function of system parameters and in view of the latest mission profile, including the most up-to-date astrometric error model. The simulations also provide insight on the capability of high-precision astrometry to reconstruct the underlying orbital elements and mass distributions of the generated companions. We investigate the synergy between the Gaia data on nearby M dwarfs and other ground-based and spaceborne programs for planet detection and characterization, with a particular focus on: a) the improvements in the determination of transiting planet parameters thanks to the exquisitely precise stellar distances determined by Gaia; b) the betterment in orbit modeling when Gaia astrometry and precision radial-velocities are available for the same targets; and c) the ability of Gaia to carefully predict the ephemerides of detected (transiting and non-transiting) planets aroundM stars, for the purpose of spectroscopic characterization of their atmospheres with dedicated observatories in space

  11. Gravitationally Lensed Quasars in Gaia: II. Discovery of 24 Lensed Quasars

    NASA Astrophysics Data System (ADS)

    Lemon, Cameron A.; Auger, Matthew W.; McMahon, Richard G.; Ostrovski, Fernanda

    2018-04-01

    We report the discovery, spectroscopic confirmation and preliminary characterisation of 24 gravitationally lensed quasars identified using Gaia observations. Candidates were selected in the Pan-STARRS footprint with quasar-like WISE colours or as photometric quasars from SDSS, requiring either multiple detections in Gaia or a single Gaia detection near a morphological galaxy. The Pan-STARRS grizY images were modelled for the most promising candidates and 60 candidate systems were followed up with the William Herschel Telescope. 13 of the lenses were discovered as Gaia multiples and 10 as single Gaia detections near galaxies. We also discover 1 lens identified through a quasar emission line in an SDSS galaxy spectrum. The lenses have median image separation 2.13″ and the source redshifts range from 1.06 to 3.36. 4 systems are quadruply-imaged and 20 are doubly-imaged. Deep CFHT data reveal an Einstein ring in one double system. We also report 12 quasar pairs, 10 of which have components at the same redshift and require further follow-up to rule out the lensing hypothesis. We compare the properties of these lenses and other known lenses recovered by our search method to a complete sample of simulated lenses to show the lenses we are missing are mainly those with small separations and higher source redshifts. The initial Gaia data release only catalogues all images of ˜ 30% of known bright lensed quasars, however the improved completeness of Gaia data release 2 will help find all bright lensed quasars on the sky.

  12. Astrometry of Solar System Objects with Gaia

    NASA Astrophysics Data System (ADS)

    Hestroffer, Daniel J.; Arenou, Frederic; Desmars, Josselin; Robert, Vincent; Thuillot, William; Arlot, Jean-Eudes; Carry, Benoit; David, Pedro; Eggl, Siegfried; Fabricius, Claus; Kudryashova, Maria; Lainey, Valery; Spoto, Federica; Tanga, Paolo; Gaia DPAC

    2016-10-01

    The Gaia ESA space mission will provide astrometric observations of a large number of celestial bodies, with unprecedented accuracy, and in an homogenous reference frame (to become the optical ICRF). The Gaia satellite is monitoring regularly the whole celestial sphere, with one complete scan in about 6month, down to approximately magnitude V≤20.7. It will provide after its nominal lifetime, (5 years, 2014-2019) about 70 astrometric points for several hundred thousands of solar system objects, asteroids from the Near-Earth region to Centaurs and bright TNOs, as well as planetary satellites and comets. The highly precise astrometric and photometric data is bound to lead to huge advances in the science of small Small Solar System Bodies (e.g. Tanga et al. 2016 P\\&SS, Hestroffer et al. 2014 COSPAR #40 ; Mignard et al. 2007 EMP).The first Gaia data release (GDR#1) is foreseen for Q3-2016 and will provide highly precise positions of selected stars down to mag V≈20. While solar system objets data is foreseen for the next data release (in 2017), science of Solar System will also highly benefit from the Gaia stellar catalogue. We will present the status of the satellite and Gaia mission, and details on the stellar data that will be published in this GDR#1. We discuss the catalogue content, number of stars, parameters and precisions, and the process of cross-matching and validation. We also touch upon the construction of combined Tycho-Gaia TGAS catalogue.A Gaia data daily processing is devoted to the identification of Solar System Objects. During this process the detection of new (or critical) objects arises and leads to the triggering of scientific alerts to be found on the web gaiafunsso.imcce.fr. We have also set up an international follow-up network called Gaia-FUN-SSO to validate the detection in space. For this goal, in case of detection the observational data must be sent to the MPC by the observers. Besides, Gaia should benefit for the classical astrometric

  13. Predicting the hypervelocity star population in Gaia

    NASA Astrophysics Data System (ADS)

    Marchetti, T.; Contigiani, O.; Rossi, E. M.; Albert, J. G.; Brown, A. G. A.; Sesana, A.

    2018-06-01

    Hypervelocity stars (HVSs) are amongst the fastest objects in our Milky Way. These stars are predicted to come from the Galactic centre (GC) and travel along unbound orbits across the Galaxy. In the coming years, the ESA satellite Gaia will provide the most complete and accurate catalogue of the Milky Way, with full astrometric parameters for more than 1 billion stars. In this paper, we present the expected sample size and properties (mass, magnitude, spatial, velocity distributions) of HVSs in the Gaia stellar catalogue. We build three Gaia mock catalogues of HVSs anchored to current observations, exploring different ejection mechanisms and GC stellar population properties. In all cases, we predict hundreds to thousands of HVSs with precise proper motion measurements within a few tens of kpc from us. For stars with a relative error in total proper motion below 10 {per cent}, the mass range extends to ˜10 M⊙ but peaks at ˜1 M⊙. The majority of Gaia HVSs will therefore probe a different mass and distance range compared to the current non-Gaia sample. In addition, a subset of a few hundreds to a few thousands of HVSs with M ˜ 3 M⊙ will be bright enough to have a precise measurement of the three-dimensional velocity from Gaia alone. Finally, we show that Gaia will provide more precise proper motion measurements for the current sample of HVS candidates. This will help identifying their birthplace narrowing down their ejection location, and confirming or rejecting their nature as HVSs. Overall, our forecasts are extremely encouraging in terms of quantity and quality of HVS data that can be exploited to constrain both the Milky Way potential and the GC properties.

  14. Gaia DR1 documentation Chapter 7: Catalogue consolidation and validation

    NASA Astrophysics Data System (ADS)

    Arenou, F.; Babusiaux, C.; Blanco-Cuaresma, S.; Borrachero, R.; Cantat-Gaudin, T.; Fabricius, C.; Findeisen, K.; Helmi, A.; Hutton, A.; Luri, X.; Marrese, P.; Marinoni, S.; Marrese, P.; Robin, A.; Sordo, R.; Soria, S.; Turon, C.; Utrilla Molina, E.; Vallenari, A.

    2017-12-01

    The Gaia Catalogue does not only produce a wealth of data, it also represents a complex processing before a Catalogue can be issued. The main data processing is being handled by three DPAC Coordination Units, CU3 for the astrometric data, CU5 for the photometric data and CU6 for the spectroscopic data. Then three Coordination Units analyse the processed data, CU4 for optical or binary stars, solar system objects and extended objects, CU7 for variable stars, and CU8 for classification. Finally, CU9 takes care of the intermediate and final publication of the Gaia data. For Gaia DR1, the situation has been simplified in the sense that CU4, CU6 and CU8 did not contribute to the first Catalogue. At the last step, several data fields may have been computed by several Coordination Units (e.g., parallaxes computed by CU3, then again by CU4 with a fit of an astrometric + binary model if the star happens to have a significant binary motion; or a mean magnitude computed by CU5 may be superseded by another estimation from CU7 if the stars happens to be a periodic variable; etc.), in several Data Processing Centres, so an (a) homogeneous, (b) convenient, (c) consistent Catalogue has to be built. First, to a so-called CompleteSource is attached astrometric and photometric information, then possible variability information is integrated, producing an homogeneous Catalogue. Second, sources that do not meet some minimum astrometric or photometric quality are filtered out. The filters applied are described in Section 4 of Gaia Collaboration et al. (2016a). Third, while flat files are kept for further operations, the data is integrated inside the Gaia Archive Core System (GACS) database; crossmatch with external catalogues is also performed, providing the convenient access to the data. Fourth, the consistency of the Catalogue is obtained through a dedicated validation of its content. Sources that do not pass the validation criteria are then filtered out. This chapter describes these

  15. Interferometric Constraints on Surface Brightness Asymmetries in Long-Period Variable Stars: A Threat to Accurate Gaia Parallaxes

    NASA Astrophysics Data System (ADS)

    Sacuto, S.; Jorissen, A.; Cruzalèbes, P.; Pasquato, E.; Chiavassa, A.; Spang, A.; Rabbia, Y.; Chesneau, O.

    2011-09-01

    A monitoring of surface brightness asymmetries in evolved giants and supergiants is necessary to estimate the threat that they represent to accurate Gaia parallaxes. Closure-phase measurements obtained with AMBER/VISA in a 3-telescope configuration are fitted by a simple model to constrain the photocenter displacement. The results for the C-type star TX Psc show a large deviation of the photocenter displacement that could bias the Gaia parallax.

  16. The ESA Gaia Archive: Data Release 1

    NASA Astrophysics Data System (ADS)

    Salgado, J.; González-Núñez, J.; Gutiérrez-Sánchez, R.; Segovia, J. C.; Durán, J.; Hernández, J. L.; Arviset, C.

    2017-10-01

    The ESA Gaia mission is producing the most accurate source catalogue in astronomy to date. This represents a challenge in archiving to make the information and data accessible to astronomers in an efficient way, due to the size and complexity of the data. Also, new astronomical missions, taking larger and larger volumes of data, are reinforcing this change in the development of archives. Archives, as simple applications to access data, are evolving into complex data centre structures where computing power services are available for users and data mining tools are integrated into the server side. In the case of astronomy missions that involve the use of large catalogues, such as Gaia (or Euclid to come), the common ways to work on the data need to be changed to the following paradigm: "move the code close to the data". This implies that data mining functionalities are becoming a must to allow for the maximum scientific exploitation of the data. To enable these capabilities, a TAP+ interface, crossmatch capabilities, full catalogue histograms, serialisation of intermediate results in cloud resources, such as VOSpace etc., have been implemented for the Gaia Data Release 1 (DR1), to enable the exploitation of these science resources by the community without any bottlenecks in the connection bandwidth. We present the architecture, infrastructure and tools already available in the Gaia Archive DR1 (http://archives.esac.esa.int/gaia/) and we describe the capabilities and infrastructure.

  17. Astrometric surveys in the Gaia era

    NASA Astrophysics Data System (ADS)

    Zacharias, Norbert

    2018-04-01

    The Gaia first data release (DR1) already provides an almost error free optical reference frame on the milli-arcsecond (mas) level allowing significantly better calibration of ground-based astrometric data than ever before. Gaia DR1 provides positions, proper motions and trigonometric parallaxes for just over 2 million stars in the Tycho-2 catalog. For over 1.1 billion additional stars DR1 gives positions. Proper motions for these, mainly fainter stars (G >= 11.5) are currently provided by several new projects which combine earlier epoch ground-based observations with Gaia DR1 positions. These data are very helpful in the interim period but will become obsolete with the second Gaia data release (DR2) expected in April 2018. The era of traditional, ground-based, wide-field astrometry with the goal to provide accurate reference stars has come to an end. Future ground-based astrometry will fill in some gaps (very bright stars, observations needed at many or specific epochs) and mainly will go fainter than the Gaia limit, like the PanSTARRS and the upcoming LSST surveys.

  18. Spectroscopic classification of Gaia17apq and Gaia17apv with Double Spectrograph on Palomar 200-inch telescope

    NASA Astrophysics Data System (ADS)

    Blagorodnova, N.; Adams, S.

    2017-03-01

    We report the classification of Gaia17apq and Gaia17apv (SN2017cao and SN2017cat), discovered by the Gaia ESA survey. The observations were performed on UT 2017-03-16 with the Double Spectrograph (DBSP; range 350-1000nm, spectral resolution R 4000) on Palomar 200-inch (P200) telescope.

  19. Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours. I. Grids of 3D corrections in the UBVRI, 2MASS, HIPPARCOS, Gaia, and SDSS systems

    NASA Astrophysics Data System (ADS)

    Bonifacio, P.; Caffau, E.; Ludwig, H.-G.; Steffen, M.; Castelli, F.; Gallagher, A. J.; Kučinskas, A.; Prakapavičius, D.; Cayrel, R.; Freytag, B.; Plez, B.; Homeier, D.

    2018-03-01

    Context. The atmospheres of cool stars are temporally and spatially inhomogeneous due to the effects of convection. The influence of this inhomogeneity, referred to as granulation, on colours has never been investigated over a large range of effective temperatures and gravities. Aim. We aim to study, in a quantitative way, the impact of granulation on colours. Methods: We use the CIFIST (Cosmological Impact of the FIrst Stars) grid of CO5BOLD (COnservative COde for the COmputation of COmpressible COnvection in a BOx of L Dimensions, L = 2, 3) hydrodynamical models to compute emerging fluxes. These in turn are used to compute theoretical colours in the UBV RI, 2MASS, HIPPARCOS, Gaia and SDSS systems. Every CO5BOLD model has a corresponding one dimensional (1D) plane-parallel LHD (Lagrangian HydroDynamics) model computed for the same atmospheric parameters, which we used to define a "3D correction" that can be applied to colours computed from fluxes computed from any 1D model atmosphere code. As an example, we illustrate these corrections applied to colours computed from ATLAS models. Results: The 3D corrections on colours are generally small, of the order of a few hundredths of a magnitude, yet they are far from negligible. We find that ignoring granulation effects can lead to underestimation of Teff by up to 200 K and overestimation of gravity by up to 0.5 dex, when using colours as diagnostics. We have identified a major shortcoming in how scattering is treated in the current version of the CIFIST grid, which could lead to offsets of the order 0.01 mag, especially for colours involving blue and UV bands. We have investigated the Gaia and HIPPARCOS photometric systems and found that the (G - Hp), (BP - RP) diagram is immune to the effects of granulation. In addition, we point to the potential of the RVS photometry as a metallicity diagnostic. Conclusions: Our investigation shows that the effects of granulation should not be neglected if one wants to use colours as

  20. The Gaia-ESO Survey Astrophysical Calibration

    NASA Astrophysics Data System (ADS)

    Pancino, E.; Gaia-ESO Survey Consortium

    2016-05-01

    The Gaia-ESO Survey is a wide field spectroscopic survey recently started with the FLAMES@VLT in Cerro Paranal, Chile. It will produce radial velocities more accurate than Gaia's for faint stars (down to V ≃ 18), and astrophysical parameters and abundances for approximately 100 000 stars, belonging to all Galactic populations. 300 nights were assigned in 5 years (with the last year subject to approval after a detailed report). In particular, to connect with other ongoing and planned spectroscopic surveys, a detailed calibration program — for the astrophysical parameters derivation — is planned, including well known clusters, Gaia benchmark stars, and special equatorial calibration fields designed for wide field/multifiber spectrographs.

  1. White Dwarfs in Gaia Data Release 1

    NASA Astrophysics Data System (ADS)

    Jordan, S.

    2017-03-01

    On September 14, the Gaia archives opened for access to the Gaia DR1. The catalogue with more than one billion star positions and more than two million parallaxes and proper motions will have enormous influence on many topics in astronomy. However, due to their extremely blue colour, parallaxes and proper motions of only six white dwarfs were directly measured. Tremblay et al. used these data and those for 46 white dwarfs in binaries in order to construct an empirical mass-radius relation. As it was the case for Hipparcos, the precision of the data does not allow for the characterisation of hydrogen envelope masses. With Gaia DR2 coming in late 2017 the prospects for white dwarf research are much better.

  2. S stars in the Gaia era: stellar parameters and nucleosynthesis

    NASA Astrophysics Data System (ADS)

    van Eck, Sophie; Karinkuzhi, Drisya; Shetye, Shreeya; Jorissen, Alain; Goriely, Stéphane; Siess, Lionel; Merle, Thibault; Plez, Bertrand

    2018-04-01

    S stars are s-process and C-enriched (0.5model atmospheres covering their whole parameter range. Detailed abundance determinations in intrinsic S stars (TP-AGB) and extrinsic S stars (binary masqueraders) can provide strong constraints on the s-process nucleosynthesis: in particular, the s-process temperature can be determined using zirconium and niobium abundances, independently of stellar evolution models. Synthetic spectra of dwarf S stars have been computed and will be sought for in spectroscopic survey data, constraining their luminosity thanks to Gaia parallaxes.

  3. Wavefront sensor for the GAIA Mission

    NASA Astrophysics Data System (ADS)

    Vosteen, Amir; Draaisma, Folkert; van Werkhoven, Willem; van Riel, Luud; Mol, Margreet; Gielesen, Wim

    2017-11-01

    TNO has developed, built and tested the Wave Front Sensor (WFS) for ESA's Gaia mission. The WFS will help Gaia create an extraordinarily precise three-dimensional map of more than one billion stars in our Galaxy. Part of ESA's Cosmic Vision programme, Gaia's build is led by EADS Astrium and is scheduled for launch in 2012. The Wave Front Sensor will be used to monitor the wave front errors of the two main telescopes mounted on the GAIA satellite. These mirrors include a 5-degree of freedom (DOF) mechanism that can be used to minimize the wave front errors during operation. The GAIA-WFS will operate over a broad wavelength (450 to 900 nm) and under cryogenic conditions (130 to 200 K operation temperature). The WFS uses an all reflective, a-thermal design and is of the type of Shack-Hartmann. The boundary condition for the design is that the focal plane of the WFS is the same plane as the focal plane of the GAIA telescopes. The spot pattern generated after a micro lens array ( MLA) by a star is compared to the pattern of one of the three calibration sources that is included in the WFS, allowing in flight calibration. We show the robust and lightweight opto mechanical design that is optimised for launch and cryogenic operation. Details are given on its alignment and commissioning. The WFS is able to measure relative wave front distortions in the order of lambda/1000, and can determine the optimum position of the focal plane with an accuracy of 50 μm

  4. Local tests of gravitation with Gaia observations of Solar System Objects

    NASA Astrophysics Data System (ADS)

    Hees, Aurélien; Le Poncin-Lafitte, Christophe; Hestroffer, Daniel; David, Pedro

    2018-04-01

    In this proceeding, we show how observations of Solar System Objects with Gaia can be used to test General Relativity and to constrain modified gravitational theories. The high number of Solar System objects observed and the variety of their orbital parameters associated with the impressive astrometric accuracy will allow us to perform local tests of General Relativity. In this communication, we present a preliminary sensitivity study of the Gaia observations on dynamical parameters such as the Sun quadrupolar moment and on various extensions to general relativity such as the parametrized post-Newtonian parameters, the fifth force formalism and a violation of Lorentz symmetry parametrized by the Standard-Model extension framework. We take into account the time sequences and the geometry of the observations that are particular to Gaia for its nominal mission (5 years) and for an extended mission (10 years).

  5. Sky Of Stars: Visualizing Gaia Data in the Fiske Planetarium

    NASA Astrophysics Data System (ADS)

    Ibarra Perez, Luz; Berta-Thompson, Zachory K.; Conant, Nickolas Alexander

    2018-06-01

    ESA’s satellite Gaia has collected and continues to collect data about the positions, kinematics, and luminosity of more than one billion stars. This census is the most accurate census of the Milky Way to this day. The Fiske Planetarium at the University of Colorado hosts a state-of-the-art 8K projector and the ability to render the 3D positions of stars in real time. Using Python, Astropy and ADQL, I wrote tools to explore the Gaia data, creating different ways to visualize this three-dimensional map of our Galaxy. I created catalogs that the Fiske planetarium can read and project, including millions of stars that our naked eyes can’t see. For the first time ever, we are able to show in the planetarium what the sky would look like if our eyes were 10X, 100X, or 1000X bigger than they really are. With accurate positions and proper motions, we can also jump in time and roughly observe what our sky will look like in a thousand or in a million years. This catalog is now used in classes and talks, so students and planetarium visitors are able to travel through these stars and observe what they have looked like or what they will look like as the years go by.

  6. Gaia and the colonization of Mars.

    PubMed

    Margulis, L; West, O

    1993-11-01

    The Gaia hypothesis states that the atmosphere, hydrosphere, surface sediments, and life on Earth behave dynamically as a single integrated physiological system. What has been traditionally viewed as the passive environment is a highly active, integral part of the gaian system. Aspects of the surface temperature and chemistry are regulated by the sum of life, the biota. Formulated first by James E. Lovelock, in the late 1960s, the Gaia hypothesis has been in the scientific literature for more than 25 years. Because of its properties of exponential growth and propagation, life is a powerful geologic force. A useful aspect of the Gaia idea is that it requires integration of scientific disciplines for the study of Earth. The recently touted Earth system science is broadly parallel with the gaian concept of the physiochemical regulation of Earth's surface. We discuss here, in a gaian context, the colonization of Mars by Earth organisms. Although colonizing Mars may be impossible, its accomplishment would be exactly equivalent to "the reproduction of Gaia by budding."

  7. Gaia: The Implications for Industrialised Societies.

    ERIC Educational Resources Information Center

    Bunyard, Peter

    1988-01-01

    Many believe that life on Earth is part of a unified system. This article reviews the Gaia hypothesis and reviews the status of the Earth's ecology. Stressed is the impact of human activity on the ecosphere including acid rain, the greenhouse effect and other examples of climate change. (CW)

  8. The Spanish network for Gaia Science Exploitation

    NASA Astrophysics Data System (ADS)

    Figueras, F.; Jordi, C.; Luri, X.; Torra, J.; REG Executive Committee Team; Gaia UB Team

    2017-03-01

    The ''Red Española de Explotación Científica de Gaia'' (REG) continues to intensify its activities facing the imminent publication of the first and second Gaia data releases (14 September, 2016 and Q4-2017, respectively). The network, supported by the MINECO under contract Acciones de dinamizaci ´on, Redes de Excelencia (2016-2017), has as major priority the task to coordinate and support the collective activities developed by its more than 150 members. At present, REG plays a prominent role in the preparation of the Spanish community for the use of the Gaia data archive (a task lead by the Spanish team), in the work to exploit the Gaia-ESO survey collected during the last four years and in supporting the preparation of the science case and survey plan for WEAVE, the new multi-object spectrograph for the WHT at Canary Islands (commissioning, 2018). These activities are described together with the schedule of future national and international science meetings and the outreach activities being organized for the first and second Data Releases

  9. Gaia DR1 documentation Chapter 6: Variability

    NASA Astrophysics Data System (ADS)

    Eyer, L.; Rimoldini, L.; Guy, L.; Holl, B.; Clementini, G.; Cuypers, J.; Mowlavi, N.; Lecoeur-Taïbi, I.; De Ridder, J.; Charnas, J.; Nienartowicz, K.

    2017-12-01

    This chapter describes the photometric variability processing of the Gaia DR1 data. Coordination Unit 7 is responsible for the variability analysis of over a billion celestial sources. In particular the definition, design, development, validation and provision of a software package for the data processing of photometrically variable objects. Data Processing Centre Geneva (DPCG) responsibilities cover all issues related to the computational part of the CU7 analysis. These span: hardware provisioning, including selection, deployment and optimisation of suitable hardware, choosing and developing software architecture, defining data and scientific workflows as well as operational activities such as configuration management, data import, time series reconstruction, storage and processing handling, visualisation and data export. CU7/DPCG is also responsible for interaction with other DPCs and CUs, software and programming training for the CU7 members, scientific software quality control and management of software and data lifecycle. Details about the specific data treatment steps of the Gaia DR1 data products are found in Eyer et al. (2017) and are not repeated here. The variability content of the Gaia DR1 focusses on a subsample of Cepheids and RR Lyrae stars around the South ecliptic pole, showcasing the performance of the Gaia photometry with respect to variable objects.

  10. Gaia and the colonization of Mars

    NASA Technical Reports Server (NTRS)

    Margulis, L.; West, O.

    1993-01-01

    The Gaia hypothesis states that the atmosphere, hydrosphere, surface sediments, and life on Earth behave dynamically as a single integrated physiological system. What has been traditionally viewed as the passive environment is a highly active, integral part of the gaian system. Aspects of the surface temperature and chemistry are regulated by the sum of life, the biota. Formulated first by James E. Lovelock, in the late 1960s, the Gaia hypothesis has been in the scientific literature for more than 25 years. Because of its properties of exponential growth and propagation, life is a powerful geologic force. A useful aspect of the Gaia idea is that it requires integration of scientific disciplines for the study of Earth. The recently touted Earth system science is broadly parallel with the gaian concept of the physiochemical regulation of Earth's surface. We discuss here, in a gaian context, the colonization of Mars by Earth organisms. Although colonizing Mars may be impossible, its accomplishment would be exactly equivalent to "the reproduction of Gaia by budding.".

  11. Gaia DR2 documentation Chapter 6: Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sartoretti, P.; Blomme, R.; David, M.; Seabroke, G.

    2018-04-01

    This chapter of the Gaia DR2 documentation describes the processing and validation of the Radial Velocity Spectrometer (RVS) data. A more detailed description of the processing is provided in Sartoretti et al. (2018) and of the validation in Katz et al. (2018). A description of the RVS instrument is provided in Cropper et al. (2018).

  12. Gaia Reveals Evidence for Merged White Dwarfs

    NASA Astrophysics Data System (ADS)

    Kilic, Mukremin; Hambly, N. C.; Bergeron, P.; Genest-Beaulieu, C.; Rowell, N.

    2018-06-01

    We use Gaia Data Release 2 to identify 13,928 white dwarfs within 100 pc of the Sun. The exquisite astrometry from Gaia reveals for the first time a bifurcation in the observed white dwarf sequence in both Gaia and the Sloan Digital Sky Survey (SDSS) passbands. The latter is easily explained by a helium atmosphere white dwarf fraction of 36%. However, the bifurcation in the Gaia colour-magnitude diagram depends on both the atmospheric composition and the mass distribution. We simulate theoretical colour-magnitude diagrams for single and binary white dwarfs using a population synthesis approach and demonstrate that there is a significant contribution from relatively massive white dwarfs that likely formed through mergers. These include white dwarf remnants of main-sequence (blue stragglers) and post-main sequence mergers. The mass distribution of the SDSS subsample, including the spectroscopically confirmed white dwarfs, also shows this massive bump. This is the first direct detection of such a population in a volume-limited sample.

  13. Mapping young stellar populations toward Orion with Gaia DR1

    NASA Astrophysics Data System (ADS)

    Zari, E.; Brown, A. G. A.; de Bruijne, J.; Manara, C. F.; de Zeeuw, P. T.

    2017-12-01

    In this work we use the first data release of the Gaia mission to explore the three-dimensional arrangement and age ordering of the many stellar groups toward the Orion OB association, aiming at a new classification and characterization of the stellar population not embedded in the Orion A and B molecular clouds. We make use of the parallaxes and proper motions provided in the Tycho Gaia Astrometric Solution (TGAS) subset of the Gaia Data Release 1 (DR1) catalog and of the combination of Gaia DR1 and 2MASS photometry. In TGAS, we find evidence for the presence of a young population at a parallax ϖ 2.65 mas, which is loosely distributed around the following known clusters: 25 Ori, ɛ Ori, and σ Ori, and NGC 1980 (ι Ori) and the Orion Nebula Cluster (ONC). The low mass counterpart of this population is visible in the color magnitude diagrams constructed by combining Gaia DR1 G-band photometry and 2MASS. We study the density distribution of the young sources in the sky using a kernel density estimation (KDE). We find the same groups as in TGAS and also some other density enhancements that might be related to the recently discovered Orion X group, Orion dust ring, and λ Ori complex. The maps also suggest that the 25 Ori group presents a northern elongation. We estimated the ages of this population using a Bayesian isochronal fitting procedure assuming a unique parallax value for all the sources, and we inferred the presence of an age gradient going from 25 Ori (13-15 Myr) to the ONC (1-2 Myr). We confirmed this age ordering by repeating the Bayesian fit using the Pan-STARRS1 data. Intriguingly, the estimated ages toward the NGC 1980 cluster span a broad range of values. This can either be due to the presence of two populations coming from two different episodes of star formation or to a large spread along the line of sight of the same population. Some confusion might arise from the presence of unresolved binaries, which are not modeled in the fit, and usually mimic

  14. The fast transient sky with Gaia

    NASA Astrophysics Data System (ADS)

    Wevers, Thomas; Jonker, Peter G.; Hodgkin, Simon T.; Kostrzewa-Rutkowska, Zuzanna; Harrison, Diana L.; Rixon, Guy; Nelemans, Gijs; Roelens, Maroussia; Eyer, Laurent; van Leeuwen, Floor; Yoldas, Abdullah

    2018-01-01

    The ESA Gaia satellite scans the whole sky with a temporal sampling ranging from seconds and hours to months. Each time a source passes within the Gaia field of view, it moves over 10 charge coupled devices (CCDs) in 45 s and a light curve with 4.5 s sampling (the crossing time per CCD) is registered. Given that the 4.5 s sampling represents a virtually unexplored parameter space in optical time domain astronomy, this data set potentially provides a unique opportunity to open up the fast transient sky. We present a method to start mining the wealth of information in the per CCD Gaia data. We perform extensive data filtering to eliminate known onboard and data processing artefacts, and present a statistical method to identify sources that show transient brightness variations on ≲2 h time-scales. We illustrate that by using the Gaia photometric CCD measurements, we can detect transient brightness variations down to an amplitude of 0.3 mag on time-scales ranging from 15 s to several hours. We search an area of ∼23.5 deg2 on the sky and find four strong candidate fast transients. Two candidates are tentatively classified as flares on M-dwarf stars, while one is probably a flare on a giant star and one potentially a flare on a solar-type star. These classifications are based on archival data and the time-scales involved. We argue that the method presented here can be added to the existing Gaia Science Alerts infrastructure for the near real-time public dissemination of fast transient events.

  15. PREFACE: Stellar Atmospheres in the Gaia Era - Preface

    NASA Astrophysics Data System (ADS)

    Lobel, Alex; De Greve, Jean-Pierre; Van Rensbergen, Walter

    2011-12-01

    Volume 328 (2011) of the Journal of Physics: Conference Series provides a record of the invited and contributed talks, and of the posters presented at the GREAT-ESF workshop entitled `Stellar Atmospheres in the Gaia Era: Quantitative Spectroscopy and Comparative Spectrum Modelling' (http://great-esf.oma.be and mirrored at http://spectri.freeshell.org/great-esf). The conference was held on 23-24 June 2011 at the Vrije Universiteit Brussel, Belgium. 47 scientists from 11 countries around the world attended the workshop. The ESA-Gaia satellite (launch mid 2013) will observe a billion stellar objects in the Galaxy and provide spectrophotometric and high-resolution spectra of an unprecedented number of stars observed with a space-based instrument. The confrontation of these data with theoretical models will significantly advance our understanding of the physics of stellar atmospheres. New stellar populations such as previously unknown emission line stars will be discovered, and fundamental questions such as the basic scenarios of stellar evolution will be addressed with Gaia data. The 33 presentations and 4 main discussion sessions at the workshop addressed important topics in spectrum synthesis methods and detailed line profile calculations urgently needed for accurate modelling of stellar spectra. It brought together leading scientists and students of the stellar physics communities investigating hot and cool star spectra. The scientific programme of the workshop consisted of 23 oral (6 invited) and 10 poster presentations about cool stars (first day; Comparative Spectrum Modelling and Quantitative Spectroscopy of Cool Stars), and hot stars (second day; Quantitative Spectroscopy of Hot Stars). The hot and cool stars communities use different spectrum modelling codes for determining basic parameters such as the effective temperature, surface gravity, iron abundance, and the chemical composition of stellar atmospheres. The chaired sessions of the first day highlighted

  16. Precision Stellar and Planetary Astrophysics with TESS and Gaia

    NASA Astrophysics Data System (ADS)

    Stevens, Daniel J.; KELT Collaboration

    2018-01-01

    There is an ever-present need for precise and accurate stellar parameters, particularly for low-mass stars. For example, some fraction of measured M dwarf radii are inflated and have effective temperatures that are suppressed relative to predictions from models, but the physical cause of these effects is still uncertain. This is exacerbated by the fact that only a handful of M dwarfs -- all from double-lined eclipsing binaries (EBs) -- have both masses and radii measured to 3% or better. In the Gaia era, we can now measure model-independent masses and radii for single-lined EBs, thus expanding the sample of stars with precisely measured parameters by at least an order of magnitude, in principle. I will illustrate how one can combine Gaia parallaxes and broad-band stellar fluxes with the eclipse and radial velocity data to provide model-independent masses and radii. I will present our expected achievable constraints on the masses and radii of single-lined EBs. I will discuss both our current effort to turn several dozens of single-lined EBs discovered by the KELT and HATNet surveys into a catalog of exquisitely characterized stars and exoplanets as well as the prospects for achieving similar science for a much larger number of systems with TESS.

  17. Gaia: Science with 1 billion objects in three dimensions

    NASA Astrophysics Data System (ADS)

    Prusti, Timo

    2018-02-01

    Gaia is an operational satellite in the ESA science programme. It is gathering data for more than a billion objects. Gaia measures positions and motions of stars in our Milky Way Galaxy, but captures many asteroids and extragalactic sources as well. The first data release has already been made and exploitation by the world-wide scientific community is underway. Further data releases will be made with further increasing accuracy. Gaia is well underway to provide its promised set of fundamental astronomical data.

  18. Verifying reddening and extinction for Gaia DR1 TGAS giants

    NASA Astrophysics Data System (ADS)

    Gontcharov, George A.; Mosenkov, Aleksandr V.

    2018-03-01

    Gaia DR1 Tycho-Gaia Astrometric Solution parallaxes, Tycho-2 photometry, and reddening/extinction estimates from nine data sources for 38 074 giants within 415 pc from the Sun are used to compare their position in the Hertzsprung-Russell diagram with theoretical estimates, which are based on the PARSEC and MIST isochrones and the TRILEGAL model of the Galaxy with its parameters being widely varied. We conclude that (1) some systematic errors of the reddening/extinction estimates are the main uncertainty in this study; (2) any emission-based 2D reddening map cannot give reliable estimates of reddening within 415 pc due to a complex distribution of dust; (3) if a TRILEGAL's set of the parameters of the Galaxy is reliable and if the solar metallicity is Z < 0.021, then the reddening at high Galactic latitudes behind the dust layer is underestimated by all 2D reddening maps based on the dust emission observations of IRAS, COBE, and Planck and by their 3D followers (we also discuss some explanations of this underestimation); (4) the reddening/extinction estimates from recent 3D reddening map by Gontcharov, including the median reddening E(B - V) = 0.06 mag at |b| > 50°, give the best fit of the empirical and theoretical data with each other.

  19. Implementing the Gaia Astrometric Global Iterative Solution (AGIS) in Java

    NASA Astrophysics Data System (ADS)

    O'Mullane, William; Lammers, Uwe; Lindegren, Lennart; Hernandez, Jose; Hobbs, David

    2011-10-01

    This paper provides a description of the Java software framework which has been constructed to run the Astrometric Global Iterative Solution for the Gaia mission. This is the mathematical framework to provide the rigid reference frame for Gaia observations from the Gaia data itself. This process makes Gaia a self calibrated, and input catalogue independent, mission. The framework is highly distributed typically running on a cluster of machines with a database back end. All code is written in the Java language. We describe the overall architecture and some of the details of the implementation.

  20. Gaia Theory in Brazilian High School Biology Textbooks

    NASA Astrophysics Data System (ADS)

    Do Carmo, Ricardo Santos; Nunes-Neto, Nei Freitas; El-Hani, Charbel Niño

    2009-04-01

    Gaia theory proposes that a cybernetic system including the biota and the physicochemical environment regulates environmental variables at a global scale, keeping them within a range that makes Earth inhabitable by living beings. One can argue that this theory can play an important role in school science, since it bears upon current environmental problems, contributes to cross-disciplinary learning, and may help students understand the nature of science. Nevertheless, discourses about Gaia include both scientific and non-scientific ideas, and, consequently, this theory has been seen as pseudoscience, or even antiscience, as an unwarranted view, entangled with mysticism. But an informed view about the contributions and risks associated with Gaia as part of science education depends on a general analysis about the treatment of this theory in school knowledge. Here, we offer the first analysis of this sort, critically evaluating how Gaia is addressed in a representative sample of Brazilian textbooks ( n = 18). We present data about the presence or not of Gaia theory among the contents covered by the textbooks, the presence of the claim that Earth is living, whether and how they use analogies to justify this claim, the discussion of evidence for and against Gaia, and the treatment of its relevance to current issues. Gaia theory is explicitly addressed in ca. 39% of the analyzed textbooks. There is a general script that the textbooks that explicitly name the theory follow when discussing Gaia. First, they argue that life affects the environment, and support this argument by means of examples, then, explain what the Gaia theory proposes, discuss evidence in favor either of the idea that Earth is living or Gaia theory in general, introduce one or more analogies to justify the claim of a living Earth, and, finally, offer remarks on the current importance of Gaia. Three analogies used by Lovelock himself were found in the analyzed textbooks, Gaia as a superorganism, the

  1. Gaia: focus, straylight and basic angle

    NASA Astrophysics Data System (ADS)

    Mora, A.; Biermann, M.; Bombrun, A.; Boyadjian, J.; Chassat, F.; Corberand, P.; Davidson, M.; Doyle, D.; Escolar, D.; Gielesen, W. L. M.; Guilpain, T.; Hernandez, J.; Kirschner, V.; Klioner, S. A.; Koeck, C.; Laine, B.; Lindegren, L.; Serpell, E.; Tatry, P.; Thoral, P.

    2016-07-01

    The Gaia all-sky astrometric survey is challenged by several issues affecting the spacecraft stability. Amongst them, we find the focus evolution, straylight and basic angle variations Contrary to pre-launch expectations, the image quality is continuously evolving, during commissioning and the nominal mission. Payload decontaminations and wavefront sensor assisted refocuses have been carried out to recover optimum performance. An ESA-Airbus DS working group analysed the straylight and basic angle issues and worked on a detailed root cause analysis. In parallel, the Gaia scientists have also analysed the data, most notably comparing the BAM signal to global astrometric solutions, with remarkable agreement. In this contribution, a status review of these issues will be provided, with emphasis on the mitigation schemes and the lessons learned for future space missions where extreme stability is a key requirement.

  2. Automated spectral classification and the GAIA project

    NASA Technical Reports Server (NTRS)

    Lasala, Jerry; Kurtz, Michael J.

    1995-01-01

    Two dimensional spectral types for each of the stars observed in the global astrometric interferometer for astrophysics (GAIA) mission would provide additional information for the galactic structure and stellar evolution studies, as well as helping in the identification of unusual objects and populations. The classification of the large quantity generated spectra requires that automated techniques are implemented. Approaches for the automatic classification are reviewed, and a metric-distance method is discussed. In tests, the metric-distance method produced spectral types with mean errors comparable to those of human classifiers working at similar resolution. Data and equipment requirements for an automated classification survey, are discussed. A program of auxiliary observations is proposed to yield spectral types and radial velocities for the GAIA-observed stars.

  3. White dwarfs in the Gaia era

    NASA Astrophysics Data System (ADS)

    Tremblay, P.-E.; Gentile-Fusillo, N.; Cummings, J.; Jordan, S.; Gänsicke, B. T.; Kalirai, J. S.

    2018-04-01

    The vast majority of stars will become white dwarfs at the end of the stellar life cycle. These remnants are precise cosmic clocks owing to their well constrained cooling rates. Gaia Data Release 2 is expected to discover hundreds of thousands of white dwarfs, which can then be observed spectroscopically with WEAVE and 4MOST. By employing spectroscopically derived atmospheric parameters combined with Gaia parallaxes, white dwarfs can constrain the stellar formation history in the early developing phases of the Milky Way, the initial mass function in the 1.5 to 8 M ⊙ range, and the stellar mass loss as well as the state of planetary systems during the post main-sequence evolution.

  4. Challenges in the optical system of GAIA

    NASA Astrophysics Data System (ADS)

    Le Poole, Rudolf S.

    2017-11-01

    The precision aimed at by ESA's Astrometry and Radial Velocity mission GAIA surpasses that of the successful HIPPARCOS mission by more than 2 orders of magnitude, while at the same time increasing the number of objects 10000 times. This overwhelming increase in performance (statistical weight increased by 8 orders of magnitude) is achieved by insisting on a full description in terms of photon shot noise as the fundamental limiting factor. Yet such measurements refer to wave front topography to be understood to the level of better than 100 pico meters, in an optical system a few meters across. Obviously such understanding relies heavily on the expected stability, and chromatic effects also are of dominant importance, requiring stellar spectral energy distributions to be determined. It is fascinating that the experience of HIPPARCOS can indeed generate sufficient confidence for these performance specifications to be within reach. Elaborating the design specifications and tolerances I hope to convince you of GAIA's imminent success.

  5. SiC challenging parts for GAIA

    NASA Astrophysics Data System (ADS)

    Bougoin, M.

    2017-11-01

    GAIA is one of the cornerstone ESA missions which aims at compiling a catalogue of about one billion stars of our galaxy. Reaching the highly demanding scientific requirements lead ASTRIUM engineers to design a mechanically and thermally ultra-stable instrument. This is the reason why, thanks to its physical properties, the SiC turned out to be indispensable. The GAIA payload includes the following hardware which is mainly made of SiC i) the 3 meters quasi octagonal torus structure, ii) two identical 1.5 meters TMA type telescopes, iii) the central sub-assembly which holds several folding mirrors and the "Radial Velocity Spectrometer", iv) the focal plane and v) the "Basic Angle Monitoring". Due to the required large size (1 - 3 meters class), accuracy and shape complexity, developing and manufacturing these SiC parts was a real challenge for BOOSTEC. It is reviewed in this paper.

  6. Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars

    NASA Astrophysics Data System (ADS)

    Gontcharov, George A.; Mosenkov, Aleksandr V.

    2017-12-01

    We compare eight sources of reddening and extinction estimates for approximately 60 000 Gaia DR1 Tycho-Gaia Astrometric Solution (TGAS) main sequence stars younger than 3 Gyr with a relative error of the Gaia parallax less than 0.1. For the majority of the stars, the best 2D dust emission-based reddening maps show considerable differences between the reddening to infinity and the one calculated to the stellar distance using the barometric law of the dust distribution. This proves that the majority of the TGAS stars are embedded in the Galactic dust layer and a proper 3D treatment of the reddening/extinction is required to calculate their dereddened colours and absolute magnitudes reliably. Sources with 3D estimates of reddening are tested in their ability to put the stars among the PARSEC and MIST theoretical isochrones in the Hertzsprung-Russell diagram based on the precise Gaia, Tycho-2, 2MASS and WISE photometry. Only the reddening/extinction estimates by Arenou et al. and Gontcharov, being appropriate for nearby stars within 280 pc, provide both the minimal number of outliers bluer than any reasonable isochrone and the correct number of stars younger than 3 Gyr in agreement with the Besançon Galaxy model.

  7. Summer Session Organizational Models at Canadian Universities

    ERIC Educational Resources Information Center

    Kops, Bill

    2010-01-01

    The issue of summer session organizational models continues to be of interest to summer session deans/directors and university administrators. The University of Victoria surveyed Canadian universities on this issue in 1994. Based on a similar survey done in 2009, this paper updates the status of Canadian university summer session organizational…

  8. Spectroscopic classification of Gaia16alf

    NASA Astrophysics Data System (ADS)

    Onori, F.; Fraser, M.; Jonker, P.; Wyrzykowski, L.; Blagorodnova, N.; Mattila, S.

    2016-04-01

    We report the spectroscopic classification of Gaia16alf, from medium resolution (R~1000; 330-990nm) spectra taken with the William Herschel Telescope + ISIS + R300B/R158R on the night of 2016 April 19. The spectrum is consistent with that of a Type Ia SN a few days before maximum light at a redshift of z=0.094.

  9. GaiaGrid : Its Implications and Implementation

    NASA Astrophysics Data System (ADS)

    Ansari, S. G.; Lammers, U.; Ter Linden, M.

    2005-12-01

    Gaia is an ESA space mission to determine positions of 1 billion objects in the Galaxy at micro-arcsecond precision. The data analysis and processing requirements of the mission involves about 20 institutes across Europe, each providing specific algorithms for specific tasks, which range from relativistic effects on positional determination, classification, astrometric binary star detection, photometric analysis, spectroscopic analysis etc. In an initial phase, a study has been ongoing over the past three years to determine the complexity of Gaia's data processing. Two processing categories have materialised: core and shell. While core deals with routine data processing, shell tasks are algorithms to carry out data analysis, which involves the Gaia Community at large. For this latter category, we are currently experimenting with use of Grid paradigms to allow access to the core data and to augment processing power to simulate and analyse the data in preparation for the actual mission. We present preliminary results and discuss the sociological impact of distributing the tasks amongst the community.

  10. Empirical photometric calibration of the Gaia red clump: Colours, effective temperature, and absolute magnitude

    NASA Astrophysics Data System (ADS)

    Ruiz-Dern, L.; Babusiaux, C.; Arenou, F.; Turon, C.; Lallement, R.

    2018-01-01

    Context. Gaia Data Release 1 allows the recalibration of standard candles such as the red clump stars. To use those stars, they first need to be accurately characterised. In particular, colours are needed to derive interstellar extinction. As no filter is available for the first Gaia data release and to avoid the atmosphere model mismatch, an empirical calibration is unavoidable. Aims: The purpose of this work is to provide the first complete and robust photometric empirical calibration of the Gaia red clump stars of the solar neighbourhood through colour-colour, effective temperature-colour, and absolute magnitude-colour relations from the Gaia, Johnson, 2MASS, HIPPARCOS, Tycho-2, APASS-SLOAN, and WISE photometric systems, and the APOGEE DR13 spectroscopic temperatures. Methods: We used a 3D extinction map to select low reddening red giants. To calibrate the colour-colour and the effective temperature-colour relations, we developed a MCMC method that accounts for all variable uncertainties and selects the best model for each photometric relation. We estimated the red clump absolute magnitude through the mode of a kernel-based distribution function. Results: We provide 20 colour versus G-Ks relations and the first Teff versus G-Ks calibration. We obtained the red clump absolute magnitudes for 15 photometric bands with, in particular, MKs = (-1.606 ± 0.009) and MG = (0.495 ± 0.009) + (1.121 ± 0.128)(G-Ks-2.1). We present a dereddened Gaia-TGAS HR diagram and use the calibrations to compare its red clump and its red giant branch bump with Padova isochrones. Full Table A.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A116

  11. Gaia Launch Imminent: A Review of Practices (Good and Bad) in Building the Gaia Ground Segment

    NASA Astrophysics Data System (ADS)

    O'Mullane, W.

    2014-05-01

    As we approach launch the Gaia ground segment is ready to process a steady stream of complex data coming from Gaia at L2. This talk will focus on the software engineering aspects of the ground segment. Of course in a short paper it is difficult to cover everything but an attempt will be made to highlight some good things, like the Dictionary Tool and some things to be careful with like computer aided software engineering tools. The usefulness of some standards like ECSS will be touched upon. Testing is also certainly part of this story as are Challenges or Rehearsals so they will not go without mention.

  12. Ultracool dwarf benchmarks with Gaia primaries

    NASA Astrophysics Data System (ADS)

    Marocco, F.; Pinfield, D. J.; Cook, N. J.; Zapatero Osorio, M. R.; Montes, D.; Caballero, J. A.; Gálvez-Ortiz, M. C.; Gromadzki, M.; Jones, H. R. A.; Kurtev, R.; Smart, R. L.; Zhang, Z.; Cabrera Lavers, A. L.; García Álvarez, D.; Qi, Z. X.; Rickard, M. J.; Dover, L.

    2017-10-01

    We explore the potential of Gaia for the field of benchmark ultracool/brown dwarf companions, and present the results of an initial search for metal-rich/metal-poor systems. A simulated population of resolved ultracool dwarf companions to Gaia primary stars is generated and assessed. Of the order of ˜24 000 companions should be identifiable outside of the Galactic plane (|b| > 10 deg) with large-scale ground- and space-based surveys including late M, L, T and Y types. Our simulated companion parameter space covers 0.02 ≤ M/M⊙ ≤ 0.1, 0.1 ≤ age/Gyr ≤ 14 and -2.5 ≤ [Fe/H] ≤ 0.5, with systems required to have a false alarm probability <10-4, based on projected separation and expected constraints on common distance, common proper motion and/or common radial velocity. Within this bulk population, we identify smaller target subsets of rarer systems whose collective properties still span the full parameter space of the population, as well as systems containing primary stars that are good age calibrators. Our simulation analysis leads to a series of recommendations for candidate selection and observational follow-up that could identify ˜500 diverse Gaia benchmarks. As a test of the veracity of our methodology and simulations, our initial search uses UKIRT Infrared Deep Sky Survey and Sloan Digital Sky Survey to select secondaries, with the parameters of primaries taken from Tycho-2, Radial Velocity Experiment, Large sky Area Multi-Object fibre Spectroscopic Telescope and Tycho-Gaia Astrometric Solution. We identify and follow up 13 new benchmarks. These include M8-L2 companions, with metallicity constraints ranging in quality, but robust in the range -0.39 ≤ [Fe/H] ≤ +0.36, and with projected physical separation in the range 0.6 < s/kau < 76. Going forward, Gaia offers a very high yield of benchmark systems, from which diverse subsamples may be able to calibrate a range of foundational ultracool/sub-stellar theory and observation.

  13. The Gaia Investigation of the Solar System

    NASA Astrophysics Data System (ADS)

    Delbo, Marco; Tanga, Paolo; Mignard, Francois; Cellino, Alberto; Hestroffer, Daniel

    2015-08-01

    The space mission Gaia of the European Space Agency (ESA) has begun its scientific whole-sky survey of all astrophysical sources with V<=20 in July 2014. The high precision astrometry is the main science driver for the mission, but Gaia will also obtain visible photometry and low-resolution spectroscopy of the observed sources, including solar system small bodies. Preliminary results show a good quality of the data, in general, in line with the expected pre-flight specifications. These data will consist a mine of information for a remote-sensing exploration of the small worlds of our Solar System. Indeed, ~250,000 asteroids will be observed by Gaia throughout its 5-years-long mission. After an update about the status of the mission and the on-going data analysis, including some preliminary results, we are going to present the plans for the data releases, the first foreseen at the end of 2016, and the general data treatment.We will show how Gaia spectroscopy will allow up to map the composition of about 100,000 asteroids throughout the Main Belt, with high signal to noise ratio. Given its advantage position outside the Earth's atmosphere, the blue part of the spectrum (roughly below 0.5 micron) will be observed for an unprecedented number of asteroids.Additionally, precise photometry and astrometry will also be important to reveal the physical nature of these small bodies. In particular, it is estimated that three-dimensional shapes, rotation, period and pole orientation will be derived for 10,000 asteroids. The masses of about 150 of the largest asteroids, will be determined from measurements of the orbital gravitational perturbations that these bodies will exert on small asteroids during mutual close approaches.Moreover, the combination of Gaia data (delivering masses and shapes) with infrared radiometric observations, e.g. from the NASA WISE mission (informing us about the size of the bodies), will allow precise asteroid bulk densities to be determined. The bulk

  14. University Administration on a Political Model.

    ERIC Educational Resources Information Center

    Walker, Donald E.

    1979-01-01

    It is suggested that recognizing the university as a political community may lead to better management and organization. The patriarchal role, the president as hero, dispersed power, how the university really functions, and a political model are described. (MLW)

  15. The Gaia-ESO Survey: Probes of the inner disk abundance gradient

    NASA Astrophysics Data System (ADS)

    Jacobson, H. R.; Friel, E. D.; Jílková, L.; Magrini, L.; Bragaglia, A.; Vallenari, A.; Tosi, M.; Randich, S.; Donati, P.; Cantat-Gaudin, T.; Sordo, R.; Smiljanic, R.; Overbeek, J. C.; Carraro, G.; Tautvaišienė, G.; San Roman, I.; Villanova, S.; Geisler, D.; Muñoz, C.; Jiménez-Esteban, F.; Tang, B.; Gilmore, G.; Alfaro, E. J.; Bensby, T.; Flaccomio, E.; Koposov, S. E.; Korn, A. J.; Pancino, E.; Recio-Blanco, A.; Casey, A. R.; Costado, M. T.; Franciosini, E.; Heiter, U.; Hill, V.; Hourihane, A.; Lardo, C.; de Laverny, P.; Lewis, J.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Sousa, S. G.; Worley, C. C.; Zaggia, S.

    2016-06-01

    Context. The nature of the metallicity gradient inside the solar circle (RGC < 8 kpc) is poorly understood, but studies of Cepheids and a small sample of open clusters suggest that it steepens in the inner disk. Aims: We investigate the metallicity gradient of the inner disk using a sample of inner disk open clusters that is three times larger than has previously been studied in the literature to better characterize the gradient in this part of the disk. Methods: We used the Gaia-ESO Survey (GES) [Fe/H] values and stellar parameters for stars in 12 open clusters in the inner disk from GES-UVES data. Cluster mean [Fe/H] values were determined based on a membership analysis for each cluster. Where necessary, distances and ages to clusters were determined via comparison to theoretical isochrones. Results: The GES open clusters exhibit a radial metallicity gradient of -0.10 ± 0.02 dex kpc-1, consistent with the gradient measured by other literature studies of field red giant stars and open clusters in the range RGC ~ 6-12 kpc. We also measure a trend of increasing [Fe/H] with increasing cluster age, as has also been found in the literature. Conclusions: We find no evidence for a steepening of the inner disk metallicity gradient inside the solar circle as earlier studies indicated. The age-metallicity relation shown by the clusters is consistent with that predicted by chemical evolution models that include the effects of radial migration, but a more detailed comparison between cluster observations and models would be premature. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 188.B-3002 and 193.B-0936. These data products have been processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge, and by the FLAMES/UVES reduction team at INAF/Osservatorio Astrofisico di Arcetri. These data have been obtained from the Gaia-ESO Survey Data Archive

  16. Gaia DR2 documentation Chapter 8: Astrophysical Parameters

    NASA Astrophysics Data System (ADS)

    Manteiga, M.; Andrae, R.; Fouesneau, M.; Creevey, O.; Ordenovic, C.; Mary, N.; Jean-Antoine-Piccolo, A.; Bailer-Jones, C. A. L.

    2018-04-01

    This chapter of the Gaia DR2 documentation describes Apsis, the Astrophysical Parameters Inference System used for processing Gaia DR2 data. Beyond this documentation, a complete description of the processing and the results, as well as additional validations, have been published in Andrae et al. (2018).

  17. Optical confirmation of Gaia18ayp brightness increase

    NASA Astrophysics Data System (ADS)

    Spano, M.; Blanco-Cuaresma, S.; Roelens, M.; Mowlavi, N.; Eyer, L.

    2018-04-01

    We report confirmation of Gaia_Science_Alerts, brightness increase of the QSO [VV2006] J233633.0-411547, Gaia18ayp . Images were obtained through modified Gunn R and V band filter of the ECAM instrument installed on the Swiss 1.2m Euler telescope at La Silla, on 2018 April 21- 22. Magnitudes according to the MJD of observations.

  18. University Satellite Campus Management Models

    ERIC Educational Resources Information Center

    Fraser, Doug; Stott, Ken

    2015-01-01

    Among the 60 or so university satellite campuses in Australia are many that are probably failing to meet the high expectations of their universities and the communities they were designed to serve. While in some cases this may be due to the demand driven system, it may also be attributable in part to the ways in which they are managed. The…

  19. A Gaia study of the Hyades open cluster

    NASA Astrophysics Data System (ADS)

    Reino, Stella; de Bruijne, Jos; Zari, Eleonora; d'Antona, Francesca; Ventura, Paolo

    2018-03-01

    We present a study of the membership of the Hyades open cluster, derive kinematically-modelled parallaxes of its members, and study the colour-absolute magnitude diagram of the cluster. We use Gaia DR1 Tycho-Gaia Astrometric Solution (TGAS) data complemented by Hipparcos-2 data for bright stars not contained in TGAS. We supplement the astrometric data with radial velocities collected from a dozen literature sources. By assuming that all cluster members move with the mean cluster velocity to within the velocity dispersion, we use the observed and the expected motions of the stars to determine individual cluster membership probabilities. We subsequently derive improved parallaxes through maximum-likelihood kinematic modelling of the cluster. This method has an iterative component to deal with 'outliers', caused for instance by double stars or escaping members. Our method extends an existing method and supports the mixed presence of stars with and without radial velocities. We find 251 candidate members, 200 of which have a literature radial velocity, and 70 of which are new candidate members with TGAS astrometry. The cluster is roughly spherical in its centre but significantly flattened at larger radii. The observed colour-absolute magnitude diagram shows a clear binary sequence. The kinematically-modelled parallaxes that we derive are a factor ˜1.7 / 2.9 more precise than the TGAS / Hipparcos-2 values and allow to derive an extremely sharp main sequence. This sequence shows evidence for fine-detailed structure which is elegantly explained by the full spectrum turbulence model of convection.

  20. Spectroscopic observation of Gaia17dht and Gaia17diu by NUTS (NOT Un-biased Transient Survey)

    NASA Astrophysics Data System (ADS)

    Fraser, M.; Dyrbye, S.; Cappella, E.

    2017-12-01

    The Nordic Optical Telescope (NOT) Unbiased Transient Survey (NUTS; ATel #8992) reports the spectroscopic classification of Gaia17dht/SN2017izz and Gaia17diu/SN2017jdb (in host galaxies SDSS J145121.24+283521.6 and LEDA 2753585 respectively).

  1. Virtual Universities: Current Models and Future Trends.

    ERIC Educational Resources Information Center

    Guri-Rosenblit, Sarah

    2001-01-01

    Describes current models of distance education (single-mode distance teaching universities, dual- and mixed-mode universities, extension services, consortia-type ventures, and new technology-based universities), including their merits and problems. Discusses future trends in potential student constituencies, faculty roles, forms of knowledge…

  2. Kinematics of symmetric Galactic longitudes to probe the spiral arms of the Milky Way with Gaia

    NASA Astrophysics Data System (ADS)

    Antoja, T.; Roca-Fàbrega, S.; de Bruijne, J.; Prusti, T.

    2016-05-01

    Aims: We model the effects of the spiral arms of the Milky Way on the disk stellar kinematics in the Gaia observable space. We also estimate the Gaia capabilities of detecting the predicted signatures. Methods: We use both controlled orbital integrations in analytic potentials and self-consistent simulations. We introduce a new strategy to investigate the effects of spiral arms, which consists of comparing the stellar kinematics of symmetric Galactic longitudes (+l and -l), in particular the median transverse velocity as determined from parallaxes and proper motions. This approach does not require the assumption of an axisymmetric model because it involves an internal comparison of the data. Results: The typical differences between the transverse velocity in symmetric longitudes in the models are of the order of ~2 km s-1, but can be larger than 10 km s-1 for certain longitudes and distances. The longitudes close to the Galactic centre and to the anti-centre are those with larger and smaller differences, respectively. The differences between the kinematics for +l and -l show clear trends that depend strongly on the properties of spiral arms. Thus, this method can be used to quantify the importance of the effects of spiral arms on the orbits of stars in the different regions of the disk, and to constrain the location of the arms, main resonances and, thus, pattern speed. Moreover, the method allows us to test different origin scenarios of spiral arms and the dynamical nature of the spiral structure (e.g. grand design versus transient multiple arms). We estimate the number of stars of each spectral type that Gaia will observe in certain representative Galactic longitudes, their characteristic errors in distance and transverse velocity, and the error in computing the median velocity as a function of distance. We will be able to measure the median transverse velocity exclusively with Gaia data, with precision smaller than ~1 km s-1 up to distances of ~4-6 kpc for

  3. Robustness and Contingent History: From Prisoner's Dilemma to Gaia Theory.

    PubMed

    Harvey, Inman

    2018-01-01

    In both social systems and ecosystems there is a need to resolve potential conflicts between the interests of individuals and the collective interest of the community. The collective interests need to survive the turbulent dynamics of social and ecological interactions. To see how different systems with different sets of interactions have different degrees of robustness, we need to look at their different contingent histories. We analyze abstract artificial life models of such systems, and note that some prominent examples rely on explicitly ahistorical frameworks; we point out where analyses that ignore a contingent historical context can be fatally flawed. The mathematical foundations of Gaia theory are presented in a form whose very basic and general assumptions point to wide applicability across complex dynamical systems. This highlights surprising connections between robustness and accumulated contingent happenstance, regardless of whether Darwinian evolution is or is not implicated. Real-life studies highlight the role of history, and artificial life studies should do likewise.

  4. Unresolved Galaxy Classifier for ESA/Gaia mission: Support Vector Machines approach

    NASA Astrophysics Data System (ADS)

    Bellas-Velidis, Ioannis; Kontizas, Mary; Dapergolas, Anastasios; Livanou, Evdokia; Kontizas, Evangelos; Karampelas, Antonios

    A software package Unresolved Galaxy Classifier (UGC) is being developed for the ground-based pipeline of ESA's Gaia mission. It aims to provide an automated taxonomic classification and specific parameters estimation analyzing Gaia BP/RP instrument low-dispersion spectra of unresolved galaxies. The UGC algorithm is based on a supervised learning technique, the Support Vector Machines (SVM). The software is implemented in Java as two separate modules. An offline learning module provides functions for SVM-models training. Once trained, the set of models can be repeatedly applied to unknown galaxy spectra by the pipeline's application module. A library of galaxy models synthetic spectra, simulated for the BP/RP instrument, is used to train and test the modules. Science tests show a very good classification performance of UGC and relatively good regression performance, except for some of the parameters. Possible approaches to improve the performance are discussed.

  5. Optical interferometry and Gaia parallaxes for a robust calibration of the Cepheid distance scale

    NASA Astrophysics Data System (ADS)

    Kervella, Pierre; Mérand, Antoine; Gallenne, Alexandre; Trahin, Boris; Borgniet, Simon; Pietrzynski, Grzegorz; Nardetto, Nicolas; Gieren, Wolfgang

    2018-04-01

    We present the modeling tool we developed to incorporate multi-technique observations of Cepheids in a single pulsation model: the Spectro-Photo-Interferometry of Pulsating Stars (SPIPS). The combination of angular diameters from optical interferometry, radial velocities and photometry with the coming Gaia DR2 parallaxes of nearby Galactic Cepheids will soon enable us to calibrate the projection factor of the classical Parallax-of-Pulsation method. This will extend its applicability to Cepheids too distant for accurate Gaia parallax measurements, and allow us to precisely calibrate the Leavitt law's zero point. As an example application, we present the SPIPS model of the long-period Cepheid RS Pup that provides a measurement of its projection factor, using the independent distance estimated from its light echoes.

  6. Runaway companions of supernova remnants with Gaia

    NASA Astrophysics Data System (ADS)

    Boubert, Douglas; Fraser, Morgan; Evans, N. Wyn

    2018-04-01

    It is expected that most massive stars have companions and thus that some core-collapse supernovae should have a runaway companion. The precise astrometry and photometry provided by Gaia allows for the systematic discovery of these runaway companions. We combine a prior on the properties of runaway stars from binary evolution with data from TGAS and APASS to search for runaway stars within ten nearby supernova remnants. We strongly confirm the existing candidate HD 37424 in S147, propose the Be star BD+50 3188 to be associated with HB 21, and suggest tentative candidates for the Cygnus and Monoceros Loops.

  7. Emergent universe model with dissipative effects

    NASA Astrophysics Data System (ADS)

    Debnath, P. S.; Paul, B. C.

    2017-12-01

    Emergent universe model is presented in general theory of relativity with isotropic fluid in addition to viscosity. We obtain cosmological solutions that permit emergent universe scenario in the presence of bulk viscosity that are described by either Eckart theory or Truncated Israel Stewart (TIS) theory. The stability of the solutions are also studied. In this case, the emergent universe (EU) model is analyzed with observational data. In the presence of viscosity, one obtains emergent universe scenario, which however is not permitted in the absence of viscosity. The EU model is compatible with cosmological observations.

  8. The Offshore Model for Universities

    ERIC Educational Resources Information Center

    Ross, Andrew

    2008-01-01

    This article discusses the ongoing effort of the World Trade Organization (WTO) to bring higher education services within the purview of the General Agreement on Trade and Services (GATS). One result of the anticipated liberalization of trade in education, the author explains, is the headlong rush of Anglophone universities into the global market…

  9. University Students' Meta-Modelling Knowledge

    ERIC Educational Resources Information Center

    Krell, Moritz; Krüger, Dirk

    2017-01-01

    Background: As one part of scientific meta-knowledge, students' meta-modelling knowledge should be promoted on different educational levels such as primary school, secondary school and university. This study focuses on the assessment of university students' meta-modelling knowledge using a paper-pencil questionnaire. Purpose: The general purpose…

  10. A 1.3 giga pixels focal plane for GAIA

    NASA Astrophysics Data System (ADS)

    Laborie, Anouk; Pouny, Pierre; Vetel, Cyril; Collados, Emmanuel; Rougier, Gilles; Davancens, Robert; Zayer, Igor; Perryman, Michael; Pace, Oscar

    2004-06-01

    The astrometric mission GAIA is a cornerstone mission of the European Space Agency, due for launch in the 2010 time frame. Requiring extremely demanding performance GAIA calls for the development of an unprecedented large focal plane featuring innovative technologies. For securing the very challenging GAIA development, a significant number of technology activities have been initiated by ESA through a competitive selection process. In this context, an industrial consortium led by EADS-Astrium (France) with e2v technologies (UK) as major subcontractor was selected for the GAIA CCD and Focal Plane Technology Demonstrators programme, which is by far the most significant and the most critical GAIA pre-development for all aspects: science performance, development schedule and cost. This programme has started since August 2002 and will end early 2005 prior to commencement of the GAIA Phase B. While the GAIA payload will host three instruments and related focal planes, the major mission objectives are assigned to the Astrometric (ASTRO) Focal Plane, which is the subject of this presentation.

  11. Testing Modified Gravity Theories via Wide Binaries and GAIA

    NASA Astrophysics Data System (ADS)

    Pittordis, Charalambos; Sutherland, Will

    2018-06-01

    The standard ΛCDM model based on General Relativity (GR) including cold dark matter (CDM) is very successful at fitting cosmological observations, but recent non-detections of candidate dark matter (DM) particles mean that various modified-gravity theories remain of significant interest. The latter generally involve modifications to GR below a critical acceleration scale ˜10-10 m s-2. Wide-binary (WB) star systems with separations ≳ 5 kAU provide an interesting test for modified gravity, due to being in or near the low-acceleration regime and presumably containing negligible DM. Here, we explore the prospects for new observations pending from the GAIA spacecraft to provide tests of GR against MOND or TeVes-like theories in a regime only partially explored to date. In particular, we find that a histogram of (3D) binary relative velocities, relative to equilibrium circular velocity predicted from the (2D) projected separation predicts a rather sharp feature in this distribution for standard gravity, with an 80th (90th) percentile value close to 1.025 (1.14) with rather weak dependence on the eccentricity distribution. However, MOND/TeVeS theories produce a shifted distribution, with a significant increase in these upper percentiles. In MOND-like theories without an external field effect, there are large shifts of order unity. With the external field effect included, the shifts are considerably reduced to ˜0.04 - 0.08, but are still potentially detectable statistically given reasonably large samples and good control of contaminants. In principle, followup of GAIA-selected wide binaries with ground-based radial velocities accurate to ≲ 0.03 { km s^{-1}} should be able to produce an interesting new constraint on modified-gravity theories.

  12. Possible systematics in the VLBI catalogs as seen from Gaia

    NASA Astrophysics Data System (ADS)

    Liu, N.; Zhu, Z.; Liu, J.-C.

    2018-01-01

    Aims: In order to investigate the systematic errors in the very long baseline interferometry (VLBI) positions of extragalactic sources (quasars) and the global differences between Gaia and VLBI catalogs, we use the first data release of Gaia (Gaia DR1) quasar positions as the reference and study the positional offsets of the second realization of the International Celestial Reference Frame (ICRF2) and the Goddard VLBI solution 2016a (gsf2016a) catalogs. Methods: We select a sample of 1032 common sources among three catalogs and adopt two methods to represent the systematics: considering the differential orientation (offset) and declination bias; analyzing with the vector spherical harmonics (VSH) functions. Results: Between two VLBI catalogs and Gaia DR1, we find that: i) the estimated orientation is consistent with the alignment accuracy of Gaia DR1 to ICRF, of 0.1 mas, but the southern and northern hemispheres show opposite orientations; ii) the declination bias in the southern hemisphere between Gaia DR1 and ICRF2 is estimated to be +152 μas, much larger than that between Gaia DR1 and gsf2016a which is +34 μas. Between two VLBI catalogs, we find that: i) the rotation component shows that ICRF2 and gsf2016a are generally consistent within 30 μas; ii) the glide component and quadrupole component report two declination-dependent offsets: dipolar deformation of +50 μas along the Z-axis, and quadrupolar deformation of -50 μas that would induce a pattern of sin2δ. Conclusions: The significant declination bias between Gaia DR1 and ICRF2 catalogs reported in previous studies is possibly attributed to the systematic errors of ICRF2 in the southern hemisphere. The global differences between ICRF2 and gsf2016a catalogs imply that possible, mainly declination-dependent systematics exit in the VLBI positions and need further investigations in the future Gaia data release and the next generation of ICRF.

  13. Gaia, an all-sky survey for standard photometry

    NASA Astrophysics Data System (ADS)

    Carrasco, J. M.; Weiler, M.; Jordi, C.; Fabricius, C.

    2017-03-01

    Gaia ESA's space mission (launched in 2013) includes two low resolution spectroscopic instruments (one in the blue, BP, and another in the red, RP, wavelength domains) to classify and derive the astrophysical parameters of the observed sources. As it is well known, Gaia is a full-sky unbiased survey down to about 20th magnitude. The scanning law yields a rather uniform coverage of the sky over the full extent (a minimum of 5 years) of the mission. Gaia data reduction is a global one over the full mission. Both sky coverage and data reduction strategy ensure an unprecedented all-sky homogeneous spectrophotometric survey. Certainly, that survey is of interest for current and future on-ground and space projects, like LSST, PLATO, EUCLID and J-PAS/J-PLUS among others. These projects will benefit from the large amount (more than one billion) and wide variety of objects observed by Gaia with good quality spectrophotometry. Synthetic photometry derived from Gaia spectrophotometry for any passband can be used to expand the set of standard sources for these new instruments to come. In the current Gaia data release scenario, BP/RP spectrophotometric data will be available in the third release (in 2018, TBC). Current preliminary results allow us to estimate the precision of synthetic photometry derived from the Gaia data. This already allows the preparation of the on-going and future surveys and space missions. We discuss here the exploitation of the Gaia spectrophotometry as standard reference due to its full-sky coverage and its expected photometric uncertainties derived from the low resolution Gaia spectra.

  14. Double-blind test program for astrometric planet detection with Gaia

    NASA Astrophysics Data System (ADS)

    Casertano, S.; Lattanzi, M. G.; Sozzetti, A.; Spagna, A.; Jancart, S.; Morbidelli, R.; Pannunzio, R.; Pourbaix, D.; Queloz, D.

    2008-05-01

    planetary systems, will discover and measure several thousands of giant planets out to 3-4 AUs from stars within 200 pc, and will characterize hundreds of multiple-planet systems, including meaningful coplanarity tests. Finally, we put Gaia's planet discovery potential into context, identifying several areas of planetary-system science (statistical properties and correlations, comparisons with predictions from theoretical models of formation and evolution, interpretation of direct detections) in which Gaia can be expected, on the basis of our results, to have a relevant impact, when combined with data coming from other ongoing and future planet search programs.

  15. Calibration and characterisation of the Gaia Red Clump

    NASA Astrophysics Data System (ADS)

    Ruiz-Dern, L.; Babusiaux, C.; Arenou, F.; Danielski, C.; Turon, C.; Sartoretti, P.

    2018-04-01

    We present new empirical Colour-Colour and Effective Temperature-Colour Gaia Red Clump calibrations. The selected sample takes into account high photometric quality, good spectrometric metallicity, homogeneous effective temperatures and low interstellar extinctions. From those calibrations we developed a method to derive the absolute magnitude, temperature and extinction of the Gaia RC. We tested our colour and extinction estimates on stars with measured spectroscopic effective temperatures and Diffuse Interstellar Band (DIB) constraints. Within the Gaia Validation team these calibrations are also being used, together with asteroseismic constraints, to check the parallax zero-point with Red Clump stars.

  16. The Gaia mission a rich resource for outreach activities

    NASA Astrophysics Data System (ADS)

    O'Flaherty, K. S.; Douglas, J.; Prusti, T.

    2008-07-01

    Space science missions, and astronomy missions in particular, capture the public imagination at all levels. ESA's Gaia mission is no exception to this. In addition to its key scientific goal of providing new insight into the origin, formation, and evolution of the Milky Way, Gaia also touches on many other scientific topics of broad appeal, for example, solar system objects, stars (including rare and exotic ones), dark matter, gravitational light bending. The mission naturally provides a rich resource for outreach possibilities whether it be to the general public, or to specific interest groups, such as scientists from other fields or educators. We present some examples of possible outreach activities for Gaia.

  17. A Study Guide for the Analysis of Gaia Astrometic Data

    NASA Astrophysics Data System (ADS)

    van Altena, W. F.

    2018-01-01

    The purpose of this paper is to enthusiastically support the use of Gaia's data and to suggest an approach for improving our backgrounds so that its data is used in the best possible manner. The principal goals of the Gaia mission are to investigate the origin and subsequent evolution of the Milky Way by mapping the Galaxy to the 20th magnitude and the determination of positions, parallaxes and proper motions of 109 stars. In addition, Gaia is to determine spectroscopic data including the metallicity, distance, extinction and radial velocities for 150× 106 stars brighter than 15th magnitude.

  18. A Collaborative University Model for Employee Wellness

    ERIC Educational Resources Information Center

    Carter, Melondie R.; Kelly, Rebecca C.; Alexander, Chelley K.; Holmes, Lauren M.

    2011-01-01

    Universities are taking a more active approach in understanding and monitoring employees' modifiable health risk factors and chronic care conditions by developing strategies to encourage employees to start and sustain healthy behaviors. WellBama, the University of Alabama's signature health and wellness program, utilizes a collaborative model in…

  19. International Universities: Misunderstandings and Emerging Models?

    ERIC Educational Resources Information Center

    Knight, Jane

    2015-01-01

    Internationalization has transformed higher education institutions and systems but there is much confusion as to what an international, binational, transnational, cosmopolitan, multinational, or global university actually means. There is no standardized model for an international university, nor should there be, but a deeper understanding of…

  20. VOSA: SED building and analysis of thousands of stars in the framework of Gaia

    NASA Astrophysics Data System (ADS)

    Rodrigo, C.; Solano, E.; Bayo, A.

    2014-07-01

    VOSA (http://svo2.cab.inta-csic.es/theory/vosa/), is a web-based tool designed to combine private photometric measurements with data available in VO services distributed worldwide to build the observational spectral energy distributions (SEDs) of hundreds of objects. VOSA also accesses various collections of models to simulate the equivalent theoretical SEDs, allows the user to decide the range of physical parameters to explore, performs the SED comparison, provides the best fitting models to the user following two different approaches (chi square and Bayesian fitting), and, for stellar sources, compares these parameters with isochrones and evolutionary tracks to estimate masses and ages. In particular, VOSA offers the advantage of deriving physical parameters using all the available photometric information instead of a restricted subset of colors. VOSA was firstly released in 2008 and its functionalities are described in Bayo et al. (2008). At the time of writing there are more than 300 active users in VOSA who have published more than 60 refereed papers. In the framework of the GENIUS (https://gaia.am.ub.es/Twiki/bin/view/GENIUS) project we are upgrading VOSA to, on one hand, provide a seamless access to Gaia data and, on the other hand, handle thousands of objects at a time. In this poster, the main functionalities to be implemented in the Gaia context will be described. The poster can be found at: http://svo.cab.inta-csic.es/files/svo//Public/SVOPapers/posters/vosa-poster3.pdf.

  1. Gaia and exoplanets: a revolution in the making

    NASA Astrophysics Data System (ADS)

    Sozzetti, Alessandro

    2017-09-01

    The Gaia global astrometry mission is now entering its fourth year of routine science operations. With the publication of the first data release in September 2016, it has begun to fulfil its promise for revolutionary science in countless aspects of Galactic astronomy and astrophysics. I briefly review the Gaia mission status of operations and the scenario for the upcoming intermediate data releases, focusing on important lessons learned. Then, I illustrate the Gaia exoplanet science case, and discuss how the field will be revolutionized by the power of microarcsecond (μas) astrometry that is about to be unleashed. I conclude by touching upon some of the synergy elements that will call for combination of Gaia data with other indirect and direct detection and characterization techniques, for much improved understanding of exoplanetary systems.

  2. Using the Gaia Hypothesis to Synthesize an Introductory Biology Course.

    ERIC Educational Resources Information Center

    Baker, Gail A.

    1993-01-01

    The Gaia Hypothesis emphasizes the interactions and feedback mechanisms between the living and nonliving process that take place on Earth. Employing this concept in instruction can emphasize the interdisciplinary nature of science and give a planetary perspective of biology. (PR)

  3. Reuleaux models at St. Petersburg State University

    NASA Astrophysics Data System (ADS)

    Kuteeva, G. A.; Sinilshchikova, G. A.; Trifonenko, B. V.

    2018-05-01

    Franz Reuleaux (1829 - 1905) is a famous mechanical engineer, a Professor of the Berlin Royal Technical Academy. He became widely known as an engineer-scientist, a Professor and industrial consultant, education reformer and leader of the technical elite of Germany. He directed the design and manufacture of over 300 models of simple mechanisms. They were sold to many famous universities for pedagogical and scientific purposes. Today, the most complete set is at Cornell University, College of Engineering. In this article we discuss the history, the modern state and our using the Reuleaux models that survived at St. Petersburg State University for educational purposes. We present description of certain models and our electronic resource with these models. We provide the information of similar electronic resources from other universities.

  4. Model Rocketry: University-Level Educational Tool

    ERIC Educational Resources Information Center

    Barrowman, James S.

    1974-01-01

    Describes how model rocketry can be a useful educational tool at the university level as a practical application of theoretical aerodynamic concepts and as a tool for students in experimental research. (BR)

  5. Aligning HST Images to Gaia: A Faster Mosaicking Workflow

    NASA Astrophysics Data System (ADS)

    Bajaj, V.

    2017-11-01

    We present a fully programmatic workflow for aligning HST images using the high-quality astrometry provided by Gaia Data Release 1. Code provided in a Jupyter Notebook works through this procedure, including parsing the data to determine the query area parameters, querying Gaia for the coordinate catalog, and using the catalog with TweakReg as reference catalog. This workflow greatly simplifies the normally time-consuming process of aligning HST images, especially those taken as part of mosaics.

  6. GaiaNIR - A future all-sky astrometry mission

    NASA Astrophysics Data System (ADS)

    Hobbs, David; Høg, Erik

    2018-04-01

    With the launch of Gaia in December 2013, Europe entered a new era of space astrometry following in the footsteps of the very successful Hipparcos mission. A weakness of Gaia is that it only operates at optical wavelengths. However, much of the Galactic centre and the spiral arm regions are obscured by interstellar extinction. An obvious improvement on Gaia is to include the Near-Infra-Red (NIR) which requires the use of new types of detectors. Additionally, to scan the entire sky and measure global absolute parallaxes the spacecraft must have a constant rotation resulting in a moving image that must be compensated for by, for example, operating the detectors in Time Delayed Integration (TDI) mode. If these technical issues can be solved a new Gaia-like mission separated by a 20 year interval would give; 1) NIR all-sky astrometry and photometry to penetrate the obscured regions and to observe intrinsically red objects with almost diffraction limited resolution; 2) improved proper motions with fourteen times smaller errors than from Gaia alone opening up new science cases, such as long period exoplanets and accurate halo measurements; 3) allow the slowly degrading accuracy of the Gaia reference frame, which will be the basis for future astronomical measurements, to be reset.

  7. Gaia Data Release 1. Pre-processing and source list creation

    NASA Astrophysics Data System (ADS)

    Fabricius, C.; Bastian, U.; Portell, J.; Castañeda, J.; Davidson, M.; Hambly, N. C.; Clotet, M.; Biermann, M.; Mora, A.; Busonero, D.; Riva, A.; Brown, A. G. A.; Smart, R.; Lammers, U.; Torra, J.; Drimmel, R.; Gracia, G.; Löffler, W.; Spagna, A.; Lindegren, L.; Klioner, S.; Andrei, A.; Bach, N.; Bramante, L.; Brüsemeister, T.; Busso, G.; Carrasco, J. M.; Gai, M.; Garralda, N.; González-Vidal, J. J.; Guerra, R.; Hauser, M.; Jordan, S.; Jordi, C.; Lenhardt, H.; Mignard, F.; Messineo, R.; Mulone, A.; Serraller, I.; Stampa, U.; Tanga, P.; van Elteren, A.; van Reeven, W.; Voss, H.; Abbas, U.; Allasia, W.; Altmann, M.; Anton, S.; Barache, C.; Becciani, U.; Berthier, J.; Bianchi, L.; Bombrun, A.; Bouquillon, S.; Bourda, G.; Bucciarelli, B.; Butkevich, A.; Buzzi, R.; Cancelliere, R.; Carlucci, T.; Charlot, P.; Collins, R.; Comoretto, G.; Cross, N.; Crosta, M.; de Felice, F.; Fienga, A.; Figueras, F.; Fraile, E.; Geyer, R.; Hernandez, J.; Hobbs, D.; Hofmann, W.; Liao, S.; Licata, E.; Martino, M.; McMillan, P. J.; Michalik, D.; Morbidelli, R.; Parsons, P.; Pecoraro, M.; Ramos-Lerate, M.; Sarasso, M.; Siddiqui, H.; Steele, I.; Steidelmüller, H.; Taris, F.; Vecchiato, A.; Abreu, A.; Anglada, E.; Boudreault, S.; Cropper, M.; Holl, B.; Cheek, N.; Crowley, C.; Fleitas, J. M.; Hutton, A.; Osinde, J.; Rowell, N.; Salguero, E.; Utrilla, E.; Blagorodnova, N.; Soffel, M.; Osorio, J.; Vicente, D.; Cambras, J.; Bernstein, H.-H.

    2016-11-01

    Context. The first data release from the Gaia mission contains accurate positions and magnitudes for more than a billion sources, and proper motions and parallaxes for the majority of the 2.5 million Hipparcos and Tycho-2 stars. Aims: We describe three essential elements of the initial data treatment leading to this catalogue: the image analysis, the construction of a source list, and the near real-time monitoring of the payload health. We also discuss some weak points that set limitations for the attainable precision at the present stage of the mission. Methods: Image parameters for point sources are derived from one-dimensional scans, using a maximum likelihood method, under the assumption of a line spread function constant in time, and a complete modelling of bias and background. These conditions are, however, not completely fulfilled. The Gaia source list is built starting from a large ground-based catalogue, but even so a significant number of new entries have been added, and a large number have been removed. The autonomous onboard star image detection will pick up many spurious images, especially around bright sources, and such unwanted detections must be identified. Another key step of the source list creation consists in arranging the more than 1010 individual detections in spatially isolated groups that can be analysed individually. Results: Complete software systems have been built for the Gaia initial data treatment, that manage approximately 50 million focal plane transits daily, giving transit times and fluxes for 500 million individual CCD images to the astrometric and photometric processing chains. The software also carries out a successful and detailed daily monitoring of Gaia health.

  8. Gaia-GOSA: An interactive service for coordination of asteroid observation campaigns

    NASA Astrophysics Data System (ADS)

    Santana-Ros, Toni; Bartczak, Przemyslaw; Michalowski, Tadeusz; Marciniak, Anna; Butkiewicz-Bak, Magda; Dudziński, Grzegorz

    2016-10-01

    We describe the Gaia-Ground-based Observational Service for Asteroids (www.gaiagosa.eu), which is a website aiming to facilitate asteroid observers in contributing to the Gaia mission by gathering lightcurves of selected targets.There are many asteroids which lightcurves cannot be covered during one observing run, like slow rotators,with periods longer than 12 hours. There are also targets with periods commensurate with the Earth's day, sotheir lightcurves cannot be covered by observing from one site only. There are also targets of special interest,like binary objects, where a large amount of data is needed. For all targets like those mentioned above, acoordination of observers is needed, also to avoid unnecessary duplication of data gathering.To that end we have created Gaia-GOSA, a web service which allows coordination between observers, focuseson interesting targets and may avoid observers to unnecessary gather data of the same object at the sametime. Furthermore, it is not necessary to be an advanced observer to contribute to the project. The websiteprepares the observing plan, providing all the necessary information to point your telescope. Thesubscription is free and observers with any level of experience are welcome.All the data gathered by Gaia-GOSA users will be reduced and analyzed by astronomers from the Astronomical Observatory of Adam Mickiewicz University in Poznan (AO AMU). The resulting catalogue, containing all the lightcurves obtained, will be used to enhance the results of the Gaia (cornerstone European Space Agency's mission) inversion algorithm.The project has been developed under funding from the European Space Agency (ESA) and initially was only devoted to help users in planning photometric observations of asteroids. However, in this poster we also present an extended version of the website, which also aims to publish predictions of stellar occultations for selected targets. This work has been done in the framework of the Small Bodies: Near

  9. The Gaia-ESO Survey: Exploring the complex nature and origins of the Galactic bulge populations

    NASA Astrophysics Data System (ADS)

    Rojas-Arriagada, A.; Recio-Blanco, A.; de Laverny, P.; Mikolaitis, Š.; Matteucci, F.; Spitoni, E.; Schultheis, M.; Hayden, M.; Hill, V.; Zoccali, M.; Minniti, D.; Gonzalez, O. A.; Gilmore, G.; Randich, S.; Feltzing, S.; Alfaro, E. J.; Babusiaux, C.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Koposov, S. E.; Pancino, E.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Damiani, F.; Donati, P.; Franciosini, E.; Hourihane, A.; Jofré, P.; Lardo, C.; Lewis, J.; Lind, K.; Magrini, L.; Morbidelli, L.; Sacco, G. G.; Worley, C. C.; Zaggia, S.

    2017-05-01

    not participate in the X-shape bulge. Their Mg enhancement level and general shape in the [Mg/Fe] vs. [Fe/H] plane is comparable to that of the thick disk sequence. The position at which [Mg/Fe] starts to decrease with [Fe/H], called the "knee", is observed in the metal-poor bulge at [Fe/H] knee = -0.37 ± 0.09, being 0.06 dex higher than that of the thick disk. Although this difference is inside the error bars, it suggest a higher star formation rate (SFR) for the bulge than for the thick disk. We estimate an upper limit for this difference of Δ [Fe/H] knee = 0.24 dex. Finally, we present a chemical evolution model that suitably fits the whole bulge sequence by assuming a fast (<1 Gyr) intense burst of stellar formation that takes place at early epochs. Conclusions: We associate metal-rich stars with the bar boxy/peanut bulge formed as the product of secular evolution of the early thin disk. On the other hand, the metal-poor subpopulation might be the product of an early prompt dissipative collapse dominated by massive stars. Nevertheless, our results do not allow us to firmly rule out the possibility that these stars come from the secular evolution of the early thick disk. This is the first time that an analysis of the bulge MDF and α-abundances has been performed in a large area on the basis of a homogeneous, fully spectroscopic analysis of high-resolution, high S/N data. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 188.B-3002. These data products have been processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge, and by the FLAMES/UVES reduction team at INAF/Osservatorio Astrofisico di Arcetri. These data have been obtained from the Gaia-ESO Survey Data Archive, prepared and hosted by the Wide Field Astronomy Unit, Institute for Astronomy, University of Edinburgh, which is funded by the UK Science and Technology Facilities Council.

  10. Predictions of stellar occultations by TNOs/Centaurs using Gaia

    NASA Astrophysics Data System (ADS)

    Desmars, Josselin; Camargo, Julio; Berard, Diane; Sicardy, Bruno; Leiva, Rodrigo; Vieira-Martins, Roberto; Braga-Ribas, Felipe; Assafin, Marcelo; Rossi, Gustavo; Chariklo occultations Team, Rio Group, Lucky Star Occultation Team, Granada Occultation Team

    2017-10-01

    Stellar occultations are the unique technique from the ground to access physical parameters of the distant solar system objects, such as the measure of the size and the shape at kilometric level, the detection of tenuous atmospheres (few nanobars), and the investigation of close vicinity (satellites, rings, jets).Predictions of stellar occultations require accurate positions of the star and the object.The Gaia DR1 catalog now allows to get stellar position to the milliarcsecond (mas) level. The main uncertainty in the prediction remains in the position of the object (tens to hundreds of mas).Now, we take advantage of the NIMA method for the orbit determination that uses the most recent observations reduced by the Gaia DR1 catalog and the astrometric positions derived from previous positive occultations.Up to now, we have detected nearly 50 positive occultations for about 20 objects that provide astrometric positions of the object at the time of the occultation. The uncertainty of these positions only depends on the uncertainty on the position of the occulted stars, which is a few mas with the Gaia DR1 catalog. The main limitation is now on the proper motion of the star which is only given for bright stars in the Tycho-Gaia Astrometric Solution. This limitation will be solved with the publicationof the Gaia DR2 expected on April 2018 giving proper motions and parallaxes for the Gaia stars. Until this date, we use hybrid stellar catalogs (UCAC5, HSOY) that provide proper motions derived from Gaia DR1 and another stellar catalog.Recently, the Gaia team presented a release of three preliminary Gaia DR2 stellar positions involved in the occultations by Chariklo (22 June and 23 July 2017) and by Triton (5 October 2017).Taking the case of Chariklo as an illustration, we will present a comparison between the proper motions of DR2 and the other catalogs and we will show how the Gaia DR2 will lead to a mas level precision in the orbit and in the prediction of stellar

  11. VizieR Online Data Catalog: Gaia DR1 and OGLE variable stars (Udalski+, 2016)

    NASA Astrophysics Data System (ADS)

    Udalski, A.; Soszynski, I.; Skowron, D. M.; Skowron, J.; Pietrukowicz, P.; Mroz, P.; Poleski, R.; Szymanski, M. K.; Kozlowski, S.; Wyrzykowski, L.; Ulaczyk, K.; Pawlak, M.

    2018-04-01

    To assess the Gaia dataset of Cepheids and RR Lyr stars presented in the Gaia DR1 (Clementini et al., 2016A&A...595A.133C, Cat. I/337) we cross-identified the sample of 3194 variable stars presented on the final Gaia pipeline list (599 Cepheid and 2595 RR Lyr candidates) with the OGLE detected objects using RA/DEC coordinates provided within Gaia DR1. (4 data files).

  12. Inferring the three-dimensional distribution of dust in the Galaxy with a non-parametric method . Preparing for Gaia

    NASA Astrophysics Data System (ADS)

    Rezaei Kh., S.; Bailer-Jones, C. A. L.; Hanson, R. J.; Fouesneau, M.

    2017-02-01

    We present a non-parametric model for inferring the three-dimensional (3D) distribution of dust density in the Milky Way. Our approach uses the extinction measured towards stars at different locations in the Galaxy at approximately known distances. Each extinction measurement is proportional to the integrated dust density along its line of sight (LoS). Making simple assumptions about the spatial correlation of the dust density, we can infer the most probable 3D distribution of dust across the entire observed region, including along sight lines which were not observed. This is possible because our model employs a Gaussian process to connect all LoS. We demonstrate the capability of our model to capture detailed dust density variations using mock data and simulated data from the Gaia Universe Model Snapshot. We then apply our method to a sample of giant stars observed by APOGEE and Kepler to construct a 3D dust map over a small region of the Galaxy. Owing to our smoothness constraint and its isotropy, we provide one of the first maps which does not show the "fingers of God" effect.

  13. The universal function in color dipole model

    NASA Astrophysics Data System (ADS)

    Jalilian, Z.; Boroun, G. R.

    2017-10-01

    In this work we review color dipole model and recall properties of the saturation and geometrical scaling in this model. Our primary aim is determining the exact universal function in terms of the introduced scaling variable in different distance than the saturation radius. With inserting the mass in calculation we compute numerically the contribution of heavy productions in small x from the total structure function by the fraction of universal functions and show the geometrical scaling is established due to our scaling variable in this study.

  14. The Gaia-ESO Survey: Calibration strategy

    NASA Astrophysics Data System (ADS)

    Pancino, E.; Lardo, C.; Altavilla, G.; Marinoni, S.; Ragaini, S.; Cocozza, G.; Bellazzini, M.; Sabbi, E.; Zoccali, M.; Donati, P.; Heiter, U.; Koposov, S. E.; Blomme, R.; Morel, T.; Símon-Díaz, S.; Lobel, A.; Soubiran, C.; Montalban, J.; Valentini, M.; Casey, A. R.; Blanco-Cuaresma, S.; Jofré, P.; Worley, C. C.; Magrini, L.; Hourihane, A.; François, P.; Feltzing, S.; Gilmore, G.; Randich, S.; Asplund, M.; Bonifacio, P.; Drew, J. E.; Jeffries, R. D.; Micela, G.; Vallenari, A.; Alfaro, E. J.; Allende Prieto, C.; Babusiaux, C.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Hambly, N.; Korn, A. J.; Lanzafame, A. C.; Smiljanic, R.; Van Eck, S.; Walton, N. A.; Bayo, A.; Carraro, G.; Costado, M. T.; Damiani, F.; Edvardsson, B.; Franciosini, E.; Frasca, A.; Lewis, J.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sacco, G. G.; Sbordone, L.; Sousa, S. G.; Zaggia, S.; Koch, A.

    2017-02-01

    The Gaia-ESO survey (GES) is now in its fifth and last year of observations and has produced tens of thousands of high-quality spectra of stars in all Milky Way components. This paper presents the strategy behind the selection of astrophysical calibration targets, ensuring that all GES results on radial velocities, atmospheric parameters, and chemical abundance ratios will be both internally consistent and easily comparable with other literature results, especially from other large spectroscopic surveys and from Gaia. The calibration of GES is particularly delicate because of (I) the large space of parameters covered by its targets, ranging from dwarfs to giants, from O to M stars; these targets have a large wide of metallicities and also include fast rotators, emission line objects, and stars affected by veiling; (II) the variety of observing setups, with different wavelength ranges and resolution; and (III) the choice of analyzing the data with many different state-of-the-art methods, each stronger in a different region of the parameter space, which ensures a better understanding of systematic uncertainties. An overview of the GES calibration and homogenization strategy is also given, along with some examples of the usage and results of calibrators in GES iDR4, which is the fourth internal GES data release and will form the basis of the next GES public data release. The agreement between GES iDR4 recommended values and reference values for the calibrating objects are very satisfactory. The average offsets and spreads are generally compatible with the GES measurement errors, which in iDR4 data already meet the requirements set by the main GES scientific goals. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 188.B-3002 and 193.B-0936.Full Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  15. VizieR Online Data Catalog: Comoving stars in Gaia DR1 (Oh+, 2017)

    NASA Astrophysics Data System (ADS)

    Oh, S.; Price-Whelan, A. M.; Hogg, D. W.; Morton, T. D.; Spergel, D. N.

    2017-08-01

    The primary data set used in this article is the Tycho-Gaia Astrometric Solution (TGAS), released as a part of Data Release 1 (DR1) of the Gaia mission (Gaia Collaboration et al. 2016, Cat. I/337; Lindegren et al. 2016A&A...595A...4L). (3 data files).

  16. Gaia16aye is a binary microlensing event and is crossing the caustic again

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, L.; Leto, G.; Altavilla, G.; Bakis, V.; Britavskiy, N.; Burgaz, U.; Butterley, T.; Carrasco, J. M.; Dhillon, V. S.; Dominik, M.; Gomboc, A.; Hardy, L. K.; Littlefair, S. P.; Maund, J. R.; Piascik, A.; Rhodes, L.; Sanchez, R. Z.; Sokolovsky, K. V.; Steele, I.; Wilson, R. W.; Hamanowicz, A.; Mroz, P.; Pawlak, M.; Rybicki, K.; Sitek, M.; Mikolajczyk, P.; Kolaczkowski, Z.; Street, R.; Bendjoya, P.; Bozza, V.; Dziedzic, J.; Niczyj, K.; Nowicki, R.; Porebski, M.

    2016-09-01

    Galactic Plane (Cygnus) transient, Gaia16aye, nicknamed Ayers Rock (19:40:01.13 +30:07:53.4, J2000), was discovered by Gaia Science Alerts, http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia16aye, on 2016-08-05 as a flare on an otherwise quiet star.

  17. Secular Extragalactic Parallax and Geometric Distances with Gaia Proper Motions

    NASA Astrophysics Data System (ADS)

    Paine, Jennie; Darling, Jeremiah K.

    2018-06-01

    The motion of the Solar System with respect to the cosmic microwave background (CMB) rest frame creates a well measured dipole in the CMB, which corresponds to a linear solar velocity of about 78 AU/yr. This motion causes relatively nearby extragalactic objects to appear to move compared to more distant objects, an effect that can be measured in the proper motions of nearby galaxies. An object at 1 Mpc and perpendicular to the CMB apex will exhibit a secular parallax, observed as a proper motion, of 78 µas/yr. The relatively large peculiar motions of galaxies make the detection of secular parallax challenging for individual objects. Instead, a statistical parallax measurement can be made for a sample of objects with proper motions, where the global parallax signal is modeled as an E-mode dipole that diminishes linearly with distance. We present preliminary results of applying this model to a sample of nearby galaxies with Gaia proper motions to detect the statistical secular parallax signal. The statistical measurement can be used to calibrate the canonical cosmological “distance ladder.”

  18. `Orphan' afterglows in the Universal structured jet model for γ-ray bursts

    NASA Astrophysics Data System (ADS)

    Rossi, Elena M.; Perna, Rosalba; Daigne, Frédéric

    2008-10-01

    The paucity of reliable achromatic breaks in γ-ray burst afterglow light curves motivates independent measurements of the jet aperture. Serendipitous searches of afterglows, especially at radio wavelengths, have long been the classic alternative. These survey data have been interpreted assuming a uniformly emitting jet with sharp edges (`top-hat' jet), in that case the ratio of weakly relativistically beamed afterglows to GRBs scales with the jet solid angle. In this paper, we consider, instead, a very wide outflow with a luminosity that decreases across the emitting surface. In particular, we adopt the universal structured jet (USJ) model, which is an alternative to the top-hat model for the structure of the jet. However, the interpretation of the survey data is very different: in the USJ model, we only observe the emission within the jet aperture and the observed ratio of prompt emission rate to afterglow rate should solely depend on selection effects. We compute the number and rate of afterglows expected in all-sky snapshot observations as a function of the survey sensitivity. We find that the current (negative) results for OA searches are in agreement with our expectations. In radio and X-ray bands, this was mainly due to the low sensitivity of the surveys, while in the optical band the sky coverage was not sufficient. In general, we find that X-ray surveys are poor tools for OA searches, if the jet is structured. On the other hand, the Faint Images of the Radio Sky at Twenty-cm radio survey and future instruments like the Allen Telescope Array (in the radio band) and especially GAIA, Panoramic Survey Telescope and Rapid Response System and Large Synoptic Survey Telescope (in the optical band) will have chances to detect afterglows.

  19. Asteroid astrometry with Gaia: stellar occultations and beyond

    NASA Astrophysics Data System (ADS)

    Tanga, Paolo; Spoto, Federica; Hestroffer, Daniel; Altmann, Martin; Bouquillon, Sebastien; Desmars, Josselin

    2017-10-01

    The first data release of star astrometry by Gaia (Sept. 2016) has given an anticipation of the mission capabilities. By providing positions with uncertainties at the level of few milli-arcsec (mas) a new frame to calibrate ground-based observations has immediately become available, thus disclosing a new possibility of exploitation for archive data. We will discuss, in particular, the new role of stellar occulations.Successful observations of occultations have been used in the past to provide accurate shape and size of the targets and to calibrate other size determination methods. Now, a new possibility of exploitation exists, as occultation astrometry provides the possibility of measuring precise asteroid position, at the level of Gaia accuracy. This approach will have an increasing impact, also thanks to the much improved prediction accuracy that Gaia is going to provide, for smaller asteroids and fainter target stars.The scientific goals of improving asteroid astrometry are multiple. For instance, reaching sensitivity to Yarkovsky drift in the Main Belt might become possible, by occultation astrometry performed on smaller asteroids, thanks to future Gaia predictions.The second data release (April 2018) will also contain astrometry of asteroids observed directly by Gaia. The properties of this new data set, that will permit direct orbit improvement, will be illustrated.

  20. Multi-Messenger Astronomy: White Dwarf Binaries, LISA and GAIA

    NASA Astrophysics Data System (ADS)

    Bueno, Michael; Breivik, Katelyn; Larson, Shane L.

    2017-01-01

    The discovery of gravitational waves has ushered in a new era in astronomy. The low-frequency band covered by the future LISA detector provides unprecedented opportunities for multi-messenger astronomy. With the Global Astrometric Interferometer for Astrophysics (GAIA) mission, we expect to discover about 1,000 eclipsing binary systems composed of a WD and a main sequence star - a sizeable increase from the approximately 34 currently known binaries of this type. In advance of the first GAIA data release and the launch of LISA within the next decade, we used the Binary Stellar Evolution (BSE) code simulate the evolution of White Dwarf Binaries (WDB) in a fixed galaxy population of about 196,000 sources. Our goal is to assess the detectability of a WDB by LISA and GAIA using the parameters from our population synthesis, we calculate GW strength h, and apparent GAIA magnitude G. We can then use a scale factor to make a prediction of how many multi- messenger sources we expect to be detectable by both LISA and GAIA in a galaxy the size of the Milky Way. We create binaries 10 times to ensure randomness in distance assignment and average our results. We then determined whether or not astronomical chirp is the difference between the total chirp and the GW chirp. With Astronomical chirp and simulations of mass transfer and tides, we can gather more information about the internal astrophysics of stars in ultra-compact binary systems.

  1. Application of Gaia Analysis Software AGIS to Nano-JASMINE

    NASA Astrophysics Data System (ADS)

    Yamada, Y.; Lammers, U.; Gouda, N.

    2011-07-01

    The core data reduction for the Nano-JASMINE mission is planned to be done with Gaia's Astrometric Global Iterative Solution (AGIS). Nano-JASMINE is an ultra small (35 kg) satellite for astrometry observations in Japan and Gaia is ESA's large (over 1000 kg) next-generation astrometry mission. The accuracy of Nano-JASMINE is about 3 mas, comparable to the Hipparcos mission, Gaia's predecessor some 20 years ago. It is challenging that such a small satellite can perform real scientific observations. The collaboration for sharing software started in 2007. In addition to similar design and operating principles of the two missions, this is possible thanks to the encapsulation of all Gaia-specific aspects of AGIS in a Parameter Database. Nano-JASMINE will be the test bench for the Gaia AGIS software. We present this idea in detail and the necessary practical steps to make AGIS work with Nano-JASMINE data. We also show the key mission parameters, goals, and status of the data reduction for the Nano-JASMINE.

  2. Gaia Data Release 1. Testing parallaxes with local Cepheids and RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Gaia Collaboration; Clementini, G.; Eyer, L.; Ripepi, V.; Marconi, M.; Muraveva, T.; Garofalo, A.; Sarro, L. M.; Palmer, M.; Luri, X.; Molinaro, R.; Rimoldini, L.; Szabados, L.; Musella, I.; Anderson, R. I.; Prusti, T.; de Bruijne, J. H. J.; Brown, A. G. A.; Vallenari, A.; Babusiaux, C.; Bailer-Jones, C. A. L.; Bastian, U.; Biermann, M.; Evans, D. W.; Jansen, F.; Jordi, C.; Klioner, S. A.; Lammers, U.; Lindegren, L.; Mignard, F.; Panem, C.; Pourbaix, D.; Randich, S.; Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette, V.; van Leeuwen, F.; Walton, N. A.; Aerts, C.; Arenou, F.; Cropper, M.; Drimmel, R.; Høg, E.; Katz, D.; Lattanzi, M. G.; O'Mullane, W.; Grebel, E. K.; Holland, A. D.; Huc, C.; Passot, X.; Perryman, M.; Bramante, L.; Cacciari, C.; Castañeda, J.; Chaoul, L.; Cheek, N.; De Angeli, F.; Fabricius, C.; Guerra, R.; Hernández, J.; Jean-Antoine-Piccolo, A.; Masana, E.; Messineo, R.; Mowlavi, N.; Nienartowicz, K.; Ordóñez-Blanco, D.; Panuzzo, P.; Portell, J.; Richards, P. J.; Riello, M.; Seabroke, G. M.; Tanga, P.; Thévenin, F.; Torra, J.; Els, S. G.; Gracia-Abril, G.; Comoretto, G.; Garcia-Reinaldos, M.; Lock, T.; Mercier, E.; Altmann, M.; Andrae, R.; Astraatmadja, T. L.; Bellas-Velidis, I.; Benson, K.; Berthier, J.; Blomme, R.; Busso, G.; Carry, B.; Cellino, A.; Cowell, S.; Creevey, O.; Cuypers, J.; Davidson, M.; De Ridder, J.; de Torres, A.; Delchambre, L.; Dell'Oro, A.; Ducourant, C.; Frémat, Y.; García-Torres, M.; Gosset, E.; Halbwachs, J.-L.; Hambly, N. C.; Harrison, D. L.; Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle, H. E.; Hutton, A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn, A. J.; Lanzafame, A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.; Osinde, J.; Pancino, E.; Pauwels, T.; Petit, J.-M.; Recio-Blanco, A.; Robin, A. C.; Siopis, C.; Smith, M.; Smith, K. W.; Sozzetti, A.; Thuillot, W.; van Reeven, W.; Viala, Y.; Abbas, U.; Abreu Aramburu, A.; Accart, S.; Aguado, J. J.; Allan, P. M.; Allasia, W.; Altavilla, G.; Álvarez, M. A.; Alves, J.; Andrei, A. H.; Anglada Varela, E.; Antiche, E.; Antoja, T.; Antón, S.; Arcay, B.; Bach, N.; Baker, S. G.; Balaguer-Núñez, L.; Barache, C.; Barata, C.; Barbier, A.; Barblan, F.; Barrado y Navascués, D.; Barros, M.; Barstow, M. A.; Becciani, U.; Bellazzini, M.; Bello García, A.; Belokurov, V.; Bendjoya, P.; Berihuete, A.; Bianchi, L.; Bienaymé, O.; Billebaud, F.; Blagorodnova, N.; Blanco-Cuaresma, S.; Boch, T.; Bombrun, A.; Borrachero, R.; Bouquillon, S.; Bourda, G.; Bragaglia, A.; Breddels, M. A.; Brouillet, N.; Brüsemeister, T.; Bucciarelli, B.; Burgess, P.; Burgon, R.; Burlacu, A.; Busonero, D.; Buzzi, R.; Caffau, E.; Cambras, J.; Campbell, H.; Cancelliere, R.; Cantat-Gaudin, T.; Carlucci, T.; Carrasco, J. M.; Castellani, M.; Charlot, P.; Charnas, J.; Chiavassa, A.; Clotet, M.; Cocozza, G.; Collins, R. S.; Costigan, G.; Crifo, F.; Cross, N. J. G.; Crosta, M.; Crowley, C.; Dafonte, C.; Damerdji, Y.; Dapergolas, A.; David, P.; David, M.; De Cat, P.; de Felice, F.; de Laverny, P.; De Luise, F.; De March, R.; de Souza, R.; Debosscher, J.; del Pozo, E.; Delbo, M.; Delgado, A.; Delgado, H. E.; Di Matteo, P.; Diakite, S.; Distefano, E.; Dolding, C.; Dos Anjos, S.; Drazinos, P.; Durán, J.; Dzigan, Y.; Edvardsson, B.; Enke, H.; Evans, N. W.; Eynard Bontemps, G.; Fabre, C.; Fabrizio, M.; Falcão, A. J.; Farràs Casas, M.; Federici, L.; Fedorets, G.; Fernández-Hernández, J.; Fernique, P.; Fienga, A.; Figueras, F.; Filippi, F.; Findeisen, K.; Fonti, A.; Fouesneau, M.; Fraile, E.; Fraser, M.; Fuchs, J.; Gai, M.; Galleti, S.; Galluccio, L.; Garabato, D.; García-Sedano, F.; Garralda, N.; Gavras, P.; Gerssen, J.; Geyer, R.; Gilmore, G.; Girona, S.; Giuffrida, G.; Gomes, M.; González-Marcos, A.; González-Núñez, J.; González-Vidal, J. J.; Granvik, M.; Guerrier, A.; Guillout, P.; Guiraud, J.; Gúrpide, A.; Gutiérrez-Sánchez, R.; Guy, L. P.; Haigron, R.; Hatzidimitriou, D.; Haywood, M.; Heiter, U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.; Holland, G.; Hunt, J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat de Fombelle, G.; Jofré, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.; Karampelas, A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas, E.; Koposov, S. E.; Kordopatis, G.; Koubsky, P.; Krone-Martins, A.; Kudryashova, M.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza, A. F.; Lavigne, J.-B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter, T.; Leccia, S.; Leclerc, N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt, H.; Leroux, F.; Liao, S.; Licata, E.; Lindstrøm, H. E. P.; Lister, T. A.; Livanou, E.; Lobel, A.; Löffler, W.; López, M.; Lorenz, D.; MacDonald, I.; Magalhães Fernandes, T.; Managau, S.; Mann, R. G.; Mantelet, G.; Marchal, O.; Marchant, J. M.; Marinoni, S.; Marrese, P. M.; Marschalkó, G.; Marshall, D. J.; Martín-Fleitas, J. M.; Martino, M.; Mary, N.; Matijevič, G.; McMillan, P. J.; Messina, S.; Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina, D.; Molinaro, M.; Molnár, L.; Moniez, M.; Montegriffo, P.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.; Morris, D.; Mulone, A. F.; Narbonne, J.; Nelemans, G.; Nicastro, L.; Noval, L.; Ordénovic, C.; Ordieres-Meré, J.; Osborne, P.; Pagani, C.; Pagano, I.; Pailler, F.; Palacin, H.; Palaversa, L.; Parsons, P.; Pecoraro, M.; Pedrosa, R.; Pentikäinen, H.; Pichon, B.; Piersimoni, A. M.; Pineau, F.-X.; Plachy, E.; Plum, G.; Poujoulet, E.; Prša, A.; Pulone, L.; Ragaini, S.; Rago, S.; Rambaux, N.; Ramos-Lerate, M.; Ranalli, P.; Rauw, G.; Read, A.; Regibo, S.; Reylé, C.; Ribeiro, R. A.; Riva, A.; Rixon, G.; Roelens, M.; Romero-Gómez, M.; Rowell, N.; Royer, F.; Ruiz-Dern, L.; Sadowski, G.; Sagristà Sellés, T.; Sahlmann, J.; Salgado, J.; Salguero, E.; Sarasso, M.; Savietto, H.; Schultheis, M.; Sciacca, E.; Segol, M.; Segovia, J. C.; Segransan, D.; Shih, I.-C.; Smareglia, R.; Smart, R. L.; Solano, E.; Solitro, F.; Sordo, R.; Soria Nieto, S.; Souchay, J.; Spagna, A.; Spoto, F.; Stampa, U.; Steele, I. A.; Steidelmüller, H.; Stephenson, C. A.; Stoev, H.; Suess, F. F.; Süveges, M.; Surdej, J.; Szegedi-Elek, E.; Tapiador, D.; Taris, F.; Tauran, G.; Taylor, M. B.; Teixeira, R.; Terrett, D.; Tingley, B.; Trager, S. C.; Turon, C.; Ulla, A.; Utrilla, E.; Valentini, G.; van Elteren, A.; Van Hemelryck, E.; van Leeuwen, M.; Varadi, M.; Vecchiato, A.; Veljanoski, J.; Via, T.; Vicente, D.; Vogt, S.; Voss, H.; Votruba, V.; Voutsinas, S.; Walmsley, G.; Weiler, M.; Weingrill, K.; Wevers, T.; Wyrzykowski, Ł.; Yoldas, A.; Žerjal, M.; Zucker, S.; Zurbach, C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende Prieto, C.; Amorim, A.; Anglada-Escudé, G.; Arsenijevic, V.; Azaz, S.; Balm, P.; Beck, M.; Bernstein, H.-H.; Bigot, L.; Bijaoui, A.; Blasco, C.; Bonfigli, M.; Bono, G.; Boudreault, S.; Bressan, A.; Brown, S.; Brunet, P.-M.; Bunclark, P.; Buonanno, R.; Butkevich, A. G.; Carret, C.; Carrion, C.; Chemin, L.; Chéreau, F.; Corcione, L.; Darmigny, E.; de Boer, K. S.; de Teodoro, P.; de Zeeuw, P. T.; Delle Luche, C.; Domingues, C. D.; Dubath, P.; Fodor, F.; Frézouls, B.; Fries, A.; Fustes, D.; Fyfe, D.; Gallardo, E.; Gallegos, J.; Gardiol, D.; Gebran, M.; Gomboc, A.; Gómez, A.; Grux, E.; Gueguen, A.; Heyrovsky, A.; Hoar, J.; Iannicola, G.; Isasi Parache, Y.; Janotto, A.-M.; Joliet, E.; Jonckheere, A.; Keil, R.; Kim, D.-W.; Klagyivik, P.; Klar, J.; Knude, J.; Kochukhov, O.; Kolka, I.; Kos, J.; Kutka, A.; Lainey, V.; LeBouquin, D.; Liu, C.; Loreggia, D.; Makarov, V. V.; Marseille, M. G.; Martayan, C.; Martinez-Rubi, O.; Massart, B.; Meynadier, F.; Mignot, S.; Munari, U.; Nguyen, A.-T.; Nordlander, T.; O'Flaherty, K. S.; Ocvirk, P.; Olias Sanz, A.; Ortiz, P.; Osorio, J.; Oszkiewicz, D.; Ouzounis, A.; Park, P.; Pasquato, E.; Peltzer, C.; Peralta, J.; Péturaud, F.; Pieniluoma, T.; Pigozzi, E.; Poels, J.; Prat, G.; Prod'homme, T.; Raison, F.; Rebordao, J. M.; Risquez, D.; Rocca-Volmerange, B.; Rosen, S.; Ruiz-Fuertes, M. I.; Russo, F.; Serraller Vizcaino, I.; Short, A.; Siebert, A.; Silva, H.; Sinachopoulos, D.; Slezak, E.; Soffel, M.; Sosnowska, D.; Straižys, V.; ter Linden, M.; Terrell, D.; Theil, S.; Tiede, C.; Troisi, L.; Tsalmantza, P.; Tur, D.; Vaccari, M.; Vachier, F.; Valles, P.; Van Hamme, W.; Veltz, L.; Virtanen, J.; Wallut, J.-M.; Wichmann, R.; Wilkinson, M. I.; Ziaeepour, H.; Zschocke, S.

    2017-09-01

    different types of pulsating stars and alternative fitting methods. Results: Good agreement is found from direct comparison of the parallaxes of RR Lyrae stars for which both TGAS and HST measurements are available. Similarly, very good agreement is found between the TGAS values and the parallaxes inferred from the absolute magnitudes of Cepheids and RR Lyrae stars analysed with the Baade-Wesselink method. TGAS values also compare favourably with the parallaxes inferred by theoretical model fitting of the multi-band light curves for two of the three classical Cepheids and one RR Lyrae star, which were analysed with this technique in our samples. The K-band PL relations show the significant improvement of the TGAS parallaxes for Cepheids and RR Lyrae stars with respect to the Hipparcos measurements. This is particularly true for the RR Lyrae stars for which improvement in quality and statistics is impressive. Conclusions: TGAS parallaxes bring a significant added value to the previous Hipparcos estimates. The relations presented in this paper represent the first Gaia-calibrated relations and form a work-in-progress milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia Data Release 2 (DR2) in 2018. Full Tables A.1-A.3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A79

  3. e-University Project: Business Model. Consultation.

    ERIC Educational Resources Information Center

    Higher Education Funding Council for England, Bristol.

    This report describes the context and goals of the Higher Education Funding Council for England's e-University project to develop Internet-based higher education. It summarizes the proposed business model and outlines next steps in implementing the project. A February 2000 letter announced the project and invited higher education institutions…

  4. Modeling Environmental Literacy of University Students

    ERIC Educational Resources Information Center

    Teksoz, Gaye; Sahin, Elvan; Tekkaya-Oztekin, Ceren

    2012-01-01

    The present study proposed an Environmental Literacy Components Model to explain how environmental attitudes, environmental responsibility, environmental concern, and environmental knowledge as well as outdoor activities related to each other. A total of 1,345 university students responded to an environmental literacy survey (Kaplowitz and Levine…

  5. Revisiting hypervelocity stars after Gaia DR2

    NASA Astrophysics Data System (ADS)

    Boubert, D.; Guillochon, J.; Hawkins, K.; Ginsburg, I.; Evans, N. W.; Strader, J.

    2018-06-01

    Hypervelocity stars are intriguing rare objects traveling at speeds large enough to be unbound from the Milky Way. Several mechanisms have been proposed for producing them, including the interaction of the Galaxy's super-massive black hole (SMBH) with a binary; rapid mass-loss from a companion to a star in a short-period binary; the tidal disruption of an infalling galaxy and finally ejection from the Large Magellanic Cloud. While previously discovered high-velocity early-type stars are thought to be the result of an interaction with the SMBH, the origin of high-velocity late type stars is ambiguous. The second data release of Gaia (DR2) enables a unique opportunity to resolve this ambiguity and determine whether any late-type candidates are truly unbound from the Milky Way. In this paper, we utilize the new proper motion and velocity information available from DR2 to re-evaluate a collection of historical data compiled on the newly-created Open Fast Stars Catalog. We find that almost all previously-known high-velocity late-type stars are most likely bound to the Milky Way. Only one late-type object (LAMOST J115209.12+120258.0) is unbound from the Galaxy. Performing integrations of orbital histories, we find that this object cannot have been ejected from the Galactic centre and thus may be either debris from the disruption of a satellite galaxy or a disc runaway.

  6. The intricate Galaxy disk: velocity asymmetries in Gaia-TGAS

    NASA Astrophysics Data System (ADS)

    Antoja, T.; de Bruijne, J.; Figueras, F.; Mor, R.; Prusti, T.; Roca-Fàbrega, S.

    2017-06-01

    We use Gaia-TGAS data to compare the transverse velocities in Galactic longitude (coming from proper motions and parallaxes) in the Milky Way disk for negative and positive longitudes as a function of distance. The transverse velocities are strongly asymmetric and deviate significantly from the expectations for an axisymmetric galaxy. The value and sign of the asymmetry changes at spatial scales of several tens of degrees in Galactic longitude and about 0.5 kpc in distance. The asymmetry is statistically significant at 95% confidence level for 57% of the region probed, which extends up to 1.2 kpc. A percentage of 24% of the region shows absolute differences at this confidence level larger than 5 km s-1 and 7% larger than 10 km s-1. The asymmetry pattern shows mild variations in the vertical direction and with stellar type. A first qualitative comparison with spiral arm models indicates that the arms are probably not the main source of the asymmetry. We briefly discuss alternative origins. This is the first time that global all-sky asymmetries are detected in the Milky Way kinematics beyond the local neighbourhood and with a purely astrometric sample.

  7. A collaborative university model for employee wellness.

    PubMed

    Carter, Melondie R; Kelly, Rebecca C; Alexander, Chelley K; Holmes, Lauren M

    2011-01-01

    Universities are taking a more active approach in understanding and monitoring employees' modifiable health risk factors and chronic care conditions by developing strategies to encourage employees to start and sustain healthy behaviors. WellBama, the University of Alabama's signature health and wellness program, utilizes a collaborative model in partnership with select colleges and departments to implement strategies to improve employees' health status. The program provides onsite health screenings and assessments, timely health advising sessions, assistance in setting and monitoring individual health goals to promote improved health, and preventive examination referrals.

  8. Object classification and outliers analysis in the forthcoming Gaia mission

    NASA Astrophysics Data System (ADS)

    Ordóñez-Blanco, D.; Arcay, B.; Dafonte, C.; Manteiga, M.; Ulla, A.

    2010-12-01

    Astrophysics is evolving towards the rational optimization of costly observational material by the intelligent exploitation of large astronomical databases from both terrestrial telescopes and spatial mission archives. However, there has been relatively little advance in the development of highly scalable data exploitation and analysis tools needed to generate the scientific returns from these large and expensively obtained datasets. Among the upcoming projects of astronomical instrumentation, Gaia is the next cornerstone ESA mission. The Gaia survey foresees the creation of a data archive and its future exploitation with automated or semi-automated analysis tools. This work reviews some of the work that is being developed by the Gaia Data Processing and Analysis Consortium for the object classification and analysis of outliers in the forthcoming mission.

  9. Perspectives for short timescale variability studies with Gaia

    NASA Astrophysics Data System (ADS)

    Roelens, M.; Eyer, L.; Mowlavi, N.; Lecoeur-Taïbi, I.; Rimoldini, L.; Blanco-Cuaresma, S.; Palaversa, L.; Süveges, M.; Charnas, J.; Wevers, T.

    2017-12-01

    We assess the potential of Gaia for detecting and characterizing short timescale variables, i.e. at timescale from a few seconds to a dozen hours, through extensive light-curve simulations for various short timescale variable types, including both periodic and non-periodic variability. We evidence that the variogram analysis applied to Gaia photometry should enable to detect such fast variability phenomena, down to amplitudes of a few millimagnitudes, with limited contamination from longer timescale variables or constant sources. This approach also gives valuable information on the typical timescale(s) of the considered variation, which could complement results of classical period search methods, and help prepare ground-based follow-up of the Gaia short timescale candidates.

  10. Discovery of the Most Ultra-Luminous QSO Using GAIA, SkyMapper, and WISE

    NASA Astrophysics Data System (ADS)

    Wolf, Christian; Bian, Fuyan; Onken, Christopher A.; Schmidt, Brian P.; Tisserand, Patrick; Alonzi, Noura; Hon, Wei Jeat; Tonry, John L.

    2018-06-01

    We report the discovery of the ultra-luminous quasi-stellar object SMSS J215728.21-360215.1 with magnitude z = 16.9 and W4 = 7.42 at redshift 4.75. Given absolute magnitudes of M145, AB = -29.3, M300, AB = -30.12, and logLbol/Lbol, ⊙ = 14.84, it is the quasi-stellar object with the highest unlensed UV-optical luminosity currently known in the Universe. It was found by combining proper-motion data from Gaia DR2 with photometry from SkyMapper DR1 and the Wide-field Infrared Survey Explorer. In the GAIA database, it is an isolated single source and thus unlikely to be strongly gravitationally lensed. It is also unlikely to be a beamed source as it is not discovered in the radio domain by either NRAO-VLA Sky Survey or Sydney University Molonglo Southern Survey. It is classed as a weak-emission-line quasi-stellar object and possesses broad absorption line features. A lightcurve from ATLAS spanning the time from 2015 October to 2017 December shows little sign of variability.

  11. The overture to a new era in Galactic science: Gaia's first data release

    NASA Astrophysics Data System (ADS)

    Altmann, M.; Bouquillon, S.

    2018-01-01

    Less than 3 years after ESA's ambitious astrometric space mission, Gaia, had been launched, the first data release (Gaia DR1) appeared in September 2016. The largest part of the Gaia DR1 is a catalogue of positions and broad band photometry for 1143 million stars - of greater scientific relevance will however be the Tycho Gaia Astrometric Solution (TGAS), which includes significantly improved full 5-parameter astrometry for the 2 million Hipparcos and Tycho2 stars. I will report on this release demonstrating its scientific potential with examples, as well as giving an outlook on the upcoming release, which will then include all 5 parameters for all Gaia stars.

  12. The empirical Gaia G-band extinction coefficient

    NASA Astrophysics Data System (ADS)

    Danielski, C.; Babusiaux, C.; Ruiz-Dern, L.; Sartoretti, P.; Arenou, F.

    2018-06-01

    Context. The first Gaia data release unlocked the access to photometric information for 1.1 billion sources in the G-band. Yet, given the high level of degeneracy between extinction and spectral energy distribution for large passbands such as the Gaia G-band, a correction for the interstellar reddening is needed in order to exploit Gaia data. Aims: The purpose of this manuscript is to provide the empirical estimation of the Gaia G-band extinction coefficient kG for both the red giants and main sequence stars in order to be able to exploit the first data release DR1. Methods: We selected two samples of single stars: one for the red giants and one for the main sequence. Both samples are the result of a cross-match between Gaia DR1 and 2MASS catalogues; they consist of high-quality photometry in the G-, J- and KS-bands. These samples were complemented by temperature and metallicity information retrieved from APOGEE DR13 and LAMOST DR2 surveys, respectively. We implemented a Markov chain Monte Carlo method where we used (G - KS)0 versus Teff and (J - KS)0 versus (G - KS)0, calibration relations to estimate the extinction coefficient kG and we quantify its corresponding confidence interval via bootstrap resampling. We tested our method on samples of red giants and main sequence stars, finding consistent solutions. Results: We present here the determination of the Gaia extinction coefficient through a completely empirical method. Furthermore we provide the scientific community with a formula for measuring the extinction coefficient as a function of stellar effective temperature, the intrinsic colour (G - KS)0, and absorption.

  13. Gaia Data Release 1. Validation of the photometry

    NASA Astrophysics Data System (ADS)

    Evans, D. W.; Riello, M.; De Angeli, F.; Busso, G.; van Leeuwen, F.; Jordi, C.; Fabricius, C.; Brown, A. G. A.; Carrasco, J. M.; Voss, H.; Weiler, M.; Montegriffo, P.; Cacciari, C.; Burgess, P.; Osborne, P.

    2017-04-01

    Aims: The photometric validation of the Gaia DR1 release of the ESA Gaia mission is described and the quality of the data shown. Methods: This is carried out via an internal analysis of the photometry using the most constant sources. Comparisons with external photometric catalogues are also made, but are limited by the accuracies and systematics present in these catalogues. An analysis of the quoted errors is also described. Investigations of the calibration coefficients reveal some of the systematic effects that affect the fluxes. Results: The analysis of the constant sources shows that the early-stage photometric calibrations can reach an accuracy as low as 3 mmag.

  14. Gaia-GBOT asteroid finding programme (gbot.obspm.fr)

    NASA Astrophysics Data System (ADS)

    Bouquillon, Sébastien; Altmann, Martin; Taris, Francois; Barache, Christophe; Carlucci, Teddy; Tanga, Paolo; Thuillot, William; Marchant, Jon; Steele, Iain; Lister, Tim; Berthier, Jerome; Carry, Benoit; David, Pedro; Cellino, Alberto; Hestroffer, Daniel J.; Andrei, Alexandre Humberto; Smart, Ricky

    2016-10-01

    The Ground Based Optical Tracking group (GBOT) consists of about ten scientists involved in the Gaia mission by ESA. Its main task is the optical tracking of the Gaia satellite itself [1]. This novel tracking method in addition to radiometric standard ones is necessary to ensure that the Gaia mission goal in terms of astrometric precision level is reached for all objects. This optical tracking is based on daily observations performed throughout the mission by using the optical CCDs of ESO's VST in Chile, of Liverpool Telescope in La Palma and of the two LCOGT's Faulkes Telescopes in Hawaii and Australia. Each night, GBOT attempts to obtain a sequence of frames covering a 20 min total period and close to Gaia meridian transit time. In each sequence, Gaia is seen as a faint moving object (Rmag ~ 21, speed > 1"/min) and its daily astrometric accuracy has to be better than 0.02" to meet the Gaia mission requirements. The GBOT Astrometric Reduction Pipeline (GARP) [2] has been specifically developed to reach this precision.More recently, a secondary task has been assigned to GBOT which consists detecting and analysing Solar System Objects (SSOs) serendipitously recorded in the GBOT data. Indeed, since Gaia oscillates around the Sun-Earth L2 point, the fields of GBOT observations are near the Ecliptic and roughly located opposite to the Sun which is advantageous for SSO observations and studies. In particular, these SSO data can potentially be very useful to help in the determination of their absolute magnitudes, with important applications to the scientific exploitation of the WISE and Gaia missions. For these reasons, an automatic SSO detection system has been created to identify moving objects in GBOT sequences of observations. Since the beginning of 2015, this SSO detection system, added to GARP for performing high precision astrometry for SSOs, is fully operational. To this date, around 9000 asteroids have been detected. The mean delay between the time of

  15. Astrometric Calibrations of HST Images in the Era of Gaia.

    NASA Astrophysics Data System (ADS)

    Kozhurina-Platais, Vera; Grogin, Norman A.; Sabbi, Elena

    2018-06-01

    It is well-known that HST images, taken with ACS/WFC and WFC3/UVIS, have substantial geometric distortion. Over the years our knowledge about this distortion has been vastly improved. Nevertheless, in certain applications it may not be good enough. Preliminary results of comparison state-of-the-art HST astrometric standards and the Gaia DR1 indicate significant scale difference, global rotation, and edge effects in the HST data. However, in terms of positional precision the HST standards are not surpassed yet. The next release of Gaia data DR2 were used to finalize and improve the HST astrometric calibrations down to 0.5 mas or better.

  16. IVS Observation of ICRF2-Gaia Transfer Sources

    NASA Astrophysics Data System (ADS)

    Le Bail, K.; Gipson, J. M.; Gordon, D.; MacMillan, D. S.; Behrend, D.; Thomas, C. C.; Bolotin, S.; Himwich, W. E.; Baver, K. D.; Corey, B. E.; Titus, M.; Bourda, G.; Charlot, P.; Collioud, A.

    2016-03-01

    The second realization of the International Celestial Reference Frame (ICRF2), which is the current fundamental celestial reference frame adopted by the International Astronomical Union, is based on Very Long Baseline Interferometry (VLBI) data at radio frequencies in X band and S band. The European Space Agency’s Gaia mission, launched on 2013 December 19, started routine scientific operations in 2014 July. By scanning the whole sky, it is expected to observe ∼500,000 Quasi Stellar Objects in the optical domain an average of 70 times each during the five years of the mission. This means that, in the future, two extragalactic celestial reference frames, at two different frequency domains, will coexist. It will thus be important to align them very accurately. In 2012, the Laboratoire d’Astrophysique de Bordeaux (LAB) selected 195 sources from ICRF2 that will be observed by Gaia and should be suitable for aligning the radio and optical frames: they are called ICRF2-Gaia transfer sources. The LAB submitted a proposal to the International VLBI Service (IVS) to regularly observe these ICRF2-Gaia transfer sources at the same rate as Gaia observes them in the optical realm, e.g., roughly once a month. We describe our successful effort to implement such a program and report on the results. Most observations of the ICRF2-Gaia transfer sources now occur automatically as part of the IVS source monitoring program, while a subset of 37 sources requires special attention. Beginning in 2013, we scheduled 25 VLBI sessions devoted in whole or in part to measuring these 37 sources. Of the 195 sources, all but one have been successfully observed in the 12 months prior to 2015 September 01. Of the sources, 87 met their observing target of 12 successful sessions per year. The position uncertainties of all of the ICRF2-Gaia transfer sources have improved since the start of this observing program. For a subset of 24 sources whose positions were very poorly known, the uncertainty

  17. VizieR Online Data Catalog: Gaia DR2 (Gaia Collaboration, 2018)

    NASA Astrophysics Data System (ADS)

    Gaia Collaboration

    2018-04-01

    Contents of Gaia DR2: The five-parameter astrometric solution - positions on the sky (alpha,delta), parallaxes, and proper motions - for more than 1.3 billion (109) sources, with a limiting magnitude of G=21 and a bright limit of G~=3. Parallax uncertainties are in the range of up to 0.04 milliarcsecond for sources at G<15, around 0.1mas for sources with G=17 and at the faint end, the uncertainty is of the order of 0.7mas at G=20. The corresponding uncertainties in the respective proper motion components are up to 0.06mas/yr (for G<15mag), 0.2mas/yr (for G=17mag) and 1.2mas/yr (for G=20mag). The Gaia DR2 parallaxes and proper motions are based only on Gaia data; they do no longer depend on the Tycho-2 Catalogue. Median radial velocities (i.e. the median value over the epochs) for more than 6 million stars with a mean G magnitude between about 4 and 13 and an effective temperature (Teff) in the range of about 3550 to 6900K. This leads to a full six-parameter solution: positions and motions on the sky with parallaxes and radial velocities, all combined with mean G magnitudes. The overall precision of the radial velocities at the bright end is in the order of 200-300m/s while at the faint end the overall precision is approximately 1.2km/s for a Teff of 4750K and about 2.5km/s for a Teff of 6500K. An additional set of more than 200 million sources for which a two-parameter solution is available: the positions on the sky (alpha,delta) combined with the mean G magnitude. These sources will have a positional uncertainty at G=20 of about 2mas, at J2015.5. G magnitudes for more than 1.5 billion sources, with precisions varying from around 1 milli-mag at the bright (G<13) end to around 20 milli-mag at G=20. Please be aware that the photometric system for the G band in Gaia DR2 will be different from the photometric system as used in Gaia DR1. GBP and GRP magnitudes for more than 1.1 billion sources, with precisions varying from a few milli-mag at the bright (G<13) end to

  18. The completeness-corrected rate of stellar encounters with the Sun from the first Gaia data release

    NASA Astrophysics Data System (ADS)

    Bailer-Jones, C. A. L.

    2018-01-01

    I report on close encounters of stars to the Sun found in the first Gaia data release (GDR1). Combining Gaia astrometry with radial velocities of around 320 000 stars drawn from various catalogues, I integrate orbits in a Galactic potential to identify those stars which pass within a few parsecs. Such encounters could influence the solar system, for example through gravitational perturbations of the Oort cloud. 16 stars are found to come within 2 pc (although a few of these have dubious data). This is fewer than were found in a similar study based on HIPPARCOS data, even though the present study has many more candidates. This is partly because I reject stars with large radial velocity uncertainties (>10 km s-1), and partly because of missing stars in GDR1 (especially at the bright end). The closest encounter found is Gl 710, a K dwarf long-known to come close to the Sun in about 1.3 Myr. The Gaia astrometry predict a much closer passage than pre-Gaia estimates, however: just 16 000 AU (90% confidence interval: 10 000-21 000 AU), which will bring this star well within the Oort cloud. Using a simple model for the spatial, velocity, and luminosity distributions of stars, together with an approximation of the observational selection function, I model the incompleteness of this Gaia-based search as a function of the time and distance of closest approach. Applying this to a subset of the observed encounters (excluding duplicates and stars with implausibly large velocities), I estimate the rate of stellar encounters within 5 pc averaged over the past and future 5 Myr to be 545 ± 59 Myr-1. Assuming a quadratic scaling of the rate within some encounter distance (which my model predicts), this corresponds to 87 ± 9 Myr-1 within 2 pc. A more accurate analysis and assessment will be possible with future Gaia data releases. Full Table 3 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  19. Stellar parametrization from Gaia RVS spectra

    NASA Astrophysics Data System (ADS)

    Recio-Blanco, A.; de Laverny, P.; Allende Prieto, C.; Fustes, D.; Manteiga, M.; Arcay, B.; Bijaoui, A.; Dafonte, C.; Ordenovic, C.; Ordoñez Blanco, D.

    2016-01-01

    Context. Among the myriad of data collected by the ESA Gaia satellite, about 150 million spectra will be delivered by the Radial Velocity Spectrometer (RVS) for stars as faint as GRVS~ 16. A specific stellar parametrization will be performed on most of these RVS spectra, I.e. those with enough high signal-to-noise ratio (S/N), which should correspond to single stars that have a magnitude in the RVS band brighter than ~14.5. Some individual chemical abundances will also be estimated for the brightest targets. Aims: We describe the different parametrization codes that have been specifically developed or adapted for RVS spectra within the GSP-Spec working group of the analysis consortium. The tested codes are based on optimisation (FERRE and GAUGUIN), projection (MATISSE), or pattern-recognition methods (Artificial Neural Networks). We present and discuss each of their expected performances in the recovered stellar atmospheric parameters (effective temperature, surface gravity, overall metallicity) for B- to K-type stars. The performances for determining of [α/Fe] ratios are also presented for cool stars. Methods: Each code has been homogeneously tested with a large grid of RVS simulated synthetic spectra of BAFGK-spectral types (dwarfs and giants), with metallicities varying from 10-2.5 to 10+ 0.5 the solar metallicity, and taking variations of ±0.4 dex in the composition of the α-elements into consideration. The tests were performed for S/N ranging from ten to 350. Results: For all the stellar types we considered, stars brighter than GRVS~ 12.5 are very efficiently parametrized by the GSP-Spec pipeline, including reliable estimations of [α/Fe]. Typical internal errors for FGK metal-rich and metal-intermediate stars are around 40 K in Teff, 0.10 dex in log(g), 0.04 dex in [M/H], and 0.03 dex in [α/Fe] at GRVS = 10.3. They degrade to 155 K in Teff, 0.15 dex in log(g), 0.10 dex in [M/H], and 0.1 dex in [α/Fe] at GRVS~ 12. Similar accuracies in Teff and [M/H] are

  20. The best-fit universe. [cosmological models

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.

    1991-01-01

    Inflation provides very strong motivation for a flat Universe, Harrison-Zel'dovich (constant-curvature) perturbations, and cold dark matter. However, there are a number of cosmological observations that conflict with the predictions of the simplest such model: one with zero cosmological constant. They include the age of the Universe, dynamical determinations of Omega, galaxy-number counts, and the apparent abundance of large-scale structure in the Universe. While the discrepancies are not yet serious enough to rule out the simplest and most well motivated model, the current data point to a best-fit model with the following parameters: Omega(sub B) approximately equal to 0.03, Omega(sub CDM) approximately equal to 0.17, Omega(sub Lambda) approximately equal to 0.8, and H(sub 0) approximately equal to 70 km/(sec x Mpc) which improves significantly the concordance with observations. While there is no good reason to expect such a value for the cosmological constant, there is no physical principle that would rule out such.

  1. The Monash University Interactive Simple Climate Model

    NASA Astrophysics Data System (ADS)

    Dommenget, D.

    2013-12-01

    The Monash university interactive simple climate model is a web-based interface that allows students and the general public to explore the physical simulation of the climate system with a real global climate model. It is based on the Globally Resolved Energy Balance (GREB) model, which is a climate model published by Dommenget and Floeter [2011] in the international peer review science journal Climate Dynamics. The model simulates most of the main physical processes in the climate system in a very simplistic way and therefore allows very fast and simple climate model simulations on a normal PC computer. Despite its simplicity the model simulates the climate response to external forcings, such as doubling of the CO2 concentrations very realistically (similar to state of the art climate models). The Monash simple climate model web-interface allows you to study the results of more than a 2000 different model experiments in an interactive way and it allows you to study a number of tutorials on the interactions of physical processes in the climate system and solve some puzzles. By switching OFF/ON physical processes you can deconstruct the climate and learn how all the different processes interact to generate the observed climate and how the processes interact to generate the IPCC predicted climate change for anthropogenic CO2 increase. The presentation will illustrate how this web-base tool works and what are the possibilities in teaching students with this tool are.

  2. Gaia Data Release 1. On-orbit performance of the Gaia CCDs at L2

    NASA Astrophysics Data System (ADS)

    Crowley, C.; Kohley, R.; Hambly, N. C.; Davidson, M.; Abreu, A.; van Leeuwen, F.; Fabricius, C.; Seabroke, G.; de Bruijne, J. H. J.; Short, A.; Lindegren, L.; Brown, A. G. A.; Sarri, G.; Gare, P.; Prusti, T.; Prod'homme, T.; Mora, A.; Martín-Fleitas, J.; Raison, F.; Lammers, U.; O'Mullane, W.; Jansen, F.

    2016-11-01

    The European Space Agency's Gaia satellite was launched into orbit around L2 in December 2013 with a payload containing 106 large-format scientific CCDs. The primary goal of the mission is to repeatedly obtain high-precision astrometric and photometric measurements of one thousand million stars over the course of five years. The scientific value of the down-linked data, and the operation of the onboard autonomous detection chain, relies on the high performance of the detectors. As Gaia slowly rotates and scans the sky, the CCDs are continuously operated in a mode where the line clock rate and the satellite rotation spin-rate are in synchronisation. Nominal mission operations began in July 2014 and the first data release is being prepared for release at the end of Summer 2016. In this paper we present an overview of the focal plane, the detector system, and strategies for on-orbit performance monitoring of the system. This is followed by a presentation of the performance results based on analysis of data acquired during a two-year window beginning at payload switch-on. Results for parameters such as readout noise and electronic offset behaviour are presented and we pay particular attention to the effects of the L2 radiation environment on the devices. The radiation-induced degradation in the charge transfer efficiency (CTE) in the (parallel) scan direction is clearly diagnosed; however, an extrapolation shows that charge transfer inefficiency (CTI) effects at end of mission will be approximately an order of magnitude less than predicted pre-flight. It is shown that the CTI in the serial register (horizontal direction) is still dominated by the traps inherent to the manufacturing process and that the radiation-induced degradation so far is only a few per cent. We also present results on the tracking of ionising radiation damage and hot pixel evolution. Finally, we summarise some of the detector effects discovered on-orbit which are still being investigated.

  3. Gaia Theory in Brazilian High School Biology Textbooks

    ERIC Educational Resources Information Center

    Do Carmo, Ricardo Santos; Nunes-Neto, Nei Freitas; El-Hani, Charbel Nino

    2009-01-01

    Gaia theory proposes that a cybernetic system including the biota and the physicochemical environment regulates environmental variables at a global scale, keeping them within a range that makes Earth inhabitable by living beings. One can argue that this theory can play an important role in school science, since it bears upon current environmental…

  4. Monitoring solar irradiance from L2 with Gaia

    NASA Astrophysics Data System (ADS)

    Serpell, E.

    2017-09-01

    Gaia is the European Space Agency's cornerstone astrometry mission to measure the positions of a billion stars in the Milky Way with unprecedented accuracy. Since early 2014 Gaia has been operating in a halo orbit around the second Sun-Earth Lagrange point that provides the stable thermal environment, without Earth eclipses, needed for the payload to function accurately. The spacecraft is equipped with a number of thermally isolated, sun-facing thermistors that provide a continuous measurement of the local equilibrium temperature. As a consequence of the spacecraft design and operational conditions these temperature measurements have been used to infer the solar output over a broad wavelength range. In this paper we present an analysis of temperature measurements made of the Gaia solar panels at frequencies of up to 1 Hz for the first 35 months of routine operations. We show that the Gaia solar panel temperature measurements are capable of precisely determining short term changes to the solar output at a level of better than 0.04% with time constants of a few minutes.

  5. First results from stellar occultations in the "GAIA era"

    NASA Astrophysics Data System (ADS)

    Benedetti-Rossi, G.; Vieira-Martins, R.; Sicardy, B.

    2017-09-01

    Stellar occultation is a powerful technique to study distant solar system bodies. It allows high angular resolution of the occulting body from the analysis of a light curve acquired with high temporal resolution with uncertainties comparable as probes. In the "GAIA era", stellar occultations is now able to obtain even more impressive results such as the presence of atmosphere, rings and topographic features.

  6. Gaia: "Thinking Like a Planet" as Transformative Learning

    ERIC Educational Resources Information Center

    Haigh, Martin

    2014-01-01

    Transformative learning may involve gentle perspective widening or something more traumatic. This paper explores the impact of a transformative pedagogy in a course that challenges learners to "think like a planet". Among six sources of intellectual anxiety, learners worry about: why Gaia Theory is neglected by their other courses; the…

  7. VizieR Online Data Catalog: Gaia-PS1-SDSS (GPS1) proper motion catalog (Tian+, 2017)

    NASA Astrophysics Data System (ADS)

    Tian, H.-J.; Gupta, P.; Sesar, B.; Rix, H.-W.; Martin, N. F.; Liu, C.; Goldman, B.; Platais, I.; Kudritzki, R.-P.; Waters, C. Z.

    2018-02-01

    In order to construct proper motions, we analyze and model catalog positions from four different imaging surveys, as discussed below. Gaia DR1 is based on observations collected between 2014 July 25 and 2015 September 16. PS1 observations were collected between 2010 and 2014. The SDSS DR9 data used here were obtained in the years between 2000 and 2008. The images from 2MASS were taken between 1997 and 2001. (1 data file).

  8. Near-Earth Asteroids Astrometry with Gaia and Beyond

    NASA Astrophysics Data System (ADS)

    Bancelin, D.; Hestroffer, D.; Thuillot, W.

    2010-05-01

    Gaia is an astrometric mission from the European Space Agency (ESA) that will be launched in Spring 2012. The Gaia telescope and spectrometer will operate in the visible wavelength scanning the whole sky during 5 years (nominal mission duration). It will observe about one billion stars and QSOs but also a large number of solar system bodies, mainly asteroids, and a few comets and planetary satellites. The unprecedented accuracy of the measures both astrometric and photometric (note that the spectroscopic observations are of little scientific value for Solar System objects science) will enable to significantly improve the knowledge of the dynamics and physical properties for a large number of asteroids. With a relatively limiting magnitude somewhat reduced to V≤20 (compared to other future or ongoing surveys) Gaia will mainly oserve main-belt asteroids (MBAs), and very few TNOs or Centaurs. The Gaia telescope will also be able to observe several thousands of Near- Earth Objects (NEOs) down to low solar elongation (observation of solar system objects are performed with elongation 45° ≤ L ≤ 135°). Gaia will not be a ''big'' NEO discover, however it can possibly discover inner-Earth orbiting objects (IEOs) or sub-Atens, from atmosphereless low solar-elongation observations. In the case of discovering a new NEO target, ground-based observations in network could be needed to avoid confusion in identifying the object in the database, or loss of the target. We are aiming to generate VO-alert for such eventuality. Ground-based observations of NEOs would also more generally enter into the operational centre in construction at the IMCCE that will deal with data mining, astrometric reduction, orbit computation, alerts, etc. On the other hand, in the framework of ESA Space Situational Awareness (SSA), ground-based astrometry, possibly complemented by Gaia data, is needed to refine the orbits and collision assessment of PHAs. High accuracy astrometric and colour

  9. Halo substructure in the SDSS-Gaia catalogue: streams and clumps

    NASA Astrophysics Data System (ADS)

    Myeong, G. C.; Evans, N. W.; Belokurov, V.; Amorisco, N. C.; Koposov, S. E.

    2018-04-01

    We use the Sloan Digital Sky Survey (SDSS)-Gaia Catalogue to identify six new pieces of halo substructure. SDSS-Gaia is an astrometric catalogue that exploits SDSS data release 9 to provide first epoch photometry for objects in the Gaia source catalogue. We use a version of the catalogue containing 245 316 stars with all phase-space coordinates within a heliocentric distance of ˜10 kpc. We devise a method to assess the significance of halo substructures based on their clustering in velocity space. The two most substantial structures are multiple wraps of a stream which has undergone considerable phase mixing (S1, with 94 members) and a kinematically cold stream (S2, with 61 members). The member stars of S1 have a median position of (X, Y, Z) = (8.12, -0.22, 2.75) kpc and a median metallicity of [Fe/H] = -1.78. The stars of S2 have median coordinates (X, Y, Z) = (8.66, 0.30, 0.77) kpc and a median metallicity of [Fe/H] = -1.91. They lie in velocity space close to some of the stars in the stream reported by Helmi et al. By modelling, we estimate that both structures had progenitors with virial masses ≈1010M⊙ and infall times ≳ 9 Gyr ago. Using abundance matching, these correspond to stellar masses between 106 and 107M⊙. These are somewhat larger than the masses inferred through the mass-metallicity relation by factors of 5 to 15. Additionally, we identify two further substructures (S3 and S4 with 55 and 40 members) and two clusters or moving group (C1 and C2 with 24 and 12) members. In all six cases, clustering in kinematics is found to correspond to clustering in both configuration space and metallicity, adding credence to the reliability of our detections.

  10. An artificial neural network to discover hypervelocity stars: candidates in Gaia DR1/TGAS

    NASA Astrophysics Data System (ADS)

    Marchetti, T.; Rossi, E. M.; Kordopatis, G.; Brown, A. G. A.; Rimoldi, A.; Starkenburg, E.; Youakim, K.; Ashley, R.

    2017-09-01

    The paucity of hypervelocity stars (HVSs) known to date has severely hampered their potential to investigate the stellar population of the Galactic Centre and the Galactic potential. The first Gaia data release (DR1, 2016 September 14) gives an opportunity to increase the current sample. The challenge is the disparity between the expected number of HVSs and that of bound background stars. We have applied a novel data mining algorithm based on machine learning techniques, an artificial neural network, to the Tycho-Gaia astrometric solution catalogue. With no pre-selection of data, we could exclude immediately ˜99 per cent of the stars in the catalogue and find 80 candidates with more than 90 per cent predicted probability to be HVSs, based only on their position, proper motions and parallax. We have cross-checked our findings with other spectroscopic surveys, determining radial velocities for 30 and spectroscopic distances for five candidates. In addition, follow-up observations have been carried out at the Isaac Newton Telescope for 22 stars, for which we obtained radial velocities and distance estimates. We discover 14 stars with a total velocity in the Galactic rest frame >400 km s-1, and five of these have a probability of >50 per cent of being unbound from the Milky Way. Tracing back their orbits in different Galactic potential models, we find one possible unbound HVS with v ˜ 520 km s-1, five bound HVSs and, notably, five runaway stars with median velocity between 400 and 780 km s-1. At the moment, uncertainties in the distance estimates and ages are too large to confirm the nature of our candidates by narrowing down their ejection location, and we wait for future Gaia releases to validate the quality of our sample. This test successfully demonstrates the feasibility of our new data-mining routine.

  11. Estimating Distances from Parallaxes. II. Performance of Bayesian Distance Estimators on a Gaia-like Catalogue

    NASA Astrophysics Data System (ADS)

    Astraatmadja, Tri L.; Bailer-Jones, Coryn A. L.

    2016-12-01

    Estimating a distance by inverting a parallax is only valid in the absence of noise. As most stars in the Gaia catalog will have non-negligible fractional parallax errors, we must treat distance estimation as a constrained inference problem. Here we investigate the performance of various priors for estimating distances, using a simulated Gaia catalog of one billion stars. We use three minimalist, isotropic priors, as well an anisotropic prior derived from the observability of stars in a Milky Way model. The two priors that assume a uniform distribution of stars—either in distance or in space density—give poor results: The root mean square fractional distance error, {f}{rms}, grows far in excess of 100% once the fractional parallax error, {f}{true}, is larger than 0.1. A prior assuming an exponentially decreasing space density with increasing distance performs well once its single parameter—the scale length— has been set to an appropriate value: {f}{rms} is roughly equal to {f}{true} for {f}{true}\\lt 0.4, yet does not increase further as {f}{true} increases up to to 1.0. The Milky Way prior performs well except toward the Galactic center, due to a mismatch with the (simulated) data. Such mismatches will be inevitable (and remain unknown) in real applications, and can produce large errors. We therefore suggest adopting the simpler exponentially decreasing space density prior, which is also less time-consuming to compute. Including Gaia photometry improves the distance estimation significantly for both the Milky Way and exponentially decreasing space density prior, yet doing so requires additional assumptions about the physical nature of stars.

  12. The Montsec Observatory and the Gaia science alerts

    NASA Astrophysics Data System (ADS)

    Carrasco, J. M.; Burgaz, U.; Vilardell, F.; Jordi, C.

    2017-03-01

    The continuous and reiterative scan of the whole sky performed by Gaia ESA's mission during its (at least) 5 years of mission allows to detect transient events (e.g., supernovae, microlensing events, cataclysmic variables, etc) almost in real time among the daily millions of observations. The pipeline in charge to discover these alerts does a quick look analysis of the daily data stream, identify those sources increasing their brightness with respect to previous Gaia observations and also analyse their spectrophotometry to decide if those sources are good candidates to be published as a Gaia Photometric Science Alerts. These events are publicly announced for follow-up observations (both photometric and spectroscopic are needed). Observatories around the world confirm, classify and study them in detail. Observations are put in common and analysed together in a common interface in order to get a single analysis as detailed and precise as possible. Our team in Barcelona contributes to this Gaia science alerts follow-up programme with the 0.8 m robotic telescope Joan Oró (TJO), at the Montsec Observatory (OAdM), located at Sant Esteve de la Sarga (Lleida, Spain) performing photometric observations to derive the lightcurves of the most interesting alerts accessible from the observatory. Until now we have contributed with about 4500 images in multicolour Johnson-Cousins passbands obtained with TJO for a total of 38 Gaia science alerts, becoming the third most contributing observatory in the programme. Here we summarise the procedure to select new targets to be observed by TJO, submit follow-up observations and we explain the analysis we did for some interesting obtained lightcurves.

  13. A Gaia DR2 Confirmation that 2MASS J12074836–3900043 is a Member of the TW HYA Association

    NASA Astrophysics Data System (ADS)

    Gagné, Jonathan; Gonzales, Eileen C.; Faherty, Jacqueline K.

    2018-05-01

    We use new data from Gaia DR2 to confirm that the young L1 $\\gamma$ candidate member of the TW Hya association (TWA) is now a bona fide member with a model-dependent mass estimate of ~15 $M_{Jup}$. The ambiguous M9 $\\gamma$ candidate member 2MASS J12474428---3816464 also gets a higher Bayesian membership probability for TWA membership as a result of Gaia DR2 data and a new radial velocity measurement, but it remains unclear whether it is a true member of TWA or if it is an unrelated young interloper, because it is separated by 4.6 km/s from the locus of TWA members in UVW space.

  14. Universality in a Neutral Evolution Model

    NASA Astrophysics Data System (ADS)

    King, Dawn; Scott, Adam; Maric, Nevena; Bahar, Sonya

    2013-03-01

    Agent-based models are ideal for investigating the complex problems of biodiversity and speciation because they allow for complex interactions between individuals and between individuals and the environment. Presented here is a ``null'' model that investigates three mating types - assortative, bacterial, and random - in phenotype space, as a function of the percentage of random death δ. Previous work has shown phase transition behavior in an assortative mating model with variable fitness landscapes as the maximum mutation size (μ) was varied (Dees and Bahar, 2010). Similarly, this behavior was recently presented in the work of Scott et al. (submitted), on a completely neutral landscape, for bacterial-like fission as well as for assortative mating. Here, in order to achieve an appropriate ``null'' hypothesis, the random death process was changed so each individual, in each generation, has the same probability of death. Results show a continuous nonequilibrium phase transition for the order parameters of the population size and the number of clusters (analogue of species) as δ is varied for three different mutation sizes of the system. The system shows increasing robustness as μ increases. Universality classes and percolation properties of this system are also explored. This research was supported by funding from: University of Missouri Research Board and James S. McDonnell Foundation

  15. Gaia Data Release 1. Astrometry: one billion positions, two million proper motions and parallaxes

    NASA Astrophysics Data System (ADS)

    Lindegren, L.; Lammers, U.; Bastian, U.; Hernández, J.; Klioner, S.; Hobbs, D.; Bombrun, A.; Michalik, D.; Ramos-Lerate, M.; Butkevich, A.; Comoretto, G.; Joliet, E.; Holl, B.; Hutton, A.; Parsons, P.; Steidelmüller, H.; Abbas, U.; Altmann, M.; Andrei, A.; Anton, S.; Bach, N.; Barache, C.; Becciani, U.; Berthier, J.; Bianchi, L.; Biermann, M.; Bouquillon, S.; Bourda, G.; Brüsemeister, T.; Bucciarelli, B.; Busonero, D.; Carlucci, T.; Castañeda, J.; Charlot, P.; Clotet, M.; Crosta, M.; Davidson, M.; de Felice, F.; Drimmel, R.; Fabricius, C.; Fienga, A.; Figueras, F.; Fraile, E.; Gai, M.; Garralda, N.; Geyer, R.; González-Vidal, J. J.; Guerra, R.; Hambly, N. C.; Hauser, M.; Jordan, S.; Lattanzi, M. G.; Lenhardt, H.; Liao, S.; Löffler, W.; McMillan, P. J.; Mignard, F.; Mora, A.; Morbidelli, R.; Portell, J.; Riva, A.; Sarasso, M.; Serraller, I.; Siddiqui, H.; Smart, R.; Spagna, A.; Stampa, U.; Steele, I.; Taris, F.; Torra, J.; van Reeven, W.; Vecchiato, A.; Zschocke, S.; de Bruijne, J.; Gracia, G.; Raison, F.; Lister, T.; Marchant, J.; Messineo, R.; Soffel, M.; Osorio, J.; de Torres, A.; O'Mullane, W.

    2016-11-01

    Context. Gaia Data Release 1 (DR1) contains astrometric results for more than 1 billion stars brighter than magnitude 20.7 based on observations collected by the Gaia satellite during the first 14 months of its operational phase. Aims: We give a brief overview of the astrometric content of the data release and of the model assumptions, data processing, and validation of the results. Methods: For stars in common with the Hipparcos and Tycho-2 catalogues, complete astrometric single-star solutions are obtained by incorporating positional information from the earlier catalogues. For other stars only their positions are obtained, essentially by neglecting their proper motions and parallaxes. The results are validated by an analysis of the residuals, through special validation runs, and by comparison with external data. Results: For about two million of the brighter stars (down to magnitude 11.5) we obtain positions, parallaxes, and proper motions to Hipparcos-type precision or better. For these stars, systematic errors depending for example on position and colour are at a level of ± 0.3 milliarcsecond (mas). For the remaining stars we obtain positions at epoch J2015.0 accurate to 10 mas. Positions and proper motions are given in a reference frame that is aligned with the International Celestial Reference Frame (ICRF) to better than 0.1 mas at epoch J2015.0, and non-rotating with respect to ICRF to within 0.03 mas yr-1. The Hipparcos reference frame is found to rotate with respect to the Gaia DR1 frame at a rate of 0.24 mas yr-1. Conclusions: Based on less than a quarter of the nominal mission length and on very provisional and incomplete calibrations, the quality and completeness of the astrometric data in Gaia DR1 are far from what is expected for the final mission products. The present results nevertheless represent a huge improvement in the available fundamental stellar data and practical definition of the optical reference frame.

  16. Testing asteroseismic radii of dwarfs and subgiants with Kepler and Gaia

    NASA Astrophysics Data System (ADS)

    Sahlholdt, C. L.; Silva Aguirre, V.; Casagrande, L.; Mosumgaard, J. R.; Bojsen-Hansen, M.

    2018-05-01

    We test asteroseismic radii of Kepler main-sequence and subgiant stars by deriving their parallaxes which are compared with those of the first Gaia data release. We compute radii based on the asteroseismic scaling relations as well as by fitting observed oscillation frequencies to stellar models for a subset of the sample, and test the impact of using effective temperatures from either spectroscopy or the infrared flux method. An offset of 3 per cent, showing no dependency on any stellar parameters, is found between seismic parallaxes derived from frequency modelling and those from Gaia. For parallaxes based on radii from the scaling relations, a smaller offset is found on average; however, the offset becomes temperature dependent which we interpret as problems with the scaling relations at high stellar temperatures. Using the hotter infrared flux method temperature scale, there is no indication that radii from the scaling relations are inaccurate by more than about 5 per cent. Taking the radii and masses from the modelling of individual frequencies as reference values, we seek to correct the scaling relations for the observed temperature trend. This analysis indicates that the scaling relations systematically overestimate radii and masses at high temperatures, and that they are accurate to within 5 per cent in radius and 13 per cent in mass for main-sequence stars with temperatures below 6400 K. However, further analysis is required to test the validity of the corrections on a star-by-star basis and for more evolved stars.

  17. The Gaia inertial reference frame and the tilting of the Milky Way disk

    SciTech Connect

    Perryman, Michael; Spergel, David N.; Lindegren, Lennart, E-mail: mac.perryman@gmail.com

    2014-07-10

    While the precise relationship between the Milky Way disk and the symmetry planes of the dark matter halo remains somewhat uncertain, a time-varying disk orientation with respect to an inertial reference frame seems probable. Hierarchical structure formation models predict that the dark matter halo is triaxial and tumbles with a characteristic rate of ∼2 rad H{sub 0}{sup −1} (∼30 μas yr{sup –1}). These models also predict a time-dependent accretion of gas, such that the angular momentum vector of the disk should be misaligned with that of the halo. These effects, as well as tidal effects of the LMC, will resultmore » in the rotation of the angular momentum vector of the disk population with respect to the quasar reference frame. We assess the accuracy with which the positions and proper motions from Gaia can be referred to a kinematically non-rotating system, and show that the spin vector of the transformation from any rigid self-consistent catalog frame to the quasi-inertial system defined by quasars should be defined to better than 1 μas yr{sup –1}. Determination of this inertial frame by Gaia will reveal any signature of the disk orientation varying with time, improve models of the potential and dynamics of the Milky Way, test theories of gravity, and provide new insights into the orbital evolution of the Sagittarius dwarf galaxy and the Magellanic Clouds.« less

  18. A universal model for nanoporous carbon supercapacitors

    SciTech Connect

    Huang, Jingsong; Sumpter, Bobby G; Meunier, Vincent

    2009-01-01

    Supercapacitors based on nanoporous carbon materials, commonly called electric double-layer capacitors (EDLCs), are emerging as a novel type of energy-storage device with the potential to substitute batteries in applications that require high power densities. Nanoporous carbon supercapacitors are generally viewed as a parallel-plate capacitor since supercapacitors store energy by charge separation in an electric double layer formed at the electrode/electrolyte interface. The EDLC model has been used to characterize the energy storage of supercapacitors for decades. We comment in this chapter on the shortcomings of the EDLC model when applied to nanoporous carbon supercapacitors. In response to the latest experimentalmore » breakthrough in nanoporous carbon supercapacitors, we have proposed a heuristic model that takes pore curvature into account as a replacement for the EDLC model. When the pore size is in the mesopore regime (2 50 nm), electrolyte counterions enter mesoporous carbons and approach the pore wall to form an electric double-cylinder capacitor (EDCC); in the micropore regime (< 2 nm), solvated/desolvated counterions line up along the pore axis to form an electric wire-in-cylinder capacitor (EWCC). In the macropore regime (> 50 nm), where pores are large enough so that pore curvature is no longer significant, the EDCC model can be reduced to the EDLC model. With the backing of experimental data and quantum density functional theory calculations, we have shown that the EDCC/EWCC model is universal for carbon supercapacitors with diverse carbon materials and electrolytes. The strengths and limitations of this new model are discussed. The new model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration, dielectric constant, and solute ion size, and may lend support to the systematic optimization of the properties of carbon supercapacitors through experiments.« less

  19. [Lübeck University Model for Physiotherapy].

    PubMed

    Bretin, Annette; Großmann, Kirsten; Schulz, ArndtPeter

    2018-02-19

    The aim of this paper is to describe the development of an innovative bachelor's degree program for physiotherapy directly affiliated with the medical department, which is a unique approach to making physiotherapy an academic course in Germany. The previous system for qualifying as a physiotherapist was amended by the adaption of qualification objectives resulting in a model that links scientific and vocational knowledge from the beginning of the study. Several lectures support interprofessionality. The vocational training is fully integrated into the curriculum. The exemplary concept is monitored by an extensive quality management program. The approach meets general recommendations of experts and can serve as a model for other universities. © Georg Thieme Verlag KG Stuttgart · New York.

  20. Gaia Data Release 1. The archive visualisation service

    NASA Astrophysics Data System (ADS)

    Moitinho, A.; Krone-Martins, A.; Savietto, H.; Barros, M.; Barata, C.; Falcão, A. J.; Fernandes, T.; Alves, J.; Silva, A. F.; Gomes, M.; Bakker, J.; Brown, A. G. A.; González-Núñez, J.; Gracia-Abril, G.; Gutiérrez-Sánchez, R.; Hernández, J.; Jordan, S.; Luri, X.; Merin, B.; Mignard, F.; Mora, A.; Navarro, V.; O'Mullane, W.; Sagristà Sellés, T.; Salgado, J.; Segovia, J. C.; Utrilla, E.; Arenou, F.; de Bruijne, J. H. J.; Jansen, F.; McCaughrean, M.; O'Flaherty, K. S.; Taylor, M. B.; Vallenari, A.

    2017-09-01

    Context. The first Gaia data release (DR1) delivered a catalogue of astrometry and photometry for over a billion astronomical sources. Within the panoplyof methods used for data exploration, visualisation is often the starting point and even the guiding reference for scientific thought. However, this is a volume of data that cannot be efficiently explored using traditional tools, techniques, and habits. Aims: We aim to provide a global visual exploration service for the Gaia archive, something that is not possible out of the box for most people. The service has two main goals. The first is to provide a software platform for interactive visual exploration of the archive contents, using common personal computers and mobile devices available to most users. The second aim is to produce intelligible and appealing visual representations of the enormous information content of the archive. Methods: The interactive exploration service follows a client-server design. The server runs close to the data, at the archive, and is responsible for hiding as far as possible the complexity and volume of the Gaia data from the client. This is achieved by serving visual detail on demand. Levels of detail are pre-computed using data aggregation and subsampling techniques. For DR1, the client is a web application that provides an interactive multi-panel visualisation workspace as well as a graphical user interface. Results: The Gaia archive Visualisation Service offers a web-based multi-panel interactive visualisation desktop in a browser tab. It currently provides highly configurable 1D histograms and 2D scatter plots of Gaia DR1 and the Tycho-Gaia Astrometric Solution (TGAS) with linked views. An innovative feature is the creation of ADQL queries from visually defined regions in plots. These visual queries are ready for use in the Gaia Archive Search/data retrieval service. In addition, regions around user-selected objects can be further examined with automatically generated SIMBAD

  1. A Universal Model for Solar Eruptions

    NASA Astrophysics Data System (ADS)

    Wyper, Peter; Antiochos, Spiro K.; DeVore, C. Richard

    2017-08-01

    We present a universal model for solar eruptions that encompasses coronal mass ejections (CMEs) at one end of the scale, to coronal jets at the other. The model is a natural extension of the Magnetic Breakout model for large-scale fast CMEs. Using high-resolution adaptive mesh MHD simulations conducted with the ARMS code, we show that so-called blowout or mini-filament coronal jets can be explained as one realisation of the breakout process. We also demonstrate the robustness of this “breakout-jet” model by studying three realisations in simulations with different ambient field inclinations. We conclude that magnetic breakout supports both large-scale fast CMEs and small-scale coronal jets, and by inference eruptions at scales in between. Thus, magnetic breakout provides a unified model for solar eruptions. P.F.W was supported in this work by an award of a RAS Fellowship and an appointment to the NASA Postdoctoral Program. C.R.D and S.K.A were supported by NASA’s LWS TR&T and H-SR programs.

  2. A fractal model of the Universe

    NASA Astrophysics Data System (ADS)

    Gottlieb, Ioan

    The book represents a revisioned, extended, completed and translated version of the book "Superposed Universes. A scientific novel and a SF story" (1995). The book contains a hypothesis by the author concerning the complexity of the Nature. An introduction to the theories of numbers, manyfolds and topology is given. The possible connection with the theory of evolution of the Universe is discussed. The book contains also in the last chapter a SF story based on the hypothesis presented. A connection with fractals theory is given. A part of his earlier studies (1955-1956) were subsequently published without citation by Ali Kyrala (Phys. Rev. vol.117, No.5, march 1, 1960). The book contains as an important appendix the early papers (some of which are published in the coauthoprship with his scientific advisors): 1) T.T. Vescan, A. Weiszmann and I.Gottlieb, Contributii la studiul problemelor geometrice ale teoriei relativitatii restranse. Academia R.P.R. Baza Timisoara. Lucrarile consfatuirii de geometrie diferentiala din 9-12 iunie 1955. In this paper the authors show a new method of the calculation of the metrics. 2) Jean Gottlieb, L'hyphotese d'un modele de la structure de la matiere, Revista Matematica y Fisica Teorica, Serie A, Volumen XY, No.1, y.2, 1964 3) I. Gottlieb, Some hypotheses on space, time and gravitation, Studies in Gravitation Theory, CIP Press, Bucharest, 1988, pp.227-234 as well as some recent papers (published in the coauthorship with his disciples): 4)M. Agop, Gottlieb speace-time. A fractal axiomatic model of the Universe. in Particles and Fields, Editors: M.Agop and P.D. Ioannou, Athens University Press, 2005, pp. 59-141 5) I. Gottlieb, M.Agop and V.Enache, Games with Cantor's dust. Chaos, Solitons and Fractals, vol.40 (2009) pp. 940-945 6) I. Gottlieb, My picture over the World, Bull. of the Polytechnic Institute of Iasi. Tom LVI)LX, Fasc. 1, 2010, pp. 1-18. The book contains also a dedication to father Vasile Gottlieb and wife Cleopatra

  3. Far-ultraviolet to Near-infrared Spectroscopy of a Nearby Hydrogen-poor Superluminous Supernova Gaia16apd

    NASA Astrophysics Data System (ADS)

    Yan, Lin; Quimby, R.; Gal-Yam, A.; Brown, P.; Blagorodnova, N.; Ofek, E. O.; Lunnan, R.; Cooke, J.; Cenko, S. B.; Jencson, J.; Kasliwal, M.

    2017-05-01

    We report the first maximum-light far-ultraviolet (FUV) to near-infrared (NIR) spectra (1000 Å - 1.62 μm, rest) of a hydrogen-poor superluminous supernova, Gaia16apd. At z = 0.1018, it is the second closest and the UV brightest SLSN-I, with 17.4 mag in Swift UVW2 band at -11 days pre-maximum. The coordinated observations with HST, Palomar, and Keck were taken at -2 to +25 days. Assuming an exponential (or t 2) form, we derived the rise time of 33 days and the peak bolometric luminosity of 3 × 1044 erg s-1. At the maximum, the photospheric temperature and velocity are 17,000 K and 14,000 km s-1, respectively. The inferred radiative and kinetic energy are roughly 1 × 1051 and 2 × 1052 erg. Gaia16apd is extremely UV luminous, and emits 50% of its total luminosity at 1000-2500 Å. Compared to the UV spectra (normalized at 3100 Å) of well studied SN1992A (Ia), SN2011fe (Ia), SN1999em (IIP), and SN1993J (IIb), it has orders of magnitude more FUV emission. This excess is interpreted primarily as a result of weaker metal-line blanketing due to a much lower abundance of iron group elements in the outer ejecta. Because these elements originate either from the natal metallicity of the star, or have been newly produced, our observation provides direct evidence that little of these freshly synthesized material, including 56Ni, were mixed into the outer ejecta, and the progenitor metallicity is likely sub-solar. This disfavors Pair-instability Supernova models with helium core masses ≥slant 90 {M}⊙ , where substantial 56Ni material is produced. A higher photospheric temperature definitely contributes to the FUV excess from Gaia16apd. Compared with Gaia16apd, we find PS1-11bam is also UV luminous.

  4. Towards a Universal Model of Reading

    PubMed Central

    Frost, Ram

    2013-01-01

    In the last decade, reading research has seen a paradigmatic shift. A new wave of computational models of orthographic processing that offer various forms of noisy position or context-sensitive coding, have revolutionized the field of visual word recognition. The influx of such models stems mainly from consistent findings, coming mostly from European languages, regarding an apparent insensitivity of skilled readers to letter-order. Underlying the current revolution is the theoretical assumption that the insensitivity of readers to letter order reflects the special way in which the human brain encodes the position of letters in printed words. The present paper discusses the theoretical shortcomings and misconceptions of this approach to visual word recognition. A systematic review of data obtained from a variety of languages demonstrates that letter-order insensitivity is not a general property of the cognitive system, neither it is a property of the brain in encoding letters. Rather, it is a variant and idiosyncratic characteristic of some languages, mostly European, reflecting a strategy of optimizing encoding resources, given the specific structure of words. Since the main goal of reading research is to develop theories that describe the fundamental and invariant phenomena of reading across orthographies, an alternative approach to model visual word recognition is offered. The dimensions of a possible universal model of reading, which outlines the common cognitive operations involved in orthographic processing in all writing systems, are discussed. PMID:22929057

  5. Towards a universal model of reading.

    PubMed

    Frost, Ram

    2012-10-01

    In the last decade, reading research has seen a paradigmatic shift. A new wave of computational models of orthographic processing that offer various forms of noisy position or context-sensitive coding have revolutionized the field of visual word recognition. The influx of such models stems mainly from consistent findings, coming mostly from European languages, regarding an apparent insensitivity of skilled readers to letter order. Underlying the current revolution is the theoretical assumption that the insensitivity of readers to letter order reflects the special way in which the human brain encodes the position of letters in printed words. The present article discusses the theoretical shortcomings and misconceptions of this approach to visual word recognition. A systematic review of data obtained from a variety of languages demonstrates that letter-order insensitivity is neither a general property of the cognitive system nor a property of the brain in encoding letters. Rather, it is a variant and idiosyncratic characteristic of some languages, mostly European, reflecting a strategy of optimizing encoding resources, given the specific structure of words. Since the main goal of reading research is to develop theories that describe the fundamental and invariant phenomena of reading across orthographies, an alternative approach to model visual word recognition is offered. The dimensions of a possible universal model of reading, which outlines the common cognitive operations involved in orthographic processing in all writing systems, are discussed.

  6. VLT spectroscopic observations of highly magnified Galactic Disk microlensing event Gaia18bmt

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, L.; Gromadzki, M.; Kruszynska, K.; Rybicki, K. A.; Zielinski, P.

    2018-06-01

    Gaia18bmt (Ra, Dec = 14:16:03.55, -56:54:48.24) was found by Gaia Science Alerts programme on 2018-06-11 (http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia18bmt/) as a significant brigthening by more than 2 mag on a 15.5 mag star in the Galactic Disk (l,b = 314.32362, 4.07498).

  7. Gaia luminosities of pulsating A-F stars in the Kepler field

    NASA Astrophysics Data System (ADS)

    Balona, L. A.

    2018-06-01

    All stars in the Kepler field brighter than 12.5 magnitude have been classified according to variability type. A catalogue of δ Scuti and γ Doradus stars is presented. The problem of low frequencies in δ Sct stars, which occurs in over 98 percent of these stars, is discussed. Gaia DR2 parallaxes were used to obtain precise luminosities, enabling the instability strips of the two classes of variable to be precisely defined. Surprisingly, it turns out that the instability region of the γ Dor stars is entirely within the δ Sct instability strip. Thus γDor stars should not be considered a separate class of variable. The observed red and blue edges of the instability strip do not agree with recent model calculations. Stellar pulsation occurs in less than half of the stars in the instability region and arguments are presented to show that this cannot be explained by assuming pulsation at a level too low to be detected. Precise Gaia DR2 luminosities of high-amplitude δ Sct stars (HADS) show that most of these are normal δ Sct stars and not transition objects. It is argued that current ideas on A star envelopes need to be revised.

  8. Hybrid Speaker Recognition Using Universal Acoustic Model

    NASA Astrophysics Data System (ADS)

    Nishimura, Jun; Kuroda, Tadahiro

    We propose a novel speaker recognition approach using a speaker-independent universal acoustic model (UAM) for sensornet applications. In sensornet applications such as “Business Microscope”, interactions among knowledge workers in an organization can be visualized by sensing face-to-face communication using wearable sensor nodes. In conventional studies, speakers are detected by comparing energy of input speech signals among the nodes. However, there are often synchronization errors among the nodes which degrade the speaker recognition performance. By focusing on property of the speaker's acoustic channel, UAM can provide robustness against the synchronization error. The overall speaker recognition accuracy is improved by combining UAM with the energy-based approach. For 0.1s speech inputs and 4 subjects, speaker recognition accuracy of 94% is achieved at the synchronization error less than 100ms.

  9. Candidate Nearby, Young Stars in Gaia's First Data Release

    NASA Astrophysics Data System (ADS)

    Chalifour, Matthieu; Kastner, Joel H.; Binks, Alex; Rodriguez, David; Punzi, Kristina; Zuckerman, Ben; Sacco, Germano

    2018-01-01

    The nearest examples of young stars are essential subjects for the study of planet and star formation. The recent data release from Gaia, which contains accurate parallax distances for ~2.5 million stars, allows age determinations via isochronal analysis for thousands of stars within ~100 pc. We have selected nearly 400 candidates nearby, young, late-type stars in the approximate mass range 0.5-1.0 Msun from the Tycho Gaia Astrometric Solution catalog on the basis of (a) D < 100 pc, (b) Galex UV detection, and (c) isochronal age <~ 80 Myr. Approximately 10% of these candidates lie within 50 pc of Earth and, hence, may represent excellent targets for direct-imaging searches for young, self-luminous planets. We discuss our ongoing efforts to assess the accuracy of these stars' isochronal ages via various diagnostic tools, including galactic kinematics, UV excess, relative X-ray luminosity, andoptical spectroscopic indicators of youth.

  10. Finding evolved stars in the inner Galactic disk with Gaia

    NASA Astrophysics Data System (ADS)

    Quiroga-Nuñez, L. H.; van Langevelde, H. J.; Pihlström, Y. M.; Sjouwerman, L. O.; Brown, A. G. A.

    2018-04-01

    The Bulge Asymmetries and Dynamical Evolution (BAaDE) survey will provide positions and line-of-sight velocities of ~20, 000 evolved, maser bearing stars in the Galactic plane. Although this Galactic region is affected by optical extinction, BAaDE targets may have Gaia cross-matches, eventually providing additional stellar information. In an initial attempt to cross-match BAaDE targets with Gaia, we have found more than 5,000 candidates. Of these, we may expect half to show SiO emission, which will allow us to obtain velocity information. The cross-match is being refined to avoid false positives using different criteria based on distance analysis, flux variability, and color assessment in the mid- and near-IR. Once the cross-matches can be confirmed, we will have a unique sample to characterize the stellar population of evolved stars in the Galactic bulge, which can be considered fossils of the Milky Way formation.

  11. Hadoop distributed batch processing for Gaia: a success story

    NASA Astrophysics Data System (ADS)

    Riello, Marco

    2015-12-01

    The DPAC Cambridge Data Processing Centre (DPCI) is responsible for the photometric calibration of the Gaia data including the low resolution spectra. The large data volume produced by Gaia (~26 billion transits/year), the complexity of its data stream and the self-calibrating approach pose unique challenges for scalability, reliability and robustness of both the software pipelines and the operations infrastructure. DPCI has been the first in DPAC to realise the potential of Hadoop and Map/Reduce and to adopt them as the core technologies for its infrastructure. This has proven a winning choice allowing DPCI unmatched processing throughput and reliability within DPAC to the point that other DPCs have started following our footsteps. In this talk we will present the software infrastructure developed to build the distributed and scalable batch data processing system that is currently used in production at DPCI and the excellent results in terms of performance of the system.

  12. Spitzer Parallax Observations of Long Duration Gaia Microlensing Events

    NASA Astrophysics Data System (ADS)

    Carey, Sean; Calchi-Novati, Sebastiano; Wyrzykowski, Lukasz; Kruszynska, Katarzyna; Gromadzki, Mariusz; Rybicki, Krzysztof

    2018-05-01

    We proposed to observe of order ten long duration (>100 day) microlensing events identified in Gaia survey data with the Spitzer Space Telescope. The long duration events are likely due to massive lenses, hence they could be isolated black holes. These observations could make defintive mass measurements for the first time of isolated stellar remanant black holes in our Galaxy. The Spitzer data provide a key component to making an umabiguous mass measurement by providing the microlensing parallax (as has been done for >500 event by Spitzer so far). The Gaia data is used for the detection of the events and measurement of the astrometric motion caused by the microlensing event. From the astrometric microlensing signature, the Einstein radius of the lens can be measured and combined with the microlensing parallax yields the lens mass and distance.

  13. Gaia: 3-dimensional census of the Milky Way Galaxy

    NASA Astrophysics Data System (ADS)

    Gilmore, Gerard

    2018-04-01

    Astrometry from space has unique advantages over ground-based observations: the all-sky coverage, relatively stable, and temperature and gravity invariant, operating environment delivers precision, accuracy and sample volume several orders of magnitude greater than ground-based results. Even more importantly, absolute astrometry is possible. The European Space Agency Cornerstone mission Gaia is delivering that promise. Gaia provides 5-D phase space measurements, 3 spatial coordinates and 2 space motions in the plane of the sky, for a representative sample of the Milky Way's stellar populations (over 2 billion stars, being 1% of the stars over 50% of the radius). Full 6-D phase space data are delivered from line-of-sight (radial) velocities for the 300 million brightest stars. These data make substantial contributions to astrophysics and fundamental physics on scales from the Solar System to cosmology. A knowledge revolution is underway.

  14. Fundamental Properties of Co-moving Stars Observed by Gaia

    NASA Astrophysics Data System (ADS)

    Bochanski, John J.; Faherty, Jacqueline K.; Gagné, Jonathan; Nelson, Olivia; Coker, Kristina; Smithka, Iliya; Desir, Deion; Vasquez, Chelsea

    2018-04-01

    We have estimated fundamental parameters for a sample of co-moving stars observed by Gaia and identified by Oh et al. We matched the Gaia observations to the 2MASS and Wide-Field Infrared Survey Explorer catalogs and fit MIST isochrones to the data, deriving estimates of the mass, radius, [Fe/H], age, distance, and extinction to 9754 stars in the original sample of 10606 stars. We verify these estimates by comparing our new results to previous analyses of nearby stars, examining fiducial cluster properties, and estimating the power-law slope of the local present-day mass function. A comparison to previous studies suggests that our mass estimates are robust, while metallicity and age estimates are increasingly uncertain. We use our calculated masses to examine the properties of binaries in the sample and show that separation of the pairs dominates the observed binding energies and expected lifetimes.

  15. Reanalysis of 24 Nearby Open Clusters using Gaia data

    NASA Astrophysics Data System (ADS)

    Yen, Steffi X.; Reffert, Sabine; Röser, Siegfried; Schilbach, Elena; Kharchenko, Nina V.; Piskunov, Anatoly E.

    2018-04-01

    We have developed a fully automated cluster characterization pipeline, which simultaneously determines cluster membership and fits the fundamental cluster parameters: distance, reddening, and age. We present results for 24 established clusters and compare them to literature values. Given the large amount of stellar data for clusters available from Gaia DR2 in 2018, this pipeline will be beneficial to analyzing the parameters of open clusters in our Galaxy.

  16. The astrometric lessons of Gaia-GBOT experiment

    NASA Astrophysics Data System (ADS)

    Bouquillon, S.; Mendez, R. A.; Altmann, M.

    2017-07-01

    To ensure the full capabilities of the Gaia's measurements, a programme of daily observations with Earth-based telescopes of the satellite itself - called Ground Based Optical Tracking (GBOT) - was implemented since the beginning of the Gaia mission (for more details concerning GBOT operating see Altmann et al. 2014 and concerning GBOT software facilities see Bouquillon et al. 2014). These observations are carried out mainly with two facilities: the 2.6m VLT Survey Telescope (ESO's VST) at the Cerro Paranal in Chile and the 2.0m Liverpool Telescope (LT) on the Canary Island of La Palma. The constraint of 20 mas on the tracking astrometric quality and the fact that Gaia is a faint and relatively fast moving target (its magnitude in a red passband is around 21 and its apparent speed around 0.04"/s), lead us to rigorously analyse the reachable astrometric precision for CCD observations of this kind of celestial objects. During LARIM 2016, we presented the main results of this study which uses the Cramér-Rao lower bound to characterize the precision limit for the PSF center when drifting in the CCD-frame. This work extends earlier studies dealing with one-dimensional detectors and stationary sources (Mendez et al. 2013 & 2014) firstly to the case of standard two-dimensional CCD sensors, and then, to moving sources. These new results have been submitted for a publication in A&A journal this year (Bouquillon et al. 2017).

  17. ROTATING STARS FROM KEPLER OBSERVED WITH GAIA DR1

    SciTech Connect

    Davenport, James R. A.

    2017-01-20

    Astrometric data from the recent Gaia Data Release 1 have been matched against the sample of stars from Kepler with known rotation periods. A total of 1299 bright rotating stars were recovered from the subset of Gaia sources with good astrometric solutions, most with temperatures above 5000 K. From these sources, 894 were selected as lying near the main sequence using their absolute G -band magnitudes. These main-sequence stars show a bimodality in their rotation period distribution, centered roughly around a 600 Myr rotation isochrone. This feature matches the bimodal period distribution found in cooler stars with Kepler , butmore » was previously undetected for solar-type stars due to sample contamination by subgiants. A tenuous connection between the rotation period and total proper motion is found, suggesting that the period bimodality is due to the age distribution of stars within ∼300 pc of the Sun, rather than a phase of rapid angular momentum loss. This work emphasizes the unique power for understanding stellar populations that is created by combining temporal monitoring from Kepler with astrometric data from Gaia .« less

  18. RAVE-Gaia and the impact on Galactic archeology

    NASA Astrophysics Data System (ADS)

    Kunder, Andrea

    2018-04-01

    The new data release (DR5) of the RAdial Velocity Experiment (RAVE) includes radial velocities of 520,781 spectra of 457,588 individual stars, of which 215,590 individual stars are released in the Tycho-Gaia astrometric solution (TGAS) in Gaia DR1. Therefore, RAVE contains the largest TGAS overlap of the recent and ongoing Milky Way spectroscopic surveys. Most of the RAVE stars also contain stellar parameters (effective temperature, surface gravity, overall metallicity), as well as individual abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni. Combining RAVE with TGAS brings the uncertainties in space velocities down by a factor of 2 for stars in the RAVE volume - 10 km s-1 uncertainties in space velocities are now able to be derived for the majority (70%) of the RAVE-TGAS sample, providing a powerful platform for chemo-dynamic analyses of the Milky Way. Here we discuss the RAVE-TGAS impact on Galactic archaeology as well as how the Gaia parallaxes can be used to break degeneracies within the RAVE spectral regime for an even better return in the derivation of stellar parameters and abundances.

  19. University - industry collaborations: models, drivers and cultures.

    PubMed

    Ehrismann, Dominic; Patel, Dhavalkumar

    2015-01-01

    The way academic institutions and pharmaceutical companies have been approaching collaborations has changed significantly in recent years. A multitude of interaction models were tested and critical factors that drive successful collaborations have been proposed. Based on this experience the current consensus in the pharmaceutical industry is to pursue one of two strategies: an open innovation approach to source discoveries wherever they occur, or investing selectively into scientific partnerships that churn out inventions that can be translated from bench to bedside internally. While these strategies may be intuitive, to form and build sustainable relationships between academia and large multinational healthcare enterprises is proving challenging. In this article we explore some of the more testing aspects of these collaborations, approaches that various industrial players have taken and provide our own views on the matter. We found that understanding and respecting each other's organisational culture and combining the intellectual and technological assets to answer big scientific questions accelerates and improves the quality of every collaboration. Upon discussing the prevailing cooperation models in the university - industry domain, we assert that science-driven collaborations where risks and rewards are shared equally without a commercial agenda in mind are the most impactful.

  20. A Model for the Development of University Curricula in Nanoelectronics

    ERIC Educational Resources Information Center

    Bruun, E.; Nielsen, I.

    2010-01-01

    Nanotechnology is having an increasing impact on university curricula in electrical engineering and in physics. Major influencers affecting developments in university programmes related to nanoelectronics are discussed and a model for university programme development is described. The model takes into account that nanotechnology affects not only…

  1. The Triad Research University or a Post 20th Century Research University Model

    ERIC Educational Resources Information Center

    Tadmor, Zehev

    2006-01-01

    In this paper, a model for the future research university is proposed, which answers some of the key challenges facing universities. It consists of three independent yet closely knitted entities: a research institute, a university teaching college and a business unit creating a "triad" structure. The possible inevitability, the advantages and…

  2. Kinematics of Stars from the TGAS (Gaia DR1) Catalogue

    NASA Astrophysics Data System (ADS)

    Vityazev, V. V.; Popov, A. V.; Tsvetkov, A. S.; Petrov, S. D.; Trofimov, D. A.; Kiyaev, V. I.

    2018-04-01

    Based on the stellar proper motions of the TGAS (Gaia DR1) catalogue, we have analyzed the velocity field of main-sequence stars and red giants from the TGAS catalogue with heliocentric distances up to 1.5 kpc. We have obtained four variants of kinematic parameters corresponding to different methods of calculating the distances from the parallaxes of stars measured with large relative errors. We have established that within the Ogorodnikov-Milne model changing the variant of distances affects significantly only the solar velocity components relative to the chosen centroid of stars, provided that the solution is obtained in narrow ranges of distances (0.1 kpc). The estimates of all the remaining kinematic parameters change little. This allows the Oort coefficients and related Galactic rotation parameters as well as all the remaining Ogorodnikov-Milne model parameters (except for the solar terms) to be reliably estimated irrespective of the parallax measurement accuracy. The main results obtained from main-sequence stars in the range of distances from 0.1 to 1.5 kpc are: A = 16.29 ± 0.06 km s-1 kpc-1, B = -11.90 ± 0.05 km s-1 kpc-1, C = -2.99 ± 0.06 km s-1 kpc-1, K = -4.04 ± 0.16 km s-1 kpc-1, and the Galactic rotation period P = 217.41 ± 0.60 Myr. The analogous results obtained from red giants in the range from 0.2 to 1.6 kpc are: the Oort constants A = 13.32 ± 0.09 km s-1 kpc-1, B = -12.71 ± 0.06 km s-1 kpc-1, C = -2.04 ± 0.08 km s-1 kpc-1, K = -2.72 ± 0.19 km s-1 kpc-1, and the Galactic rotation period P = 236.03 ± 0.98 Myr. The Galactic rotation velocity gradient along the radius vector (the slope of the Galactic rotation curve) is -4.32 ± 0.08 km s-1 kpc-1 for main-sequence stars and -0.61 ± 0.11 km s-1 kpc-1 for red giants. This suggests that the Galactic rotation velocity determined from main-sequence stars decreases with increasing distance from the Galactic center faster than it does for red giants.

  3. A Universal Model for Solar Eruptions

    NASA Technical Reports Server (NTRS)

    Wyper, Peter F.; Antiochos, Spiro K.; Devore, C. Richard

    2017-01-01

    Magnetically driven eruptions on the Sun, from stellar-scale coronal mass ejections1 to small-scale coronal X-ray and extreme-ultraviolet jets, have frequently been observed to involve the ejection of the highly stressed magnetic flux of a filament. Theoretically, these two phenomena have been thought to arise through very different mechanisms: coronal mass ejections from an ideal (non-dissipative) process, whereby the energy release does not require a change in the magnetic topology, as in the kink or torus instability; and coronal jets from a resistive process, involving magnetic reconnection. However, it was recently concluded from new observations that all coronal jets are driven by filament ejection, just like large mass ejections. This suggests that the two phenomena have physically identical origin and hence that a single mechanism may be responsible, that is, either mass ejections arise from reconnection, or jets arise from an ideal instability. Here we report simulations of a coronal jet driven by filament ejection, whereby a region of highly sheared magnetic field near the solar surface becomes unstable and erupts. The results show that magnetic reconnection causes the energy release via 'magnetic breakout', a positive feedback mechanism between filament ejection and reconnection. We conclude that if coronal mass ejections and jets are indeed of physically identical origin (although on different spatial scales) then magnetic reconnection (rather than an ideal process) must also underlie mass ejections, and that magnetic breakout is a universal model for solar eruptions.

  4. A universal model for solar eruptions.

    PubMed

    Wyper, Peter F; Antiochos, Spiro K; DeVore, C Richard

    2017-04-26

    Magnetically driven eruptions on the Sun, from stellar-scale coronal mass ejections to small-scale coronal X-ray and extreme-ultraviolet jets, have frequently been observed to involve the ejection of the highly stressed magnetic flux of a filament. Theoretically, these two phenomena have been thought to arise through very different mechanisms: coronal mass ejections from an ideal (non-dissipative) process, whereby the energy release does not require a change in the magnetic topology, as in the kink or torus instability; and coronal jets from a resistive process involving magnetic reconnection. However, it was recently concluded from new observations that all coronal jets are driven by filament ejection, just like large mass ejections. This suggests that the two phenomena have physically identical origin and hence that a single mechanism may be responsible, that is, either mass ejections arise from reconnection, or jets arise from an ideal instability. Here we report simulations of a coronal jet driven by filament ejection, whereby a region of highly sheared magnetic field near the solar surface becomes unstable and erupts. The results show that magnetic reconnection causes the energy release via 'magnetic breakout'-a positive-feedback mechanism between filament ejection and reconnection. We conclude that if coronal mass ejections and jets are indeed of physically identical origin (although on different spatial scales) then magnetic reconnection (rather than an ideal process) must also underlie mass ejections, and that magnetic breakout is a universal model for solar eruptions.

  5. Universal Behavior of a Cyclic Oxidation Model

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2003-01-01

    A mathematical model has been generated to represent the iterative, discrete growth and spallation processes associated with cyclic oxidation. Parabolic growth kinetics (k(sub p)) over and a constant spall area (F(sub A)) were assumed, with spalling occurring interfacially at the thickest regions of the scale. Although most models require numerical techniques, the regularity and simplicity of this progression permitted an approximation by algebraic expressions. Normalization could now be performed to reflect all parametric effects, and a universal cyclic oxidation response was generated: W(sub u) = 1/2 {3J(sub u)(sup 1/2)+ J(sub u)(sup 3/2)} where W, is weight change normalized by the maximum and J(sub u) is the cycle number normalized by the number to reach maximum. Similarly, the total amount of metal consumed was represented by a single normalized curve. The factor [(S(sub c)-l)(raised dot)sqrt(F(sub A)k(sub p)DELTAt)] was identified as a general figure of merit, where S(sub c) is the mass ratio of oxide to oxygen and DELTAt is the cycle duration. A cyclic oxidation failure map was constructed, in normalized k(sub p)-F(sub A) space, as defined by the locus of points corresponding to a critical amount of metal consumption in a given time. All three constructions describe behavior for every value of growth rate, spall fraction, and cycle duration by means of single curves, but with two branches corresponding to the times before and after steady state is achieved.

  6. Astrometry and dynamics of Solar System Objects with Gaia GDR observations and catalogues

    NASA Astrophysics Data System (ADS)

    Hestroffer, Daniel J. G. J.; Tanga, Paolo

    2017-06-01

    The Gaia ESA space mission has started to provide its harvest with the first Gaia data release DR1, published in September 2016. Gaia DR1 provides positions for about 1 billion stars and proper motion for the Tycho-Gaia TGAS of 2 million stars with unprecedented accuracy. The second data release DR2 will be the major step in the Gaia mission, providing all astrometric parameters (including parallax and proper motion) for a billion stars, in an absolute reference frame - to become the optical ICRF. Gaia DR2 will also provide epoch astrometry for about 13000 asteroids from its direct observations, down to magnitude V≈20.7. We will discuss the improvement brought by Gaia over 5 years of nominal mission, starting with DR1, and focusing especially on the dynamics of asteroids and other Solar System Objects. This includes use of the catalogue for calibrating future and past photometric and astrometric observations (in particular new reduction of ancient photographic plates digitalised by the NAROO programme), new perspectives for orbit determination and stellar occultations, detection of small acceleration or perturbations for the asteroids. Also we illustrate the ground-based activity coordinated by the Gaia-FUN-SSO network for follow-up observations of newly discovered Near Earth Object.

  7. Predicting the 4th caustic crossing in Gaia16aye binary microlensing event

    NASA Astrophysics Data System (ADS)

    Mroz, P.; Wyrzykowski, L.; Rybicki, K.; Altavilla, G.; Bakis, V.; Bendjoya, P.; Birenbaum, G.; Blagorodnova, N.; Blanco-Cuaresma, S.; Bonanos, A.; Bozza, V.; Britavskiy, N.; Burgaz, U.; Butterley, T.; Capuozzo, P.; Carrasco, J. M.; Chruslinska, M.; Damljanovic, G.; Dennefeld, M.; Dhillon, V. S.; Dominik, M.; Esenoglu, H.; Fossey, S.; Gomboc, A.; Hallokoun, N.; Hamanowicz, A.; Hardy, L. K.; Hudec, R.; Khamitov, I.; Klencki, J.; Kolaczkowski, Z.; Kolb, U.; Leonini, S.; Leto, G.; Lewis, F.; Liakos, A.; Littlefair, S. P.; Maoz, D.; Maund, J. R.; Mikolajczyk, P.; Palaversa, L.; Pawlak, M.; Penny, M.; Piascik, A.; Reig, P.; Rhodes, L.; Russell, D.; Sanchez, R. Z.; Shappee, B.; Shvartzvald, Y.; Sitek, M.; Sniegowska, M.; Sokolovsky, K.; Steele, I.; Street, R.; Tomasella, L.; Trascinelli, L.; Wiersema, K.; Wilson, R. W.; Zharkov, I.; Zola, S.; Zubareva, A.

    2016-11-01

    Gaia16aye, nicknamed Ayers Rock (19:40:01.13 +30:07:53.4, J2000) is a spectacular binary microlensing event in the Northern Galactic Plane. The event has been observed by Gaia, ASAS-SN survey and a network of follow-up telescopes, coordinated by the Time Domain WP of the EC's OPTICON grant.

  8. Astrometric Search Method for Individually Resolvable Gravitational Wave Sources with Gaia

    NASA Astrophysics Data System (ADS)

    Moore, Christopher J.; Mihaylov, Deyan P.; Lasenby, Anthony; Gilmore, Gerard

    2017-12-01

    Gravitational waves (GWs) cause the apparent position of distant stars to oscillate with a characteristic pattern on the sky. Astrometric measurements (e.g., those made by Gaia) provide a new way to search for GWs. The main difficulty facing such a search is the large size of the data set; Gaia observes more than one billion stars. In this Letter the problem of searching for GWs from individually resolvable supermassive black hole binaries using astrometry is addressed for the first time; it is demonstrated how the data set can be compressed by a factor of more than 1 06, with a loss of sensitivity of less than 1%. This technique was successfully used to recover artificially injected GW signals from mock Gaia data and to assess the GW sensitivity of Gaia. Throughout the Letter the complementarity of Gaia and pulsar timing searches for GWs is highlighted.

  9. On the use of Gaia magnitudes and new tables of bolometric corrections

    NASA Astrophysics Data System (ADS)

    Casagrande, L.; VandenBerg, Don A.

    2018-06-01

    The availability of reliable bolometric corrections and reddening estimates, rather than the quality of parallaxes will be one of the main limiting factors in determining the luminosities of a large fraction of Gaia stars. With this goal in mind, we provide Gaia GBP, G, and GRP synthetic photometry for the entire MARCS grid, and test the performance of our synthetic colours and bolometric corrections against space-borne absolute spectrophotometry. We find indication of a magnitude-dependent offset in Gaia DR2 G magnitudes, which must be taken into account in high accuracy investigations. Our interpolation routines are easily used to derive bolometric corrections at desired stellar parameters, and to explore the dependence of Gaia photometry on Teff, log g, {[Fe/H]}, [α /{Fe}] and E(B - V). Gaia colours for the Sun and Vega, and Teff-dependent extinction coefficients, are also provided.

  10. Near-Earth asteroids orbits using Gaia and ground-based observations

    NASA Astrophysics Data System (ADS)

    Bancelin, D.; Hestroffer, D.; Thuillot, W.

    2011-05-01

    Potentially Hazardous Asteroids (PHAs) are Near-Earth Asteroids caraterised by a Minimum Orbital Intersection Distance (MOID) with Earth less to 0.05 A.U and an absolute magnitude H<22. Those objects have sometimes a so significant close approach with Earth that they can be put on a chaotic orbit. This kind of orbit is very sensitive for exemple to the initial conditions, to the planetary theory used (for instance JPL's model versus IMCCE's model) or even to the numerical integrator used (Lie Series, Bulirsch-Stoer or Radau). New observations (optical, radar, flyby or satellite mission) can improve those orbits and reduce the uncertainties on the Keplerian elements.The Gaia mission is an astrometric mission that will be launched in 2012 and will observe a large number of Solar System Objects down to magnitude V≤20. During the 5-year mission, Gaia will continuously scan the sky with a specific strategy: objects will be observed from two lines of sight separated with a constant basic angle. Five constants already fixed determinate the nominal scanning law of Gaia: The inertial spin rate (1°/min) that describe the rotation of the spacecraft around an axis perpendicular to those of the two fields of view, the solar-aspect angle (45°) that is the angle between the Sun and the spacecraft rotation axis, the precession period (63.12 days) which is the precession of the spin axis around the Sun-Earth direction. Two other constants are still free parameters: the initial spin phase, and the initial precession angle that will be fixed at the start of the nominal science operations. These latter are constraint by scientific outcome (e.g. possibility of performing test of fundamental physics) together with operational requirements (downlink to Earth windows). Several sets of observations of specific NEOs will hence be provided according to the initial precession angle. The purpose here is to study the statistical impact of the initial precession angle on the error

  11. A Review of Research on Universal Design Educational Models

    ERIC Educational Resources Information Center

    Rao, Kavita; Ok, Min Wook; Bryant, Brian R.

    2014-01-01

    Universal design for learning (UDL) has gained considerable attention in the field of special education, acclaimed for its promise to promote inclusion by supporting access to the general curriculum. In addition to UDL, there are two other universal design (UD) educational models referenced in the literature, universal design of instruction (UDI)…

  12. Transition from AdS universe to DS universe in the BPP model

    NASA Astrophysics Data System (ADS)

    Kim, Wontae; Yoon, Myungseok

    2007-04-01

    It can be shown that in the BPP model the smooth phase transition from the asymptotically decelerated AdS universe to the asymptotically accelerated DS universe is possible by solving the modified semiclassical equations of motion. This transition comes from noncommutative Poisson algebra, which gives the constant curvature scalars asymptotically. The decelerated expansion of the early universe is due to the negative energy density with the negative pressure induced by quantum back reaction, and the accelerated late-time universe comes from the positive energy and the negative pressure which behave like dark energy source in recent cosmological models.

  13. Detection of spectroscopic binaries in the Gaia-ESO Survey

    NASA Astrophysics Data System (ADS)

    Van der Swaelmen, M.; Merle, T.; Van Eck, S.; Jorissen, A.

    2017-12-01

    The Gaia-ESO survey (GES) is a ground-based spectroscopic survey, complementing the Gaia mission, in order to obtain high accuracy radial velocities and chemical abundances for 10^5 stars. Thanks to the numerous spectra collected by the GES, the detection of spectroscopic multiple system candidates (SBn, n ≥ 2) is one of the science case that can be tackled. We developed at IAA (Institut d'Astronomie et d'Astrophysique) a novative automatic method to detect multiple components from the cross-correlation function (CCF) of spectra and applied it to the CCFs provided by the GES. Since the bulk of the Milky Way field targets has been observed in both HR10 and HR21 GIRAFFE settings, we are also able to compare the efficiency of our SB detection tool depending on the wavelength range. In particular, we show that HR21 leads to a less efficient detection compared to HR10. The presence of strong and/or saturated lines (Ca II triplet, Mg I line, Paschen lines) in the wavelength domain covered by HR21 hampers the computation of CCFs, which tend to be broadened compared to their HR10 counterpart. The main drawback is that the minimal detectable radial velocity difference is ˜ \\SI{60}km/s for HR21 while it is ˜ \\SI{25}km/s for HR10. A careful design of CCF masks (especially masking Ca triplet lines) can substantially improve the detectability rate of HR21. Since HR21 spectra are quite similar to the one produced by the RVS spectrograph of the Gaia mission, analysis of RVS spectra in the context of spectroscpic binaries can take adavantage of the lessons learned from the GES to maximize the detection rate.

  14. [Dr James Lovelock and story about GAIA hypothesis].

    PubMed

    Gajić, Vladimir

    2011-01-01

    Gaia is the Anglo-Saxon term for the Hellenic term Gea or Ge, which means Earth. The GAIA hypothesis was launched almost 40 years ago by the famous chemist James Lovelock, who was engaged by the National Aeronautics and Space Administration (NASA) to create a sensitive instrument for searching forms of extraterrestrial life on other planets. Then he published the book The ages of GAIA, which perturbed the world's scientific public of those days. Lovelock struck upon this idea in the late sixties of the past century, during the space race with Russians, when he was hired hy the National Aeronautics and Space Administration to conduct a series of experiments to find and explore life forms on the planet Mars. Experiments executed by the American module Viking failed to trace any life form, as Lovelock had predicted. He called it a dead equilibrium. Then he turned to Earth, whose perspective is totally different from its first neighbors. Venus and Mars, and is far from a dead equilibrium. DAISYWORLD: In this hypothesis. Lovelock represents Earth as one living, giant super organism, composed of all living creatures and its material environnent. In that super organisnm, the level of oxygen, weather conditions, ocean salinity and so on are under constant influence of physical, chemical and biological processes, which provide the existence for such life forms on Earth. Dr James Lovelock represents a pioneer of climatology, and his hypothesis gives a unique insight into the correlation of dynamic processes on our planet, no matter whether they are of physical or biological nature.

  15. The Gaia FGK benchmark stars. High resolution spectral library

    NASA Astrophysics Data System (ADS)

    Blanco-Cuaresma, S.; Soubiran, C.; Jofré, P.; Heiter, U.

    2014-06-01

    Context. An increasing number of high-resolution stellar spectra is available today thanks to many past and ongoing spectroscopic surveys. Consequently, numerous methods have been developed to perform an automatic spectral analysis on a massive amount of data. When reviewing published results, biases arise and they need to be addressed and minimized. Aims: We are providing a homogeneous library with a common set of calibration stars (known as the Gaia FGK benchmark stars) that will allow us to assess stellar analysis methods and calibrate spectroscopic surveys. Methods: High-resolution and signal-to-noise spectra were compiled from different instruments. We developed an automatic process to homogenize the observed data and assess the quality of the resulting library. Results: We built a high-quality library that will facilitate the assessment of spectral analyses and the calibration of present and future spectroscopic surveys. The automation of the process minimizes the human subjectivity and ensures reproducibility. Additionally, it allows us to quickly adapt the library to specific needs that can arise from future spectroscopic analyses. Based on NARVAL and HARPS data obtained within the Gaia Data Processing and Analysis Consortium (DPAC) and coordinated by the GBOG (Ground-Based Observations for Gaia) working group, and on data retrieved from the ESO-ADP database.The library of spectra is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/566/A98

  16. Implementation of the Global Parameters Determination in Gaia's Astrometric Solution (AGIS)

    NASA Astrophysics Data System (ADS)

    Raison, F.; Olias, A.; Hobbs, D.; Lindegren, L.

    2010-12-01

    Gaia is ESA’s space astrometry mission with a foreseen launch date in early 2012. Its main objective is to perform a stellar census of the 1000 Million brightest objects in our galaxy (completeness to V=20 mag) from which an astrometric catalog of micro-arcsec level accuracy will be constructed. A key element in this endeavor is the Astrometric Global Iterative Solution (AGIS). A core part of AGIS is to determine the accurate spacecraft attitude, geometric instrument calibration and astrometric model parameters for a well-behaved subset of all the objects (the ‘primary stars’). In addition, a small number of global parameters will be estimated, one of these being PPN γ. We present here the implementation of the algorithms dedicated to the determination of the global parameters.

  17. Prospects for asteroid mass determination from close encounters between asteroids: ESA's Gaia space mission and beyond

    NASA Astrophysics Data System (ADS)

    Ivantsov, Anatoliy; Hestroffer, Daniel; Eggl, Siegfried

    2018-04-01

    We present a catalog of potential candidates for asteroid mass determination based on mutual close encounters of numbered asteroids with massive perturbers (D>20 km). Using a novel geometric approach tuned to optimize observability, we predict optimal epochs for mass determination observations. In contrast to previous studies that often used simplified dynamical models, we have numerically propagated the trajectories of all numbered asteroids over the time interval from 2013 to 2023 using relativistic equations of motion including planetary perturbations, J2 of the Sun, the 16 major asteroid perturbers and the perturbations due to non-sphericities of the planets. We compiled a catalog of close encounters between asteroids where the observable perturbation of the sky plane trajectory is greater than 0.5 mas so that astrometric measurements of the perturbed asteroids in the Gaia data can be leveraged. The catalog v1.0 is available at ftp://dosya.akdeniz.edu.tr/ivantsov.

  18. The Toy model: Understanding the early universe

    NASA Astrophysics Data System (ADS)

    Fisher, Peter H.; Price, Richard H.

    2018-04-01

    In many branches of science, progress is being made by taking advantage of insights from other branches of science. Cosmology, the structure and evolution of the universe, is certainly an area that is currently beset by problems in understanding. We show here that the scientific insights from the studies of early childhood development, in particular, those of Piaget, give a new way of looking at the early universe. This new approach can not only be invaluable in undergraduate teaching, but can even be the basis of semi-quantitative predictions.

  19. Radial Distribution of Stellar Motions in Gaia DR2

    NASA Astrophysics Data System (ADS)

    Kawata, Daisuke; Baba, Junichi; Ciucǎ, Ioana; Cropper, Mark; Grand, Robert J. J.; Hunt, Jason A. S.; Seabroke, George

    2018-06-01

    By taking advantage of the superb measurements of position and velocity for an unprecedented large number of stars provided in Gaia DR2, we have generated the first maps of the rotation velocity, Vrot, and vertical velocity, Vz, distributions as a function of the Galactocentric radius, Rgal, across a radial range of 5 < Rgal < 12 kpc. In the R - Vrot map, we have identified many diagonal ridge features, which are compared with the location of the spiral arms and the expected outer Lindblad resonance of the Galactic bar. We have detected also radial wave-like oscillations of the peak of the vertical velocity distribution.

  20. Comoving Stars in Gaia DR1: An Abundance of Very Wide Separation Comoving Pairs

    NASA Astrophysics Data System (ADS)

    Oh, Semyeong; Price-Whelan, Adrian M.; Hogg, David W.; Morton, Timothy D.; Spergel, David N.

    2017-06-01

    The primary sample of the Gaia Data Release 1 is the Tycho-Gaia Astrometric Solution (TGAS): ≈2 million Tycho-2 sources with improved parallaxes and proper motions relative to the initial catalog. This increased astrometric precision presents an opportunity to find new binary stars and moving groups. We search for high-confidence comoving pairs of stars in TGAS by identifying pairs of stars consistent with having the same 3D velocity using a marginalized likelihood ratio test to discriminate candidate comoving pairs from the field population. Although we perform some visualizations using (bias-corrected) inverse parallax as a point estimate of distance, the likelihood ratio is computed with a probabilistic model that includes the covariances of parallax and proper motions and marginalizes the (unknown) true distances and 3D velocities of the stars. We find 13,085 comoving star pairs among 10,606 unique stars with separations as large as 10 pc (our search limit). Some of these pairs form larger groups through mutual comoving neighbors: many of these pair networks correspond to known open clusters and OB associations, but we also report the discovery of several new comoving groups. Most surprisingly, we find a large number of very wide (> 1 pc) separation comoving star pairs, the number of which increases with increasing separation and cannot be explained purely by false-positive contamination. Our key result is a catalog of high-confidence comoving pairs of stars in TGAS. We discuss the utility of this catalog for making dynamical inferences about the Galaxy, testing stellar atmosphere models, and validating chemical abundance measurements.

  1. Information Technology: A Model for Brandon University.

    ERIC Educational Resources Information Center

    Bazillion, Richard J.

    Information technology is having a profound effect on higher education in North America, and Brandon University in Manitoba (Canada) is in a position to join this movement in its early stages. The case for integrating information technology into the curriculum is argued, and the potential role of the new library complex in the teaching function is…

  2. Differential Validation of a Path Analytic Model of University Dropout.

    ERIC Educational Resources Information Center

    Winteler, Adolf

    Tinto's conceptual schema of college dropout forms the theoretical framework for the development of a model of university student dropout intention. This study validated Tinto's model in two different departments within a single university. Analyses were conducted on a sample of 684 college freshmen in the Education and Economics Department. A…

  3. Southwest University's No-Fee Teacher-Training Model

    ERIC Educational Resources Information Center

    Chen, Shijian; Yang, Shuhan; Li, Linyuan

    2013-01-01

    The training model for Southwest University's no-fee teacher education program has taken shape over several years. Based on a review of the documentation and interviews with administrators and no-fee preservice students from different specialties, this article analyzes Southwest University's no-fee teacher-training model in terms of three main…

  4. Model Preservation Program for a Small University Library.

    ERIC Educational Resources Information Center

    Robbins, Louise S.

    This report proposes a preservation program assuming a model of a university library serving 5,000 or fewer students and 350 or fewer faculty members. The model program is not for a comprehensive university or research institution, and the library's collection is one developed and used as a curriculum-support collection. The goal of the…

  5. A Career Success Model for Academics at Malaysian Research Universities

    ERIC Educational Resources Information Center

    Abu Said, Al-Mansor; Mohd Rasdi, Roziah; Abu Samah, Bahaman; Silong, Abu Daud; Sulaiman, Suzaimah

    2015-01-01

    Purpose: The purpose of this paper is to develop a career success model for academics at the Malaysian research universities. Design/methodology/approach: Self-administered and online surveys were used for data collection among 325 academics from Malaysian research universities. Findings: Based on the analysis of structural equation modeling, the…

  6. School Based/University Collaborative Effort: A Pre Service Model.

    ERIC Educational Resources Information Center

    Bercik, Janet T.

    This paper discusses the principles and describes the planning and development of a student teaching program model for Northeastern Illinois University students. The program is in its fourth year and was collaboratively designed by faculty from the university and a local middle school. The model is based on the importance of communication,…

  7. An Analytical Model for University Identity and Reputation Strategy Work

    ERIC Educational Resources Information Center

    Steiner, Lars; Sundstrom, Agneta C.; Sammalisto, Kaisu

    2013-01-01

    Universities face increasing global competition, pressuring them to restructure and find new identities. A multidimensional model: identity, image and reputation of strategic university identity and reputation work is developed. The model includes: organizational identity; employee and student attitudes; symbolic identity; influence from…

  8. 3D maps of the local interstellar medium: the impact of Gaia

    NASA Astrophysics Data System (ADS)

    Capitanio, L.; Lallement, R.; Vergely, J. L.; Elyajouri, M.; Babusiaux, C.; Ruiz-Dern, L.; Monreal-Ibero, A.; Arenou, F.; Danielski, C.

    2017-12-01

    Gaia parallaxes combined with colour excess and absorption measurements from large stellar surveys will allow building increasingly precise three-dimensional maps of the interstellar matter (ISM). Reciprocally, detailed maps of the ISM will allow improving photometric calibrations of Gaia and measuring more precisely the amounts of reddening. In the future, the extraction of a diffuse interstellar band (DIB) from Gaia RVS (Radial Velocity Spectrometer) spectra will allow to build a tomography of the carrier of this DIB and compare it with dust and gas distributions. Here we show several results that illustrate current progress in local ISM mapping and a first example of the stellar-interstellar synergy linked to Gaia: a) how Gaia-DR1 parallaxes already modify the ISM maps obtained by means of a full-3D inversion of a compilation of colour excess data, b) how DIB measurements and corresponding Gaia parallaxes can complement colour excess data and improve the maps, c) new hierarchical methods combining distinct surveys, d) improved maps including APOGEE colour excess estimates deduced from the recent Gaia-based photometric calibrations of Ruiz-Dern et al (this issue), e) additional inclusion of LAMOST colour excess estimates (Wang et al, 2016).

  9. Detection of Yarkovsky acceleration in the context of precovery observations and the future Gaia catalogue

    NASA Astrophysics Data System (ADS)

    Desmars, J.

    2015-03-01

    Context. The Yarkovsky effect is a weak non-gravitational force leading to a small variation of the semi-major axis of an asteroid. Using radar measurements and astrometric observations, it is possible to measure a drift in semi-major axis through orbit determination. Aims: This paper aims to detect a reliable drift in semi-major axis of near-Earth asteroids (NEAs) from ground-based observations and to investigate the impact of precovery observations and the future Gaia catalogue in the detection of a secular drift in semi-major axis. Methods: We have developed a precise dynamical model of an asteroid's motion taking the Yarkovsky acceleration into account and allowing the fitting of the drift in semi-major axis. Using statistical methods, we investigate the quality and the robustness of the detection. Results: By filtering spurious detections with an estimated maximum drift depending on the asteroid's size, we found 46 NEAs with a reliable drift in semi-major axis in good agreement with the previous studies. The measure of the drift leads to a better orbit determination and constrains some physical parameters of these objects. Our results are in good agreement with the 1 /D dependence of the drift and with the expected ratio of prograde and retrograde NEAs. We show that the uncertainty of the drift mainly depends on the length of orbital arc and in this way we highlight the importance of the precovery observations and data mining in the detection of consistent drift. Finally, we discuss the impact of Gaia catalogue in the determination of drift in semi-major axis.

  10. The kinematics of the Scorpius-Centaurus OB association from Gaia DR1

    NASA Astrophysics Data System (ADS)

    Wright, Nicholas J.; Mamajek, Eric E.

    2018-05-01

    We present a kinematic study of the Scorpius-Centaurus (Sco-Cen) OB association (Sco OB2) using Gaia DR1 parallaxes and proper motions. Our goal is to test the classical theory that OB associations are the expanded remnants of dense and compact star clusters disrupted by processes such as residual gas expulsion. Gaia astrometry is available for 258 out of 433 members of the association, with revised Hipparcos astrometry used for the remainder. We use these data to confirm that the three subgroups of Sco-Cen are gravitationally unbound and have non-isotropic velocity dispersions, suggesting that they have not had time to dynamically relax. We also explore the internal kinematics of the subgroups to search for evidence of expansion. We test Blaauw's classical linear model of expansion, search for velocity trends along the Galactic axes, compare the expanding and non-expanding convergence points, perform traceback analysis assuming both linear trajectories and using an epicycle approximation, and assess the evidence for expansion in proper motions corrected for virtual expansion/contraction. None of these methods provide coherent evidence for expansion of the subgroups, with no evidence to suggest that the subgroups had a more compact configuration in the past. We find evidence for kinematic substructure within the subgroups that supports the view that they were not formed by the disruption of individual star clusters. We conclude that Sco-Cen was likely to have been born highly substructured, with multiple small-scale star formation events contributing to the overall OB association, and not as single, monolithic burst of clustered star formation.

  11. Hypervelocity star candidates in Gaia DR1/TGAS

    NASA Astrophysics Data System (ADS)

    Marchetti, T.; Rossi, E. M.; Kordopatis, G.; Brown, A. G. A.; Rimoldi, A.; Starkenburg, E.; Youakim, K.; Ashley, R.

    2018-04-01

    Hypervelocity stars (HVSs) are characterized by a total velocity in excess of the Galactic escape speed, and with trajectories consistent with coming from the Galactic Centre. We apply a novel data mining routine, an artificial neural network, to discover HVSs in the TGAS subset of the first data release of the Gaia satellite, using only the astrometry of the stars. We find 80 stars with a predicted probability >90% of being HVSs, and we retrieved radial velocities for 47 of those. We discover 14 objects with a total velocity in the Galactic rest frame >400 km s-1, and 5 of these have a probability >50% of being unbound from the Milky Way. Tracing back orbits in different Galactic potentials, we discover 1 HVS candidate, 5 bound HVS candidates, and 5 runaway star candidates with remarkably high velocities, between 400 and 780 km s-1. We wait for future Gaia releases to confirm the goodness of our sample and to increase the number of HVS candidates.

  12. Determination of astrophysical parameters of quasars within the Gaia mission

    NASA Astrophysics Data System (ADS)

    Delchambre, L.

    2018-01-01

    We describe methods designed to determine the astrophysical parameters of quasars based on spectra coming from the red and blue spectrophotometers of the Gaia satellite. These methods principally rely on two already published algorithms that are the weighted principal component analysis and the weighted phase correlation. The presented approach benefits from a fast implementation, an intuitive interpretation as well as strong diagnostic tools on the potential errors that may arise during predictions. The production of a semi-empirical library of spectra as they will be observed by Gaia is also covered and subsequently used for validation purpose. We detail the pre-processing that is necessary in order for these spectra to be fully exploitable by our algorithms along with the procedures that are used to predict the redshifts of the quasars, their continuum slopes, the total equivalent width of their emission lines and whether these are broad absorption line (BAL) quasars or not. Performances of these procedures were assessed in comparison with the extremely randomized trees learning method and were proven to provide better results on the redshift predictions and on the ratio of correctly classified observations though the probability of detection of BAL quasars remains restricted by the low resolution of these spectra as well as by their limited signal-to-noise ratio. Finally, the triggering of some warning flags allows us to obtain an extremely pure subset of redshift predictions where approximately 99 per cent of the observations come along with absolute errors that are below 0.1.

  13. Visualizing Gaia Data with Science Teachers at AMNH

    NASA Astrophysics Data System (ADS)

    Faherty, Jacqueline K.; Desir, Deion; Coker, Kristina; Nelson, Olivia; Vasquez, Chelsea; Smithka, Iliya

    2018-01-01

    The American Museum of Natural History is an accredited graduate school and offers an innovative Master of Arts in Teaching (MAT) degree that leverages its unique scientific resources and long history of leadership in teacher education and professional development. The MAT program consists of 15-months of intensive mentoring, classroom experience, lab work, and professional development with AMNH scientists and educators. It is then followed by a 4 year commitment by all degree awardees to teach at an in needs New York high school. During the second summer of their first 15 months of the program, students are paired with a scientific mentor to obtain an REU like experience in Astronomy, Geology or Paleontology. During the summer of 2017 five teachers worked on incorporating a subset of the Tycho Gaia Astrometric Survey into the Partiview open source software. The result is an interactive experience where we can fly live through all of TGAS and highlight nearby clusters and associations. The tool is (1) a demonstration of the power of Partiview at visualizing a vast dataset such as Gaia, and (2) an extremely powerful instrument for teaching science through visualization.

  14. The Gaia Archive at ESAC: a VO-inside archive

    NASA Astrophysics Data System (ADS)

    Gonzalez-Nunez, J.

    2015-12-01

    The ESDC (ESAC Science Data Center) is one of the active members of the IVOA (International Virtual Observatory Alliance) that have defined a set of standards, libraries and concepts that allows to create flexible,scalable and interoperable architectures on the data archives development. In the case of astronomy science that involves the use of big catalogues, as in Gaia or Euclid, TAP, UWS and VOSpace standards can be used to create an architecture that allows the explotation of this valuable data from the community. Also, new challenges arise like the implementation of the new paradigm "move code close to the data", what can be partially obtained by the extension of the protocols (TAP+, UWS+, etc) or the languages (ADQL). We explain how we have used VO standards and libraries for the Gaia Archive that, not only have producing an open and interoperable archive but, also, minimizing the developement on certain areas. Also we will explain how we have extended these protocols and the future plans.

  15. Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties

    NASA Astrophysics Data System (ADS)

    Gaia Collaboration; Brown, A. G. A.; Vallenari, A.; Prusti, T.; de Bruijne, J. H. J.; Mignard, F.; Drimmel, R.; Babusiaux, C.; Bailer-Jones, C. A. L.; Bastian, U.; Biermann, M.; Evans, D. W.; Eyer, L.; Jansen, F.; Jordi, C.; Katz, D.; Klioner, S. A.; Lammers, U.; Lindegren, L.; Luri, X.; O'Mullane, W.; Panem, C.; Pourbaix, D.; Randich, S.; Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette, V.; van Leeuwen, F.; Walton, N. A.; Aerts, C.; Arenou, F.; Cropper, M.; Høg, E.; Lattanzi, M. G.; Grebel, E. K.; Holland, A. D.; Huc, C.; Passot, X.; Perryman, M.; Bramante, L.; Cacciari, C.; Castañeda, J.; Chaoul, L.; Cheek, N.; De Angeli, F.; Fabricius, C.; Guerra, R.; Hernández, J.; Jean-Antoine-Piccolo, A.; Masana, E.; Messineo, R.; Mowlavi, N.; Nienartowicz, K.; Ordóñez-Blanco, D.; Panuzzo, P.; Portell, J.; Richards, P. J.; Riello, M.; Seabroke, G. M.; Tanga, P.; Thévenin, F.; Torra, J.; Els, S. G.; Gracia-Abril, G.; Comoretto, G.; Garcia-Reinaldos, M.; Lock, T.; Mercier, E.; Altmann, M.; Andrae, R.; Astraatmadja, T. L.; Bellas-Velidis, I.; Benson, K.; Berthier, J.; Blomme, R.; Busso, G.; Carry, B.; Cellino, A.; Clementini, G.; Cowell, S.; Creevey, O.; Cuypers, J.; Davidson, M.; De Ridder, J.; de Torres, A.; Delchambre, L.; Dell'Oro, A.; Ducourant, C.; Frémat, Y.; García-Torres, M.; Gosset, E.; Halbwachs, J.-L.; Hambly, N. C.; Harrison, D. L.; Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle, H. E.; Hutton, A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn, A. J.; Lanzafame, A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.; Osinde, J.; Pancino, E.; Pauwels, T.; Petit, J.-M.; Recio-Blanco, A.; Robin, A. C.; Sarro, L. M.; Siopis, C.; Smith, M.; Smith, K. W.; Sozzetti, A.; Thuillot, W.; van Reeven, W.; Viala, Y.; Abbas, U.; Abreu Aramburu, A.; Accart, S.; Aguado, J. J.; Allan, P. M.; Allasia, W.; Altavilla, G.; Álvarez, M. A.; Alves, J.; Anderson, R. I.; Andrei, A. H.; Anglada Varela, E.; Antiche, E.; Antoja, T.; Antón, S.; Arcay, B.; Bach, N.; Baker, S. G.; Balaguer-Núñez, L.; Barache, C.; Barata, C.; Barbier, A.; Barblan, F.; Barrado y Navascués, D.; Barros, M.; Barstow, M. A.; Becciani, U.; Bellazzini, M.; Bello García, A.; Belokurov, V.; Bendjoya, P.; Berihuete, A.; Bianchi, L.; Bienaymé, O.; Billebaud, F.; Blagorodnova, N.; Blanco-Cuaresma, S.; Boch, T.; Bombrun, A.; Borrachero, R.; Bouquillon, S.; Bourda, G.; Bouy, H.; Bragaglia, A.; Breddels, M. A.; Brouillet, N.; Brüsemeister, T.; Bucciarelli, B.; Burgess, P.; Burgon, R.; Burlacu, A.; Busonero, D.; Buzzi, R.; Caffau, E.; Cambras, J.; Campbell, H.; Cancelliere, R.; Cantat-Gaudin, T.; Carlucci, T.; Carrasco, J. M.; Castellani, M.; Charlot, P.; Charnas, J.; Chiavassa, A.; Clotet, M.; Cocozza, G.; Collins, R. S.; Costigan, G.; Crifo, F.; Cross, N. J. G.; Crosta, M.; Crowley, C.; Dafonte, C.; Damerdji, Y.; Dapergolas, A.; David, P.; David, M.; De Cat, P.; de Felice, F.; de Laverny, P.; De Luise, F.; De March, R.; de Martino, D.; de Souza, R.; Debosscher, J.; del Pozo, E.; Delbo, M.; Delgado, A.; Delgado, H. E.; Di Matteo, P.; Diakite, S.; Distefano, E.; Dolding, C.; Dos Anjos, S.; Drazinos, P.; Duran, J.; Dzigan, Y.; Edvardsson, B.; Enke, H.; Evans, N. W.; Eynard Bontemps, G.; Fabre, C.; Fabrizio, M.; Faigler, S.; Falcão, A. J.; Farràs Casas, M.; Federici, L.; Fedorets, G.; Fernández-Hernández, J.; Fernique, P.; Fienga, A.; Figueras, F.; Filippi, F.; Findeisen, K.; Fonti, A.; Fouesneau, M.; Fraile, E.; Fraser, M.; Fuchs, J.; Gai, M.; Galleti, S.; Galluccio, L.; Garabato, D.; García-Sedano, F.; Garofalo, A.; Garralda, N.; Gavras, P.; Gerssen, J.; Geyer, R.; Gilmore, G.; Girona, S.; Giuffrida, G.; Gomes, M.; González-Marcos, A.; González-Núñez, J.; González-Vidal, J. J.; Granvik, M.; Guerrier, A.; Guillout, P.; Guiraud, J.; Gúrpide, A.; Gutiérrez-Sánchez, R.; Guy, L. P.; Haigron, R.; Hatzidimitriou, D.; Haywood, M.; Heiter, U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.; Holland, G.; Hunt, J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat de Fombelle, G.; Jofré, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.; Karampelas, A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas, E.; Koposov, S. E.; Kordopatis, G.; Koubsky, P.; Krone-Martins, A.; Kudryashova, M.; Kull, I.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza, A. F.; Lavigne, J.-B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter, T.; Leccia, S.; Leclerc, N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt, H.; Leroux, F.; Liao, S.; Licata, E.; Lindstrøm, H. E. P.; Lister, T. A.; Livanou, E.; Lobel, A.; Löffler, W.; López, M.; Lorenz, D.; MacDonald, I.; Magalhães Fernandes, T.; Managau, S.; Mann, R. G.; Mantelet, G.; Marchal, O.; Marchant, J. M.; Marconi, M.; Marinoni, S.; Marrese, P. M.; Marschalkó, G.; Marshall, D. J.; Martín-Fleitas, J. M.; Martino, M.; Mary, N.; Matijevič, G.; Mazeh, T.; McMillan, P. J.; Messina, S.; Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina, D.; Molinaro, R.; Molinaro, M.; Molnár, L.; Moniez, M.; Montegriffo, P.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.; Morris, D.; Mulone, A. F.; Muraveva, T.; Musella, I.; Narbonne, J.; Nelemans, G.; Nicastro, L.; Noval, L.; Ordénovic, C.; Ordieres-Meré, J.; Osborne, P.; Pagani, C.; Pagano, I.; Pailler, F.; Palacin, H.; Palaversa, L.; Parsons, P.; Pecoraro, M.; Pedrosa, R.; Pentikäinen, H.; Pichon, B.; Piersimoni, A. M.; Pineau, F.-X.; Plachy, E.; Plum, G.; Poujoulet, E.; Prša, A.; Pulone, L.; Ragaini, S.; Rago, S.; Rambaux, N.; Ramos-Lerate, M.; Ranalli, P.; Rauw, G.; Read, A.; Regibo, S.; Reylé, C.; Ribeiro, R. A.; Rimoldini, L.; Ripepi, V.; Riva, A.; Rixon, G.; Roelens, M.; Romero-Gómez, M.; Rowell, N.; Royer, F.; Ruiz-Dern, L.; Sadowski, G.; Sagristà Sellés, T.; Sahlmann, J.; Salgado, J.; Salguero, E.; Sarasso, M.; Savietto, H.; Schultheis, M.; Sciacca, E.; Segol, M.; Segovia, J. C.; Segransan, D.; Shih, I.-C.; Smareglia, R.; Smart, R. L.; Solano, E.; Solitro, F.; Sordo, R.; Soria Nieto, S.; Souchay, J.; Spagna, A.; Spoto, F.; Stampa, U.; Steele, I. A.; Steidelmüller, H.; Stephenson, C. A.; Stoev, H.; Suess, F. F.; Süveges, M.; Surdej, J.; Szabados, L.; Szegedi-Elek, E.; Tapiador, D.; Taris, F.; Tauran, G.; Taylor, M. B.; Teixeira, R.; Terrett, D.; Tingley, B.; Trager, S. C.; Turon, C.; Ulla, A.; Utrilla, E.; Valentini, G.; van Elteren, A.; Van Hemelryck, E.; van Leeuwen, M.; Varadi, M.; Vecchiato, A.; Veljanoski, J.; Via, T.; Vicente, D.; Vogt, S.; Voss, H.; Votruba, V.; Voutsinas, S.; Walmsley, G.; Weiler, M.; Weingrill, K.; Wevers, T.; Wyrzykowski, Ł.; Yoldas, A.; Žerjal, M.; Zucker, S.; Zurbach, C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende Prieto, C.; Amorim, A.; Anglada-Escudé, G.; Arsenijevic, V.; Azaz, S.; Balm, P.; Beck, M.; Bernstein, H.-H.; Bigot, L.; Bijaoui, A.; Blasco, C.; Bonfigli, M.; Bono, G.; Boudreault, S.; Bressan, A.; Brown, S.; Brunet, P.-M.; Bunclark, P.; Buonanno, R.; Butkevich, A. G.; Carret, C.; Carrion, C.; Chemin, L.; Chéreau, F.; Corcione, L.; Darmigny, E.; de Boer, K. S.; de Teodoro, P.; de Zeeuw, P. T.; Delle Luche, C.; Domingues, C. D.; Dubath, P.; Fodor, F.; Frézouls, B.; Fries, A.; Fustes, D.; Fyfe, D.; Gallardo, E.; Gallegos, J.; Gardiol, D.; Gebran, M.; Gomboc, A.; Gómez, A.; Grux, E.; Gueguen, A.; Heyrovsky, A.; Hoar, J.; Iannicola, G.; Isasi Parache, Y.; Janotto, A.-M.; Joliet, E.; Jonckheere, A.; Keil, R.; Kim, D.-W.; Klagyivik, P.; Klar, J.; Knude, J.; Kochukhov, O.; Kolka, I.; Kos, J.; Kutka, A.; Lainey, V.; LeBouquin, D.; Liu, C.; Loreggia, D.; Makarov, V. V.; Marseille, M. G.; Martayan, C.; Martinez-Rubi, O.; Massart, B.; Meynadier, F.; Mignot, S.; Munari, U.; Nguyen, A.-T.; Nordlander, T.; Ocvirk, P.; O'Flaherty, K. S.; Olias Sanz, A.; Ortiz, P.; Osorio, J.; Oszkiewicz, D.; Ouzounis, A.; Palmer, M.; Park, P.; Pasquato, E.; Peltzer, C.; Peralta, J.; Péturaud, F.; Pieniluoma, T.; Pigozzi, E.; Poels, J.; Prat, G.; Prod'homme, T.; Raison, F.; Rebordao, J. M.; Risquez, D.; Rocca-Volmerange, B.; Rosen, S.; Ruiz-Fuertes, M. I.; Russo, F.; Sembay, S.; Serraller Vizcaino, I.; Short, A.; Siebert, A.; Silva, H.; Sinachopoulos, D.; Slezak, E.; Soffel, M.; Sosnowska, D.; Straižys, V.; ter Linden, M.; Terrell, D.; Theil, S.; Tiede, C.; Troisi, L.; Tsalmantza, P.; Tur, D.; Vaccari, M.; Vachier, F.; Valles, P.; Van Hamme, W.; Veltz, L.; Virtanen, J.; Wallut, J.-M.; Wichmann, R.; Wilkinson, M. I.; Ziaeepour, H.; Zschocke, S.

    2016-11-01

    Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims: A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods: The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results: Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the Hipparcos and Tycho-2 catalogues - a realisation of the Tycho-Gaia Astrometric Solution (TGAS) - and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of 3000 Cepheid and RR Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr-1 for the proper motions. A systematic component of 0.3 mas should be added to the parallax uncertainties. For the subset of 94 000 Hipparcos stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr-1. For the secondary astrometric data set, the typical uncertainty of the positions is 10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to 0.03 mag over the magnitude range 5 to 20.7. Conclusions: Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five

  16. SALT spectroscopic classification of Gaia18blo as AGN at z=2.09

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, L.; Gromadzki, Sz.,; Kozlowski, M.; Buckley, D. A. H.; Ihanec, N.

    2018-06-01

    Gaia18blo (AT2018chv, 13:11:50.55 -37:30:49.43), was discovered by the Gaia Science Alerts programme on 2018-06-05 as a smooth 0.4 mag increase on a 18.9 mag blueish source at Galactic Plane latitude of about 25 deg (http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia18blo/) We observed the target with the Southern African Large Telescope (SALT) using the Robert Stobie Spectrograph (RSS) on 2018-06-08 with PG300 grating, slit size 1.5 arcsec.

  17. University Start-ups: A Better Business Model

    NASA Astrophysics Data System (ADS)

    Dehn, J.; Webley, P. W.

    2015-12-01

    Many universities look to start-up companies as a way to attract faculty, supporting research and students as traditional federal sources become harder to come by. University affiliated start-up companies can apply for a broader suite of grants, as well as market their services to a broad customer base. Often university administrators see this as a potential panacea, but national statistics show this is not the case. Rarely do universities profit significantly from their start-ups. With a success rates of around 20%, most start-ups end up costing the university money as well as faculty-time. For the faculty, assuming they want to continue in academia, a start-up is often unattractive because it commonly leads out of academia. Running a successful business as well as maintaining a strong teaching and research load is almost impossible to do at the same time. Most business models and business professionals work outside of academia, and the models taught in business schools do not merge well in a university environment. To mitigate this a new business model is proposed where university start-ups are aligned with the academic and research missions of the university. A university start-up must work within the university, directly support research and students, and the work done maintaining the business be recognized as part of the faculty member's university obligations. This requires a complex conflict of interest management plan and for the companies to be non-profit in order to not jeopardize the university's status. This approach may not work well for all universities, but would be ideal for many to conserve resources and ensure a harmonious relationship with their start-ups and faculty.

  18. Implementing a university-community-retail partnership model to facilitate community education on universal design.

    PubMed

    Price, Christine A; Zavotka, Susan L; Teaford, Margaret H

    2004-10-01

    A collaborative partnership model was used to develop and implement a state-wide community education program on universal design. University faculty, extension professionals, older adult service agencies, service learning students, and a community retail chain made up the original partnership. This collaboration resulted in a five-stage partnership model. The model was used to develop and disseminate a consumer education program to promote aging in place. The five stages include (a) identifying partner strengths and shared learning, (b) program development, (c) implementing the universal design program, (d) facilitating collaborative outreach, and (e) shifting toward sustainable outreach. A lack of knowledge exists among consumers, builders, and health care professionals regarding strategies for aging in place. Collaborations between educators, outreach professionals, students, and a retail partner resulted in increased interest and awareness about universal design changes that enable seniors to age in place.

  19. Disadvantaged Rural Students: Five Models of School-University Collaboration.

    ERIC Educational Resources Information Center

    Edwards, Peter; And Others

    This paper describes five models of school-university collaboration designed to maximize academic achievement opportunities for disadvantaged rural students. Project SHAPE (School and Homes As Partners in Education) at the State University of New York (SUNY) at Plattsburgh is an extended school day program established in partnership with…

  20. The "Beijing Consensus" and the Chinese Model of University Autonomy

    ERIC Educational Resources Information Center

    Zha, Qiang; Hayhoe, Ruth

    2014-01-01

    This paper attempts to address connections between the Chinese model for development or the "Beijing Consensus" and Chinese universities. Chinese universities seem to be caught between serving governmental agendas and pursuing their own goals as an academic community. Up until recently, they had become used to following the lead of the…

  1. Rural Free Universities: Extending the UFM Model. Final Report.

    ERIC Educational Resources Information Center

    Maes, Sue C.

    Operating under a grant, the University for Man (UFM) in Manhattan, Kansas, tested the transferability of the UFM free university/community education model using four existing statewide delivery systems (public libraries, a private college consortium, a state cooperative extension service, an office of rural affairs) in five states: Kentucky,…

  2. Universal Priors for Sparse Modeling(PREPRINT)

    DTIC Science & Technology

    2009-08-01

    Ingenierı́a Eléctrica, Universidad de la República J. Herrera y Reissig 565, Montevideo 11300, Uruguay 2fefo@fing.edu.uy Abstract—Sparse data models, where...Aj‖0 = |Aj | as its cardinality . The goal of sparse modeling is to design a dictionary D such that X = DA with ‖Aj‖0 sufficiently small (usually below

  3. Simple universal models capture all classical spin physics.

    PubMed

    De las Cuevas, Gemma; Cubitt, Toby S

    2016-03-11

    Spin models are used in many studies of complex systems because they exhibit rich macroscopic behavior despite their microscopic simplicity. Here, we prove that all the physics of every classical spin model is reproduced in the low-energy sector of certain "universal models," with at most polynomial overhead. This holds for classical models with discrete or continuous degrees of freedom. We prove necessary and sufficient conditions for a spin model to be universal and show that one of the simplest and most widely studied spin models, the two-dimensional Ising model with fields, is universal. Our results may facilitate physical simulations of Hamiltonians with complex interactions. Copyright © 2016, American Association for the Advancement of Science.

  4. A model for the development of university curricula in nanoelectronics

    NASA Astrophysics Data System (ADS)

    Bruun, E.; Nielsen, I.

    2010-12-01

    Nanotechnology is having an increasing impact on university curricula in electrical engineering and in physics. Major influencers affecting developments in university programmes related to nanoelectronics are discussed and a model for university programme development is described. The model takes into account that nanotechnology affects not only physics but also electrical engineering and computer engineering because of the advent of new nanoelectronics devices. The model suggests that curriculum development tends to follow one of three major tracks: physics; electrical engineering; computer engineering. Examples of European curricula following this framework are identified and described. These examples may serve as sources of inspiration for future developments and the model presented may provide guidelines for a systematic selection of topics in the university programmes.

  5. Spectroscopic classification of Gaia18adv by NUTS (NOT Un-biased Transient Survey)

    NASA Astrophysics Data System (ADS)

    Gall, C.; Benetti, S.; Wyrzykowski, L.; Stritzinger, M.; Holmbo, S.; Dong, S.; Siltala, Lauri; NUTS Collaboration

    2018-01-01

    The Nordic Optical Telescope (NOT) Unbiased Transient Survey (NUTS; ATel #8992) collaboration reports the spectroscopic classification of Gaia18adv (SN2018hh) near the host galaxy SDSS J121341.37+282640.0.

  6. Using Gaia as an Astrometric Tool for Deep Ground-based Surveys

    NASA Astrophysics Data System (ADS)

    Casetti-Dinescu, Dana I.; Girard, Terrence M.; Schriefer, Michael

    2018-04-01

    Gaia DR1 positions are used to astrometrically calibrate three epochs' worth of Subaru SuprimeCam images in the fields of globular cluster NGC 2419 and the Sextans dwarf spheroidal galaxy. Distortion-correction ``maps'' are constructed from a combination of offset dithers and reference to Gaia DR1. These are used to derive absolute proper motions in the field of NGC 2419. Notably, we identify the photometrically-detected Monoceros structure in the foreground of NGC 2419 as a kinematically-cold population of stars, distinct from Galactic-field stars. This project demonstrates the feasibility of combining Gaia with deep, ground-based surveys, thus extending high-quality astrometry to magnitudes beyond the limits of Gaia.

  7. The project office of the Gaia Data Processing and Analysis Consortium

    NASA Astrophysics Data System (ADS)

    Mercier, E.; Els, S.; Gracia, G.; O'Mullane, W.; Lock, T.; Comoretto, G.

    2010-07-01

    Gaia is Europe's future astrometry satellite which is currently under development. The data collected by Gaia will be treated and analyzed by the "Data Processing and Analysis Consortium" (DPAC). DPAC consists of over 400 scientists in more than 22 countries, which are currently developing the required data reduction, analysis and handling algorithms and routines. DPAC is organized in Coordination Units (CU's) and Data Processing Centres (DPCs). Each of these entities is individually responsible for the development of software for the processing of the different data. In 2008, the DPAC Project Office (PO) has been set-up with the task to manage the day-to-day activities of the consortium including implementation, development and operations. This paper describes the tasks DPAC faces and the role of the DPAC PO in the Gaia framework and how it supports the DPAC entities in their effort to fulfill the Gaia promise.

  8. Quantum graviton creation in a model universe

    NASA Technical Reports Server (NTRS)

    Berger, B. K.

    1974-01-01

    Consideration of the mechanism of production of gravitons in the empty, anisotropic, spatially inhomogeneous Gowdy three-torus cosmology. The Gowdy cosmology is an exact solution of the vacuum Einstein equations and is obtained as a generalization of the homogeneous empty Bianchi Type I (Kasner) cosmology by permitting the metric components to depend on one of the space variables in addition to time. The Hamiltonian methods of Arnowitt, Deser, and Misner are employed to identify the dynamical variables which are to be quantized. The WKB regime solution is identical to that found by Doroshkevich, Zel'dovich, and Novikov (DZN) for a universe containing collisionless anisotropic radiation. Using a procedure similar to that of Parker (1971) or Zel'dovich and Starobinskii (1971) for defining quantum number, it is found that the DZN large-time radiation consists of quanta (gravitons) created from an initial vacuum. The quantum behavior is much like the semiclassical enhancement of quantum number with the added feature of creation of quanta from vacuum fluctuations.

  9. Model Development for A University-Based Learning Disability Clinic.

    ERIC Educational Resources Information Center

    Martin, Larry L.; And Others

    The report presents a model for appraisal and individualized educational programing for learning disabled children at the School of Education, Auburn University, Alabama. Descriptions by clinic staff of visitations to exemplary models and a summary of a regional conference on learning disabilities introduce the report. The clinic model is…

  10. University Business Models and Online Practices: A Third Way

    ERIC Educational Resources Information Center

    Rubin, Beth

    2013-01-01

    Higher Education is in a state of change, and the existing business models do not meet the needs of stakeholders. This article contrasts the current dominant business models of universities, comparing the traditional non-profit against the for-profit online model, examining the structural features and online teaching practices that underlie each.…

  11. Some thoughts on GAIA and the sulfur cycle

    NASA Technical Reports Server (NTRS)

    Lovelock, J. E.

    1985-01-01

    The data hypothesis states that the composition, oxidation reduction state, and temperature of the troposphere are actively regulated by the biota for the biota. One of the early predictions of the Gaia hypothesis was that there should be a sulfur compound made by the biota in the oceans. It would need to be stable enough against oxidation in water to allow its transfer to the air. Either the sulfur compound itself or its atmospheric oxidation product would have to return sulfur from the sea to the land surfaces. The most likely candidate for this role was dimethyl sulfide. Another sulfur compound of interest from a Gaian viewpoint CS2 (carbon disulfide) is discussed. Theories on the production of dimethyl sulfide and carbon disulfide related to the Gaian hypothesis are examined.

  12. The Structure Of The Gaia Deployable Sunshield Assembly

    NASA Astrophysics Data System (ADS)

    Pereira, Carlos; Urgoiti, Eduardo; Pinto, Inaki

    2012-07-01

    GAIA is an ESA mission with launch date in 2013. Its main objective is to map the stars. After launch it will unfold a 10.2 m diameter sunshield .The structure of this shield consists of twelve 3.5 meter long composite trusses which act as scaffold to two multilayer insulation blankets. Due to thermal stability constraints the planarity of the shield must be better than 1.0 mm. The trusses are therefore lightweight structures capable of withstanding the launch loads and once deployed, the thermal environment of the spacecraft with a minimum of distortion. This paper details: • The material selection for the composite structure • Validation of the chosen materials and truss layout • The modification of manufacturing process in order to lightweight the structure • The extensive structural and thermal stability testing The sunshield has been delivered to the satellite prime after successful mechanical, thermal and deployment tests.

  13. Laser metrology and optic active control system for GAIA

    NASA Astrophysics Data System (ADS)

    D'Angelo, F.; Bonino, L.; Cesare, S.; Castorina, G.; Mottini, S.; Bertinetto, F.; Bisi, M.; Canuto, E.; Musso, F.

    2017-11-01

    The Laser Metrology and Optic Active Control (LM&OAC) program has been carried out under ESA contract with the purpose to design and validate a laser metrology system and an actuation mechanism to monitor and control at microarcsec level the stability of the Basic Angle (angle between the lines of sight of the two telescopes) of GAIA satellite. As part of the program, a breadboard (including some EQM elements) of the laser metrology and control system has been built and submitted to functional, performance and environmental tests. In the followings we describe the mission requirements, the system architecture, the breadboard design, and finally the performed validation tests. Conclusion and appraisals from this experience are also reported.

  14. Gaia's view of the λ Boo star puzzle

    NASA Astrophysics Data System (ADS)

    Murphy, Simon J.; Paunzen, Ernst

    2017-04-01

    The evolutionary status of the chemically peculiar class of λ Boo stars has been intensely debated. It is now agreed that the λ Boo phenomenon affects A stars of all ages, from star formation to the terminal age main sequence, but the cause of the chemical peculiarity is still a puzzle. We revisit the debate of their ages and temperatures in order to shed light on the phenomenon, using the new parallaxes in Gaia Data Release 1 with existing Hipparcos parallaxes and multicolour photometry. We find that no single formation mechanism is able to explain all the observations, and suggest that there are multiple channels producing λ Boo spectra. The relative importance of these channels varies with age, temperature and environment.

  15. Gaia: unravelling the chemical and dynamical history of our Galaxy

    NASA Astrophysics Data System (ADS)

    Pancino, E.

    The Gaia astrometric mission - the Hipparcos successor - is described in some detail, with its three instruments: the two (spectro)photometers (BP and RP) covering the range 330-1050 nm, the white light (G-band) imager dedicated to astrometry, and the radial velocity spectrometer (RVS) covering the range 847-874 nm at a resolution R≃11500. The whole sky will be scanned repeatedly providing data for ˜109 point-like objects, down to a magnitude of V≃20, aiming to the full 6D reconstruction of the Milky Way kinematical and dinamical structure with unprecendented precision. The horizon of scientific questions that can find an answer with such a set of data is vast, including besides the Galaxy: Solar system studies, stellar astrophysics, exoplanets, supernovae, Local group physics, unresolved galaxies, Quasars, and fundamental physics. The Italian involvement in the mission preparation is briefly outlined.

  16. On the accuracy of mass measurement for microlensing black holes as seen by Gaia and OGLE

    NASA Astrophysics Data System (ADS)

    Rybicki, Krzysztof A.; Wyrzykowski, Łukasz; Klencki, Jakub; de Bruijne, Jos; Belczyński, Krzysztof; Chruślińska, Martyna

    2018-05-01

    We investigate the impact of combining Gaia astrometry from space with precise, high cadence OGLE photometry from the ground. For the archival event OGLE3-ULENS-PAR-02, which is likely a black hole, we simulate a realistic astrometric time series of Gaia measurements and combine it with the real photometric data collected by the OGLE project. We predict that at the end of the nominal 5 yr of the Gaia mission, for the events brighter than G ≈ 15.5 mag at the baseline, caused by objects heavier than 10 M⊙, it will be possible to unambiguously derive masses of the lenses, with accuracy between a few and 15 per cent. We find that fainter events (G < 17.5) can still have their lens masses determined, provided that they are heavier than 30 M⊙. We estimate that the rate of astrometric microlensing events caused by the stellar-origin black holes is ≈ 4 × 10- 7 yr- 1, which implies, that after 5 yr of Gaia operation and ≈5 × 106 bright sources in Gaia, it will be possible to identify few such events in the Gaia final catalogues.

  17. Prediction of stellar occultations by distant solar system bodies in the Gaia era

    NASA Astrophysics Data System (ADS)

    Desmars, Josselin; Camargo, Julio; Sicardy, Bruno; Braga-Ribas, Felipe; Vieira-Martins, Roberto; Assafin, Marcelo; Bérard, Diane; Benedetti-Rossi, Gustavo

    2018-04-01

    Stellar occultations are a unique technique to access physical characteristics of distant solar system objects from the ground. They allow the measure of the size and the shape at kilometric level, the detection of tenuous atmospheres (few nanobars), and the investigation of close vicinity (satellites, rings) of Transneptunian objects and Centaurs. This technique is made successful thanks to accurate predictions of occultations. Accuracy of the predictions depends on the uncertainty in the position of the occulted star and the object's orbit. The Gaia stellar catalogue (Gaia Collaboration (2017)) now allows to get accurate astrometric stellar positions (to the mas level). The main uncertainty remains on the orbit. In this context, we now take advantage of the NIMA method (Desmars et al.(2015)) for the orbit determination and of the Gaia DR1 catalogue for the astrometry. In this document, we show how the orbit determination is improved by reducing current and some past observations with Gaia DR1. Moreover, we also use more than 45 past positive occultations observed in the 2009-2017 period to derive very accurate astrometric positions only depending on the position of the occulted stars (about few mas with Gaia DR1). We use the case of (10199) Chariklo as an illustration. The main limitation lies in the imprecision of the proper motions which is going to be solved by the Gaia DR2 release.

  18. Using Java for distributed computing in the Gaia satellite data processing

    NASA Astrophysics Data System (ADS)

    O'Mullane, William; Luri, Xavier; Parsons, Paul; Lammers, Uwe; Hoar, John; Hernandez, Jose

    2011-10-01

    In recent years Java has matured to a stable easy-to-use language with the flexibility of an interpreter (for reflection etc.) but the performance and type checking of a compiled language. When we started using Java for astronomical applications around 1999 they were the first of their kind in astronomy. Now a great deal of astronomy software is written in Java as are many business applications. We discuss the current environment and trends concerning the language and present an actual example of scientific use of Java for high-performance distributed computing: ESA's mission Gaia. The Gaia scanning satellite will perform a galactic census of about 1,000 million objects in our galaxy. The Gaia community has chosen to write its processing software in Java. We explore the manifold reasons for choosing Java for this large science collaboration. Gaia processing is numerically complex but highly distributable, some parts being embarrassingly parallel. We describe the Gaia processing architecture and its realisation in Java. We delve into the astrometric solution which is the most advanced and most complex part of the processing. The Gaia simulator is also written in Java and is the most mature code in the system. This has been successfully running since about 2005 on the supercomputer "Marenostrum" in Barcelona. We relate experiences of using Java on a large shared machine. Finally we discuss Java, including some of its problems, for scientific computing.

  19. A setup for Gaia-DR1: the star formation history of our thin disc environment

    NASA Astrophysics Data System (ADS)

    Miret-Roig, N.; Romero-Gómez, M.; Figueras, F.; Mor, R.

    2017-03-01

    The first Gaia Data Release (Gaia-DR1, 14 September 2016) primes the pump and paves the way for a new golden age of the galactic astronomy. Gaia-DR1 will provide new parallaxes and proper motions for about two million well-behaved Tycho-2 stars placed in the solar neighborhood. This TGAS (Tycho-Gaia Astrometric Solution) catalogue is being obtained through the combination of the Gaia observations with the positions of the stars obtained by Hipparcos (ESA 1997) when available, or Tycho-2. The aim of the work presented here has been to evaluate the capabilities of Gaia and future on-ground spectroscopic surveys to derive the dynamical age and place of birth of the Young Local Associations (YLAs). Test particle simulations in realistic galactic potentials and different scenarios for the accuracy on astrometric and spectroscopic data allow us to quantify our future capabilities to trace back in time the star formation history of our thin disc environment.

  20. Effect of intrinsic magnetic field decrease on the low- to middle-latitude upper atmosphere dynamics simulated by GAIA

    NASA Astrophysics Data System (ADS)

    Tao, C.; Jin, H.; Shinagawa, H.; Fujiwara, H.; Miyoshi, Y.

    2017-12-01

    The effects of decreasing the intrinsic magnetic field on the upper atmospheric dynamics at low to middle latitudes are investigated using the Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA). GAIA incorporates a meteorological reanalysis data set at low altitudes (<30 km), which enables us to investigate the atmospheric response to various waves under dynamic and chemical interactions with the ionosphere. In this simulation experiment, we reduced the magnetic field strength to as low as 10% of the current value. The averaged neutral velocity, density, and temperature at low to middle latitudes at 300 km altitude show little change with the magnetic field variation, while the dynamo field, current density, and the ionospheric conductivities are modified significantly. The wind velocity and tidal wave amplitude in the thermosphere remain large owing to the small constraint on plasma motion for a small field. On the other hand, the superrotation feature at the dip equator is weakened by 20% for a 10% magnetic field because the increase in ion drag for the small magnetic field prevents the superrotation.

  1. Effect of intrinsic magnetic field decrease on the low- to middle-latitude upper atmosphere dynamics simulated by GAIA

    NASA Astrophysics Data System (ADS)

    Tao, Chihiro; Jin, Hidekatsu; Shinagawa, Hiroyuki; Fujiwara, Hitoshi; Miyoshi, Yasunobu

    2017-09-01

    The effects of decreasing the intrinsic magnetic field on the upper atmospheric dynamics at low to middle latitudes are investigated using the Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA). GAIA incorporates a meteorological reanalysis data set at low altitudes (<30 km), which enables us to investigate the atmospheric response to various waves under dynamic and chemical interactions with the ionosphere. In this simulation experiment, we reduced the magnetic field strength to as low as 10% of the current value. The averaged neutral velocity, density, and temperature at low to middle latitudes at 300 km altitude show little change with the magnetic field variation, while the dynamo field, current density, and the ionospheric conductivities are modified significantly. The wind velocity and tidal wave amplitude in the thermosphere remain large owing to the small constraint on plasma motion for a small field. On the other hand, the superrotation feature at the dip equator is weakened by 20% for a 10% magnetic field because the increase in ion drag for the small magnetic field prevents the superrotation.

  2. Thermal cut-off response modelling of universal motors

    NASA Astrophysics Data System (ADS)

    Thangaveloo, Kashveen; Chin, Yung Shin

    2017-04-01

    This paper presents a model to predict the thermal cut-off (TCO) response behaviour in universal motors. The mathematical model includes the calculations of heat loss in the universal motor and the flow characteristics around the TCO component which together are the main parameters for TCO response prediction. In order to accurately predict the TCO component temperature, factors like the TCO component resistance, the effect of ambient, and the flow conditions through the motor are taken into account to improve the prediction accuracy of the model.

  3. What Is FRBR? A Conceptual Model for the Bibliographic Universe

    ERIC Educational Resources Information Center

    Tillett, Barbara

    2005-01-01

    From 1992 to 1995 the IFLA Study Group on Functional Requirements for Bibliographic Records (FRBR) developed an entity relationship model as a generalised view of the bibliographic universe, intended to be independent of any cataloguing code or implementation. The FRBR report itself includes a description of the conceptual model (the entities,…

  4. Integrating an Interprofessional Education Model at a Private University

    ERIC Educational Resources Information Center

    Parker, Ramona Ann; Gottlieb, Helmut; Dominguez, Daniel G.; Sanchez-Diaz, Patricia C.; Jones, Mary Elaine

    2015-01-01

    In 2012, a private University in South Texas sought to prepare eight cohorts of 25 nursing, optometry, pharmacy, physical therapy, and health care administration students with an interprofessional education activity as a model for collaborative learning. The two semester interprofessional activity used a blended model (Blackboard Learn®,…

  5. University-Industry Research Collaboration: A Model to Assess University Capability

    ERIC Educational Resources Information Center

    Abramo, Giovanni; D'Angelo, Ciriaco Andrea; Di Costa, Flavia

    2011-01-01

    Scholars and policy makers recognize that collaboration between industry and the public research institutions is a necessity for innovation and national economic development. This work presents an econometric model which expresses the university capability for collaboration with industry as a function of size, location and research quality. The…

  6. Faculties of Education in Traditional Universities and Universities of the Third Age: A Partnership Model in Gerontagogy

    ERIC Educational Resources Information Center

    Lemieux, Andre; Boutin, Gerald; Riendeau, Jean

    2007-01-01

    This article discusses "Universities of the Third Age", whose function is quite distinct from established universities' traditional role in teaching, research, and community services. Consequently, there is an urgent need to develop a model of partnership between traditional universities and Universities of the Third Age, ensuring better…

  7. The evolution of the Sun's birth cluster and the search for the solar siblings with Gaia

    NASA Astrophysics Data System (ADS)

    Martínez-Barbosa, C. A.; Brown, A. G. A.; Boekholt, T.; Portegies Zwart, S.; Antiche, E.; Antoja, T.

    2016-03-01

    We use self-consistent numerical simulations of the evolution and disruption of the Sun's birth cluster in the Milky Way potential to investigate the present-day phase-space distribution of the Sun's siblings. The simulations include the gravitational N-body forces within the cluster and the effects of stellar evolution on the cluster population. In addition, the gravitational forces due to the Milky Way potential are accounted for in a self-consistent manner. Our aim is to understand how the astrometric and radial velocity data from the Gaia mission can be used to pre-select solar sibling candidates. We vary the initial conditions of the Sun's birth cluster, as well as the parameters of the Galactic potential. In particular, we use different configurations and strengths of the bar and spiral arms. We show that the disruption time-scales of the cluster are insensitive to the details of the non-axisymmetric components of the Milky Way model and we make predictions, averaged over the different simulated possibilities, about the number of solar siblings that should appear in surveys such as Gaia or GALAH. We find a large variety of present-day phase-space distributions of solar siblings, which depend on the cluster initial conditions and the Milky Way model parameters. We show that nevertheless robust predictions can be made about the location of the solar siblings in the space of parallaxes (ϖ), proper motions (μ) and radial velocities (Vr). By calculating the ratio of the number of simulated solar siblings to that of the number of stars in a model Galactic disc, we find that this ratio is above 0.5 in the region given by: ϖ ≥ 5 mas, 4 ≤ μ ≤ 6 mas yr-1, and -2 ≤ Vr ≤ 0 km s-1. Selecting stars from this region should increase the probability of success in identifying solar siblings through follow-up observations. However the proposed pre-selection criterion is sensitive to our assumptions, in particular about the Galactic potential. Using a more

  8. Implementation of a University-wide Retention Model

    NASA Astrophysics Data System (ADS)

    Davis, E. J.; Campbell, A.

    2006-12-01

    Eleven years ago, Bowie State University and NASA Goddard Space Flight Center entered into an agreement to enhance the science, mathematics, engineering and technology /(SMET/) domains. A Model Institutions for Excellence Award provided the financial basis for a number of initiatives that have led to increased retention and graduation rates. Initiatives such as a scholarship program, tutoring center, Summer Academy, safety-net program, research focus and mentoring have had a significant impact on students entering graduate and professional school and SMET related employment. Successes documented through various assessment activities and tracking of student progress, have led to implementation of the `retention model' urilized by the SMET MIE Initiatives throughout the University. The MIE retention efforts include each of the aforementioned initiatives plus pre-college and second-year experience programs. It is anticipated that the University-wide application of the `retention model' will provide the incentives necessary to obtain similar results throughout the student body.

  9. Toward a renewed Galactic Cepheid distance scale from Gaia and optical interferometry

    NASA Astrophysics Data System (ADS)

    Kervella, Pierre; Mérand, Antoine; Gallenne, Alexandre; Trahin, Boris; Nardetto, Nicolas; Anderson, Richard I.; Breitfelder, Joanne; Szabados, Laszlo; Bond, Howard E.; Borgniet, Simon; Gieren, Wolfgang; Pietrzyński, Grzegorz

    2017-09-01

    Through an innovative combination of multiple observing techniques and modeling, we are assembling a comprehensive understanding of the pulsation and close environment of Cepheids. We developed the SPIPS modeling tool that combines all observables (radial velocimetry, photometry, angular diameters from interferometry) to derive the relevant physical parameters of the star (effective temperature, infrared excess, reddening, …) and the ratio of the distance and the projection factor d/p. We present the application of SPIPS to the long-period Cepheid RS Pup, for which we derive p = 1.25±0.06. The addition of this massive Cepheid consolidates the existing sample of p-factor measurements towards long-period pulsators. This allows us to conclude that p is constant or mildly variable around p = 1.29±0.04 (±3%) as a function of the pulsation period. The forthcoming Gaia DR2 will provide a considerable improvement in quantity and accuracy of the trigonometric parallaxes of Cepheids. From this sample, the SPIPS modeling tool will enable a robust calibration of the Cepheid distance scale.

  10. Sloppy-model universality class and the Vandermonde matrix.

    PubMed

    Waterfall, Joshua J; Casey, Fergal P; Gutenkunst, Ryan N; Brown, Kevin S; Myers, Christopher R; Brouwer, Piet W; Elser, Veit; Sethna, James P

    2006-10-13

    In a variety of contexts, physicists study complex, nonlinear models with many unknown or tunable parameters to explain experimental data. We explain why such systems so often are sloppy: the system behavior depends only on a few "stiff" combinations of the parameters and is unchanged as other "sloppy" parameter combinations vary by orders of magnitude. We observe that the eigenvalue spectra for the sensitivity of sloppy models have a striking, characteristic form with a density of logarithms of eigenvalues which is roughly constant over a large range. We suggest that the common features of sloppy models indicate that they may belong to a common universality class. In particular, we motivate focusing on a Vandermonde ensemble of multiparameter nonlinear models and show in one limit that they exhibit the universal features of sloppy models.

  11. The Gaia-ESO Survey: Churning through the Milky Way

    NASA Astrophysics Data System (ADS)

    Hayden, M. R.; Recio-Blanco, A.; de Laverny, P.; Mikolaitis, S.; Guiglion, G.; Hill, V.; Gilmore, G.; Randich, S.; Bayo, A.; Bensby, T.; Bergemann, M.; Bragaglia, A.; Casey, A.; Costado, M.; Feltzing, S.; Franciosini, E.; Hourihane, A.; Jofre, P.; Koposov, S.; Kordopatis, G.; Lanzafame, A.; Lardo, C.; Lewis, J.; Lind, K.; Magrini, L.; Monaco, L.; Morbidelli, L.; Pancino, E.; Sacco, G.; Stonkute, E.; Worley, C. C.; Zwitter, T.

    2018-01-01

    Context. There have been conflicting results with respect to the extent that radial migration has played in the evolution of the Galaxy. Additionally, observations of the solar neighborhood have shown evidence of a merger in the past history of the Milky Way that drives enhanced radial migration. Aims: We attempt to determine the relative fraction of stars that have undergone significant radial migration by studying the orbital properties of metal-rich ([Fe/H] > 0.1) stars within 2 kpc of the Sun. We also aim to investigate the kinematic properties, such as velocity dispersion and orbital parameters, of stellar populations near the Sun as a function of [Mg/Fe] and [Fe/H], which could show evidence of a major merger in the past history of the Milky Way. Methods: We used a sample of more than 3000 stars selected from the fourth internal data release of the Gaia-ESO Survey. We used the stellar parameters from the Gaia-ESO Survey along with proper motions from PPMXL to determine distances, kinematics, and orbital properties for these stars to analyze the chemodynamic properties of stellar populations near the Sun. Results: Analyzing the kinematics of the most metal-rich stars ([Fe/H] > 0.1), we find that more than half have small eccentricities (e< 0.2) or are on nearly circular orbits. Slightly more than 20% of the metal-rich stars have perigalacticons Rp> 7 kpc. We find that the highest [Mg/Fe], metal-poor populations have lower vertical and radial velocity dispersions compared to lower [Mg/Fe] populations of similar metallicity by 10 km s-1. The median eccentricity increases linearly with [Mg/Fe] across all metallicities, while the perigalacticon decreases with increasing [Mg/Fe] for all metallicities. Finally, the most [Mg/Fe]-rich stars are found to have significant asymmetric drift and rotate more than 40 km s-1 slower than stars with lower [Mg/Fe] ratios. Conclusions: While our results cannot constrain how far stars have migrated, we propose that migration

  12. Determining Empirical Stellar Masses and Radii from Transits and Gaia Parallaxes as Illustrated by Spitzer Observations of KELT-11b

    NASA Astrophysics Data System (ADS)

    Beatty, Thomas G.; Stevens, Daniel J.; Collins, Karen A.; Colón, Knicole D.; James, David J.; Kreidberg, Laura; Pepper, Joshua; Rodriguez, Joseph E.; Siverd, Robert J.; Stassun, Keivan G.; Kielkopf, John F.

    2017-07-01

    Using the Spitzer Space Telescope, we observed a transit at 3.6 μm of KELT-11b. We also observed three partial planetary transits from the ground. We simultaneously fit these observations, ground-based photometry from Pepper et al., radial velocity data from Pepper et al., and a spectral energy distribution (SED) model using catalog magnitudes and the Hipparcos parallax to the system. The only significant difference between our results and those of Pepper et al. is that we find the orbital period to be shorter by 37 s, 4.73610 ± 0.00003 versus 4.73653 ± 0.00006 days, and we measure a transit center time of {{BJD}}{TDB} 2457483.4310 ± 0.0007, which is 42 minutes earlier than predicted. Using our new photometry, we precisely measure the density of the star KELT-11 to 4%. By combining the parallax and catalog magnitudes of the system, we are able to measure the radius of KELT-11b essentially empirically. Coupled with the stellar density, this gives a parallactic mass and radius of 1.8 {M}⊙ and 2.9 {R}⊙ , which are each approximately 1σ higher than the adopted model-estimated mass and radius. If we conduct the same fit using the expected parallax uncertainty from the final Gaia data release, this difference increases to 4σ. The differences between the model and parallactic masses and radii for KELT-11 demonstrate the role that precise Gaia parallaxes, coupled with simultaneous photometric, radial velocity, and SED fitting, can play in determining stellar and planetary parameters. With high-precision photometry of transiting planets and high-precision Gaia parallaxes, the parallactic mass and radius uncertainties of stars become 1% and 3%, respectively. TESS is expected to discover 60-80 systems where these measurements will be possible. These parallactic mass and radius measurements have uncertainties small enough that they may provide observational input into the stellar models themselves.

  13. Gaia TGAS search for Large Magellanic Cloud runaway supergiant stars. Candidate hypervelocity star discovery and the nature of R 71

    NASA Astrophysics Data System (ADS)

    Lennon, Daniel J.; van der Marel, Roeland P.; Ramos Lerate, Mercedes; O'Mullane, William; Sahlmann, Johannes

    2017-07-01

    Aims: Our research aims to search for runaway stars in the Large Magellanic Cloud (LMC) among the bright Hipparcos supergiant stars included in the Gaia DR1 Tycho-Gaia astrometric solution (TGAS) catalogue. Methods: We compute the space velocities of the visually brightest stars in the Large Magellanic Cloud that are included in the TGAS proper motion catalogue. This sample of 31 stars contains a luminous blue variable (LBV), emission line stars, blue and yellow supergiants, and an SgB[e] star. We combine these results with published radial velocities to derive their space velocities, and by comparing with predictions from stellar dynamical models we obtain each star's (peculiar) velocity relative to its local stellar environment. Results: Two of the 31 stars have unusually high proper motions. Of the remaining 29 stars we find that most objects in this sample have velocities that are inconsistent with a runaway nature, being in very good agreement with model predictions of a circularly rotating disk model. Indeed the excellent fit to the model implies that the TGAS uncertainty estimates are likely overestimated. The fastest outliers in this subsample contain the LBV R 71 and a few other well known emission line objects though in no case do we derive velocities consistent with fast ( 100 km s-1) runaways. On the contrary our results imply that R 71 in particular has a moderate deviation from the local stellar velocity field (40 km s-1) lending support to the proposition that this object cannot have evolved as a normal single star since it lies too far from massive star forming complexes to have arrived at its current position during its lifetime. Our findings therefore strengthen the case for this LBV being the result of binary evolution. Of the two stars with unusually high proper motions we find that one, the isolated B1.5 Ia+ supergiant Sk-67 2 (HIP 22237), is a candidate hypervelocity star, the TGAS proper motion implying a very large peculiar transverse

  14. PEPSI deep spectra. II. Gaia benchmark stars and other M-K standards

    NASA Astrophysics Data System (ADS)

    Strassmeier, K. G.; Ilyin, I.; Weber, M.

    2018-04-01

    Context. High-resolution échelle spectra confine many essential stellar parameters once the data reach a quality appropriate to constrain the various physical processes that form these spectra. Aim. We provide a homogeneous library of high-resolution, high-S/N spectra for 48 bright AFGKM stars, some of them approaching the quality of solar-flux spectra. Our sample includes the northern Gaia benchmark stars, some solar analogs, and some other bright Morgan-Keenan (M-K) spectral standards. Methods: Well-exposed deep spectra were created by average-combining individual exposures. The data-reduction process relies on adaptive selection of parameters by using statistical inference and robust estimators. We employed spectrum synthesis techniques and statistics tools in order to characterize the spectra and give a first quick look at some of the science cases possible. Results: With an average spectral resolution of R ≈ 220 000 (1.36 km s-1), a continuous wavelength coverage from 383 nm to 912 nm, and S/N of between 70:1 for the faintest star in the extreme blue and 6000:1 for the brightest star in the red, these spectra are now made public for further data mining and analysis. Preliminary results include new stellar parameters for 70 Vir and α Tau, the detection of the rare-earth element dysprosium and the heavy elements uranium, thorium and neodymium in several RGB stars, and the use of the 12C to 13C isotope ratio for age-related determinations. We also found Arcturus to exhibit few-percent Ca II H&K and Hα residual profile changes with respect to the KPNO atlas taken in 1999. Based on data acquired with PEPSI using the Large Binocular Telescope (LBT) and the Vatican Advanced Technology Telescope (VATT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT

  15. Global distribution of neutral wind shear associated with sporadic E layers derived from GAIA

    NASA Astrophysics Data System (ADS)

    Shinagawa, H.; Miyoshi, Y.; Jin, H.; Fujiwara, H.

    2017-04-01

    There have been a number of papers reporting that the statistical occurrence rate of the sporadic E (Es) layer depends not only on the local time and season but also on the geographical location, implying that geographical and seasonal dependence in vertical neutral wind shear is one of the factors responsible for the geographical and seasonal dependence in Es layer occurrences rate. To study the role of neutral wind shear in the global distribution of the Es layer occurrence rate, we employ a self-consistent atmosphere-ionosphere coupled model called GAIA (Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy), which incorporates meteorological reanalysis data in the lower atmosphere. The average distribution of neutral wind shear in the lower thermosphere is derived for the June-August and December-February periods, and the global distribution of vertical ion convergence is obtained to estimate the Es layer occurrence rate. It is found that the local and seasonal dependence of neutral wind shear is an important factor in determining the dependence of the Es layer occurrence rate on geographical distribution and seasonal variation. However, there are uncertainties in the simulated vertical neutral wind shears, which have larger scales than the observed wind shear scales. Furthermore, other processes such as localization of magnetic field distribution, background metallic ion distribution, ionospheric electric fields, and chemical processes of metallic ions are also likely to make an important contribution to geographical distribution and seasonal variation of the Es occurrence rate.

  16. Estimating Distances from Parallaxes. III. Distances of Two Million Stars in the Gaia DR1 Catalogue

    NASA Astrophysics Data System (ADS)

    Astraatmadja, Tri L.; Bailer-Jones, Coryn A. L.

    2016-12-01

    We infer distances and their asymmetric uncertainties for two million stars using the parallaxes published in the Gaia DR1 (GDR1) catalogue. We do this with two distance priors: A minimalist, isotropic prior assuming an exponentially decreasing space density with increasing distance, and an anisotropic prior derived from the observability of stars in a Milky Way model. We validate our results by comparing our distance estimates for 105 Cepheids which have more precise, independently estimated distances. For this sample we find that the Milky Way prior performs better (the rms of the scaled residuals is 0.40) than the exponentially decreasing space density prior (rms is 0.57), although for distances beyond 2 kpc the Milky Way prior performs worse, with a bias in the scaled residuals of -0.36 (versus -0.07 for the exponentially decreasing space density prior). We do not attempt to include the photometric data in GDR1 due to the lack of reliable color information. Our distance catalog is available at http://www.mpia.de/homes/calj/tgas_distances/main.html as well as at CDS. This should only be used to give individual distances. Combining data or testing models should be done with the original parallaxes, and attention paid to correlated and systematic uncertainties.

  17. Enabling data science in the Gaia mission archive: The present-day mass function and age distribution

    NASA Astrophysics Data System (ADS)

    Tapiador, D.; Berihuete, A.; Sarro, L. M.; Julbe, F.; Huedo, E.

    2017-04-01

    Recent advances in large scale computing architectures enable new opportunities to extract value out of the vast amounts of data being currently generated. However, their successful adoption is not straightforward in areas like science, as there are still some barriers that need to be overcome. Those comprise (i) the existence of legacy code that needs to be ported, (ii) the lack of high-level and use case specific frameworks that facilitate a smoother transition, or (iii) the scarcity of profiles with the balanced skill sets between the technological and scientific domains. The European Space Agency's Gaia mission will create the largest and most precise three dimensional chart of our galaxy (the Milky Way), providing unprecedented position, parallax and proper motion measurements for about one billion stars. The successful exploitation of this data archive will depend on the ability to offer the proper infrastructure upon which scientists will be able to do exploration and modelling with this huge data set. In this paper, we present and contextualize these challenges by building two probabilistic models using Hierarchical Bayesian Modelling. These models represent a key challenge in astronomy and are of paramount importance for the Gaia mission itself. Moreover, we approach the implementation by leveraging a generic distributed processing engine through an existing software package for Markov chain Monte Carlo sampling. The two computationally intensive models are then validated with simulated data in different scenarios under specific restrictions, and their performance is assessed to prove their scalability. We argue that this approach will not only serve for the models in hand but also for exemplifying how to address similar problems in science, which may need to both scale to bigger data sets and reuse existing software as much as possible. This will lead to shorter time to science in massive data archives.

  18. Gaia Data Release 1. Cross-match with external catalogues. Algorithm and results

    NASA Astrophysics Data System (ADS)

    Marrese, P. M.; Marinoni, S.; Fabrizio, M.; Giuffrida, G.

    2017-11-01

    Context. Although the Gaia catalogue on its own will be a very powerful tool, it is the combination of this highly accurate archive with other archives that will truly open up amazing possibilities for astronomical research. The advanced interoperation of archives is based on cross-matching, leaving the user with the feeling of working with one single data archive. The data retrieval should work not only across data archives, but also across wavelength domains. The first step for seamless data access is the computation of the cross-match between Gaia and external surveys. Aims: The matching of astronomical catalogues is a complex and challenging problem both scientifically and technologically (especially when matching large surveys like Gaia). We describe the cross-match algorithm used to pre-compute the match of Gaia Data Release 1 (DR1) with a selected list of large publicly available optical and IR surveys. Methods: The overall principles of the adopted cross-match algorithm are outlined. Details are given on the developed algorithm, including the methods used to account for position errors, proper motions, and environment; to define the neighbours; and to define the figure of merit used to select the most probable counterpart. Results: Statistics on the results are also given. The results of the cross-match are part of the official Gaia DR1 catalogue.

  19. Molecular Modeling and Computational Chemistry at Humboldt State University.

    ERIC Educational Resources Information Center

    Paselk, Richard A.; Zoellner, Robert W.

    2002-01-01

    Describes a molecular modeling and computational chemistry (MM&CC) facility for undergraduate instruction and research at Humboldt State University. This facility complex allows the introduction of MM&CC throughout the chemistry curriculum with tailored experiments in general, organic, and inorganic courses as well as a new molecular modeling…

  20. The University Model and Educational Change. SSEC Publication No. 130.

    ERIC Educational Resources Information Center

    Ford, Richard B.

    In the sixties the crisis of the credibility and competence of schools resulted in the funding of programs to remedy school problems. The model for curriculum reform came from the university and, more particularly, from liberal arts departments having the capacity to improve curriculum content and teacher expertise. In a few instances attempts…

  1. The Corporate University Model for Continuous Learning, Training and Development.

    ERIC Educational Resources Information Center

    El-Tannir, Akram A.

    2002-01-01

    Corporate universities typically convey corporate culture and provide systematic curriculum aimed at achieving strategic objectives. Virtual access and company-specific content combine to provide opportunities for continuous and active learning, a model that is becoming pervasive. (Contains 17 references.) (SK)

  2. Explaining formation of Astronomical Jets using Dynamic Universe Model

    NASA Astrophysics Data System (ADS)

    Naga Parameswara Gupta, Satyavarapu

    2016-07-01

    Astronomical jets are observed from the centres of many Galaxies including our own Milkyway. The formation of such jet is explained using SITA simulations of Dynamic Universe Model. For this purpose the path traced by a test neutron is calculated and depicted using a set up of one densemass of the mass equivalent to mass of Galaxy center, 90 stars with similar masses of stars near Galaxy center, mass equivalents of 23 Globular Cluster groups, 16 Milkyway parts, Andromeda and Triangulum Galaxies at appropriate distances. Five different kinds of theoretical simulations gave positive results The path travelled by this test neutron was found to be an astronomical jet emerging from Galaxy center. This is another result from Dynamic Universe Model. It solves new problems like a. Variable Mass Rocket Trajectory Problem b. Explaining Very long baseline interferometry (VLBI) observations c. Astronomical jets observed from Milkyway Center d. Prediction of Blue shifted Galaxies e. Explaining Pioneer Anomaly f. Prediction of New Horizons satellite trajectory etc. Dynamic Universe Model never reduces to General relativity on any condition. It uses a different type of mathematics based on Newtonian physics. This mathematics used here is simple and straightforward. As there are no differential equations present in Dynamic Universe Model, the set of equations give single solution in x y z Cartesian coordinates for every point mass for every time step

  3. Universal Instructional Design as a Model for Educational Programs

    ERIC Educational Resources Information Center

    Higbee, Jeanne L.

    2007-01-01

    This article describes Universal Instructional Design as an inclusive pedagogical model for use in educational programs, whether provided by traditional educational institutions, community-based initiatives, or workplace literacy projects. For the benefit of public relations specialists and classroom educators alike, the article begins with a…

  4. Modeling Environmental Literacy of Malaysian Pre-University Students

    ERIC Educational Resources Information Center

    Shamuganathan, Sheila; Karpudewan, Mageswary

    2015-01-01

    In this study attempt was made to model the environmental literacy of Malaysian pre-university students enrolled in a matriculation college. Students enrolled in the matriculation colleges in Malaysia are the top notch students in the country. Environmental literacy of this group is perceived important because in the future these students will be…

  5. Resource Allocation Procedure at Queensland University: A Dynamic Modelling Project.

    ERIC Educational Resources Information Center

    Galbraith, Peter L.; Carss, Brian W.

    A structural reorganization of the University of Queensland, Australia, was undertaken to promote efficient resource management, and a resource allocation model was developed to aid in policy evaluation and planning. The operation of the restructured system was based on creating five resource groups to manage the distribution of academic resources…

  6. Modelling the implications of moving towards universal coverage in Tanzania.

    PubMed

    Borghi, Josephine; Mtei, Gemini; Ally, Mariam

    2012-03-01

    A model was developed to assess the impact of possible moves towards universal coverage in Tanzania over a 15-year time frame. Three scenarios were considered: maintaining the current situation ('the status quo'); expanded health insurance coverage (the estimated maximum achievable coverage in the absence of premium subsidies, coverage restricted to those who can pay); universal coverage to all (government revenues used to pay the premiums for the poor). The model estimated the costs of delivering public health services and all health services to the population as a proportion of Gross Domestic Product (GDP), and forecast revenue from user fees and insurance premiums. Under the status quo, financial protection is provided to 10% of the population through health insurance schemes, with the remaining population benefiting from subsidized user charges in public facilities. Seventy-six per cent of the population would benefit from financial protection through health insurance under the expanded coverage scenario, and 100% of the population would receive such protection through a mix of insurance cover and government funding under the universal coverage scenario. The expanded and universal coverage scenarios have a significant effect on utilization levels, especially for public outpatient care. Universal coverage would require an initial doubling in the proportion of GDP going to the public health system. Government health expenditure would increase to 18% of total government expenditure. The results are sensitive to the cost of health system strengthening, the level of real GDP growth, provider reimbursement rates and administrative costs. Promoting greater cross-subsidization between insurance schemes would provide sufficient resources to finance universal coverage. Alternately, greater tax funding for health could be generated through an increase in the rate of Value-Added Tax (VAT) or expanding the income tax base. The feasibility and sustainability of efforts to

  7. Predicted space motions for hypervelocity and runaway stars: proper motions and radial velocities for the Gaia Era

    SciTech Connect

    Kenyon, Scott J.; Brown, Warren R.; Geller, Margaret J.

    We predict the distinctive three-dimensional space motions of hypervelocity stars (HVSs) and runaway stars moving in a realistic Galactic potential. For nearby stars with distances less than 10 kpc, unbound stars are rare; proper motions alone rarely isolate bound HVSs and runaways from indigenous halo stars. At large distances of 20-100 kpc, unbound HVSs are much more common than runaways; radial velocities easily distinguish both from indigenous halo stars. Comparisons of the predictions with existing observations are encouraging. Although the models fail to match observations of solar-type HVS candidates from SEGUE, they agree well with data for B-type HVS andmore » runaways from other surveys. Complete samples of g ≲ 20 stars with Gaia should provide clear tests of formation models for HVSs and runaways and will enable accurate probes of the shape of the Galactic potential.« less

  8. Mapping young stellar populations towards Orion with Gaia DR1

    NASA Astrophysics Data System (ADS)

    Zari, Eleonora; Brown, Anthony G. A.

    2018-04-01

    OB associations are prime sites for the study of star formation processes and of the interaction between young massive stars with the interstellar medium. Furthermore, the kinematics and structure of the nearest OB associations provide detailed insight into the properties and origin of the Gould Belt. In this context, the Orion complex has been extensively studied. However, the spatial distribution of the stellar population is still uncertain: in particular, the distances and ages of the various sub-groups composing the Orion OB association, and their connection to the surrounding interstellar medium, are not well determined. We used the first Gaia data release to characterize the stellar population in Orion, with the goal to obtain new distance and age estimates of the numerous stellar groups composing the Orion OB association. We found evidence of the existence of a young and rich population spread over the entire region, loosely clustered around some known groups. This newly discovered population of young stars provides a fresh view of the star formation history of the Orion region.

  9. Kinematics of OB-associations in Gaia epoch

    NASA Astrophysics Data System (ADS)

    Mel'nik, A. M.; Dambis, A. K.

    2017-12-01

    We use stellar proper motions from the Tycho-Gaia Astrometric Solution (TGAS) catalogue to study the kinematics of OB-associations. The TGAS proper motions of OB-associations generally agree well with the Hipparcos proper motions. The parameters of the Galactic rotation curve obtained with TGAS and Hipparcos proper motions agree within the errors. The average one-dimensional velocity dispersion inside 18 OB-associations with more than 10 TGAS stars is σv = 3.9 km s-1, which is considerably smaller, by a factor of 0.4, than the velocity dispersions derived from Hipparcos data. The effective contribution from orbital motions of binary OB-stars into the velocity dispersion σv inside OB-associations is σb = 1.2 km s-1. The median virial and stellar masses of OB-associations are equal to 7.1 × 105 and 9.0 × 103 M⊙, respectively. Thus, OB-associations must be unbound objects, provided they do not include a lot of dense gas. The median star-formation efficiency is ε = 2.1 per cent. Nearly one-third of stars of OB-associations must lie outside their tidal radius. We found that the Per OB1 and Car OB1 associations are expanding with the expansion started in a small region of 11-27 pc 7-10 Myr ago. The average expansion velocity is 6.3 km s-1.

  10. The Gaia On-Board Scientific Data Handling

    NASA Astrophysics Data System (ADS)

    Arenou, F.; Babusiaux, C.; Chéreau, F.; Mignot, S.

    2005-01-01

    Because Gaia will perform a continuous all-sky survey at a medium (Spectro) or very high (Astro) angular resolution, the on-board processing needs to cope with a high variety of objects and densities which calls for generic and adaptive algorithms at the detection level, but not only. Consequently, the Pyxis scientific algorithms developed for the on-board data handling cover a large range of application: detection and confirmation of astronomical objects, background sky estimation, classification of detected objects, Near-Earth Objects onboard detection, and window selection and positioning. Very dense fields, where the real-time computing requirements should remain within fixed bounds, are particularly challenging. Another constraint stems from the limited telemetry bandwidth and an additional compromise has to be found between scientific requirements and constraints in terms of the mass, volume and power budgets of the satellite. The rationale for the on-board data handling procedure is described here, together with the developed algorithms, the main issues and the expected scientific performances in the Astro and Spectro instruments.

  11. The GALAH survey: observational overview and Gaia DR1 companion

    NASA Astrophysics Data System (ADS)

    Martell, S. L.; Sharma, S.; Buder, S.; Duong, L.; Schlesinger, K. J.; Simpson, J.; Lind, K.; Ness, M.; Marshall, J. P.; Asplund, M.; Bland-Hawthorn, J.; Casey, A. R.; De Silva, G.; Freeman, K. C.; Kos, J.; Lin, J.; Zucker, D. B.; Zwitter, T.; Anguiano, B.; Bacigalupo, C.; Carollo, D.; Casagrande, L.; Da Costa, G. S.; Horner, J.; Huber, D.; Hyde, E. A.; Kafle, P. R.; Lewis, G. F.; Nataf, D.; Navin, C. A.; Stello, D.; Tinney, C. G.; Watson, F. G.; Wittenmyer, R.

    2017-03-01

    The Galactic Archaeology with HERMES (GALAH) survey is a massive observational project to trace the Milky Way's history of star formation, chemical enrichment, stellar migration and minor mergers. Using high-resolution (R ≃ 28 000) spectra, taken with the High Efficiency and Resolution Multi-Element Spectrograph (HERMES) instrument at the Anglo-Australian Telescope, GALAH will determine stellar parameters and abundances of up to 29 elements for up to one million stars. Selecting targets from a colour-unbiased catalogue built from 2MASS, APASS and UCAC4 data, we expect to observe dwarfs at 0.3-3 kpc and giants at 1-10 kpc. This enables a thorough local chemical inventory of the Galactic thin and thick discs, and also captures smaller samples of the bulge and halo. In this paper, we present the plan, process and progress as of early 2016 for GALAH survey observations. In our first two years of survey observing we have accumulated the largest high-quality spectroscopic data set at this resolution, over 200 000 stars. We also present the first public GALAH data catalogue: stellar parameters (Teff, log(g), [Fe/H], [α/Fe]), radial velocity, distance modulus and reddening for 10 680 observations of 9860 Tycho-2 stars, 7894 of which are included in the first Gaia data release.

  12. Astrometry with A-Track Using Gaia DR1 Catalogue

    NASA Astrophysics Data System (ADS)

    Kılıç, Yücel; Erece, Orhan; Kaplan, Murat

    2018-04-01

    In this work, we built all sky index files from Gaia DR1 catalogue for the high-precision astrometric field solution and the precise WCS coordinates of the moving objects. For this, we used build-astrometry-index program as a part of astrometry.net code suit. Additionally, we added astrometry.net's WCS solution tool to our previously developed software which is a fast and robust pipeline for detecting moving objects such as asteroids and comets in sequential FITS images, called A-Track. Moreover, MPC module was added to A-Track. This module is linked to an asteroid database to name the found objects and prepare the MPC file to report the results. After these innovations, we tested a new version of the A-Track code on photometrical data taken by the SI-1100 CCD with 1-meter telescope at TÜBİTAK National Observatory, Antalya. The pipeline can be used to analyse large data archives or daily sequential data. The code is hosted on GitHub under the GNU GPL v3 license.

  13. GAIA: A WINDOW TO LARGE-SCALE MOTIONS

    SciTech Connect

    Nusser, Adi; Branchini, Enzo; Davis, Marc, E-mail: adi@physics.technion.ac.il, E-mail: branchin@fis.uniroma3.it, E-mail: mdavis@berkeley.edu

    2012-08-10

    Using redshifts as a proxy for galaxy distances, estimates of the two-dimensional (2D) transverse peculiar velocities of distant galaxies could be obtained from future measurements of proper motions. We provide the mathematical framework for analyzing 2D transverse motions and show that they offer several advantages over traditional probes of large-scale motions. They are completely independent of any intrinsic relations between galaxy properties; hence, they are essentially free of selection biases. They are free from homogeneous and inhomogeneous Malmquist biases that typically plague distance indicator catalogs. They provide additional information to traditional probes that yield line-of-sight peculiar velocities only. Further, becausemore » of their 2D nature, fundamental questions regarding vorticity of large-scale flows can be addressed. Gaia, for example, is expected to provide proper motions of at least bright galaxies with high central surface brightness, making proper motions a likely contender for traditional probes based on current and future distance indicator measurements.« less

  14. Gaia DR1 Evidence of Disrupting the Perseus Arm

    NASA Astrophysics Data System (ADS)

    Baba, Junichi; Kawata, Daisuke; Matsunaga, Noriyuki; Grand, Robert J. J.; Hunt, Jason A. S.

    2018-02-01

    We have discovered a clear sign of the disruption phase of the Perseus arm in the Milky Way using Cepheid variables, taking advantage of the accurately measured distances of Cepheids and the proper motions from Gaia Data Release 1. Both the Galactocentric radial and rotation velocities of 77 Cepheids within 1.5 kpc of the Perseus arm are correlated with their distances from the locus of the Perseus arm, as the trailing side is rotating faster and moving inward compared to the leading side. We also found a negative vertex deviation for the Cepheids on the trailing side, ‑27.°6 ± 2.°4, in contrast to the positive vertex deviation in the solar neighborhood. This is, to our knowledge, the first direct evidence that the vertex deviation around the Perseus arm is affected by the spiral arm. We compared these observational trends with our N-body/hydrodynamics simulations based on a static density-wave spiral scenario and with those based on a transient dynamic spiral scenario. Although our comparisons are limited to qualitative trends, they strongly favor the conclusion that the Perseus arm is in the disruption phase of a transient arm.

  15. Designs that make a difference: the Cardiac Universal Bed model.

    PubMed

    Johnson, Jackie; Brown, Katherine Kay; Neal, Kelly

    2003-01-01

    Information contained in this article includes some of the findings from a joint research project conducted by Corazon Consulting and Ohio State University Medical Center on national trends in Cardiac Universal Bed (CUB) utilization. This article outlines current findings and "best practice" standards related to the benefits of developing care delivery models to differentiate an organization with a competitive advantage in the highly dynamic marketplace of cardiovascular care. (OSUMC, a Corazon client, is incorporating the CUB into their Ross Heart Hospital slated to open this spring.)

  16. The Gaia-ESO Survey: evidence of atomic diffusion in M67?

    NASA Astrophysics Data System (ADS)

    Bertelli Motta, C.; Pasquali, A.; Richer, J.; Michaud, G.; Salaris, M.; Bragaglia, A.; Magrini, L.; Randich, S.; Grebel, E. K.; Adibekyan, V.; Blanco-Cuaresma, S.; Drazdauskas, A.; Fu, X.; Martell, S.; Tautvaišienė, G.; Gilmore, G.; Alfaro, E. J.; Bensby, T.; Flaccomio, E.; Koposov, S. E.; Korn, A. J.; Lanzafame, A. C.; Smiljanic, R.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Damiani, F.; Franciosini, E.; Heiter, U.; Hourihane, A.; Jofré, P.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Sousa, S. G.; Worley, C. C.; Zaggia, S.

    2018-07-01

    Investigating the chemical homogeneity of stars born from the same molecular cloud at virtually the same time is very important for our understanding of the chemical enrichment of the interstellar medium and with it the chemical evolution of the Galaxy. One major cause of inhomogeneities in the abundances of open clusters is stellar evolution of the cluster members. In this work, we investigate variations in the surface chemical composition of member stars of the old open cluster M67 as a possible consequence of atomic diffusion effects taking place during the main-sequence phase. The abundances used are obtained from high-resolution UVES/FLAMES spectra within the framework of the Gaia-ESO Survey. We find that the surface abundances of stars on the main sequence decrease with increasing mass reaching a minimum at the turn-off. After deepening of the convective envelope in subgiant branch stars, the initial surface abundances are restored. We found the measured abundances to be consistent with the predictions of stellar evolutionary models for a cluster with the age and metallicity of M67. Our findings indicate that atomic diffusion poses a non-negligible constraint on the achievable precision of chemical tagging methods.

  17. Calibration of the photometric G passband for Gaia Data Release 1

    NASA Astrophysics Data System (ADS)

    Maíz Apellániz, J.

    2017-12-01

    Context. On September 2016 the first data from Gaia were released (DR1). The first release included photometry for over 109 sources in the very broad G system. Aims: The aims here are to test the correspondence between G magnitudes in DR1 and the synthetic equivalents derived using spectral energy distributions from observed and model spectrophotometry; to correct the G passband curve; and to measure the zero point in the Vega system. Methods: I have computed the synthetic G and Tycho-2 BTVT photometry for a sample of stars using the Next Generation Spectral Library (NGSL) and the Hubble Space Telescope (HST) CALSPEC spectroscopic standards. Results: I have found that the nominal G passband curve is too blue for the DR1 photometry, as shown by the presence of a color term in the comparison between observed and synthetic magnitudes. A correction to the passband applying a power law in λ with an exponent of 0.783 eliminates the color term. The corrected passband has a Vega zero point of 0.070 ± 0.004 mag. Tables 1 and 2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/L8

  18. The fall of the Northern Unicorn: tangential motions in the Galactic anticentre with SDSS and Gaia

    NASA Astrophysics Data System (ADS)

    de Boer, T. J. L.; Belokurov, V.; Koposov, S. E.

    2018-01-01

    We present the first detailed study of the behaviour of the stellar proper motion across the entire Galactic anticentre area visible in the Sloan Digital Sky Survey (SDSS) data. We use recalibrated SDSS astrometry in combination with positions from Gaia DR1 to provide tangential motion measurements with a systematic uncertainty <5 km s-1 for the Main Sequence stars at the distance of the Monoceros Ring. We demonstrate that Monoceros members rotate around the Galaxy with azimuthal speeds of ∼230 km s-1, only slightly lower than that of the Sun. Additionally, both vertical and azimuthal components of their motion are shown to vary considerably but gradually as a function of Galactic longitude and latitude. The stellar overdensity in the anti-centre region can be split into two components, the narrow, stream-like ACS and the smooth Ring. According to our analysis, these two structures show very similar but clearly distinct kinematic trends, which can be summarized as follows: the amplitude of the velocity variation in vϕ and vz in the ACS is higher compared to the Ring, whose velocity gradients appear to be flatter. Currently, no model available can explain the entirety of the data in this area of the sky. However, the new accurate kinematic map introduced here should provide strong constraints on the genesis of the Monoceros Ring and the associated substructure.

  19. The Gaia-ESO Survey: Evidence of atomic diffusion in M67?

    NASA Astrophysics Data System (ADS)

    Motta, C. Bertelli; Pasquali, A.; Richer, J.; Michaud, G.; Salaris, M.; Bragaglia, A.; Magrini, L.; Randich, S.; Grebel, E. K.; Adibekyan, V.; Blanco-Cuaresma, S.; Drazdauskas, A.; Fu, X.; Martell, S.; TautvaišienÄ--, G.; Gilmore, G.; Alfaro, E. J.; Bensby, T.; Flaccomio, E.; Koposov, S. E.; Korn, A. J.; Lanzafame, A. C.; Smiljanic, R.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Damiani, F.; Franciosini, E.; Heiter, U.; Hourihane, A.; Jofré, P.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Sousa, S. G.; Worley, C. C.; Zaggia, S.

    2018-04-01

    Investigating the chemical homogeneity of stars born from the same molecular cloud at virtually the same time is very important for our understanding of the chemical enrichment of the interstellar medium and with it the chemical evolution of the Galaxy. One major cause of inhomogeneities in the abundances of open clusters is stellar evolution of the cluster members. In this work, we investigate variations in the surface chemical composition of member stars of the old open cluster M67 as a possible consequence of atomic diffusion effects taking place during the main-sequence phase. The abundances used are obtained from high-resolution UVES/FLAMES spectra within the framework of the Gaia-ESO Survey. We find that the surface abundances of stars on the main sequence decrease with increasing mass reaching a minimum at the turn-off. After deepening of the convective envelope in sub-giant branch stars, the initial surface abundances are restored. We found the measured abundances to be consistent with the predictions of stellar evolutionary models for a cluster with the age and metallicity of M67. Our findings indicate that atomic diffusion poses a non-negligible constraint on the achievable precision of chemical tagging methods.

  20. Probing Models of Dark Matter and the Early Universe

    NASA Astrophysics Data System (ADS)

    Orlofsky, Nicholas David

    This thesis discusses models for dark matter (DM) and their behavior in the early universe. An important question is how phenomenological probes can directly search for signals of DM today. Another topic of investigation is how the DM and other processes in the early universe must evolve. Then, astrophysical bounds on early universe dynamics can constrain DM. We will consider these questions in the context of three classes of DM models--weakly interacting massive particles (WIMPs), axions, and primordial black holes (PBHs). Starting with WIMPs, we consider models where the DM is charged under the electroweak gauge group of the Standard Model. Such WIMPs, if generated by a thermal cosmological history, are constrained by direct detection experiments. To avoid present or near-future bounds, the WIMP model or cosmological history must be altered in some way. This may be accomplished by the inclusion of new states that coannihilate with the WIMP or a period of non-thermal evolution in the early universe. Future experiments are likely to probe some of these altered scenarios, and a non-observation would require a high degree of tuning in some of the model parameters in these scenarios. Next, axions, as light pseudo-Nambu-Goldstone bosons, are susceptible to quantum fluctuations in the early universe that lead to isocurvature perturbations, which are constrained by observations of the cosmic microwave background (CMB). We ask what it would take to allow axion models in the face of these strong CMB bounds. We revisit models where inflationary dynamics modify the axion potential and discuss how isocurvature bounds can be relaxed, elucidating the difficulties in these constructions. Avoiding disruption of inflationary dynamics provides important limits on the parameter space. Finally, PBHs have received interest in part due to observations by LIGO of merging black hole binaries. We ask how these PBHs could arise through inflationary models and investigate the opportunity

  1. Get Ready for Gaia: Cool White Dwarfs in Common Proper Motion with Tycho Stars

    NASA Astrophysics Data System (ADS)

    Hambly, N.; Rowell, N.; Lam, M.

    2017-03-01

    We discuss the Gaia Data Release 1 (September 2016) and preliminary work on maximising the benefit for cool white dwarf (WD) science in advance of the full parallax catalogue which will appear around one year later in DR2. The Tycho catalogue is used in conjunction with the all-sky ground based astrometric/ photometric SuperCOSMOS Sky Survey in order to identify candidate faint common proper motion objects to the Tycho stars. Gaia DR1 is supplemented by the Tycho-Gaia Astrometric Solution catalogue containing some 2 million parallaxes with Hipparcos-like precision for Tycho stars. While hotter, brighter WDs are present in Tycho, cooler examples are much rarer (if present at all) and CPM offers one method to infer precision distances for a statistically useful sample of these very faint WDs.

  2. Precise CCD positions of Triton in 2014-2016 from the Gaia DR1

    NASA Astrophysics Data System (ADS)

    Wang, N.; Peng, Q. Y.; Peng, H. W.; Zhang, Q. F.

    2018-04-01

    755 CCD observations during the years 2014-2016 have been reduced to derive the precise positions of Triton, the first satellite of Neptune. The observations were made by the 1 m telescope at Yunnan Observatory over 15 nights during the years 2014-2016. The theoretical position of Triton was retrieved from the Jet Propulsion Laboratory Horizons system. Our results show that when the newest Gaia catalogue (Gaia DR1) is referred to the mean O-Cs (observed minus computed) residuals are about 0.042 and -0.006 arcsec, the dispersions are 0.012 and 0.012 arcsec in right ascension and declination, respectively. The dispersions are improved very significantly when the Gaia DR1 is referred to. However, the agreement in right ascension is not so good as that in declination, the reason might come from the uncertainty of planet ephemeris. More observations are needed to confirm this.

  3. The optical alignment of the two GAIA three mirror anastigmatic telescopes

    NASA Astrophysics Data System (ADS)

    Erdmann, Matthias; Pierot, Dominique

    2017-11-01

    Gaia is an ambitious ESA mission to chart a threedimensional map of our Galaxy, the Milky Way, in the process revealing the composition, formation and evolution of the Galaxy. Gaia will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and cinematic census of about one billion stars in our Galaxy. The payload consists of 2 Three Mirror Anastigmat (TMA) telescopes (aperture size 1.5 m x 0.5 m), 3 instruments (astrometer, photometer and spectrometer) and 106 butted CCDs assembled to a single 0.9 Giga-Pixel focal plane. In this paper we are describing the optical alignment of the two Gaia telescopes and the tooling that was used.

  4. Clouds, Streams and Bridges. Redrawing the blueprint of the Magellanic System with Gaia DR1

    NASA Astrophysics Data System (ADS)

    Belokurov, Vasily; Erkal, Denis; Deason, Alis J.; Koposov, Sergey E.; De Angeli, Francesca; Evans, Dafydd Wyn; Fraternali, Filippo; Mackey, Dougal

    2017-04-01

    We present the discovery of stellar tidal tails around the Large and the Small Magellanic Clouds (LMC and SMC, respectively) in the Gaia DR1 data. In between the Clouds, their tidal arms are stretched towards each other to form an almost continuous stellar bridge. Our analysis relies on the exquisite quality of the Gaia's photometric catalogue to build detailed star-count maps of the Clouds. We demonstrate that the Gaia DR1 data can be used to detect variable stars across the whole sky, and, in particular, RR Lyrae stars in and around the LMC and the SMC. Additionally, we use a combination of Gaia and GALEX to follow the distribution of Young Main Sequence stars in the Magellanic System. Viewed by Gaia, the Clouds show unmistakable signs of interaction. Around the LMC, clumps of RR Lyrae are observable as far as ˜20°, in agreement with the most recent map of Mira-like stars reported in Deason et al. The SMC's outer stellar density contours show a characteristic S-shape, symptomatic of the onset of tidal stripping. Beyond several degrees from the centre of the dwarf, the Gaia RR Lyrae stars trace the Cloud's trailing arm, extending towards the LMC. This stellar tidal tail mapped with RR Lyrae is not aligned with the gaseous Magellanic Bridge, and is shifted by some ˜5° from the Young Main Sequence bridge. We use the offset between the bridges to put constraints on the density of the hot gaseous corona of the Milky Way.

  5. On the estimation of stellar parameters with uncertainty prediction from Generative Artificial Neural Networks: application to Gaia RVS simulated spectra

    NASA Astrophysics Data System (ADS)

    Dafonte, C.; Fustes, D.; Manteiga, M.; Garabato, D.; Álvarez, M. A.; Ulla, A.; Allende Prieto, C.

    2016-10-01

    Aims: We present an innovative artificial neural network (ANN) architecture, called Generative ANN (GANN), that computes the forward model, that is it learns the function that relates the unknown outputs (stellar atmospheric parameters, in this case) to the given inputs (spectra). Such a model can be integrated in a Bayesian framework to estimate the posterior distribution of the outputs. Methods: The architecture of the GANN follows the same scheme as a normal ANN, but with the inputs and outputs inverted. We train the network with the set of atmospheric parameters (Teff, log g, [Fe/H] and [α/ Fe]), obtaining the stellar spectra for such inputs. The residuals between the spectra in the grid and the estimated spectra are minimized using a validation dataset to keep solutions as general as possible. Results: The performance of both conventional ANNs and GANNs to estimate the stellar parameters as a function of the star brightness is presented and compared for different Galactic populations. GANNs provide significantly improved parameterizations for early and intermediate spectral types with rich and intermediate metallicities. The behaviour of both algorithms is very similar for our sample of late-type stars, obtaining residuals in the derivation of [Fe/H] and [α/ Fe] below 0.1 dex for stars with Gaia magnitude Grvs < 12, which accounts for a number in the order of four million stars to be observed by the Radial Velocity Spectrograph of the Gaia satellite. Conclusions: Uncertainty estimation of computed astrophysical parameters is crucial for the validation of the parameterization itself and for the subsequent exploitation by the astronomical community. GANNs produce not only the parameters for a given spectrum, but a goodness-of-fit between the observed spectrum and the predicted one for a given set of parameters. Moreover, they allow us to obtain the full posterior distribution over the astrophysical parameters space once a noise model is assumed. This can be

  6. The Gaia-ESO Survey: double-, triple-, and quadruple-line spectroscopic binary candidates

    NASA Astrophysics Data System (ADS)

    Merle, T.; Van Eck, S.; Jorissen, A.; Van der Swaelmen, M.; Masseron, T.; Zwitter, T.; Hatzidimitriou, D.; Klutsch, A.; Pourbaix, D.; Blomme, R.; Worley, C. C.; Sacco, G.; Lewis, J.; Abia, C.; Traven, G.; Sordo, R.; Bragaglia, A.; Smiljanic, R.; Pancino, E.; Damiani, F.; Hourihane, A.; Gilmore, G.; Randich, S.; Koposov, S.; Casey, A.; Morbidelli, L.; Franciosini, E.; Magrini, L.; Jofre, P.; Costado, M. T.; Jeffries, R. D.; Bergemann, M.; Lanzafame, A. C.; Bayo, A.; Carraro, G.; Flaccomio, E.; Monaco, L.; Zaggia, S.

    2017-12-01

    efficient discovery of many new multiple systems. With the detection of the SB1 candidates that will be the subject of a forthcoming paper, the study of the statistical and physical properties of the spectroscopic multiple systems will soon be possible for the entire GES sample. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 188.B-3002. These data products have been processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge, and by the FLAMES/UVES reduction team at INAF/Osservatorio Astrofisico di Arcetri. These data have been obtained from the Gaia-ESO Survey Data Archive, prepared and hosted by the Wide Field Astronomy Unit, Institute for Astronomy, University of Edinburgh, which is funded by the UK Science and Technology Facilities Council.

  7. Towards a library of synthetic galaxy spectra and preliminary results of classification and parametrization of unresolved galaxies for Gaia. II

    NASA Astrophysics Data System (ADS)

    Tsalmantza, P.; Kontizas, M.; Rocca-Volmerange, B.; Bailer-Jones, C. A. L.; Kontizas, E.; Bellas-Velidis, I.; Livanou, E.; Korakitis, R.; Dapergolas, A.; Vallenari, A.; Fioc, M.

    2009-09-01

    Aims: This paper is the second in a series, implementing a classification system for Gaia observations of unresolved galaxies. Our goals are to determine spectral classes and estimate intrinsic astrophysical parameters via synthetic templates. Here we describe (1) a new extended library of synthetic galaxy spectra; (2) its comparison with various observations; and (3) first results of classification and parametrization experiments using simulated Gaia spectrophotometry of this library. Methods: Using the PÉGASE.2 code, based on galaxy evolution models that take account of metallicity evolution, extinction correction, and emission lines (with stellar spectra based on the BaSeL library), we improved our first library and extended it to cover the domain of most of the SDSS catalogue. Our classification and regression models were support vector machines (SVMs). Results: We produce an extended library of 28 885 synthetic galaxy spectra at zero redshift covering four general Hubble types of galaxies, over the wavelength range between 250 and 1050 nm at a sampling of 1 nm or less. The library is also produced for 4 random values of redshift in the range of 0-0.2. It is computed on a random grid of four key astrophysical parameters (infall timescale and 3 parameters defining the SFR) and, depending on the galaxy type, on two values of the age of the galaxy. The synthetic library was compared and found to be in good agreement with various observations. The first results from the SVM classifiers and parametrizers are promising, indicating that Hubble types can be reliably predicted and several parameters estimated with low bias and variance.

  8. The Gaia-ESO Survey: Galactic evolution of sulphur and zinc

    NASA Astrophysics Data System (ADS)

    Duffau, S.; Caffau, E.; Sbordone, L.; Bonifacio, P.; Andrievsky, S.; Korotin, S.; Babusiaux, C.; Salvadori, S.; Monaco, L.; François, P.; Skúladóttir, Á.; Bragaglia, A.; Donati, P.; Spina, L.; Gallagher, A. J.; Ludwig, H.-G.; Christlieb, N.; Hansen, C. J.; Mott, A.; Steffen, M.; Zaggia, S.; Blanco-Cuaresma, S.; Calura, F.; Friel, E.; Jiménez-Esteban, F. M.; Koch, A.; Magrini, L.; Pancino, E.; Tang, B.; Tautvaišienė, G.; Vallenari, A.; Hawkins, K.; Gilmore, G.; Randich, S.; Feltzing, S.; Bensby, T.; Flaccomio, E.; Smiljanic, R.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Damiani, F.; Franciosini, E.; Hourihane, A.; Jofré, P.; Lardo, C.; Lewis, J.; Morbidelli, L.; Sousa, S. G.; Worley, C. C.

    2017-08-01

    Context. Due to their volatile nature, when sulphur and zinc are observed in external galaxies, their determined abundances represent the gas-phase abundances in the interstellar medium. This implies that they can be used as tracers of the chemical enrichment of matter in the Universe at high redshift. Comparable observations in stars are more difficult and, until recently, plagued by small number statistics. Aims: We wish to exploit the Gaia-ESO Survey (GES) data to study the behaviour of sulphur and zinc abundances of a large number of Galactic stars, in a homogeneous way. Methods: By using the UVES spectra of the GES sample, we are able to assemble a sample of 1301 Galactic stars, including stars in open and globular clusters in which both sulphur and zinc were measured. Results: We confirm the results from the literature that sulphur behaves as an α-element. We find a large scatter in [Zn/Fe] ratios among giant stars around solar metallicity. The lower ratios are observed in giant stars at Galactocentric distances less than 7.5 kpc. No such effect is observed among dwarf stars, since they do not extend to that radius. Conclusions: Given the sample selection, giants and dwarfs are observed at different Galactic locations, and it is plausible, and compatible with simple calculations, that Zn-poor giants trace a younger population more polluted by SN Ia yields. It is necessary to extend observations in order to observe both giants and dwarfs at the same Galactic location. Further theoretical work on the evolution of zinc is also necessary. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 188.B-3002, 193.B-0936.The full table of S abundances is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/A128

  9. Geometrothermodynamic model for the evolution of the Universe

    SciTech Connect

    Gruber, Christine; Quevedo, Hernando, E-mail: christine.gruber@correo.nucleares.unam.mx, E-mail: quevedo@nucleares.unam.mx

    Using the formalism of geometrothermodynamics to derive a fundamental thermodynamic equation, we construct a cosmological model in the framework of relativistic cosmology. In a first step, we describe a system without thermodynamic interaction, and show it to be equivalent to the standard ΛCDM paradigm. The second step includes thermodynamic interaction and produces a model consistent with the main features of inflation. With the proposed fundamental equation we are thus able to describe all the known epochs in the evolution of our Universe, starting from the inflationary phase.

  10. Roles of University Support for International Students in the United States: Analysis of a Systematic Model of University Identification, University Support, and Psychological Well-Being

    ERIC Educational Resources Information Center

    Cho, Jaehee; Yu, Hongsik

    2015-01-01

    Unlike previous research on international students' social support, this current study applied the concept of organizational support to university contexts, examining the effects of university support. Mainly based on the social identity/self-categorization stress model, this study developed and tested a path model composed of four key…

  11. When growth models are not universal: evidence from marine invertebrates

    PubMed Central

    Hirst, Andrew G.; Forster, Jack

    2013-01-01

    The accumulation of body mass, as growth, is fundamental to all organisms. Being able to understand which model(s) best describe this growth trajectory, both empirically and ultimately mechanistically, is an important challenge. A variety of equations have been proposed to describe growth during ontogeny. Recently, the West Brown Enquist (WBE) equation, formulated as part of the metabolic theory of ecology, has been proposed as a universal model of growth. This equation has the advantage of having a biological basis, but its ability to describe invertebrate growth patterns has not been well tested against other, more simple models. In this study, we collected data for 58 species of marine invertebrate from 15 different taxa. The data were fitted to three growth models (power, exponential and WBE), and their abilities were examined using an information theoretic approach. Using Akaike information criteria, we found changes in mass through time to fit an exponential equation form best (in approx. 73% of cases). The WBE model predominantly overestimates body size in early ontogeny and underestimates it in later ontogeny; it was the best fit in approximately 14% of cases. The exponential model described growth well in nine taxa, whereas the WBE described growth well in one of the 15 taxa, the Amphipoda. Although the WBE has the advantage of being developed with an underlying proximate mechanism, it provides a poor fit to the majority of marine invertebrates examined here, including species with determinate and indeterminate growth types. In the original formulation of the WBE model, it was tested almost exclusively against vertebrates, to which it fitted well; the model does not however appear to be universal given its poor ability to describe growth in benthic or pelagic marine invertebrates. PMID:23945691

  12. The first all-sky view of the Milky Way stellar halo with Gaia+2MASS RR Lyrae

    NASA Astrophysics Data System (ADS)

    Iorio, G.; Belokurov, V.; Erkal, D.; Koposov, S. E.; Nipoti, C.; Fraternali, F.

    2018-02-01

    We exploit the first Gaia data release to study the properties of the Galactic stellar halo as traced by RR Lyrae. We demonstrate that it is possible to select a pure sample of RR Lyrae using only photometric information available in the Gaia+2MASS catalogue. The final sample contains about 21 600 RR Lyrae covering an unprecedented fraction ( ˜ 60 per cent) of the volume of the Galactic inner halo (R < 28 kpc). We study the morphology of the stellar halo by analysing the RR Lyrae distribution with parametric and non-parametric techniques. Taking advantage of the uniform all-sky coverage, we test halo models more sophisticated than usually considered in the literature, such as those with varying flattening, tilts and/or offset of the halo with respect to the Galactic disc. A consistent picture emerges: the inner halo is well reproduced by a smooth distribution of stars settled on triaxial density ellipsoids. The shortest axis is perpendicular to the Milky Way's disc, while the longest axis forms an angle of ˜70° with the axis connecting the Sun and the Galactic Centre. The elongation along the major axis is mild (p = 1.27), and the vertical flattening is shown to evolve from a squashed state with q ≈ 0.57 in the centre to a more spherical q ≈ 0.75 at the outer edge of our data set. Within the radial range probed, the density profile of the stellar halo is well approximated by a single power law with exponent α = -2.96. We do not find evidence of tilt or offset of the halo with respect to the Galaxy's disc.

  13. DES meets Gaia: discovery of strongly lensed quasars from a multiplet search

    NASA Astrophysics Data System (ADS)

    Agnello, A.; Lin, H.; Kuropatkin, N.; Buckley-Geer, E.; Anguita, T.; Schechter, P. L.; Morishita, T.; Motta, V.; Rojas, K.; Treu, T.; Amara, A.; Auger, M. W.; Courbin, F.; Fassnacht, C. D.; Frieman, J.; More, A.; Marshall, P. J.; McMahon, R. G.; Meylan, G.; Suyu, S. H.; Glazebrook, K.; Morgan, N.; Nord, B.; Abbott, T. M. C.; Abdalla, F. B.; Annis, J.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Bernstein, R. A.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Drlica-Wagner, A.; Eifler, T. F.; Flaugher, B.; García-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, J. Gschwend G.; Honscheid, K.; James, D. J.; Kuehn, K.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Menanteau, F.; Miquel, R.; Ogando, R. L. C.; Plazas, A. A.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Tucker, D.; Wechsler, R.

    2018-06-01

    We report the discovery, spectroscopic confirmation and first lens models of the first, strongly lensed quasars from a combined search in WISE and Gaia-DR1 over the DES footprint. Their Einstein radii span a range between ≈2.0″ and ≈0.4″. Two of these (WGD2038-4008, r.a.=20:38:02.65, dec.=-40:08:14.64; WGD2021-4115, r.a.=20:21:39.45, dec.=-41:15:57.11) also have confirmed deflector redshifts. The four-image lens WGD2038-4008, with source- and deflector- redshifts zs = 0.777 ± 0.001 and zl = 0.230 ± 0.002 respectively, has a deflector with radius Reff ≈ 3.4″, stellar mass log (M_{\\star }/M_{⊙})=11.64^{+0.20}_{-0.43}, and extended isophotal shape variation. Simple lens models yield Einstein radii RE = (1.30 ± 0.04)″, axis ratio q = 0.75 ± 0.1 (compatible with that of the starlight) and considerable shear-ellipticity degeneracies. The two-image lens WGD2021-4115has zs = 1.390 ± 0.001 and zl = 0.335 ± 0.002, and Einstein radius RE = (1.1 ± 0.1)″, but higher-resolution imaging is needed to accurately separate the deflector and faint quasar image. Analogous lens-model degeneracies hold for the other six lenses (J0146-1133, J0150-4041, J0235-2433, J0245-0556, J0259-2338, J0508-2748) shown in this paper.

  14. Alignment and qualification of the Gaia telescope using a Shack-Hartmann sensor

    NASA Astrophysics Data System (ADS)

    Dovillaire, G.; Pierot, D.

    2017-09-01

    Since almost 20 years, Imagine Optic develops, manufactures and offers to its worldwide customers reliable and accurate wavefront sensors and adaptive optics solutions. Long term collaboration between Imagine Optic and Airbus Defence and Space has been initiated on the Herschel program. More recently, a similar technology has been used to align and qualify the GAIA telescope.

  15. Observations of GAIA-identified Cataclysmic Variables Using the TUBITAK National Observatory

    NASA Astrophysics Data System (ADS)

    Esenoglu, Hasan H.; Kirbiyik, Halil; Kaynar, Suleyman; Okuyan, Oguzhan; Hamitoglu, Irek; Galeev, Almaz; Uluc, Kadir; Kocak, Murat; Kilic, Sila E.; Parmaksizoglu, Murat; Erece, Orhan; Ozisik, Tuncay; Gulsecen, Hulusi

    2016-07-01

    TUBITAK National Observatory supports the GAIA alerts with observations using three telescopes (RTT150, T100, T60) at the site with a limited time quota. We have observed 10 variable stars among GAIA sources discovered in the years 2014-2016 that may be candidate Cataclysmic Variables (CVs). Our TUG observations at this stage involve photometry and spectroscopy to aid the identification of these sources. The first preliminary result of our observations of Gaia14aat among them showed a dwarf nova outburst with an amplitude of 2.69 mag. We aim to construct a GAIA astrophysics group to study CVs along with supported studies using the SRG (Spectrum Roentgen Gamma astrophysical observatory) after the year of 2016. These observations will basically involve spectroscopy, narrow-band CCD imaging and photometry using several filters to aid the identification of these sources. RTT150 observations with very narrow filters (like H-alpha, SII, OIII with band width of range of 2 to 5 nm) will reveal whether shell around the SRG sources to aid identification novae among them.

  16. Gaia16ada: the most recent outburst of the supernova impostor in NGC 4559

    NASA Astrophysics Data System (ADS)

    Bomans, Dominik J.; Mueller, Ancla; Becker, Alexander; Weis, Kerstin; Granzer, Thomas

    2016-02-01

    On February 11, 2016 the Gaia Photometric Alerts page (http://gsaweb.ast.cam.ac.uk/alerts) reported a possible transient near NGC 4559 at RA=12:35:52.28 DEC=+27:55:55.5, spatially coincident with a supernova impostor, with 3 previous recorded outbursts.

  17. Gaia16aye binary microlensing event is rising for the 5th time

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, L.; Mroz, P.; Rybicki, K.; Altavilla, G.; Bakis, V.; Bendjoya, P.; Birenbaum, G.; Blagorodnova, N.; Blanco-Cuaresma, S.; Bonanos, A.; Bozza, V.; Britavskiy, N.; Burgaz, U.; Butterley, T.; Capuozzo, P.; Carrasco, J. M.; Chruslinska, M.; Damljanovic, G.; Dapergolas, T.; Dennefeld, M.; Dhillon, V. S.; Dominik, M.; Esenoglu, H.; Fossey, S.; Gomboc, A.; Hallokoun, N.; Hamanowicz, A.; Hardy, L. K.; Hudec, R.; Khamitov, I.; Klencki, J.; Kolaczkowski, Z.; Kolb, U.; Leonini, S.; Leto, G.; Lewis, F.; Liakos, A.; Littlefair, S. P.; Maoz, D.; Maund, J. R.; Mikolajczyk, P.; Palaversa, L.; Pawlak, M.; Penny, M.; Piascik, A.; Reig, P.; Rhodes, L.; Russell, D.; Sanchez, R. Z.; Shappee, B.; Shvartzvald, Y.; Sitek, M.; Sniegowska, M.; Sokolovsky, K.; Steele, I.; Street, R.; Tomasella, L.; Trascinelli, L.; Wiersema, K.; Wilson, R. W.; Zharkov, I.; Zola, S.; Zubareva, A.

    2017-05-01

    Gaia16aye, nicknamed Ayers Rock (19:40:01.13 +30:07:53.4, J2000) was detected in August 2016 and continue on-going, becoming the longest microlensing event found in the Galactic Disk (ATEL #9376, #9507).

  18. The CNES Gaia Data Processing Center: A Challenge and its Solutions

    NASA Astrophysics Data System (ADS)

    Chaoul, Laurence; Valette, Veronique

    2011-08-01

    After a brief reminder of the ESA Gaia project, this paper presents the data processing consortium (DPAC) and then the CNES data processing centre (DPCC). We focus on the challenge in terms of organisational aspects, processing capabilities, databases volumetry, and how we deal with these topics.

  19. Universally Sloppy Parameter Sensitivities in Systems Biology Models

    PubMed Central

    Gutenkunst, Ryan N; Waterfall, Joshua J; Casey, Fergal P; Brown, Kevin S; Myers, Christopher R; Sethna, James P

    2007-01-01

    Quantitative computational models play an increasingly important role in modern biology. Such models typically involve many free parameters, and assigning their values is often a substantial obstacle to model development. Directly measuring in vivo biochemical parameters is difficult, and collectively fitting them to other experimental data often yields large parameter uncertainties. Nevertheless, in earlier work we showed in a growth-factor-signaling model that collective fitting could yield well-constrained predictions, even when it left individual parameters very poorly constrained. We also showed that the model had a “sloppy” spectrum of parameter sensitivities, with eigenvalues roughly evenly distributed over many decades. Here we use a collection of models from the literature to test whether such sloppy spectra are common in systems biology. Strikingly, we find that every model we examine has a sloppy spectrum of sensitivities. We also test several consequences of this sloppiness for building predictive models. In particular, sloppiness suggests that collective fits to even large amounts of ideal time-series data will often leave many parameters poorly constrained. Tests over our model collection are consistent with this suggestion. This difficulty with collective fits may seem to argue for direct parameter measurements, but sloppiness also implies that such measurements must be formidably precise and complete to usefully constrain many model predictions. We confirm this implication in our growth-factor-signaling model. Our results suggest that sloppy sensitivity spectra are universal in systems biology models. The prevalence of sloppiness highlights the power of collective fits and suggests that modelers should focus on predictions rather than on parameters. PMID:17922568

  20. Universally sloppy parameter sensitivities in systems biology models.

    PubMed

    Gutenkunst, Ryan N; Waterfall, Joshua J; Casey, Fergal P; Brown, Kevin S; Myers, Christopher R; Sethna, James P

    2007-10-01

    Quantitative computational models play an increasingly important role in modern biology. Such models typically involve many free parameters, and assigning their values is often a substantial obstacle to model development. Directly measuring in vivo biochemical parameters is difficult, and collectively fitting them to other experimental data often yields large parameter uncertainties. Nevertheless, in earlier work we showed in a growth-factor-signaling model that collective fitting could yield well-constrained predictions, even when it left individual parameters very poorly constrained. We also showed that the model had a "sloppy" spectrum of parameter sensitivities, with eigenvalues roughly evenly distributed over many decades. Here we use a collection of models from the literature to test whether such sloppy spectra are common in systems biology. Strikingly, we find that every model we examine has a sloppy spectrum of sensitivities. We also test several consequences of this sloppiness for building predictive models. In particular, sloppiness suggests that collective fits to even large amounts of ideal time-series data will often leave many parameters poorly constrained. Tests over our model collection are consistent with this suggestion. This difficulty with collective fits may seem to argue for direct parameter measurements, but sloppiness also implies that such measurements must be formidably precise and complete to usefully constrain many model predictions. We confirm this implication in our growth-factor-signaling model. Our results suggest that sloppy sensitivity spectra are universal in systems biology models. The prevalence of sloppiness highlights the power of collective fits and suggests that modelers should focus on predictions rather than on parameters.

  1. Swift detections of the flaring blazar GAIA 18ayp (PKS 2333-415) in X-rays and the UV

    NASA Astrophysics Data System (ADS)

    Grupe, Dirk; Komossa, S.; Angioni, R.; Schartel, N.

    2018-04-01

    We report Swift observations of the z=1.41 QSO GAIA 18ayp (PKS 2333-415) which was detected by GAIA in an optically flaring state on 2018-April-14. Swift observed GAIA 18ayp on 2018 April 23 for a total of 1.4 ks. The QSO is clearly detected in X-rays and the UV. The X-ray position found using the enhanced XRT position (Goad et al. 2007, Evans et al. 2009) is RA-2000 = 23 36 34.1, Dec-2000 = -41 15 21.4 with an uncertainty of 3.0".

  2. Universality and depinning models for plastic yield in amorphous materials

    NASA Astrophysics Data System (ADS)

    Budrikis, Zoe; Fernandez Castellano, David; Sandfeld, Stefan; Zaiser, Michael; Zapperi, Stefano

    Plastic yield in amorphous materials occurs as a result of complex collective dynamics of local reorganizations, which gives rise to rich phenomena such as strain localization, intermittent dynamics and power-law distributed avalanches. While such systems have received considerable attention, both theoretical and experimental, controversy remains over the nature of the yielding transition. We present a new fully-tensorial coarsegrained model in 2D and 3D, and demonstrate that the exponents describing avalanche distributions are universal under a variety of loading conditions, system dimensionality and size, and boundary conditions. Our results show that while depinning-type models in general are apt to describe the system, mean field depinning models are not.

  3. DES meets Gaia: discovery of strongly lensed quasars from a multiplet search

    SciTech Connect

    Agnello, A.; et al.

    We report the discovery, spectroscopic confirmation and first lens models of the first two, strongly lensed quasars from a combined search in WISE and Gaia over the DES footprint. The four-image lensWGD2038-4008 (r.a.=20:38:02.65, dec.=-40:08:14.64) has source- and lens-redshiftsmore » $$z_{s}=0.777 \\pm 0.001$$ and $$z_l = 0.230 \\pm 0.002$$ respectively. Its deflector has effective radius $$R_{\\rm eff} \\approx 3.4^{\\prime\\prime}$$, stellar mass $$\\log(M_{\\star}/M_{\\odot}) = 11.64^{+0.20}_{-0.43}$$, and shows extended isophotal shape variation. Simple lens models yield Einstein radii $$R_{\\rm E}=(1.30\\pm0.04)^{\\prime\\prime},$$ axis ratio $$q=0.75\\pm0.1$$ (compatible with that of the starlight) and considerable shear-ellipticity degeneracies. The two-image lensWGD2021-4115 (r.a.=20:21:39.45, dec.=--41:15:57.11) has $$z_{s}=1.390\\pm0.001$$ and $$z_l = 0.335 \\pm 0.002$$, and Einstein radius $$R_{\\rm E} = (1.1\\pm0.1)^{\\prime\\prime},$$ but higher-resolution imaging is needed to accurately separate the deflector and faint quasar image. We also show high-rank candidate doubles selected this way, some of which have been independently identified with different techniques, and discuss a DES+WISE quasar multiplet selection.« less

  4. Not all stars form in clusters - measuring the kinematics of OB associations with Gaia

    NASA Astrophysics Data System (ADS)

    Ward, Jacob L.; Kruijssen, J. M. Diederik

    2018-04-01

    It is often stated that star clusters are the fundamental units of star formation and that most (if not all) stars form in dense stellar clusters. In this monolithic formation scenario, low-density OB associations are formed from the expansion of gravitationally bound clusters following gas expulsion due to stellar feedback. N-body simulations of this process show that OB associations formed this way retain signs of expansion and elevated radial anisotropy over tens of Myr. However, recent theoretical and observational studies suggest that star formation is a hierarchical process, following the fractal nature of natal molecular clouds and allowing the formation of large-scale associations in situ. We distinguish between these two scenarios by characterizing the kinematics of OB associations using the Tycho-Gaia Astrometric Solution catalogue. To this end, we quantify four key kinematic diagnostics: the number ratio of stars with positive radial velocities to those with negative radial velocities, the median radial velocity, the median radial velocity normalized by the tangential velocity, and the radial anisotropy parameter. Each quantity presents a useful diagnostic of whether the association was more compact in the past. We compare these diagnostics to models representing random motion and the expanding products of monolithic cluster formation. None of these diagnostics show evidence of expansion, either from a single cluster or multiple clusters, and the observed kinematics are better represented by a random velocity distribution. This result favours the hierarchical star formation model in which a minority of stars forms in bound clusters and large-scale, hierarchically structured associations are formed in situ.

  5. New generation of universal modeling for centrifugal compressors calculation

    NASA Astrophysics Data System (ADS)

    Galerkin, Y.; Drozdov, A.

    2015-08-01

    The Universal Modeling method is in constant use from mid - 1990th. Below is presented the newest 6th version of the Method. The flow path configuration of 3D impellers is presented in details. It is possible to optimize meridian configuration including hub/shroud curvatures, axial length, leading edge position, etc. The new model of vaned diffuser includes flow non-uniformity coefficient based on CFD calculations. The loss model was built from the results of 37 experiments with compressors stages of different flow rates and loading factors. One common set of empirical coefficients in the loss model guarantees the efficiency definition within an accuracy of 0.86% at the design point and 1.22% along the performance curve. The model verification was made. Four multistage compressors performances with vane and vaneless diffusers were calculated. As the model verification was made, four multistage compressors performances with vane and vaneless diffusers were calculated. Two of these compressors have quite unusual flow paths. The modeling results were quite satisfactory in spite of these peculiarities. One sample of the verification calculations is presented in the text. This 6th version of the developed computer program is being already applied successfully in the design practice.

  6. Gaia Data Release 1. Open cluster astrometry: performance, limitations, and future prospects

    NASA Astrophysics Data System (ADS)

    Gaia Collaboration; van Leeuwen, F.; Vallenari, A.; Jordi, C.; Lindegren, L.; Bastian, U.; Prusti, T.; de Bruijne, J. H. J.; Brown, A. G. A.; Babusiaux, C.; Bailer-Jones, C. A. L.; Biermann, M.; Evans, D. W.; Eyer, L.; Jansen, F.; Klioner, S. A.; Lammers, U.; Luri, X.; Mignard, F.; Panem, C.; Pourbaix, D.; Randich, S.; Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette, V.; Walton, N. A.; Aerts, C.; Arenou, F.; Cropper, M.; Drimmel, R.; Høg, E.; Katz, D.; Lattanzi, M. G.; O'Mullane, W.; Grebel, E. K.; Holland, A. D.; Huc, C.; Passot, X.; Perryman, M.; Bramante, L.; Cacciari, C.; Castañeda, J.; Chaoul, L.; Cheek, N.; De Angeli, F.; Fabricius, C.; Guerra, R.; Hernández, J.; Jean-Antoine-Piccolo, A.; Masana, E.; Messineo, R.; Mowlavi, N.; Nienartowicz, K.; Ordóñez-Blanco, D.; Panuzzo, P.; Portell, J.; Richards, P. J.; Riello, M.; Seabroke, G. M.; Tanga, P.; Thévenin, F.; Torra, J.; Els, S. G.; Gracia-Abril, G.; Comoretto, G.; Garcia-Reinaldos, M.; Lock, T.; Mercier, E.; Altmann, M.; Andrae, R.; Astraatmadja, T. L.; Bellas-Velidis, I.; Benson, K.; Berthier, J.; Blomme, R.; Busso, G.; Carry, B.; Cellino, A.; Clementini, G.; Cowell, S.; Creevey, O.; Cuypers, J.; Davidson, M.; De Ridder, J.; de Torres, A.; Delchambre, L.; Dell'Oro, A.; Ducourant, C.; Frémat, Y.; García-Torres, M.; Gosset, E.; Halbwachs, J.-L.; Hambly, N. C.; Harrison, D. L.; Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle, H. E.; Hutton, A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn, A. J.; Lanzafame, A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.; Osinde, J.; Pancino, E.; Pauwels, T.; Petit, J.-M.; Recio-Blanco, A.; Robin, A. C.; Sarro, L. M.; Siopis, C.; Smith, M.; Smith, K. W.; Sozzetti, A.; Thuillot, W.; van Reeven, W.; Viala, Y.; Abbas, U.; Abreu Aramburu, A.; Accart, S.; Aguado, J. J.; Allan, P. M.; Allasia, W.; Altavilla, G.; Álvarez, M. A.; Alves, J.; Anderson, R. I.; Andrei, A. H.; Anglada Varela, E.; Antiche, E.; Antoja, T.; Antón, S.; Arcay, B.; Bach, N.; Baker, S. G.; Balaguer-Núñez, L.; Barache, C.; Barata, C.; Barbier, A.; Barblan, F.; Barrado y Navascués, D.; Barros, M.; Barstow, M. A.; Becciani, U.; Bellazzini, M.; Bello García, A.; Belokurov, V.; Bendjoya, P.; Berihuete, A.; Bianchi, L.; Bienaymé, O.; Billebaud, F.; Blagorodnova, N.; Blanco-Cuaresma, S.; Boch, T.; Bombrun, A.; Borrachero, R.; Bouquillon, S.; Bourda, G.; Bouy, H.; Bragaglia, A.; Breddels, M. A.; Brouillet, N.; Brüsemeister, T.; Bucciarelli, B.; Burgess, P.; Burgon, R.; Burlacu, A.; Busonero, D.; Buzzi, R.; Caffau, E.; Cambras, J.; Campbell, H.; Cancelliere, R.; Cantat-Gaudin, T.; Carlucci, T.; Carrasco, J. M.; Castellani, M.; Charlot, P.; Charnas, J.; Chiavassa, A.; Clotet, M.; Cocozza, G.; Collins, R. S.; Costigan, G.; Crifo, F.; Cross, N. J. G.; Crosta, M.; Crowley, C.; Dafonte, C.; Damerdji, Y.; Dapergolas, A.; David, P.; David, M.; De Cat, P.; de Felice, F.; de Laverny, P.; De Luise, F.; De March, R.; de Martino, D.; de Souza, R.; Debosscher, J.; del Pozo, E.; Delbo, M.; Delgado, A.; Delgado, H. E.; Di Matteo, P.; Diakite, S.; Distefano, E.; Dolding, C.; Dos Anjos, S.; Drazinos, P.; Durán, J.; Dzigan, Y.; Edvardsson, B.; Enke, H.; Evans, N. W.; Eynard Bontemps, G.; Fabre, C.; Fabrizio, M.; Faigler, S.; Falcão, A. J.; Farràs Casas, M.; Federici, L.; Fedorets, G.; Fernández-Hernández, J.; Fernique, P.; Fienga, A.; Figueras, F.; Filippi, F.; Findeisen, K.; Fonti, A.; Fouesneau, M.; Fraile, E.; Fraser, M.; Fuchs, J.; Gai, M.; Galleti, S.; Galluccio, L.; Garabato, D.; García-Sedano, F.; Garofalo, A.; Garralda, N.; Gavras, P.; Gerssen, J.; Geyer, R.; Gilmore, G.; Girona, S.; Giuffrida, G.; Gomes, M.; González-Marcos, A.; González-Núñez, J.; González-Vidal, J. J.; Granvik, M.; Guerrier, A.; Guillout, P.; Guiraud, J.; Gúrpide, A.; Gutiérrez-Sánchez, R.; Guy, L. P.; Haigron, R.; Hatzidimitriou, D.; Haywood, M.; Heiter, U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.; Holland, G.; Hunt, J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat de Fombelle, G.; Jofré, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.; Karampelas, A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas, E.; Koposov, S. E.; Kordopatis, G.; Koubsky, P.; Krone-Martins, A.; Kudryashova, M.; Kull, I.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza, A. F.; Lavigne, J.-B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter, T.; Leccia, S.; Leclerc, N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt, H.; Leroux, F.; Liao, S.; Licata, E.; Lindstrøm, H. E. P.; Lister, T. A.; Livanou, E.; Lobel, A.; Löffler, W.; López, M.; Lorenz, D.; MacDonald, I.; Magalhães Fernandes, T.; Managau, S.; Mann, R. G.; Mantelet, G.; Marchal, O.; Marchant, J. M.; Marconi, M.; Marinoni, S.; Marrese, P. M.; Marschalkó, G.; Marshall, D. J.; Martín-Fleitas, J. M.; Martino, M.; Mary, N.; Matijevič, G.; Mazeh, T.; McMillan, P. J.; Messina, S.; Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina, D.; Molinaro, R.; Molinaro, M.; Molnár, L.; Moniez, M.; Montegriffo, P.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.; Morris, D.; Mulone, A. F.; Muraveva, T.; Musella, I.; Narbonne, J.; Nelemans, G.; Nicastro, L.; Noval, L.; Ordénovic, C.; Ordieres-Meré, J.; Osborne, P.; Pagani, C.; Pagano, I.; Pailler, F.; Palacin, H.; Palaversa, L.; Parsons, P.; Pecoraro, M.; Pedrosa, R.; Pentikäinen, H.; Pichon, B.; Piersimoni, A. M.; Pineau, F.-X.; Plachy, E.; Plum, G.; Poujoulet, E.; Prša, A.; Pulone, L.; Ragaini, S.; Rago, S.; Rambaux, N.; Ramos-Lerate, M.; Ranalli, P.; Rauw, G.; Read, A.; Regibo, S.; Reylé, C.; Ribeiro, R. A.; Rimoldini, L.; Ripepi, V.; Riva, A.; Rixon, G.; Roelens, M.; Romero-Gómez, M.; Rowell, N.; Royer, F.; Ruiz-Dern, L.; Sadowski, G.; Sagristà Sellés, T.; Sahlmann, J.; Salgado, J.; Salguero, E.; Sarasso, M.; Savietto, H.; Schultheis, M.; Sciacca, E.; Segol, M.; Segovia, J. C.; Segransan, D.; Shih, I.-C.; Smareglia, R.; Smart, R. L.; Solano, E.; Solitro, F.; Sordo, R.; Soria Nieto, S.; Souchay, J.; Spagna, A.; Spoto, F.; Stampa, U.; Steele, I. A.; Steidelmüller, H.; Stephenson, C. A.; Stoev, H.; Suess, F. F.; Süveges, M.; Surdej, J.; Szabados, L.; Szegedi-Elek, E.; Tapiador, D.; Taris, F.; Tauran, G.; Taylor, M. B.; Teixeira, R.; Terrett, D.; Tingley, B.; Trager, S. C.; Turon, C.; Ulla, A.; Utrilla, E.; Valentini, G.; van Elteren, A.; Van Hemelryck, E.; vanLeeuwen, M.; Varadi, M.; Vecchiato, A.; Veljanoski, J.; Via, T.; Vicente, D.; Vogt, S.; Voss, H.; Votruba, V.; Voutsinas, S.; Walmsley, G.; Weiler, M.; Weingrill, K.; Wevers, T.; Wyrzykowski, Ł.; Yoldas, A.; Žerjal, M.; Zucker, S.; Zurbach, C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende Prieto, C.; Amorim, A.; Anglada-Escudé, G.; Arsenijevic, V.; Azaz, S.; Balm, P.; Beck, M.; Bernstein, H.-H.; Bigot, L.; Bijaoui, A.; Blasco, C.; Bonfigli, M.; Bono, G.; Boudreault, S.; Bressan, A.; Brown, S.; Brunet, P.-M.; Bunclark, P.; Buonanno, R.; Butkevich, A. G.; Carret, C.; Carrion, C.; Chemin, L.; Chéreau, F.; Corcione, L.; Darmigny, E.; de Boer, K. S.; de Teodoro, P.; de Zeeuw, P. T.; Delle Luche, C.; Domingues, C. D.; Dubath, P.; Fodor, F.; Frézouls, B.; Fries, A.; Fustes, D.; Fyfe, D.; Gallardo, E.; Gallegos, J.; Gardiol, D.; Gebran, M.; Gomboc, A.; Gómez, A.; Grux, E.; Gueguen, A.; Heyrovsky, A.; Hoar, J.; Iannicola, G.; Isasi Parache, Y.; Janotto, A.-M.; Joliet, E.; Jonckheere, A.; Keil, R.; Kim, D.-W.; Klagyivik, P.; Klar, J.; Knude, J.; Kochukhov, O.; Kolka, I.; Kos, J.; Kutka, A.; Lainey, V.; LeBouquin, D.; Liu, C.; Loreggia, D.; Makarov, V. V.; Marseille, M. G.; Martayan, C.; Martinez-Rubi, O.; Massart, B.; Meynadier, F.; Mignot, S.; Munari, U.; Nguyen, A.-T.; Nordlander, T.; O'Flaherty, K. S.; Ocvirk, P.; Olias Sanz, A.; Ortiz, P.; Osorio, J.; Oszkiewicz, D.; Ouzounis, A.; Palmer, M.; Park, P.; Pasquato, E.; Peltzer, C.; Peralta, J.; Péturaud, F.; Pieniluoma, T.; Pigozzi, E.; Poels, J.; Prat, G.; Prod'homme, T.; Raison, F.; Rebordao, J. M.; Risquez, D.; Rocca-Volmerange, B.; Rosen, S.; Ruiz-Fuertes, M. I.; Russo, F.; Sembay, S.; Serraller Vizcaino, I.; Short, A.; Siebert, A.; Silva, H.; Sinachopoulos, D.; Slezak, E.; Soffel, M.; Sosnowska, D.; Straižys, V.; ter Linden, M.; Terrell, D.; Theil, S.; Tiede, C.; Troisi, L.; Tsalmantza, P.; Tur, D.; Vaccari, M.; Vachier, F.; Valles, P.; Van Hamme, W.; Veltz, L.; Virtanen, J.; Wallut, J.-M.; Wichmann, R.; Wilkinson, M. I.; Ziaeepour, H.; Zschocke, S.

    2017-05-01

    Context. The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS). This is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are calculated using Hipparcos and Tycho-2 positions in 1991.25 as prior information. Aims: We investigate the scientific potential and limitations of the TGAS component by means of the astrometric data for open clusters. Methods: Mean cluster parallax and proper motion values are derived taking into account the error correlations within the astrometric solutions for individual stars, an estimate of the internal velocity dispersion in the cluster, and, where relevant, the effects of the depth of the cluster along the line of sight. Internal consistency of the TGAS data is assessed. Results: Values given for standard uncertainties are still inaccurate and may lead to unrealistic unit-weight standard deviations of least squares solutions for cluster parameters. Reconstructed mean cluster parallax and proper motion values are generally in very good agreement with earlier Hipparcos-based determination, although the Gaia mean parallax for the Pleiades is a significant exception. We have no current explanation for that discrepancy. Most clusters are observed to extend to nearly 15 pc from the cluster centre, and it will be up to future Gaia releases to establish whether those potential cluster-member stars are still dynamically bound to the clusters. Conclusions: The Gaia DR1 provides the means to examine open clusters far beyond their more easily visible cores, and can provide membership assessments based on proper motions and parallaxes. A combined HR diagram shows the same features as observed before using the Hipparcos data, with clearly increased luminosities for older A and F dwarfs. Tables D.1 to D.19 are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A

  7. The Optical Gravitational Lensing Experiment. Gaia South Ecliptic Pole Field as Seen by OGLE-IV

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Udalski, A.; Poleski, R.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Ulaczyk, K.; Skowron, J.

    2012-09-01

    We present a comprehensive analysis of the Gaia South Ecliptic Pole (GSEP) field, 5.3 square degrees area around the South Ecliptic Pole on the outskirts of the LMC, based on the data collected during the fourth phase of the Optical Gravitational Lensing Experiment, OGLE-IV. The GSEP field will be observed during the commissioning phase of the ESA Gaia space mission for testing and calibrating the Gaia instruments. We provide the photometric maps of the GSEP region containing the mean VI photometry of all detected stellar objects and their equatorial coordinates. We show the quality and completeness of the OGLE-IV photometry and color-magnitude diagrams of this region. We conducted an extensive search for variable stars in the GSEP field leading to the discovery of 6789 variable stars. In this sample we found 132 classical Cepheids, 686 RR Lyr type stars, 2819 long-period, and 1377 eclipsing variables. Several objects deserving special attention were also selected, including a new classical Cepheid in a binary eclipsing system. To provide empirical data for the Gaia Science Alert system we also conducted a search for optical transients. We discovered two firm type Ia supernovae and nine additional supernova candidates. To facilitate future Gaia supernovae detections we prepared a list of more than 1900 galaxies to redshift about 0.1 located in the GSEP field. Finally, we present the results of astrometric study of the GSEP field. With the 26 months time base of the presented here OGLE-IV data, proper motions of stars could be detected with the accuracy reaching 2 mas/yr. Astrometry allowed to distinguish galactic foreground variable stars detected in the GSEP field from LMC objects and to discover about 50 high proper motion stars (proper motion ≥ 100 mas/yr). Among them three new nearby white dwarfs were found. All data presented in this paper are available to the astronomical community from the OGLE Internet archive.

  8. Universal Free School Breakfast: A Qualitative Model for Breakfast Behaviors

    PubMed Central

    Harvey-Golding, Louise; Donkin, Lynn Margaret; Blackledge, John; Defeyter, Margaret Anne

    2015-01-01

    In recent years, the provision of school breakfast has increased significantly in the UK. However, research examining the effectiveness of school breakfast is still within relative stages of infancy, and findings to date have been rather mixed. Moreover, previous evaluations of school breakfast schemes have been predominantly quantitative in their methodologies. Currently, there are few qualitative studies examining the subjective perceptions and experiences of stakeholders, and thereby an absence of knowledge regarding the sociocultural impacts of school breakfast. The purpose of this study was to investigate the beliefs, views and attitudes, and breakfast consumption behaviors, among key stakeholders, served by a council-wide universal free school breakfast initiative, within the North West of England, UK. A sample of children, parents, and school staff were recruited from three primary schools, participating in the universal free school breakfast scheme, to partake in semi-structured interviews and small focus groups. A Grounded Theory analysis of the data collected identified a theoretical model of breakfast behaviors, underpinned by the subjective perceptions and experiences of these key stakeholders. The model comprises of three domains relating to breakfast behaviors, and the internal and external factors that are perceived to influence breakfast behaviors, among children, parents, and school staff. Findings were validated using triangulation methods, member checks, and inter-rater reliability measures. In presenting this theoretically grounded model for breakfast behaviors, this paper provides a unique qualitative insight into the breakfast consumption behaviors and barriers to breakfast consumption, within a socioeconomically deprived community, participating in a universal free school breakfast intervention program. PMID:26125017

  9. A discriminant function model for admission at undergraduate university level

    NASA Astrophysics Data System (ADS)

    Ali, Hamdi F.; Charbaji, Abdulrazzak; Hajj, Nada Kassim

    1992-09-01

    The study is aimed at predicting objective criteria based on a statistically tested model for admitting undergraduate students to Beirut University College. The University is faced with a dual problem of having to select only a fraction of an increasing number of applicants, and of trying to minimize the number of students placed on academic probation (currently 36 percent of new admissions). Out of 659 new students, a sample of 272 students (45 percent) were selected; these were all the students on the Dean's list and on academic probation. With academic performance as the dependent variable, the model included ten independent variables and their interactions. These variables included the type of high school, the language of instruction in high school, recommendations, sex, academic average in high school, score on the English Entrance Examination, the major in high school, and whether the major was originally applied for by the student. Discriminant analysis was used to evaluate the relative weight of the independent variables, and from the analysis three equations were developed, one for each academic division in the College. The predictive power of these equations was tested by using them to classify students not in the selected sample into successful and unsuccessful ones. Applicability of the model to other institutions of higher learning is discussed.

  10. Critical mingling and universal correlations in model binary active liquids

    NASA Astrophysics Data System (ADS)

    Bain, Nicolas; Bartolo, Denis

    2017-06-01

    Ensembles of driven or motile bodies moving along opposite directions are generically reported to self-organize into strongly anisotropic lanes. Here, building on a minimal model of self-propelled bodies targeting opposite directions, we first evidence a critical phase transition between a mingled state and a phase-separated lane state specific to active particles. We then demonstrate that the mingled state displays algebraic structural correlations also found in driven binary mixtures. Finally, constructing a hydrodynamic theory, we single out the physical mechanisms responsible for these universal long-range correlations typical of ensembles of oppositely moving bodies.

  11. Organizational Models and Mythologies of the American Research University. ASHE 1986 Annual Meeting Paper.

    ERIC Educational Resources Information Center

    Alpert, Daniel

    Features of the matrix model of the research university and myths about the academic enterprise are described, along with serious dissonances in the U.S. university system. The linear model, from which the matrix model evolved, describes the university's structure, perceived mission, and organizational behavior. A matrix model portrays in concise,…

  12. Anisotropic, nonsingular early universe model leading to a realistic cosmology

    SciTech Connect

    Dechant, Pierre-Philippe; Lasenby, Anthony N.; Hobson, Michael P.

    2009-02-15

    We present a novel cosmological model in which scalar field matter in a biaxial Bianchi IX geometry leads to a nonsingular 'pancaking' solution: the hypersurface volume goes to zero instantaneously at the 'big bang', but all physical quantities, such as curvature invariants and the matter energy density remain finite, and continue smoothly through the big bang. We demonstrate that there exist geodesics extending through the big bang, but that there are also incomplete geodesics that spiral infinitely around a topologically closed spatial dimension at the big bang, rendering it, at worst, a quasiregular singularity. The model is thus reminiscent ofmore » the Taub-NUT vacuum solution in that it has biaxial Bianchi IX geometry and its evolution exhibits a dimensionality reduction at a quasiregular singularity; the two models are, however, rather different, as we will show in a future work. Here we concentrate on the cosmological implications of our model and show how the scalar field drives both isotropization and inflation, thus raising the question of whether structure on the largest scales was laid down at a time when the universe was still oblate (as also suggested by [T. S. Pereira, C. Pitrou, and J.-P. Uzan, J. Cosmol. Astropart. Phys. 9 (2007) 6.][C. Pitrou, T. S. Pereira, and J.-P. Uzan, J. Cosmol. Astropart. Phys. 4 (2008) 4.][A. Guemruekcueoglu, C. Contaldi, and M. Peloso, J. Cosmol. Astropart. Phys. 11 (2007) 005.]). We also discuss the stability of our model to small perturbations around biaxiality and draw an analogy with cosmological perturbations. We conclude by presenting a separate, bouncing solution, which generalizes the known bouncing solution in closed FRW universes.« less

  13. Supporting universal prevention programs: a two-phased coaching model.

    PubMed

    Becker, Kimberly D; Darney, Dana; Domitrovich, Celene; Keperling, Jennifer Pitchford; Ialongo, Nicholas S

    2013-06-01

    Schools are adopting evidence-based programs designed to enhance students' emotional and behavioral competencies at increasing rates (Hemmeter et al. in Early Child Res Q 26:96-109, 2011). At the same time, teachers express the need for increased support surrounding implementation of these evidence-based programs (Carter and Van Norman in Early Child Educ 38:279-288, 2010). Ongoing professional development in the form of coaching may enhance teacher skills and implementation (Noell et al. in School Psychol Rev 34:87-106, 2005; Stormont et al. 2012). There exists a need for a coaching model that can be applied to a variety of teacher skill levels and one that guides coach decision-making about how best to support teachers. This article provides a detailed account of a two-phased coaching model with empirical support developed and tested with coaches and teachers in urban schools (Becker et al. 2013). In the initial universal coaching phase, all teachers receive the same coaching elements regardless of their skill level. Then, in the tailored coaching phase, coaching varies according to the strengths and needs of each teacher. Specifically, more intensive coaching strategies are used only with teachers who need additional coaching supports, whereas other teachers receive just enough support to consolidate and maintain their strong implementation. Examples of how coaches used the two-phased coaching model when working with teachers who were implementing two universal prevention programs (i.e., the PATHS curriculum and PAX Good Behavior Game [PAX GBG]) provide illustrations of the application of this model. The potential reach of this coaching model extends to other school-based programs as well as other settings in which coaches partner with interventionists to implement evidence-based programs.

  14. Supporting Universal Prevention Programs: A Two-Phased Coaching Model

    PubMed Central

    Becker, Kimberly D.; Darney, Dana; Domitrovich, Celene; Keperling, Jennifer Pitchford; Ialongo, Nicholas S.

    2013-01-01

    Schools are adopting evidence-based programs designed to enhance students’ emotional and behavioral competencies at increasing rates (Hemmeter, Snyder, & Artman, 2011). At the same time, teachers express the need for increased support surrounding implementation of these evidence-based programs (Carter & Van Norman, 2010). Ongoing professional development in the form of coaching may enhance teacher skills and implementation (Noell et al., 2005; Stormont, Reinke, Newcomer, Darney, & Lewis, 2012). There exists a need for a coaching model that can be applied to a variety of teacher skill levels and one that guides coach decision-making about how best to support teachers. This article provides a detailed account of a two-phased coaching model with empirical support developed and tested with coaches and teachers in urban schools (Becker, Bradshaw, Domitrovich, & Ialongo, 2013). In the initial universal coaching phase, all teachers receive the same coaching elements regardless of their skill level. Then, in the tailored coaching phase, coaching varies according to the strengths and needs of each teacher. Specifically, more intensive coaching strategies are used only with teachers who need additional coaching supports whereas other teachers receive just enough support to consolidate and maintain their strong implementation. Examples of how coaches used the two-phased coaching model when working with teachers who were implementing two universal prevention programs (i.e., the PATHS® curriculum and PAX Good Behavior Game [PAX GBG]) provide illustrations of the application of this model. The potential reach of this coaching model extends to other school-based programs as well as other settings in which coaches partner with interventionists to implement evidence-based programs. PMID:23660973

  15. A Model for Cooperative Student Teaching Involving a Nearby Majority Black University and a Nearby Majority White University.

    ERIC Educational Resources Information Center

    Mercer, Walter A.

    Major features of the cooperative student teaching model include 1) a pattern of student teaching assignments within the school system which would provide for proportional inclusion of prospective teachers--from the nearby majority black university and the nearby majority white university--to each school serving as a student teaching facility; 2)…

  16. The Gaia-ESO Survey: Lithium enrichment histories of the Galactic thick and thin disc

    NASA Astrophysics Data System (ADS)

    Fu, X.; Romano, D.; Bragaglia, A.; Mucciarelli, A.; Lind, K.; Delgado Mena, E.; Sousa, S. G.; Randich, S.; Bressan, A.; Sbordone, L.; Martell, S.; Korn, A. J.; Abia, C.; Smiljanic, R.; Jofré, P.; Pancino, E.; Tautvaišienė, G.; Tang, B.; Magrini, L.; Lanzafame, A. C.; Carraro, G.; Bensby, T.; Damiani, F.; Alfaro, E. J.; Flaccomio, E.; Morbidelli, L.; Zaggia, S.; Lardo, C.; Monaco, L.; Frasca, A.; Donati, P.; Drazdauskas, A.; Chorniy, Y.; Bayo, A.; Kordopatis, G.

    2018-02-01

    Lithium abundance in most of the warm metal-poor main sequence stars shows a constarnt plateau (A(Li) 2.2 dex) and then the upper envelope of the lithium vs. metallicity distribution increases as we approach solar metallicity. Meteorites, which carry information about the chemical composition of the interstellar medium (ISM) at the solar system formation time, show a lithium abundance A(Li) 3.26 dex. This pattern reflects the Li enrichment history of the ISM during the Galaxy lifetime. After the initial Li production in big bang nucleosynthesis, the sources of the enrichment include asymptotic giant branch (AGB) stars, low-mass red giants, novae, type II supernovae, and Galactic cosmic rays. The total amount of enriched Li is sensitive to the relative contribution of these sources. Thus different Li enrichment histories are expected in the Galactic thick and thin disc. We investigate the main sequence stars observed with UVES in Gaia-ESO Survey iDR4 catalogue and find a Li-anticorrelation independent of [Fe/H], Teff, and log(g). Since in stellar evolution different α enhancements at the same metallicity do not lead to a measurable Li abundance change, the anticorrelation indicates that more Li is produced during the Galactic thin disc phase than during the Galactic thick disc phase. We also find a correlation between the abundance of Li and s-process elements Ba and Y, and they both decrease above the solar metallicity, which can be explained in the framework of the adopted Galactic chemical evolution models. The full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/A38

  17. Is the Milky Way still breathing? RAVE-Gaia streaming motions

    NASA Astrophysics Data System (ADS)

    Carrillo, I.; Minchev, I.; Kordopatis, G.; Steinmetz, M.; Binney, J.; Anders, F.; Bienaymé, O.; Bland-Hawthorn, J.; Famaey, B.; Freeman, K. C.; Gilmore, G.; Gibson, B. K.; Grebel, E. K.; Helmi, A.; Just, A.; Kunder, A.; McMillan, P.; Monari, G.; Munari, U.; Navarro, J.; Parker, Q. A.; Reid, W.; Seabroke, G.; Sharma, S.; Siebert, A.; Watson, F.; Wojno, J.; Wyse, R. F. G.; Zwitter, T.

    2018-04-01

    We use data from the Radial Velocity Experiment (RAVE) and the Tycho-Gaia astrometric solution (TGAS) catalogue to compute the velocity fields yielded by the radial (VR), azimuthal (Vϕ),and vertical (Vz) components of associated Galactocentric velocity. We search in particular for variation in all three velocity components with distance above and below the disc mid-plane, as well as how each component of Vz (line-of-sight and tangential velocity projections) modifies the obtained vertical structure. To study the dependence of velocity on proper motion and distance, we use two main samples: a RAVE sample including proper motions from the Tycho-2, PPMXL, and UCAC4 catalogues, and a RAVE-TGAS sample with inferred distances and proper motions from the TGAS and UCAC5 catalogues. In both samples, we identify asymmetries in VR and Vz. Below the plane, we find the largest radial gradient to be ∂VR/∂R = -7.01 ± 0.61 km s-1 kpc-1, in agreement with recent studies. Above the plane, we find a similar gradient with ∂VR/∂R = -9.42 ± 1.77 km s-1 kpc-1. By comparing our results with previous studies, we find that the structure in Vz is strongly dependent on the adopted proper motions. Using the Galaxia Milky Way model, we demonstrate that distance uncertainties can create artificial wave-like patterns. In contrast to previous suggestions of a breathing mode seen in RAVE data, our results support a combination of bending and breathing modes, likely generated by a combination of external or internal and external mechanisms.

  18. Preference Mining Using Neighborhood Rough Set Model on Two Universes.

    PubMed

    Zeng, Kai

    2016-01-01

    Preference mining plays an important role in e-commerce and video websites for enhancing user satisfaction and loyalty. Some classical methods are not available for the cold-start problem when the user or the item is new. In this paper, we propose a new model, called parametric neighborhood rough set on two universes (NRSTU), to describe the user and item data structures. Furthermore, the neighborhood lower approximation operator is used for defining the preference rules. Then, we provide the means for recommending items to users by using these rules. Finally, we give an experimental example to show the details of NRSTU-based preference mining for cold-start problem. The parameters of the model are also discussed. The experimental results show that the proposed method presents an effective solution for preference mining. In particular, NRSTU improves the recommendation accuracy by about 19% compared to the traditional method.

  19. Universal Knight shift anomaly in the periodic Anderson model

    SciTech Connect

    Jiang, M.; Curro, N. J.; Scalettar, R. T.

    Here, we report a Determinant Quantum Monte Carlo investigation which quantifies the behavior of the susceptibility and the entropy in the framework of the periodic Anderson model (PAM), focussing on the evolution with different degree of conduction electron (c) -local moment (f) hybridization. These results capture the behavior observed in several experiments, including the universal behavior of the NMR Knight shift anomaly below the crossover temperature, T*. We find that T* is a measure of the onset of c-f correlations and grows with increasing hybridization. Our results suggest that the NMR Knight shift and spin-lattice relaxation rate measurements in non-Fermimore » liquid materials are strongly influenced by temperature-dependent hybridization processes. Furthermore, our results provide a microscopic basis for the phenomenological two-fluid model of Kondo lattice behavior, and its evolution with pressure and temperature.« less

  20. Universality of entropy scaling in one dimensional gapless models.

    PubMed

    Korepin, V E

    2004-03-05

    We consider critical models in one dimension. We study the ground state in the thermodynamic limit (infinite lattice). We are interested in an entropy of a subsystem. We calculate the entropy of a part of the ground state from a space interval (0,x). At zero temperature it describes the entanglement of the part of the ground state from this interval with the rest of the ground state. We obtain an explicit formula for the entropy of the subsystem at any temperature. At zero temperature our formula reproduces a logarithmic formula, discovered by Vidal, Latorre, Rico, and Kitaev for spin chains. We prove our formula by means of conformal field theory and the second law of thermodynamics. Our formula is universal. We illustrate it for a Bose gas with a delta interaction and for the Hubbard model.

  1. Cylindrically symmetric cosmological model of the universe in modified gravity

    NASA Astrophysics Data System (ADS)

    Mishra, B.; Vadrevu, Samhita

    2017-02-01

    In this paper, we have constructed the cosmological models of the universe in a cylindrically symmetric space time in two classes of f(R,T) gravity (Harko et al. in Phys. Rev. D 84:024020, 2011). We have discussed two cases: one in the linear form and the other in the quadratic form of R. The matter is considered to be in the form of perfect fluid. It is observed that in the first case, the pressure and energy density remain the same, which reduces to a Zeldovich fluid. In the second case we have studied the quadratic function of f(R,T) gravity in the form f(R)=λ(R+R2) and f(T)=λ T. In the second case the pressure is in the negative domain and the energy density is in the positive domain, which confirms that the equation of state parameter is negative. The physical properties of the constructed models are studied.

  2. Modeling Spacecraft Fuel Slosh at Embry-Riddle Aeronautical University

    NASA Technical Reports Server (NTRS)

    Schlee, Keith L.

    2007-01-01

    As a NASA-sponsored GSRP Fellow, I worked with other researchers and analysts at Embry-Riddle Aeronautical University and NASA's ELV Division to investigate the effect of spacecraft fuel slosh. NASA's research into the effects of fuel slosh includes modeling the response in full-sized tanks using equipment such as the Spinning Slosh Test Rig (SSTR), located at Southwest Research Institute (SwRI). NASA and SwRI engineers analyze data taken from SSTR runs and hand-derive equations of motion to identify model parameters and characterize the sloshing motion. With guidance from my faculty advisor, Dr. Sathya Gangadharan, and NASA flight controls analysts James Sudermann and Charles Walker, I set out to automate this parameter identification process by building a simple physical experimental setup to model free surface slosh in a spherical tank with a simple pendulum analog. This setup was then modeled using Simulink and SimMechanics. The Simulink Parameter Estimation Tool was then used to identify the model parameters.

  3. Modeling universal dynamics of cell spreading on elastic substrates.

    PubMed

    Fan, Houfu; Li, Shaofan

    2015-11-01

    A three-dimensional (3D) multiscale moving contact line model is combined with a soft matter cell model to study the universal dynamics of cell spreading over elastic substrates. We have studied both the early stage and the late stage cell spreading by taking into account the actin tension effect. In this work, the cell is modeled as an active nematic droplet, and the substrate is modeled as a St. Venant Kirchhoff elastic medium. A complete 3D simulation of cell spreading has been carried out. The simulation results show that the spreading area versus spreading time at different stages obeys specific power laws, which is in good agreement with experimental data and theoretical prediction reported in the literature. Moreover, the simulation results show that the substrate elasticity may affect force dipole distribution inside the cell. The advantage of this approach is that it combines the hydrodynamics of actin retrograde flow with moving contact line model so that it can naturally include actin tension effect resulting from actin polymerization and actomyosin contraction, and thus it might be capable of simulating complex cellular scale phenomenon, such as cell spreading or even crawling.

  4. Gaia eclipsing binary and multiple systems. Supervised classification and self-organizing maps

    NASA Astrophysics Data System (ADS)

    Süveges, M.; Barblan, F.; Lecoeur-Taïbi, I.; Prša, A.; Holl, B.; Eyer, L.; Kochoska, A.; Mowlavi, N.; Rimoldini, L.

    2017-07-01

    Context. Large surveys producing tera- and petabyte-scale databases require machine-learning and knowledge discovery methods to deal with the overwhelming quantity of data and the difficulties of extracting concise, meaningful information with reliable assessment of its uncertainty. This study investigates the potential of a few machine-learning methods for the automated analysis of eclipsing binaries in the data of such surveys. Aims: We aim to aid the extraction of samples of eclipsing binaries from such databases and to provide basic information about the objects. We intend to estimate class labels according to two different, well-known classification systems, one based on the light curve morphology (EA/EB/EW classes) and the other based on the physical characteristics of the binary system (system morphology classes; detached through overcontact systems). Furthermore, we explore low-dimensional surfaces along which the light curves of eclipsing binaries are concentrated, and consider their use in the characterization of the binary systems and in the exploration of biases of the full unknown Gaia data with respect to the training sets. Methods: We have explored the performance of principal component analysis (PCA), linear discriminant analysis (LDA), Random Forest classification and self-organizing maps (SOM) for the above aims. We pre-processed the photometric time series by combining a double Gaussian profile fit and a constrained smoothing spline, in order to de-noise and interpolate the observed light curves. We achieved further denoising, and selected the most important variability elements from the light curves using PCA. Supervised classification was performed using Random Forest and LDA based on the PC decomposition, while SOM gives a continuous 2-dimensional manifold of the light curves arranged by a few important features. We estimated the uncertainty of the supervised methods due to the specific finite training set using ensembles of models constructed

  5. The Gaia Catalogue Second Data Release and Its Implications to Optical Observations of Man-Made Earth Orbiting Objects

    NASA Technical Reports Server (NTRS)

    Frith, James M.; Buckalew, Brent A.; Cowardin, Heather M.; Lederer, Susan M.

    2018-01-01

    The Gaia catalogue second data release and its implications to optical observations of man-made Earth orbiting objects. Abstract and not the Final Paper is attached. The Gaia spacecraft was launched in December 2013 by the European Space Agency to produce a three-dimensional, dynamic map of objects within the Milky Way. Gaia's first year of data was released in September 2016. Common sources from the first data release have been combined with the Tycho-2 catalogue to provide a 5 parameter astrometric solution for approximately 2 million stars. The second Gaia data release is scheduled to come out in April 2018 and is expected to provide astrometry and photometry for more than 1 billion stars, a subset of which with a the full 6 parameter astrometric solution (adding radial velocity) and positional accuracy better than 0.002 arcsec (2 mas). In addition to precise astrometry, a unique opportunity exists with the Gaia catalogue in its production of accurate, broadband photometry using the Gaia G filter. In the past, clear filters have been used by various groups to maximize likelihood of detection of dim man-made objects but these data were very difficult to calibrate. With the second release of the Gaia catalogue, a ground based system utilizing the G band filter will have access to 1.5 billion all-sky calibration sources down to an accuracy of 0.02 magnitudes or better. In this talk, we will discuss the advantages and practicalities of implementing the Gaia filters and catalogue into data pipelines designed for optical observations of man-made objects.

  6. A Model of Reading Teaching for University EFL Students: Need Analysis and Model Design

    ERIC Educational Resources Information Center

    Hamra, Arifuddin; Syatriana, Eny

    2012-01-01

    This study designed a model of teaching reading for university EFL students based on the English curriculum at the Faculty of Languages and Literature and the concept of the team-based learning in order to improve the reading comprehension of the students. What kind of teaching model can help students to improve their reading comprehension? The…

  7. Walking the Walk: Modeling Social Model and Universal Design in the Disabilities Office

    ERIC Educational Resources Information Center

    Thornton, Melanie; Downs, Sharon

    2010-01-01

    Making the shift from the medical model of disability to the social model requires postsecondary disabilities offices to carefully examine and revise policies and procedures to reflect this paradigm shift, which gives them the credibility to work toward such change on the campus level. The process followed by one university is covered in-depth, as…

  8. A Universal Model of Giftedness--An Adaptation of the Munich Model

    ERIC Educational Resources Information Center

    Jessurun, J. H.; Shearer, C. B.; Weggeman, M. C. D. P.

    2016-01-01

    The Munich Model of Giftedness (MMG) by Heller and his colleagues, developed for the identification of gifted children, is adapted and expanded, with the aim of making it more universally usable as a model for the pathway from talents to performance. On the side of the talent-factors, the concept of multiple intelligences is introduced, and the…

  9. Implications of Higgs’ universality for physics beyond the Standard Model

    NASA Astrophysics Data System (ADS)

    Goldman, T.; Stephenson, G. J.

    2017-06-01

    We emulate Cabibbo by assuming a kind of universality for fermion mass terms in the Standard Model. We show that this is consistent with all current data and with the concept that deviations from what we term Higgs’ universality are due to corrections from currently unknown physics of nonetheless conventional form. The application to quarks is straightforward, while the application to leptons makes use of the recognition that Dark Matter can provide the “sterile” neutrinos needed for the seesaw mechanism. Requiring agreement with neutrino oscillation results leads to the prediction that the mass eigenstates of the sterile neutrinos are separated by quadratically larger ratios than for the charged fermions. Using consistency with the global fit to LSND-like, short-baseline oscillations to determine the scale of the lowest mass sterile neutrino strongly suggests that the recently observed astrophysical 3.55 keV γ-ray line is also consistent with the mass expected for the second most massive sterile neutrino in our analysis.

  10. Tactile Architectural Models as Universal ‘Urban Furniture’

    NASA Astrophysics Data System (ADS)

    Kłopotowska, Agnieszka

    2017-10-01

    Tactile architectural models and maquettes have been built in the external public spaces of Polish cities since the latter half of the 00s of the 21st century. These objects are designed for the blind, but also other people - tourists, children, and those who arrive in wheelchairs. This collection has got currently more than 70 implements, which places Poland in the group of European leaders. Unfortunately, this “furniture”, is not always “convenient” and safe for all recipients. Studies, which have been conducted together with Maciej Kłopotowski since 2016 across the country, show a number of serious design and executive mistakes or examples of misuse. The purpose of this article is drawing attention to these issues and pointing out ways how they can be avoided. These objects may become completely valuable, universal tool for learning and a great way of studying architecture in an alternative way.

  11. Einstein's 1917 static model of the universe: a centennial review

    NASA Astrophysics Data System (ADS)

    O'Raifeartaigh, Cormac; O'Keeffe, Michael; Nahm, Werner; Mitton, Simon

    2017-08-01

    We present a historical review of Einstein's 1917 paper ` Cosmological Considerations in the General Theory of Relativity' to mark the centenary of a key work that set the foundations of modern cosmology. We find that the paper followed as a natural next step after Einstein's development of the general theory of relativity and that the work offers many insights into his thoughts on relativity, astronomy and cosmology. Our review includes a description of the observational and theoretical background to the paper; a paragraph-by-paragraph guided tour of the work; a discussion of Einstein's views of issues such as the relativity of inertia, the curvature of space and the cosmological constant. Particular attention is paid to little-known aspects of the paper such as Einstein's failure to test his model against observation, his failure to consider the stability of the model and a mathematical oversight concerning his interpretation of the role of the cosmological constant. We recall the response of theorists and astronomers to Einstein's cosmology in the context of the alternate models of the universe proposed by Willem de Sitter, Alexander Friedman and Georges Lemaître. Finally, we consider the relevance of the Einstein World in today's `emergent' cosmologies.

  12. Gaia DR1 completeness within 250 pc and star formation history of the Solar neighbourhood

    NASA Astrophysics Data System (ADS)

    Bernard, E. J.

    2017-12-01

    Taking advantage of the Gaia DR1, we combined TGAS parallaxes with the Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. Our dynamically-evolved SFH is in excellent agreement with that calculated from the Hipparcos catalogue within 80 pc of the Sun, showing an enhanced star formation rate (SFR) in the past ˜4 Gyr. We then correct the SFR for the disc thickening with age to obtain a SFR that is representative of the whole solar cylinder, and show that even with an extreme correction our results are not consistent with an exponentially decreasing SFR as found by recent studies. Finally, we discuss how this technique can be applied out to ˜5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ.

  13. The white dwarf mass-radius relation with Gaia, Hubble and FUSE

    NASA Astrophysics Data System (ADS)

    Joyce, Simon R. G.; Barstow, Martin A.; Casewell, Sarah L.; Holberg, Jay B.; Bond, Howard E.

    2018-04-01

    White dwarfs are becoming useful tools for many areas of astronomy. They can be used as accurate chronometers over Gyr timescales. They are also clues to the history of star formation in our galaxy. Many of these studies require accurate estimates of the mass of the white dwarf. The theoretical mass-radius relation is often invoked to provide these mass estimates. While the theoretical mass-radius relation is well developed, observational tests of this relation show a much larger scatter in the results than expected. High precision observational tests to confirm this relation are required. Gaia is providing distance measurements which will remove one of the main source of uncertainty affecting most previous observations. We combine Gaia distances with spectra from the Hubble and FUSE satelites to make precise tests of the white dwarf mass-radius relation.

  14. Detection of Double White Dwarf Binaries with Gaia, LSST and eLISA

    NASA Astrophysics Data System (ADS)

    Korol, V.; Rossi, E. M.; Groot, P. J.

    2017-03-01

    According to simulations around 108 double degenerate white dwarf binaries are expected to be present in the Milky Way. Due to their intrinsic faintness, the detection of these systems is a challenge, and the total number of detected sources so far amounts only to a few tens. This will change in the next two decades with the advent of Gaia, the LSST and eLISA. We present an estimation of how many compact DWDs with orbital periods less than a few hours we will be able to detect 1) through electromagnetic radiation with Gaia and LSST and 2) through gravitational wave radiation with eLISA. We find that the sample of simultaneous electromagnetic and gravitational waves detections is expected to be substantial, and will provide us a powerful tool for probing the white dwarf astrophysics and the structure of the Milky Way, letting us into the era of multi-messenger astronomy for these sources.

  15. Dynamics of the Oort Cloud In the Gaia Era I: Close Encounters

    NASA Astrophysics Data System (ADS)

    Torres, S.; Portegies Zwart, S.; Brown, A. G. A.

    2018-04-01

    Comets in the Oort cloud evolve under the influence of internal and external perturbations from giant planets to stellar passages, the Galactic tides, and the interstellar medium.Using the positions, parallaxes and proper motions from TGAS in Gaia DR1 and combining them with the radial velocities from the RAVE-DR5, Geneva-Copenhagen and Pulkovo catalogues, we calculated the closest encounters the Sun has had with other stars in the recent past and will have in the near future. We find that the stars with high proper motions near to the present time are missing in the Gaia-TGAS, and those to tend to be the closest ones. The quality of the data allows putting better constraints on the encounter parameters, compared to previous surveys.

  16. Asteroid masses with Gaia from ground and space-based observations

    NASA Astrophysics Data System (ADS)

    Ivantsov, Anatoliy; Hestroffer, Daniel; Thuillot, William; Bancelin, David

    2013-04-01

    Determination of masses of large asteroids is one of the expected scientific outputs from the future Gaia astrometric space mission. With the exception of binary asteroids or fly-by with a space probe, the error in mass determination depends on the size of perturbation effect produced on the motion of small asteroids. Considering the 5 years nominal duration of the Gaia mission, there will be mutual close encounters between asteroids occurring either close to the beginning or to the end of the mission. So that the maximum of deflection angle pertained to the perturbation maxima will not be observed directly by Gaia. Since astrometric data of the perturbed body before and after the encounter are mandatory to derive a perturber mass, the precision of mass determinations based solely on the Gaia observations will deteriorate in such cases. The possible way out consists in acquiring ground-based observations of high astrometric precision in time either before or after the Gaia operations, as it was suggested in [1]. By adding such data, it is expected to increase the number of derived asteroids masses [2]. This paper updates earlier predictions of encounters of large asteroids with smaller ones, e.g. [3], in terms of newly discovered asteroids and available ground-based observations. The method used consists in the computation of the offsets in right ascension and declination between the unperturbed and perturbed solutions fitted to the available observations for each small (perturbed) asteroid. For the purpose of decreasing CPU time, a special filter was applied based on the solution of the two-body problem and systematical search for close encounters, e.g. less than 0.1 A.U., of all known asteroids with the large (perturber) ones. The obtained list of asteroids-candidates was used as the input file for the mentioned above accurate calculations. Such a procedure was used for a few asteroids in [2]. The maximum visible offset corresponds to the dates when the

  17. Optical monitoring of QSO in the framework of the Gaia space mission

    NASA Astrophysics Data System (ADS)

    Taris, F.; Damljanovic, G.; Andrei, A.; Klotz, A.; Vachier, F.

    2015-08-01

    The Gaia astrometric mission of the European Space Agency has been launched the 19th December 2013. It will provide an astrometric catalogue of 500 000 extragalactic sources that could be the basis of a new optical reference frame. On the other hand, the current International Celestial Reference Frame (ICRF) is based on the observations of extragalactic sources at radio wavelength. The astrometric coordinates of sources in these two reference systems will have roughly the same uncertainty. It is then mandatory to observe a set of common targets at both optical and radio wavelength to link the ICRF with what could be called the GCRF (Gaia Celestial Reference Frame). We will show in this paper some results obtained with the TJO, Telescopi Juan Oro, from Observatori Astronomic del Montsec in Spain. It also presents some results obtained with the Lomb-Scargle and CLEAN algorithm methods applied to optical magnitude obtained with the TAROT telescopes.

  18. Gaia DR1 completeness within 250 pc & star formation history of the Solar neighbourhood

    NASA Astrophysics Data System (ADS)

    Bernard, Edouard J.

    2018-04-01

    We took advantage of the Gaia DR1 to combine TGAS parallaxes with Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. We present the determination of the completeness within this volume, and compare the resulting SFH with that calculated from the Hipparcos catalogue within 80 pc of the Sun. We also show how this technique will be applied out to ~5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ, rather than extrapolating based on the stars from these components that are today in the solar neighbourhood.

  19. VizieR Online Data Catalog: ASC Gaia Attitude Star Catalog (Smart, 2015)

    NASA Astrophysics Data System (ADS)

    Smart, R. L.

    2015-04-01

    The ASC is a compilation produced for the Gaia mission. We have combined data from the following catalogs or datasets to produce a homogenous list of positions, proper motions, photometry in a blue and red band and estimates of the magnitudes in the Gaia G and G_RVS bands: Tycho2, UCAC4, Hipparcos, PPMXL, GSC2.3 and Sky2000. Originally ASC sources were selected from the Initial Gaia Source List (IGSL, I/324). However, here we produce a cleaner catalog starting from the bright source catalogs and using the following criteria: 1) The candidate must be in the Tycho2, UCAC4, Hipparcos or Sky2000 catalog. 2) The Gaia G magnitude must be brighter than 13.4. 3) The star must be isolated from other objects of similar magnitudes 4) The object must not be in the Washington Double Star catalog 5) If a healpix 6th region has more than 1000 objects the magnitude limit is reduced to reduce the number of objects in that region. Since the ASC was produced independently from the IGSL using different procedures there is not a direct 1 to 1 match between ASC and IGSL entries. We have matched the ASC to the IGSL and found that 9 out of the 8 million entries do not have a clear match. Since there may still remain ambiguous matches in the 8 million matched objects, we decided to assign the sourceIDs of the IGSL with the adjustment that the runningnumber is equal to the IGSL runningnumber + 320000. Included Catalogs: Tycho2, UCAC4, Sky2000, HIPPARCOS for candidates and the PPMXL, GSC2.3 were used to calculating magnitudes. (2 data files).

  20. GAIA - A New Approach To Decision Making on Climate Disruption Issues

    NASA Astrophysics Data System (ADS)

    Paxton, L. J.; Weiss, M.; Schaefer, R. K.; Swartz, W. H.; Nix, M.; Strong, S. B.; Fountain, G. H.; Babin, S. M.; Pikas, C. K.; Parker, C. L.; Global Assimilation of InformationAction

    2011-12-01

    GAIA - the Global Assimilation of Information for Action program - provides a broadly extensible framework for enabling the development of a deeper understanding of the issues associated with climate disruption. The key notion of GAIA is that the global climate problem is so complex that a "system engineering" approach is needed in order to make it understandable. The key tenet of system engineering is to focus on requirements and to develop a cost-effective process for satisfying those requirements. To demonstrate this approach we focused first on the impact of climate disruption on public health. GAIA is described in some detail on our website (http://gaia.jhuapl.edu). Climate disruption is not just a scientific problem; one of the key issues that our community has is that of translating scientific results into knowledge that can be used to make informed decisions. In order to support decision makers we have to understand their issues and how to communicate with them. In this talk, we describe how we have built a community of interest that combines subject matter experts from diverse communities (public health, climate change, government, public policy, industry, etc) with policy makers and representatives from industry to develop, on a "level playing field", an understanding of each other's points of view and issues. The first application of this technology was the development of a workshop on Climate, Climate Change and Public Health held April 12-14, 2011. This paper describes our approach to going beyond the workshop environment to continue to engage the decision maker's community in a variety of ways that translate abstract scientific data into actionable information. Key ideas we will discuss include the development of social media, simulations of global/national/local environments affected by climate disruption, and visualizations of the monetary and health impacts of choosing not to address mitigation or adaptation to climate disruption.

  1. Revisiting TW Hydrae association in light of Gaia-DR1

    NASA Astrophysics Data System (ADS)

    Teixeira, R.; Gonoretzky, E. R.; Ducourant, C.; Galli, P. A. B.; Krone-Martins, A. G. O.

    2018-04-01

    TW Hydrae is a very young and nearby association with about 30 known members which is an excellent target for studies on stellar evolution since several of its members present a particular interest (planetary system, brown dwarfs, etc.). With the new data from TGAS and the Gaia DR1 eventually combined with others astrometric data we intend to improve our kinematic knowledge of this association.

  2. Refuting S 825AB System Classification through Astrometry and Gaia Satellite Data

    NASA Astrophysics Data System (ADS)

    Lyman, Noah; Musegades, Lila; Davis, Edward; Briney, Micah; Francis, Aaron; Niebuhr, Cole; Rowe, David; Harshaw, Richard; Genet, Russell

    2018-04-01

    A student-led team of researchers studied double star S 825AB (WDS 23100+3651). Analysis of ten CCD images obtained by the Sierra Research Observatory yielded an average position angle of 318.37º and an average separation of 67.38". Comparing these results to published findings in the Washington Double Star Catalog and measurements taken from the European Space Agency's Gaia astrometry satellite, the team concluded that S 825AB is not a binary system.

  3. Systematic error of the Gaia DR1 TGAS parallaxes from data for the red giant clump

    NASA Astrophysics Data System (ADS)

    Gontcharov, G. A.

    2017-08-01

    Based on the Gaia DR1 TGAS parallaxes and photometry from the Tycho-2, Gaia, 2MASS, andWISE catalogues, we have produced a sample of 100 000 clump red giants within 800 pc of the Sun. The systematic variations of the mode of their absolute magnitude as a function of the distance, magnitude, and other parameters have been analyzed. We show that these variations reach 0.7 mag and cannot be explained by variations in the interstellar extinction or intrinsic properties of stars and by selection. The only explanation seems to be a systematic error of the Gaia DR1 TGAS parallax dependent on the square of the observed distance in kpc: 0.18 R 2 mas. Allowance for this error reduces significantly the systematic dependences of the absolute magnitude mode on all parameters. This error reaches 0.1 mas within 800 pc of the Sun and allows an upper limit for the accuracy of the TGAS parallaxes to be estimated as 0.2 mas. A careful allowance for such errors is needed to use clump red giants as "standard candles." This eliminates all discrepancies between the theoretical and empirical estimates of the characteristics of these stars and allows us to obtain the first estimates of the modes of their absolute magnitudes from the Gaia parallaxes: mode( M H ) = -1.49 m ± 0.04 m , mode( M Ks ) = -1.63 m ± 0.03 m , mode( M W1) = -1.67 m ± 0.05 m mode( M W2) = -1.67 m ± 0.05 m , mode( M W3) = -1.66 m ± 0.02 m , mode( M W4) = -1.73 m ± 0.03 m , as well as the corresponding estimates of their de-reddened colors.

  4. Tycho- Gaia Astrometric Solution Parallaxes and Proper Motions for Five Galactic Globular Clusters

    SciTech Connect

    Watkins, Laura L.; Van der Marel, Roeland P., E-mail: lwatkins@stsci.edu

    2017-04-20

    We present a pilot study of Galactic globular cluster (GC) proper motion (PM) determinations using Gaia data. We search for GC stars in the Tycho- Gaia Astrometric Solution (TGAS) catalog from Gaia Data Release 1 (DR1), and identify five members of NGC 104 (47 Tucanae), one member of NGC 5272 (M3), five members of NGC 6121 (M4), seven members of NGC 6397, and two members of NGC 6656 (M22). By taking a weighted average of member stars, fully accounting for the correlations between parameters, we estimate the parallax (and, hence, distance) and PM of the GCs. This provides a homogeneousmore » PM study of multiple GCs based on an astrometric catalog with small and well-controlled systematic errors and yields random PM errors similar to existing measurements. Detailed comparison to the available Hubble Space Telescope ( HST ) measurements generally shows excellent agreement, validating the astrometric quality of both TGAS and HST . By contrast, comparison to ground-based measurements shows that some of those must have systematic errors exceeding the random errors. Our parallax estimates have uncertainties an order of magnitude larger than previous studies, but nevertheless imply distances consistent with previous estimates. By combining our PM measurements with literature positions, distances, and radial velocities, we measure Galactocentric space motions for the clusters and find that these also agree well with previous analyses. Our analysis provides a framework for determining more accurate distances and PMs of Galactic GCs using future Gaia data releases. This will provide crucial constraints on the near end of the cosmic distance ladder and provide accurate GC orbital histories.« less

  5. Gaia16apd - a link between fast and slowly declining type I superluminous supernovae

    NASA Astrophysics Data System (ADS)

    Kangas, T.; Blagorodnova, N.; Mattila, S.; Lundqvist, P.; Fraser, M.; Burgaz, U.; Cappellaro, E.; Carrasco Martínez, J. M.; Elias-Rosa, N.; Hardy, L. K.; Harmanen, J.; Hsiao, E. Y.; Isern, J.; Kankare, E.; Kołaczkowski, Z.; Nielsen, M. B.; Reynolds, T. M.; Rhodes, L.; Somero, A.; Stritzinger, M. D.; Wyrzykowski, Ł.

    2017-07-01

    We present ultraviolet (UV), optical and infrared photometry and optical spectroscopy of the type Ic superluminous supernova (SLSN) Gaia16apd (=SN 2016eay), covering its evolution from 26 d before the g-band peak to 234.1 d after the peak. Gaia16apd was followed as a part of the NOT Unbiased Transient Survey (NUTS). It is one of the closest SLSNe known (z = 0.102 ± 0.001), with detailed optical and UV observations covering the peak. Gaia16apd is a spectroscopically typical type Ic SLSN, exhibiting the characteristic blue early spectra with O II absorption, and reaches a peak Mg = -21.8 ± 0.1 mag. However, photometrically it exhibits an evolution intermediate between the fast and slowly declining type Ic SLSNe, with an early evolution closer to the fast-declining events. Together with LSQ12dlf, another SLSN with similar properties, it demonstrates a possible continuum between fast and slowly declining events. It is unusually UV-bright even for an SLSN, reaching a non-K-corrected Muvm2 ≃ -23.3 mag, the only other type Ic SLSN with similar UV brightness being SN 2010gx. Assuming that Gaia16apd was powered by magnetar spin-down, we derive a period of P = 1.9 ± 0.2 ms and a magnetic field of B = 1.9 ± 0.2 × 1014 G for the magnetar. The estimated ejecta mass is between 8 and 16 M⊙, and the kinetic energy between 1.3 and 2.5 × 1052 erg, depending on opacity and assuming that the entire ejecta is swept up into a thin shell. Despite the early photometric differences, the spectra at late times are similar to slowly declining type Ic SLSNe, implying that the two subclasses originate from similar progenitors.

  6. The Correlation between Mixing Length and Metallicity on the Giant Branch: Implications for Ages in the Gaia Era

    SciTech Connect

    Tayar, Jamie; Somers, Garrett; Pinsonneault, Marc H.

    2017-05-01

    In the updated APOGEE- Kepler catalog, we have asteroseismic and spectroscopic data for over 3000 first ascent red giants. Given the size and accuracy of this sample, these data offer an unprecedented test of the accuracy of stellar models on the post-main-sequence. When we compare these data to theoretical predictions, we find a metallicity dependent temperature offset with a slope of around 100 K per dex in metallicity. We find that this effect is present in all model grids tested, and that theoretical uncertainties in the models, correlated spectroscopic errors, and shifts in the asteroseismic mass scale are insufficient tomore » explain this effect. Stellar models can be brought into agreement with the data if a metallicity-dependent convective mixing length is used, with Δ α {sub ML,YREC} ∼ 0.2 per dex in metallicity, a trend inconsistent with the predictions of three-dimensional stellar convection simulations. If this effect is not taken into account, isochrone ages for red giants from the Gaia data will be off by as much as a factor of two even at modest deviations from solar metallicity ([Fe/H] = −0.5).« less

  7. Universal thermodynamics of the one-dimensional attractive Hubbard model

    NASA Astrophysics Data System (ADS)

    Cheng, Song; Yu, Yi-Cong; Batchelor, M. T.; Guan, Xi-Wen

    2018-03-01

    The one-dimensional (1D) Hubbard model, describing electrons on a lattice with an on-site repulsive interaction, provides a paradigm for the physics of quantum many-body phenomena. Here, by solving the thermodynamic Bethe ansatz equations, we study the universal thermodynamics, quantum criticality, and magnetism of the 1D attractive Hubbard model. We show that the compressibility and the susceptibility of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)-like state obey simple additivity rules at low temperatures, indicating an existence of two free quantum fluids. The magnetic properties, such as magnetization and susceptibility, reveal three physical regions: quantum fluids at low temperatures, a non-Fermi liquid at high temperatures, and the quantum fluid to non-Fermi liquid crossover in between. The lattice interaction is seen to significantly influence the nature of the FFLO-like state in 1D. Furthermore, we show that the dimensionless Wilson ratio provides an ideal parameter to map out the various phase boundaries and to characterize the two free fluids of the FLLO-like state. The quantum scaling functions for the thermal and magnetic properties yield the same dynamic critical exponent z =2 and correlation critical exponent ν =1 /2 in the quantum critical region whenever a phase transition occurs. Our results provide a rigorous understanding of quantum criticality and free fluids of many-body systems on a 1D lattice.

  8. The University of British Columbia model of interprofessional education.

    PubMed

    Charles, Grant; Bainbridge, Lesley; Gilbert, John

    2010-01-01

    The College of Health Disciplines, at the University of British Columbia (UBC) has a long history of developing interprofessional learning opportunities for students and practitioners. Historically, many of the courses and programmes were developed because they intuitively made sense or because certain streams of funding were available at particular times. While each of them fit generally within our understanding of interprofessional education in the health and human service education programs, they were not systematically developed within an educational or theoretical framework. This paper discusses the model we have subsequently developed at the College for conceptualizing the various types of interprofessional experiences offered at UBC. It has been developed so that we can offer the broadest range of courses and most effective learning experiences for our students. Our model is based on the premise that there are optimal learning times for health and human services students (and practitioners) depending upon their stage of development as professionals in their respective disciplines and their readiness to learn and develop new perspectives on professional interaction.

  9. MUSE--Model for University Strategic Evaluation. AIR 2002 Forum Paper.

    ERIC Educational Resources Information Center

    Kutina, Kenneth L.; Zullig, Craig M.; Starkman, Glenn D.; Tanski, Laura E.

    A model for simulating college and university operations, finances, program investments, and market response in terms of applicants, acceptances, and retention has been developed and implemented using the system dynamics approach. The Model for University Strategic Evaluation (MUSE) is a simulation of the total operations of the university,…

  10. The SUPERBLINK catalog of stars with large proper motions, with enhancements from the first GAIA release.

    NASA Astrophysics Data System (ADS)

    Lepine, Sebastien

    2018-01-01

    The SUPERBLINK survey of stars with proper motion larger than 40 mas/yr is now complete for the entire sky down to magnitude V=20. The SUPERBLINK catalog provides astrometric and photometric data for a little over 2.7 million individual stars, and identifies their counterparts in a variety of large catalogs including ROSAT in the X-ray, GALEX in the ultraviolet, GAIA and SDSS in the optical, and 2MASS and WISE in the infrared. The addition of GAIA data notably yields proper motions to an accuracy of ~2mas/yr for 94% of the entries. Parallaxes with accuracies better than 10% are also now available for about 155,000 of these stars. Besides from identifying local populations of low-mass stars and white dwarfs, the catalog nows begins to map out with some detail the distribution in velocity space of various local stellar populations, including young M dwarfs and old metal-poor M subdwarfs. The catalog also allows one to search for common proper motion pairs, and other kinematic groups like nearby cluster members, moving group members, and local streams. This demonstrates the potential for nearby star research as more complete data becomes available from the GAIA mission.

  11. The Gaia spectrophotometric standard stars survey: II. Instrumental effects of six ground-based observing campaigns

    NASA Astrophysics Data System (ADS)

    Altavilla, G.; Marinoni, S.; Pancino, E.; Galleti, S.; Ragaini, S.; Bellazzini, M.; Cocozza, G.; Bragaglia, A.; Carrasco, J. M.; Castro, A.; Di Fabrizio, L.; Federici, L.; Figueras, F.; Gebran, M.; Jordi, C.; Masana, E.; Schuster, W.; Valentini, G.; Voss, H.

    2015-08-01

    The Gaia SpectroPhotometric Standard Stars (SPSS) survey started in 2006, was awarded almost 450 observing nights and accumulated almost 100 000 raw data frames with both photometric and spectroscopic observations. Such large observational effort requires careful, homogeneous, and automatic data reduction and quality control procedures. In this paper, we quantitatively evaluate instrumental effects that might have a significant (i.e., ≥ 1 %) impact on the Gaia SPSS flux calibration. The measurements involve six different instruments, monitored over the eight years of observations dedicated to the Gaia flux standards campaigns: DOLORES@TNG in La Palma, EFOSC2@NTT and ROSS@REM in La Silla, CAFOS@2.2 m in Calar Alto, BFOSC@Cassini in Loiano, and LaRuca@1.5 m in San Pedro Mártir. We examine and quantitatively evaluate the following effects: CCD linearity and shutter times, calibration frames stability, lamp flexures, second order contamination, light polarization, and fringing. We present methods to correct for the relevant effects which can be applied to a wide range of observational projects at similar instruments. Based on data obtained with BFOSC@Cassini in Loiano, Italy; EFOSC2@NTT in La Silla, Chile; DOLORES@TNG in La Palma, Spain; CAFOS@2.2 m in Calar Alto, Spain; LaRuca@1.5 m in San Pedro Mártir, Mexico (see acknowledgements for more details).

  12. Accuracy of the HST Standard Astrometric Catalogs w.r.t. Gaia

    NASA Astrophysics Data System (ADS)

    Kozhurina-Platais, V.; Grogin, N.; Sabbi, E.

    2018-02-01

    The goal of astrometric calibration of the HST ACS/WFC and WFC3/UVIS imaging instruments is to provide a coordinate system free of distortion to the precision level of 0.1 pixel 4-5 mas or better. This astrometric calibration is based on two HST astrometric standard fields in the vicinity of the globular clusters, 47 Tuc and omega Cen, respectively. The derived calibration of the geometric distortion is assumed to be accurate down to 2-3 mas. Is this accuracy in agreement with the true value? Now, with the access to globally accurate positions from the first Gaia data release (DR1), we found that there are measurable offsets, rotation, scale and other deviations of distortion parameters in two HST standard astrometric catalogs. These deviations from the distortion-free and properly aligned coordinate system should be accounted and corrected for, so that the high precision HST positions are free of any systematic errors. We also found that the precision of the HST pixel coordinates is substantially better than the accuracy listed in the Gaia DR1. Therefore, in order to finalize the components of distortion in the HST standard catalogs, the next release of Gaia data is needed.

  13. To Boldly Go Where No Man has Gone Before: Seeking Gaia's Astrometric Solution with AGIS

    NASA Astrophysics Data System (ADS)

    Lammers, U.; Lindegren, L.; O'Mullane, W.; Hobbs, D.

    2009-09-01

    Gaia is ESA's ambitious space astrometry mission with a foreseen launch date in late 2011. Its main objective is to perform a stellar census of the 1,000 million brightest objects in our galaxy (completeness to V=20 mag) from which an astrometric catalog of micro-arcsec (μas) level accuracy will be constructed. A key element in this endeavor is the Astrometric Global Iterative Solution (AGIS) - the mathematical and numerical framework for combining the ≈80 available observations per star obtained during Gaia's 5 yr lifetime into a single global astrometic solution. AGIS consists of four main algorithmic cores which improve the source astrometic parameters, satellite attitude, calibration, and global parameters in a block-iterative manner. We present and discuss this basic scheme, the algorithms themselves and the overarching system architecture. The latter is a data-driven distributed processing framework designed to achieve an overall system performance that is not I/O limited. AGIS is being developed as a pure Java system by a small number of geographically distributed European groups. We present some of the software engineering aspects of the project and show used methodologies and tools. Finally we will briefly discuss how AGIS is embedded into the overall Gaia data processing architecture.

  14. On-sky verification of the 6-h periodic basic angle variations of the Gaia satellite

    NASA Astrophysics Data System (ADS)

    Liao, Shilong; Lattanzi, Mario G.; Vecchiato, Alberto; Qi, Zhaoxiang; Crosta, Mariateresa; Tang, Zhenghong

    2018-04-01

    A Basic Angle (BA) of 106.5° separates the view directions of Gaia's two fields of view (FoV). A precise determination of the BA variations (BAV) is essential to guarantee a correct reconstruction of the global astrometric sphere, as residual systematic errors would result in, e.g., a bias in the parallaxes of the final Gaia catalog. The Basic Angle Monitoring (BAM) device, which provides a reliable and accurate estimation of BAV, shows that there exists a ~1 mas amplitude, 6-h period BA oscillation. It's essential to verify to what extent this signal is caused by real BAV, or is at least in part an effect of the BAM device itself. Here, we propose an astrometric on-sky approach to re-determine the 6-h periodic BAV. The results of this experiment, which treated a full day (17 Oct 2016) of Gaia astrometric data, recover a value for the 6-h oscillation of 1.856+/-0.857 mas. This is consistent, within the errors, with the BAM finding for that day.

  15. Chemical composition of the stellar cluster Gaia1: no surprise behind Sirius

    NASA Astrophysics Data System (ADS)

    Mucciarelli, A.; Monaco, L.; Bonifacio, P.; Saviane, I.

    2017-07-01

    We observed six He-clump stars of the intermediate-age stellar cluster Gaia1 with the MIKE/Magellan spectrograph. A possible extra-galactic origin of this cluster, recently discovered thanks to the first data release of the ESA Gaia mission, has been suggested, based on its orbital parameters. Abundances for Fe, α, proton- and neutron-capture elements have been obtained. We find no evidence of intrinsic abundance spreads. The iron abundance is solar ([FeI/H] = + 0.00 ± 0.01; σ = 0.03 dex). All the other abundance ratios are generally solar-scaled, similar to the Galactic thin disk and open cluster stars of similar metallicity. The chemical composition of Gaia1 does not support an extra-galactic origin for this stellar cluster, which can be considered as a standard Galactic open cluster. The full Table A.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/603/L7

  16. VizieR Online Data Catalog: OGLE: Gaia South Ecliptic Pole Field (Soszynski+, 2012)

    NASA Astrophysics Data System (ADS)

    Soszynski, I.; Udalski, A.; Poleski, R.; Kozlowski, S.; Wyrzykowski, L.; Pietrukowicz, P.; Szymanski, M. K.; Kubiak, M.; Pietrzynski, G.; Ulaczyk, K.; Skowron, J.

    2013-03-01

    We present a comprehensive analysis of the Gaia South Ecliptic Pole (GSEP) field, 5.3 square degrees area around the South Ecliptic Pole on the outskirts of the LMC, based on the data collected during the fourth phase of the Optical Gravitational Lensing Experiment, OGLE-IV. The GSEP field will be observed during the commissioning phase of the ESA Gaia space mission for testing and calibrating the Gaia instruments. We provide the photometric maps of the GSEP region containing the mean VI photometry of all detected stellar objects and their equatorial coordinates. We show the quality and completeness of the OGLE-IV photometry and color-magnitude diagrams of this region. We conducted an extensive search for variable stars in the GSEP field leading to the discovery of 6789 variable stars. In this sample we found 132 classical Cepheids, 686 RR Lyr type stars, 2819 long-period, and 1377 eclipsing variables. Several objects deserving special attention were also selected, including a new classical Cepheid in a binary eclipsing system. (9 data files).

  17. Detection of spectroscopic binaries: lessons from the Gaia-ESO survey

    NASA Astrophysics Data System (ADS)

    van der Swaelmen, Mathieu; Merle, Thibault; van Eck, Sophie; Jorissen, Alain; Zwitter, Tomaž

    2018-04-01

    The Gaia-ESO survey (GES; Gilmore et al. (2012), Randich et al. (2013)) is a spectroscopic survey complementing the Gaia mission to bring accurate radial velocities and chemical abundances for 105 stars. Merle et al. (submitted to A&A see also this volume) developped a tool (DOE) to detect multiple peaks in the cross-correlation functions (CCFs) of GES spectra. Using the GIRAFFE HR10 and HR21 settings, we were able to compare the efficiency of our SB detection tool depending on the wavelength range and resolution. We show that a careful design of CCF masks can improve the detection rate in the HR21 settings. HR21 spectra are similar to the ones produced by the RVS spectrograph of the Gaia mission, though the lower resolution of RVS spectra may result in a lower detection efficiency than the case of HR21. Analysis of RVS spectra in the context of spectroscopic binaries can take advantage of the lessons learnt from the GES to maximize the detection rate.

  18. A Probabilistic Approach to Fitting Period–luminosity Relations and Validating Gaia Parallaxes

    SciTech Connect

    Sesar, Branimir; Fouesneau, Morgan; Bailer-Jones, Coryn A. L.

    Pulsating stars, such as Cepheids, Miras, and RR Lyrae stars, are important distance indicators and calibrators of the “cosmic distance ladder,” and yet their period–luminosity–metallicity (PLZ) relations are still constrained using simple statistical methods that cannot take full advantage of available data. To enable optimal usage of data provided by the Gaia mission, we present a probabilistic approach that simultaneously constrains parameters of PLZ relations and uncertainties in Gaia parallax measurements. We demonstrate this approach by constraining PLZ relations of type ab RR Lyrae stars in near-infrared W 1 and W 2 bands, using Tycho- Gaia Astrometric Solution (TGAS) parallaxmore » measurements for a sample of ≈100 type ab RR Lyrae stars located within 2.5 kpc of the Sun. The fitted PLZ relations are consistent with previous studies, and in combination with other data, deliver distances precise to 6% (once various sources of uncertainty are taken into account). To a precision of 0.05 mas (1 σ ), we do not find a statistically significant offset in TGAS parallaxes for this sample of distant RR Lyrae stars (median parallax of 0.8 mas and distance of 1.4 kpc). With only minor modifications, our probabilistic approach can be used to constrain PLZ relations of other pulsating stars, and we intend to apply it to Cepheid and Mira stars in the near future.« less

  19. Impact of quasar proper motions on the alignment between the International Celestial Reference Frame and the Gaia reference frame

    NASA Astrophysics Data System (ADS)

    Liu, J.-C.; Malkin, Z.; Zhu, Z.

    2018-03-01

    The International Celestial Reference Frame (ICRF) is currently realized by the very long baseline interferometry (VLBI) observations of extragalactic sources with the zero proper motion assumption, while Gaia will observe proper motions of these distant and faint objects to an accuracy of tens of microarcseconds per year. This paper investigates the difference between VLBI and Gaia quasar proper motions and it aims to understand the impact of quasar proper motions on the alignment of the ICRF and Gaia reference frame. We use the latest time series data of source coordinates from the International VLBI Service analysis centres operated at Goddard Space Flight Center (GSF2017) and Paris observatory (OPA2017), as well as the Gaia auxiliary quasar solution containing 2191 high-probability optical counterparts of the ICRF2 sources. The linear proper motions in right ascension and declination of VLBI sources are derived by least-squares fits while the proper motions for Gaia sources are simulated taking into account the acceleration of the Solar system barycentre and realistic uncertainties depending on the source brightness. The individual and global features of source proper motions in GSF2017 and OPA2017 VLBI data are found to be inconsistent, which may result from differences in VLBI observations, data reduction and analysis. A comparison of the VLBI and Gaia proper motions shows that the accuracies of the components of rotation and glide between the two systems are 2-4 μas yr- 1 based on about 600 common sources. For the future alignment of the ICRF and Gaia reference frames at different wavelengths, the proper motions of quasars must necessarily be considered.

  20. VizieR Online Data Catalog: Radio fluxes of 195 ICRF2-Gaia transfer sources (Le Bail+, 2016)

    NASA Astrophysics Data System (ADS)

    Le Bail, K.; Gipson, J. M.; Gordon, D.; MacMillan, D. S.; Behrend, D.; Thomas, C. C.; Bolotin, S.; Himwich, W. E.; Baver, K. D.; Corey, B. E.; Titus, M.; Bourda, G.; Charlot, P.; Collioud, A.

    2016-07-01

    The second realization of the International Celestial Reference Frame (ICRF2) is based on Very Long Baseline Interferometry (VLBI) data at radio frequencies in X band and S band. The European Space Agency's Gaia mission, launched on 2013 December 19, started routine scientific operations in 2014 July. By scanning the whole sky, it is expected to observe ~500000 Quasi Stellar Objects in the optical domain. This means that, in the future, two extragalactic celestial reference frames, at two different frequency domains, will coexist. It will thus be important to align them very accurately. In 2012, the Laboratoire d'Astrophysique de Bordeaux (LAB) selected 195 sources from ICRF2 that will be observed by Gaia and should be suitable for aligning the radio and optical frames: they are called ICRF2-Gaia transfer sources. The LAB submitted a proposal to the International VLBI Service (IVS) to regularly observe these ICRF2-Gaia transfer sources at the same rate as Gaia observes them in the optical realm, e.g., roughly once a month. Of the 195 sources, all but one have been successfully observed in the 12 months prior to 2015 September 01. Table1 lists the 195 ICRF2-Gaia transfer sources. Beginning in 2003 June, the Goddard VLBI group developed a program to purposefully monitor when sources were observed and to increase the observations of "under-observed" sources. In 2013 March, we added all 195 ICRF2-Gaia transfer sources to the IVS source monitoring program with an observation target of 12 successful sessions per year. (1 data file).

  1. On the kinematic detection of accreted streams in the Gaia era: a cautionary tale

    NASA Astrophysics Data System (ADS)

    Jean-Baptiste, I.; Di Matteo, P.; Haywood, M.; Gómez, A.; Montuori, M.; Combes, F.; Semelin, B.

    2017-08-01

    The ΛCDM cosmological scenario predicts that our Galaxy should contain hundreds of stellar streams in the solar vicinity, fossil relics of the merging history of the Milky Way and more generally of the hierarchical growth of galaxies. Because of the mixing time scales in the inner Galaxy, it has been claimed that these streams should be difficult to detect in configuration space but can still be identifiable in kinematic-related spaces like the energy/angular momenta spaces, E - Lz and L⊥ - Lz, or spaces of orbital/velocity parameters. By means of high-resolution, dissipationless N-body simulations containing between 25 × 106 and 35 × 106 particles, we model the accretion of a series of up to four 1:10 mass ratio satellites then up to eight 1:100 satellites and search systematically for the signature of accretions in these spaces. The novelty of this work with respect to the majority of those already published is our analysis of fully consistent models, where both the satellite(s) and the Milky Way galaxy are "live" systems, which can react to the interaction and experience kinematical heating, tidal effects and dynamical friction (the latter, a process often neglected in previous studies). We find that, in agreement with previous works, all spaces are rich in substructures, but that, contrary to previous works, the origin of these substructures - accreted or in-situ - cannot be determined for the following reasons. In all spaces considered (1) each satellite provides the origin of several independent over-densities; (2) over-densities of multiple satellites overlap; (3) satellites of different masses can produce similar substructures; (4) the overlap between the in-situ and the accreted population is considerable everywhere; and (5) in-situ stars also form substructures in response to the satellite(s') accretion. These points are valid even if the search is restricted to kinematically-selected halo stars only. As we are now entering the "Gaia era", our

  2. Detailed chemical abundance analysis of the thick disk star cluster Gaia 1

    NASA Astrophysics Data System (ADS)

    Koch, Andreas; Hansen, Terese T.; Kunder, Andrea

    2018-01-01

    Star clusters, particularly those objects in the disk-bulge-halo interface are as yet poorly charted, despite the fact that they carry important information about the formation and the structure of the Milky Way. Here, we present a detailed chemical abundance study of the recently discovered object Gaia 1. Photometry has previously suggested it as an intermediate-age, moderately metal-rich system, although the exact values for its age and metallicity remained ambiguous in the literature. We measured detailed chemical abundances of 14 elements in four red giant members, from high-resolution (R = 25 000) spectra that firmly establish Gaia 1 as an object associated with the thick disk. The resulting mean Fe abundance is -0.62 ± 0.03(stat.)± 0.10(sys.) dex, which is more metal-poor than indicated by previous spectroscopy from the literature, but it is fully in line with values from isochrone fitting. We find that Gaia 1 is moderately enhanced in the α-elements, which allowed us to consolidate its membership with the thick disk via chemical tagging. The cluster's Fe-peak and neutron-capture elements are similar to those found across the metal-rich disks, where the latter indicate some level of s-process activity. No significant spread in iron nor in other heavy elements was detected, whereas we find evidence of light-element variations in Na, Mg, and Al. Nonetheless, the traditional Na-O and Mg-Al (anti-)correlations, typically seen in old globular clusters, are not seen in our data. This confirms that Gaia 1 is rather a massive and luminous open cluster than a low-mass globular cluster. Finally, orbital computations of the target stars bolster our chemical findings of Gaia 1's present-day membership with the thick disk, even though it remains unclear which mechanisms put it in that place. This paper includes data gathered with the 2.5 meter du Pont Telescope located at Las Campanas Observatory, Chile.Full Table 2 is available at the CDS via anonymous ftp to http

  3. VizieR Online Data Catalog: The Initial Gaia Source List (IGSL) (Smart, 2013)

    NASA Astrophysics Data System (ADS)

    Smart, R. L.; Nicastro, L.

    2013-11-01

    The IGSL is a compilation catalog produced for the Gaia mission. We have combined data from the following catalogs or datasets to produce a homogenous list of positons, proper motions, photometry in a blue and red band and estimates of the magnitudes in the Gaia G and G_RVS bands. Included Catalogs: Tycho2, LQRF, UCAC4, SDSS-DR9, PPMXL, GSC23, GEPC, OGLE, Sky2000, 2MASS. Note that in compiling the various entries we did not consider the individual flags. Overall, we think this catalog is reliable but there will be errors, mismatches and duplicates. The user should use this catalog with that in mind, it is fine for statistical studies that has some way to remove obviously incorrect entries but it should only be used with care for individual objects. The source catalogs used to produce the IGSL are: * The Gaia Ecliptic Pole Catalog, version 3.0 (GEPC) Altmann & Bastian 2009, "Ecliptic Poles Catalogue Version 1.1" ESA Document GAIA-C3-TN-ARI-MA-002 URL http://www.rssd.esa.int/llink/livelink/open/2885828 * GSC2.3: GSC2 version 2.3, Lasker et al. 2008AJ....136..735L (I/305) * an excerpt of the 4th version of the Gaia Initial QSO Catalog (GIQC) as compiled by the GWP-S-335-13000, formed by Alexandre H. Andrei, Christophe Barache, Dario N. da Silva Neto, Francois Taris, Geraldine Bourda, Jean-Francois Le Campion, Jean Souchay, J.J. Pereira Osorio, Julio I. Bueno de Camargo, Marcelo Assafin, Roberto Vieira Martins, Sebastien Bouquillon, Sebastien Lambert, Sonia Anton, Patrick Charlot * OGLE: Optical Gravitational Lensing Experiment version III (Szymaski et al., 2011, Cat. J/AcA/61/83) * PPMXL: Positions and Proper Motions "Extra Large" Catalog, Roeser et al. (2010, Cat. I/317) * SDSS: Sloan Digital Sky Survey data release 9, Cat. V/139 * UCAC4: Zacharias et al., 2012, Cat. I/322 * Tycho-2, Hoeg et al., 2000, Cat. I/259 (1 data file).

  4. Universality away from critical points in a thermostatistical model

    NASA Astrophysics Data System (ADS)

    Lapilli, C. M.; Wexler, C.; Pfeifer, P.

    Nature uses phase transitions as powerful regulators of processes ranging from climate to the alteration of phase behavior of cell membranes to protect cells from cold, building on the fact that thermodynamic properties of a solid, liquid, or gas are sensitive fingerprints of intermolecular interactions. The only known exceptions from this sensitivity are critical points. At a critical point, two phases become indistinguishable and thermodynamic properties exhibit universal behavior: systems with widely different intermolecular interactions behave identically. Here we report a major counterexample. We show that different members of a family of two-dimensional systems —the discrete p-state clock model— with different Hamiltonians describing different microscopic interactions between molecules or spins, may exhibit identical thermodynamic behavior over a wide range of temperatures. The results generate a comprehensive map of the phase diagram of the model and, by virtue of the discrete rotors behaving like continuous rotors, an emergent symmetry, not present in the Hamiltonian. This symmetry, or many-to-one map of intermolecular interactions onto thermodynamic states, demonstrates previously unknown limits for macroscopic distinguishability of different microscopic interactions.

  5. Metropolitan Universities: An Emerging Model in American Higher Education.

    ERIC Educational Resources Information Center

    Johnson, Daniel M., Ed.; Bell, David A., Ed.

    This volume contains 29 readings reprinted from the journal "Metropolitan Universities: An International Forum," selected to demonstrate the unique mission and characteristics of metropolitan universities and to recognize the special challenges they face in addressing the nation's major urban issues. The papers include: "What Is a Metropolitan…

  6. University of Phoenix Says Test Scores Vindicate Its Academic Model

    ERIC Educational Resources Information Center

    Blumenstyk, Goldie

    2008-01-01

    The University of Phoenix is often derided by traditional academics for caring more about its bottom line than about academic quality, and every year, the annual report issued by its parent company focuses more on profits than student performance. This article reports that the institution that has become the largest private university in North…

  7. Model of Collaboration between Two Universities: Meeting the Challenge.

    ERIC Educational Resources Information Center

    Easterbrooks, Susan R.; Laughton, Joan M.

    This paper describes a collaborative program of Georgia State University and the University of Georgia to train prospective teachers of the deaf in accordance with recent standards developed by the Council on Education of the Deaf (CED). The program involves: (1) a shared advisory committee; (2) foundation coursework taken separately at the two…

  8. University as Foundations: The New Model of Lower Saxony.

    ERIC Educational Resources Information Center

    Palandt, Klaus

    2003-01-01

    In Lower Saxony, the legal status of universities as foundations under public law is offered because increased autonomy is a core condition for effective and economical management of resources and can attract increased private and public funding and improve corporate identity. A university senate can apply to receive this status. The university…

  9. Alternative Model of Funding for Academic Research in Nigerian Universities

    ERIC Educational Resources Information Center

    Olayiwola, Shina

    2010-01-01

    Funding of academic research in Nigerian universities by Government (5 per cent recurrent grants) is a policy dictated by the National Universities Commission (NUC) as the central body for allocating research funds. This research fund, little as it is, is irregular and inadequate and to make it worse is difficult to access. These aforementioned…

  10. A Working Model of a New American University

    ERIC Educational Resources Information Center

    Crow, Michael M.; Loui, Kimberly

    2006-01-01

    American universities confront unique challenges as they move into the twenty-first century. These include rapid population growth, demographic and economic changes on both global and regional levels, and the numerous local challenges that face today's communities. Modern universities must engage, and in turn be engaged by, their communities in…

  11. Universal Breadwinner versus Universal Caregiver Model: Fathers' Involvement in Caregiving and Well-Being of Mothers of Offspring with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Chou, Yueh-Ching; Kröger, Teppo; Pu, Cheng-yun

    2016-01-01

    Background: The universal breadwinner model means both parents are employed; while the universal caregiver model implies that the father's hours of caregiving are equal or higher to those of the mother. This study aims to examine the hypothesis that the universal caregiver model is more related to the overall well-being of mothers of children with…

  12. Toward University Modeling Instruction--Biology: Adapting Curricular Frameworks from Physics to Biology

    ERIC Educational Resources Information Center

    Manthey, Seth; Brewe, Eric

    2013-01-01

    University Modeling Instruction (UMI) is an approach to curriculum and pedagogy that focuses instruction on engaging students in building, validating, and deploying scientific models. Modeling Instruction has been successfully implemented in both high school and university physics courses. Studies within the physics education research (PER)…

  13. Model for a university-based clinical research development infrastructure.

    PubMed

    Havermahl, Tamara; LaPensee, Elizabeth; Williams, David; Clauw, Daniel; Parker, Robert A; Downey, Brad; Liu, Jing; Myles, James

    2015-01-01

    The Research Development Core (RDC) is housed within the Michigan Institute for Clinical & Health Research (MICHR) at the University of Michigan (U-M). Established in 2006, RDC provides no-cost, in-person consultations to help U-M investigators strengthen their grant proposals. RDC offers investigators feedback and critique on all aspects of their study design, plus partnerships, funding mechanisms, and future directions. This article describes RDC's model and provides data describing the success of its services.RDC is composed of a multidisciplinary team of professionals in grant development. It comprises two senior faculty codirectors from the U-M Medical School, two senior biostatisticians, outside faculty content experts, and RDC administrative staff. Investigators contact RDC to request a consultation and submit advance grant materials for review by the RDC team. During the consultation, investigators explain their project and identify challenges. The RDC team and additional experts offer feedback that is captured in meeting notes and provided to investigators. RDC commitments beyond the meetings are implemented and carefully tracked. Investigators may also request grant editing, budgeting, or proposal submission assistance. Investigators using RDC have been awarded $44.5 million since 2011.The demand for RDC consultations doubled from 2010 to 2011 and reached a high of 131 consultations in 2012. Investigator feedback has been positive: 80% reported that RDC had a strong impact on their proposal, and over 90% indicated that they would recommend RDC to colleagues. MICHR is committed to providing investigators with RDC services to better ensure strong grant applications and successful research careers.

  14. Model for a University-Based Clinical Research Development Infrastructure

    PubMed Central

    Havermahl, Tamara; LaPensee, Elizabeth; Williams, David; Clauw, Daniel; Parker, Robert A.; Downey, Brad; Liu, Jing; Myles, James

    2014-01-01

    The Research Development Core (RDC) is housed within the Michigan Institute for Clinical & Health Research (MICHR) at the University of Michigan (U-M). Established in 2006, RDC provides no-cost, in-person consultations to help U-M investigators strengthen their grant proposals. RDC offers investigators feedback and critique on all aspects of their study design, plus partnerships, funding mechanisms and future directions. This article describes RDC’s model and provides data describing the success of its services. The RDC is composed of a multidisciplinary team of professionals in grant development. It is comprised of two senior faculty co-directors from the U-M Medical School, two senior biostatisticians, outside faculty content experts, and RDC administrative staff. Investigators contact RDC to request a consultation and submit advance grant materials for review by the RDC team. During the consultation, investigators explain their project and identify challenges. The RDC team and additional experts offer feedback that is captured in meeting notes and provided to investigators. RDC commitments beyond the meetings are implemented and carefully tracked. Investigators may also request grant editing, budgeting, or proposal submission assistance. Investigators utilizing RDC have been awarded $44.5 million since 2011. The demand for RDC consultations doubled from 2010 to 2011, and reached a high of 131 consultations in 2012. Investigator feedback has been positive: 80% reported RDC had a strong impact on their proposal, and over 90% indicated they would recommend RDC to colleagues. MICHR is committed to providing investigators with RDC services to better ensure strong grant applications and successful research careers. PMID:25340362

  15. Extracción de conocimiento en bases de datos astronómicas mediante redes de neuronas artificiales: aplicaciones en la misión Gaia

    NASA Astrophysics Data System (ADS)

    Fustes Villadóniga, Diego

    2014-02-01

    improve the AP estimates, wavelet signal processing techniques, applied to the RVS spectrum, are studied. Despite the effectiveness shown by ANNs in estimating APs, in principle they lack the ability to provide an uncertainty value on these estimates, making it impossible to determine their reliability. Because of this, a new architecture for the ANN is presented in which the inputs and outputs are reversed, so that the ANN estimates the RVS spectrum from the APs. Such an architecture is called Generative ANN (GANN) and is applied to the AP estimation of a set of simulated RVS spectra for the Gaia mission, where it is more effective than the conventional ANN model, in the case of faint stars with low SNR. Finally, the GANN can be applied for obtaining the posterior probability of each of the APs according to the RVS spectrum, allowing for their more complete analysis. Given the nature of the Gaia mission, which is the first astronomical mission that will observe, in an unbiased way, the entire sky up to magnitude 20, a large number of outliers are expected. The OA package in CU8 handles the processing of this type of objects, which are defined as those that could not be reliably classified by the methods in the upstream classification packages. OA methods are based on the unsupervised learning of all outliers. Such learning has two parts: clustering and dimensionality reduction. The Self-Organizing Map (SOM) algorithm is selected as a basis for this learning. Its effectiveness is demonstrated when it is applied, with an optimal configuration, to the Gaia simulations. Furthermore, the algorithm is applied to real outliers from the SDSS catalog. Since a subsequent identification of the clusters obtained by the SOM is necessary, two different methods of identification are applied. The first method is based on the similarity between the SOM prototypes and the Gaia simulations, and the second method is based on the recovery of stored classifications in the SIMBAD catalog by

  16. Investigation on the governance model and effect of medical schools merged with comprehensive universities in China.

    PubMed

    Bai, Ge; Luo, Li

    2013-08-01

    This investigation analyzes the management of medical schools merged with comprehensive universities through internet search and research review to reveal management model and effect of the merger. The conclusion is safely reached that governance models are divided into two different patterns: centralized management and decentralized management. Eight universities, representing the two models, were selected and evaluated comprehensively. Among them, the universities that carried out decentralized management have greater development after the merger based on a quality comparison concerning freshmen, faculty, teaching, and research between the two patterns. © 2013 Wiley Publishing Asia Pty Ltd and Chinese Cochrane Center, West China Hospital of Sichuan University.

  17. VizieR Online Data Catalog: Distances of Gaia DR1 TGAS sources (Astraatmadja+, 2016)

    NASA Astrophysics Data System (ADS)

    Astraatmadja, T. L.; Bailer-Jones, C. A. L.

    2016-09-01

    This is a catalogue of distances and their asymmetric uncertainties inferred from the parallaxes published in the Gaia DR1 catalogue. Two priors are used: The exponentially decreasing space density and the Milky Way prior. For the exponentially decreasing space density prior, two scale lengths are used: 110pc and 1350pc. The former is based on a fitting of the true distance distribution of a subset of the GUMS catalogue (Robin et al., 2012, Cat. VI/137) which are limited to V<11. This is the magnitude at which Tycho-2 is 99% complete. The latter is based on the same procedure but limited to G=20.7, which is the expected limiting magnitude of Gaia. For the Milky Way prior, the parameters are described in the paper. We report the mode of the posterior PDF, the median, the 90% credible interval, and a standard deviation in distance which are calculated by scaling the 90% into 68.3%. The Cepheids data used for the validation of the results are included here as well. They are taken from Groenewegen (2013, Cat. J/A+A/550/A70) and cross-matched with Hipparcos and/or Tycho by making a Simbad query of each Cepheids and finding the corresponding Hipparcos and/or Tyho identifier. The distances are inferred either by neglecting the systematic uncertainties of 0.3mas (Gaia Collaboration et al., 2016, Cat. I/337) for reasons described in the paper, or by adding a systematic uncertainties of 0.3mas in quadrature with the random parallax uncertainties. We provide both results here. (4 data files).

  18. Stellar Occultations by TNOs and Centaurs: first results in the “Gaia era”

    NASA Astrophysics Data System (ADS)

    Rossi, Gustavo; Vieira-Martins, Roberto; Sicardy, Bruno; Ortiz, Jose Luis; Rio Group, Lucky Star Occultation Team, Granada Occultation Team

    2017-10-01

    After the first release of the GAIA catalog (in September/2016), stellar positions are now known with unprecedented accuracy, reaching values of the order of milliarcseconds. This improvement reflected into a stunning accuracy on the astrometry of moving objects, such as TNOs. Unfortunately, Gaia stars proper motions will be only available on the second data release (DR2) next year, so there is still a need to use hybrid stellar catalogs for occultation predictions until then. Despite that, stellar occultations predictions are now much more accurate, and the biggest uncertainties comes mainly from the object ephemerides. This issue will be overcome by large surveys such as the LSST, which will provide positions for the known TNOs and it is expected to increase the number of known TNOs by nearly 40,000, with an unprecedent amount of acquired information.This huge amount of data also poses a new era in stellar occultations: predictions will be very accurate and the participation of professional astronomers, laboratories, and the amateur community will be crucial to observe the predicted events; observation campaigns will need to be selected according to a specific scientific purpose such as the probability to detect rings or archs around a body, the presence of atmosphere or even the detection of topographic features; the development of softwares capable of reducing the data more efficiently and an easier method to coordinate observation campaigns are needed.Here we present some impressive results obtained from predictions and observed occultations in 2017 (among them we have Pluto, Chariklo and Haumea), the problems we are starting to face in the beginning of the “Gaia era” and the future challenges of stellar occultation.

  19. Gaia Confirms that SDSS J102915+172927 is a Dwarf Star

    NASA Astrophysics Data System (ADS)

    Bonifacio, P.; Caffau, E.; Spite, M.; Spite, F.; François, P.; Zaggia, S.; Arenou, F.; Haigron, R.; Leclerc, N.; Marchal, O.; Panuzzo, P.; Plum, G.; Sartoretti, P.

    2018-05-01

    The Gaia Data Release 2 provides a parallax of 0.734+/-0.073 mas for SDSS J102915+172927, currently the most metal-poor known object. This parallax implies that it is dwarf star, ruling out the scenario that it is a subgiant. The subgiant scenario had as a corollary that the star had been formed in a medium highly enriched in C, thus making line cooling efficient during the collapse, that was also highly enriched in Fe by Type Ia SNe. This scenario can also now be ruled out for this star, reinforcing the need of dust cooling and fragmentation to explain its formation.

  20. Testing the Distance Scale of the Gaia TGAS Catalogue by the Kinematic Method

    NASA Astrophysics Data System (ADS)

    Bobylev, V. V.; Bajkova, A. T.

    2018-03-01

    We have studied the simultaneous and separate solutions of the basic kinematic equations obtained using the stellar velocities calculated on the basis of data from the Gaia TGAS and RAVE5 catalogues. By comparing the values of Ω'0 found by separately analyzing only the line-of-sight velocities of stars and only their proper motions, we have determined the distance scale correction factor p to be close to unity, 0.97 ± 0.04. Based on the proper motions of stars from the Gaia TGAS catalogue with relative trigonometric parallax errors less than 10% (they are at a mean distance of 226 pc), we have found the components of the group velocity vector for the sample stars relative to the Sun ( U, V, W)⊙ = (9.28, 20.35, 7.36) ± (0.05, 0.07, 0.05) km s-1, the angular velocity of Galactic rotation Ω0 = 27.24 ± 0.30 km s-1 kpc-1, and its first derivative Ω'0 = -3.77 ± 0.06 km s-1 kpc-2; here, the circular rotation velocity of the Sun around the Galactic center is V 0 = 218 ± 6 km s-1 kpc (for the adopted distance R 0 = 8.0 ± 0.2 kpc), while the Oort constants are A = 15.07 ± 0.25 km s-1 kpc-1 and B = -12.17 ± 0.39 km s-1 kpc-1, p = 0.98 ± 0.08. The kinematics of Gaia TGAS stars with parallax errors more than 10% has been studied by invoking the distances from a paper by Astraatmadja and Bailer-Jones that were corrected for the Lutz-Kelker bias. We show that the second derivative of the angular velocity of Galactic rotation Ω'0 = 0.864 ± 0.021 km s-1 kpc-3 is well determined from stars at a mean distance of 537 pc. On the whole, we have found that the distances of stars from the Gaia TGAS catalogue calculated using their trigonometric parallaxes do not require any additional correction factor.

  1. Towards a Theory of University Entrepreneurship: Developing a Theoretical Model

    ERIC Educational Resources Information Center

    Woollard, David

    2010-01-01

    This paper sets out to develop a robust theory in a largely atheoretical field of study. The increasing importance of entrepreneurship in delivering the "Third Mission" calls for an enhanced understanding of the university entrepreneurship phenomenon, not solely as a subject of academic interest but also to guide the work of practitioners in the…

  2. From Universal Laws of Cognition to Specific Cognitive Models

    ERIC Educational Resources Information Center

    Chater, Nick; Brown, Gordon D. A.

    2008-01-01

    The remarkable successes of the physical sciences have been built on highly general quantitative laws, which serve as the basis for understanding an enormous variety of specific physical systems. How far is it possible to construct universal principles in the cognitive sciences, in terms of which specific aspects of perception, memory, or decision…

  3. Process-Model Feminism in the Corporate University

    ERIC Educational Resources Information Center

    Spitzer-Hanks, D. T.

    2016-01-01

    In a period characterised by worries over the rise of the corporate university, it is important to ask what role feminism plays in the academy, and whether that role is commensurate with feminist values and ethics. Commercial and political pressures brought to bear on the encounter between instructor and student can rob teaching of its efficacy,…

  4. Recommendations to Improve Space Projection Models and University Space Usage

    ERIC Educational Resources Information Center

    Stigall, Sam W.

    2007-01-01

    In today"s economy, public university administrators need to reflect on current practices for reporting and projecting space requirements to government entities as the cost of constructing new facilities or renovating space rises while income from legislative appropriations diminishes. As stewards of public buildings and funds, institutions…

  5. Modelling Graduate Skill Transfer from University to the Workplace

    ERIC Educational Resources Information Center

    Jackson, Denise

    2016-01-01

    This study explores skill transfer in graduates as they transition from university to the workplace. Graduate employability continues to dominate higher education agendas yet the transfer of acquired skills is often assumed. The study is prompted by documented concern with graduate performance in certain employability skills, and prevalent skill…

  6. Evaluation of Stress Management Education: The University of Maryland Model.

    ERIC Educational Resources Information Center

    Allen, Roger J.

    This study evaluated the efficacy of the undergraduate service program "Controlling Stress & Tension" at the University of Maryland in terms of improving the health status of participants across biomedical stress reactivity and psychometric variables. Six hundred fifty-three participants were compared to 264 control subjects for pre-…

  7. Is There a Latin American Model of the University?

    ERIC Educational Resources Information Center

    Bernasconi, Andres

    2008-01-01

    Recently, Latin America has seen the advent of research activities to meet the call for research that long preceded them and of the full-time research faculty who engage in them. These developments have taken place as the region partakes in contemporary worldwide trends that have affected universities elsewhere: the consequences of the increased…

  8. SRC: A Model of Industry-University Cooperation.

    ERIC Educational Resources Information Center

    Cavin, Ralph K., III; Phillips, D. Howard

    1988-01-01

    Describes the Semiconductor Research Corporation (SRC), a non-profit research cooperative designed to conduct research in the field of integrated circuits, principally in U.S. universities, with membership restricted to U.S.-owned companies. Analyzes SRC's impact on the U.S. educational system. (TW)

  9. An Iterative Needs Assessment/Evaluation Model for a Japanese University English-Language Program

    ERIC Educational Resources Information Center

    Brown, Kathleen A.

    2009-01-01

    The focus of this study is the development and implementation of the Iterative Needs Assessment/Evaluation Model for use as part of an English curriculum reform project at a four-year university in Japan. Three questions were addressed in this study: (a) what model components were necessary for use in a Japanese university setting; (b) what survey…

  10. A Decision Support Model and Tool to Assist Financial Decision-Making in Universities

    ERIC Educational Resources Information Center

    Bhayat, Imtiaz; Manuguerra, Maurizio; Baldock, Clive

    2015-01-01

    In this paper, a model and tool is proposed to assist universities and other mission-based organisations to ascertain systematically the optimal portfolio of projects, in any year, meeting the organisations risk tolerances and available funds. The model and tool presented build on previous work on university operations and decision support systems…

  11. An Unusually Effective School/University Programme: The Plymouth and Peninsula Model

    ERIC Educational Resources Information Center

    la Velle, Linda; Reynolds, David; Nichol, Jon

    2013-01-01

    This article describes a novel UK school/university partnership, the "Plymouth Model" designed to encourage young people from disadvantaged backgrounds to aim for higher education (HE) study. The model incorporates the activity of university students, researchers and teachers working together to improve aspirations and outcomes for…

  12. Evaluating the Liberal Arts Model in the Context of the Dutch University College

    ERIC Educational Resources Information Center

    Cooper, Nathan

    2018-01-01

    The Liberal Arts model of undergraduate education within small, internationally-focused University Colleges is becoming increasingly popular in Europe. This trend is most notable in the Netherlands, where the liberal arts model is acclaimed as filling a gap in Dutch undergraduate education at conventional research universities. This paper explores…

  13. The Gaia-ESO Survey: Sodium and aluminium abundances in giants and dwarfs. Implications for stellar and Galactic chemical evolution

    NASA Astrophysics Data System (ADS)

    Smiljanic, R.; Romano, D.; Bragaglia, A.; Donati, P.; Magrini, L.; Friel, E.; Jacobson, H.; Randich, S.; Ventura, P.; Lind, K.; Bergemann, M.; Nordlander, T.; Morel, T.; Pancino, E.; Tautvaišienė, G.; Adibekyan, V.; Tosi, M.; Vallenari, A.; Gilmore, G.; Bensby, T.; François, P.; Koposov, S.; Lanzafame, A. C.; Recio-Blanco, A.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Franciosini, E.; Heiter, U.; Hill, V.; Hourihane, A.; Jofré, P.; Lardo, C.; de Laverny, P.; Lewis, J.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Sbordone, L.; Sousa, S. G.; Worley, C. C.; Zaggia, S.

    2016-05-01

    Context. Stellar evolution models predict that internal mixing should cause some sodium overabundance at the surface of red giants more massive than ~1.5-2.0 M⊙. The surface aluminium abundance should not be affected. Nevertheless, observational results disagree about the presence and/or the degree of Na and Al overabundances. In addition, Galactic chemical evolution models adopting different stellar yields lead to very different predictions for the behavior of [Na/Fe] and [Al/Fe] versus [Fe/H]. Overall, the observed trends of these abundances with metallicity are not well reproduced. Aims: We readdress both issues, using new Na and Al abundances determined within the Gaia-ESO Survey. Our aim is to obtain better observational constraints on the behavior of these elements using two samples: I) more than 600 dwarfs of the solar neighborhood and of open clusters and II) low- and intermediate-mass clump giants in six open clusters. Methods: Abundances were determined using high-resolution UVES spectra. The individual Na abundances were corrected for nonlocal thermodynamic equilibrium effects. For the Al abundances, the order of magnitude of the corrections was estimated for a few representative cases. For giants, the abundance trends with stellar mass are compared to stellar evolution models. For dwarfs, the abundance trends with metallicity and age are compared to detailed chemical evolution models. Results: Abundances of Na in stars with mass below ~2.0 M⊙, and of Al in stars below ~3.0 M⊙, seem to be unaffected by internal mixing processes. For more massive stars, the Na overabundance increases with stellar mass. This trend agrees well with predictions of stellar evolutionary models. For Al, our only cluster with giants more massive than 3.0 M⊙, NGC 6705, is Al enriched. However, this might be related to the environment where the cluster was formed. Chemical evolution models that well fit the observed [Na/Fe] vs. [Fe/H] trend in solar neighborhood dwarfs

  14. Predictive models for suicidal thoughts and behaviors among Spanish University students: rationale and methods of the UNIVERSAL (University & mental health) project.

    PubMed

    Blasco, Maria Jesús; Castellví, Pere; Almenara, José; Lagares, Carolina; Roca, Miquel; Sesé, Albert; Piqueras, José Antonio; Soto-Sanz, Victoria; Rodríguez-Marín, Jesús; Echeburúa, Enrique; Gabilondo, Andrea; Cebrià, Ana Isabel; Miranda-Mendizábal, Andrea; Vilagut, Gemma; Bruffaerts, Ronny; Auerbach, Randy P; Kessler, Ronald C; Alonso, Jordi

    2016-05-04

    Suicide is a leading cause of death among young people. While suicide prevention is considered a research and intervention priority, longitudinal data is needed to identify risk and protective factors associate with suicidal thoughts and behaviors. Here we describe the UNIVERSAL (University and Mental Health) project which aims are to: (1) test prevalence and 36-month incidence of suicidal thoughts and behaviors; and (2) identify relevant risk and protective factors associated with the incidence of suicidal thoughts and behaviors among university students in Spain. An ongoing multicenter, observational, prospective cohort study of first year university students in 5 Spanish universities. Students will be assessed annually during a 36 month follow-up. The surveys will be administered through an online, secure web-based platform. A clinical reappraisal will be completed among a subsample of respondents. Suicidal thoughts and behaviors will be assess with the Self-Injurious Thoughts and Behaviors Interview (SITBI) and the Columbia-Suicide Severity Rating Scale (C-SSRS). Risk and protective factors will include: mental disorders, measured with the Composite International Diagnostic Interview version 3.0 (CIDI 3.0) and Screening Scales (CIDI-SC), and the Epi-Q Screening Survey (EPI-Q-SS), socio-demographic variables, self-perceived health status, health behaviors, well-being, substance use disorders, service use and treatment. The UNIVERSAL project is part of the International College Surveys initiative, which is a core project within the World Mental Health consortium. Lifetime and the 12-month prevalence will be calculated for suicide ideation, plans and attempts. Cumulative incidence of suicidal thoughts and behaviors, and mental disorders will be measured using the actuarial method. Risk and protective factors of suicidal thoughts and behaviors will be analyzed by Cox proportional hazard models. The study will provide valid, innovative and useful data for developing

  15. Stellar Parameters, Chemical composition and Models of chemical evolution

    NASA Astrophysics Data System (ADS)

    Mishenina, T.; Pignatari, M.; Côté, B.; Thielemann, F.-K.; Soubiran, C.; Basak, N.; Gorbaneva, T.; Korotin, S. A.; Kovtyukh, V. V.; Wehmeyer, B.; Bisterzo, S.; Travaglio, C.; Gibson, B. K.; Jordan, C.; Paul, A.; Ritter, C.; Herwig, F.

    2018-04-01

    We present an in-depth study of metal-poor stars, based high resolution spectra combined with newly released astrometric data from Gaia, with special attention to observational uncertainties. The results are compared to those of other studies, including Gaia benchmark stars. Chemical evolution models are discussed, highlighting few puzzles that are still affecting our understanding of stellar nucleosynthesis and of the evolution of our Galaxy.

  16. The Formation and Evolution of Galactic Disks with APOGEE and the Gaia Survey

    NASA Astrophysics Data System (ADS)

    Li, Chengdong; Zhao, Gang; Zhai, Meng; Jia, Yunpeng

    2018-06-01

    We explore the structure and evolutionary history of Galactic disks with Apache Point Observatory Galactic Evolution Experiment data release 13 (DR13 hereafter) and Gaia Tycho-Gaia Astrometric Solution data. We use the [α/M] ratio to allocate stars into particular Galactic components to elucidate the chemical and dynamical properties of the thin and thick disks. The spatial motions of the sample stars are obtained in Galactic Cartesian and cylindrical coordinates. We analyze the abundance trends and metallicity and [α/M] gradients of the thick and thin disks. We confirm the existence of metal-weak thick-disk stars in Galactic disks. A kinematical method is used to select the thin- and thick-disk stars for comparison. We calculate the scale length and scale height of the kinematically and chemically selected thick and thin disks based on the axisymmetric Jeans equation. We conclude that the scale length of the thick disk is approximately equal to that of the thin disk via a kinematical approach. For the chemical selection, this disparity is about 1 kpc. Finally, we get the stellar orbital parameters and try to unveil the formation scenario of the thick disk. We conclude that the gas-rich merger and radial migration are more reasonable formation scenarios for the thick disk.

  17. Anatomy of the hyper-runaway star LP 40-365 with Gaia

    NASA Astrophysics Data System (ADS)

    Raddi, R.; Hollands, M. A.; Gänsicke, B. T.; Townsley, D. M.; Hermes, J. J.; Gentile Fusillo, N. P.; Koester, D.

    2018-06-01

    LP 40-365 (aka GD 492) is a nearby low-luminosity hyper-runaway star with an extremely unusual atmospheric composition, which has been proposed as the remnant of a white dwarf that survived a subluminous Type Ia supernova (SN Ia) in a single-degenerate scenario. Adopting the Gaia Data Release (DR2) parallax, ϖ = 1.58 ± 0.03 mas, we estimate a radius of 0.18 ± 0.01 R⊙, confirming LP 40-365 as a subluminous star that is ≃ 15 times larger than a typical white dwarf and is compatible with the SN Ia remnant scenario. We present an updated kinematic analysis, making use of the Gaia parallax and proper motion, and confirm that LP 40-365 is leaving the Milky Way at about 1.5 times the escape velocity of the Solar neighbourhood with a rest-frame velocity of 852 ± 10 km s-1. Integrating the past trajectories of LP 40-365, we confirm it crossed the Galactic disc 5.0 ± 0.3 Myr ago in the direction of Carina, likely coming from beneath the plane. Finally, we estimate that LP 40-365 was ejected from its progenitor binary with a velocity of at least 600 km s-1, which is compatible with theoretical predictions for close binaries containing a white dwarf and a helium-star donor.

  18. CCD astrometric observations of Amalthea and Thebe in the Gaia era

    NASA Astrophysics Data System (ADS)

    Robert, V.; Saquet, E.; Colas, F.; Arlot, J.-E.

    2017-05-01

    In the framework of the 2014-2015 campaign of mutual events, we observed Jupiter's inner satellites Amalthea (JV) and Thebe (JXIV). We focused on estimating whether the positioning accuracy determined from direct astrometry could compete with that derived from photometric observations of eclipses, for dynamical purposes. We present the analysis of 35 observations of Amalthea and 19 observations of Thebe realized with the 1-m telescope at the Pic du Midi observatory during three nights in 2015, January and April. The images were reduced through an optimal process that includes image and spherical corrections using the Gaia-DR1 catalogue to provide the most accurate equatorial (RA, Dec.) positions. We compared the observed positions of both satellites with the theoretical positions from JPL JUP310 satellite ephemerides and from the IMCCE INPOP13c planetary ephemeris. The values of rms (O-C) in equatorial positions are ±112 mas for the Amalthea observations, or 330 km at Jupiter, and ±90 mas for the Thebe observations, or 270 km at Jupiter. Using the Gaia-DR1 catalogue allowed us to eliminate systematic errors due to the star references up to 120 mas, or 350 km at Jupiter, by comparison with the UCAC4 catalogue.

  19. Siriusly, a newly identified intermediate-age Milky Way stellar cluster: a spectroscopic study of Gaia 1

    NASA Astrophysics Data System (ADS)

    Simpson, J. D.; De Silva, G. M.; Martell, S. L.; Zucker, D. B.; Ferguson, A. M. N.; Bernard, E. J.; Irwin, M.; Penarrubia, J.; Tolstoy, E.

    2017-11-01

    We confirm the reality of the recently discovered Milky Way stellar cluster Gaia 1 using spectra acquired with the HERMES and AAOmega spectrographs of the Anglo-Australian Telescope. This cluster had been previously undiscovered due to its close angular proximity to Sirius, the brightest star in the sky at visual wavelengths. Our observations identified 41 cluster members, and yielded an overall metallicity of [{Fe}/{H}]=-0.13± 0.13 and barycentric radial velocity of vr = 58.30 ± 0.22 km s-1. These kinematics provide a dynamical mass estimate of 12.9^{+4.6}_{-3.9}× 10^3 M_{⊙}. Isochrone fits to Gaia, 2MASS, and Pan-STARRS1 photometry indicate that Gaia 1 is an intermediate age (˜3 Gyr) stellar cluster. Combining the spatial and kinematic data we calculate Gaia 1 has a circular orbit with a radius of about 12 kpc, but with a large out of plane motion: z_{max}=1.1^{+0.4}_{-0.3} kpc. Clusters with such orbits are unlikely to survive long due to the number of plane passages they would experience.

  20. Development of a large blazed transmission grating by effective binary index modulation for the GAIA radial velocity spectrometer

    NASA Astrophysics Data System (ADS)

    Erdmann, M.; Kley, E.-B.; Zeitner, U.

    2017-11-01

    Gaia is an ambitious ESA mission to chart a three-dimensional map of our Galaxy, the Milky Way, in the process revealing the composition, formation and evolution of the Galaxy. Gaia will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and cinematic census of about one billion stars in our Galaxy. The payload consists of 2 Three Mirror Anastigmat (TMA) telescopes (aperture size 1.5 m x 0.5 m), 3 instruments (astrometer, photometer and spectrometer) and 106 butted CCDs assembled to a 0.9 Giga-Pixel focal plane. The Radial Velocity Spectrometer (RVS) of Gaia measures the red shift of the stars in the spectral band between 847 nm and 874 nm. The spectrometer is a fully refractive optics consisting of 2 Fery prisms, 2 prisms, a pass band filter and a blazed transmission grating (instrument mass about 30 kg). It is located in the vicinity of the focal plane and illuminates 12 of the 106 Charge Coupled Devices (CCDs). Gaia is in the implementation phase, the launch of the 2120 kg mass satellite is planned in Dec. 2012.

  1. Universities as Hubs for Next-Generation Networks: A Model for Universities to Spur 21st Century Internet Access and Innovation in Their Communities

    ERIC Educational Resources Information Center

    Lennett, Benjamin; Morris, Sarah J.; Byrum, Greta

    2012-01-01

    Based on a request for information (RFI) submitted to The University Community Next Generation Innovation Project (Gig.U), the paper describes a model for universities to develop next generation broadband infrastructure in their communities. In the our view universities can play a critical role in spurring next generation networks into their…

  2. Universal Session-Level Change Processes in an Early Session of Psychotherapy: Path Models

    ERIC Educational Resources Information Center

    Kolden, Gregory G.; Chisholm-Stockard, Sarah M.; Strauman, Timothy J.; Tierney, Sandy C.; Mullen, Elizabeth A.; Schneider, Kristin L.

    2006-01-01

    The authors used structural equation modeling to investigate universal change processes identified in the generic model of psychotherapy (GMP). Three path models of increasing complexity were examined in Study 1 in dynamic therapy. The best fitting model from Study one was replicated in Study two for participants receiving either cognitive or…

  3. The Teaching Artist: A Model for University Dance Teacher Training

    ERIC Educational Resources Information Center

    Huddy, Avril; Stevens, Kym

    2011-01-01

    This paper describes a teaching model, "The Teaching Artist", developed to address the pedagogical and cultural divide between the traditional dance teacher and the dance artist who teaches: traditionally, one teaching about dance and the other, teaching through dance. The "Teaching Artist" model was developed through the…

  4. A Leadership Model for University Geology Department Teacher Inservice Programs.

    ERIC Educational Resources Information Center

    Sheldon, Daniel S.; And Others

    1983-01-01

    Provides geology departments and science educators with a leadership model for developing earth science inservice programs. Model emphasizes cooperation/coordination among departments, science educators, and curriculum specialists at local/intermediate/state levels. Includes rationale for inservice programs and geology department involvement in…

  5. Cost Efficiency in the University: A Departmental Evaluation Model

    ERIC Educational Resources Information Center

    Gimenez, Victor M.; Martinez, Jose Luis

    2006-01-01

    This article presents a model for the analysis of cost efficiency within the framework of data envelopment analysis models. It calculates the cost excess, separating a unit of production from its optimal or frontier levels, and, at the same time, breaks these excesses down into three explanatory factors: (a) technical inefficiency, which depends…

  6. UCODE, a computer code for universal inverse modeling

    USGS Publications Warehouse

    Poeter, E.P.; Hill, M.C.

    1999-01-01

    This article presents the US Geological Survey computer program UCODE, which was developed in collaboration with the US Army Corps of Engineers Waterways Experiment Station and the International Ground Water Modeling Center of the Colorado School of Mines. UCODE performs inverse modeling, posed as a parameter-estimation problem, using nonlinear regression. Any application model or set of models can be used; the only requirement is that they have numerical (ASCII or text only) input and output files and that the numbers in these files have sufficient significant digits. Application models can include preprocessors and postprocessors as well as models related to the processes of interest (physical, chemical and so on), making UCODE extremely powerful for model calibration. Estimated parameters can be defined flexibly with user-specified functions. Observations to be matched in the regression can be any quantity for which a simulated equivalent value can be produced, thus simulated equivalent values are calculated using values that appear in the application model output files and can be manipulated with additive and multiplicative functions, if necessary. Prior, or direct, information on estimated parameters also can be included in the regression. The nonlinear regression problem is solved by minimizing a weighted least-squares objective function with respect to the parameter values using a modified Gauss-Newton method. Sensitivities needed for the method are calculated approximately by forward or central differences and problems and solutions related to this approximation are discussed. Statistics are calculated and printed for use in (1) diagnosing inadequate data or identifying parameters that probably cannot be estimated with the available data, (2) evaluating estimated parameter values, (3) evaluating the model representation of the actual processes and (4) quantifying the uncertainty of model simulated values. UCODE is intended for use on any computer operating

  7. Education for Sustainability in University Studies: A Model for Reorienting the Curriculum

    ERIC Educational Resources Information Center

    Junyent, Merce; de Ciurana, Anna M. Geli

    2008-01-01

    A decisive factor for achieving a culture of sustainability is university training for future professionals. The aim of this article is to bring new elements to the process of reorienting university studies towards sustainability. Presented here is the ACES model (Curriculum Greening of Higher Education, acronym in Spanish), which is the result of…

  8. The Analysis of Organizational Diagnosis on Based Six Box Model in Universities

    ERIC Educational Resources Information Center

    Hamid, Rahimi; Siadat, Sayyed Ali; Reza, Hoveida; Arash, Shahin; Ali, Nasrabadi Hasan; Azizollah, Arbabisarjou

    2011-01-01

    Purpose: The analysis of organizational diagnosis on based six box model at universities. Research method: Research method was descriptive-survey. Statistical population consisted of 1544 faculty members of universities which through random strafed sampling method 218 persons were chosen as the sample. Research Instrument were organizational…

  9. University Rankings, Global Models, and Emerging Hegemony: Critical Analysis from Japan

    ERIC Educational Resources Information Center

    Ishikawa, Mayumi

    2009-01-01

    The study analyzes how the emergence of dominant models in higher education and power they embody affect non-Western, non-English language universities such as those in Japan. Based on extended micro-level participant observation in a Japanese research university aspiring to become a "world-class" institution, their struggles and the…

  10. Partnerships in Medical Education: An Exploration of Library Service Models for Postgraduate Medicine at Macquarie University

    ERIC Educational Resources Information Center

    Simons, Mary

    2008-01-01

    Macquarie University's new medical school, The Australian School of Advanced Medicine (ASAM), is developing a postgraduate program that incorporates a partnership with Macquarie University Library. The curriculum encompasses contemporary models of competency-based assessment, teamwork and lifelong learning that are integrated with research and…

  11. A Model of Institutional Creative Change for Assessing Universities as Learning Organizations

    ERIC Educational Resources Information Center

    Sternberg, Robert J.

    2015-01-01

    Universities, like students, differ in their ability to learn and to recreate themselves. In this article, I present a 3-part model of institutional creative change for assessing universities as learning organizations that can move creatively into the future. The first part, prerequisites, deals with actual ability to change creatively and belief…

  12. The University in the Knowledge Economy: The Triple Helix Model and Its Implications

    ERIC Educational Resources Information Center

    Zheng, Peijun; Harris, Michael

    2007-01-01

    In the context of the global knowledge economy, the three major players--university, industry, and government--are becoming increasingly interdependent. As more intensified interactions and relationships of increasing complexity among the institutions evolve, the Triple Helix model attempts to describe not only interactions among university,…

  13. Old Borrowings and New Models of the University in East Asia

    ERIC Educational Resources Information Center

    Kim, Terri

    2007-01-01

    This paper illustrates the transfer of university models from Europe and America to East Asia and will consider how international power relations in different times transform ideas about the university, in the process of global transfer. These relations will be identified with different forms of the state: imperial, colonial, welfare and market…

  14. The Effect of Academic Culture on the Implementation of the EFQM Excellence Model in UK Universities

    ERIC Educational Resources Information Center

    Davies, John; Douglas, Alex; Douglas, Jacqueline

    2007-01-01

    Purpose: The paper seeks to explore the effect of academic culture on the implementation of the European Foundation for Quality Management's (EFQM) Excellence Model in UK universities. Design/methodology/approach: A literature review reveals several aspects, which collectively define the academic culture in UK universities. These aspects were…

  15. World-Class Higher Education and the Emerging Chinese Model of the University

    ERIC Educational Resources Information Center

    Li, Jun

    2012-01-01

    China's recent quest to develop world-class universities is a significant phenomenon within the worldwide transformation of tertiary education. Taking a cultural approach and drawing on empirical findings, this article investigates the emerging Chinese model of the university, considering its key features and contributions to global communities.…

  16. The Practicum Course Model: Embracing the Museum-University Culture Clash

    ERIC Educational Resources Information Center

    Kingsley, Jennifer P.

    2016-01-01

    Museums and universities have natural connections. Yet with few exceptions, collaborations between them segregate each partner to its traditional sphere of activity. This article presents a practicum course model that blurs and overlaps the distinctive roles of the museum and university in productive and mutually beneficial ways. In particular,…

  17. The Charlotte Action Research Project: A Model for Direct and Mutually Beneficial Community-University Engagement

    ERIC Educational Resources Information Center

    Morrell, Elizabeth; Sorensen, Janni; Howarth, Joe

    2015-01-01

    This article describes the evolution of the Charlotte Action Research Project (CHARP), a community-university partnership founded in 2008 at the University of North Carolina at Charlotte, and focuses particularly on the program's unique organizational structure. Research findings of a project evaluation suggest that the CHARP model's unique…

  18. Metabolic Modeling of the Last Universal Common Ancestor

    NASA Astrophysics Data System (ADS)

    Broddrick, J. T.; Yurkovich, J. T.; Palsson, B. O.

    2017-07-01

    The origin and diversity of life on earth are intimately linked to metabolic processes. Using recent assessments of early metabolic capabilities, we construct a metabolic model of a primordial organism that could be representative of the LUCA.

  19. On the universality of the attribution-affect model of helping.

    PubMed

    Reisenzein, Rainer

    2015-08-01

    Although Pilati et al.'s (2014) findings question the strong quantitative universality of the attribution-affect model of helping, they are consistent with a weak form of quantitative universality, as well as with the qualitative universality of the theory. However, universality is put into question by previous studies revealing significant and sizeable between-study differences in the strength of the causal paths postulated by the theory. These differences may in part reflect differences in the type of helping situations studied. © 2015 International Union of Psychological Science.

  20. Modelling Facebook Usage among University Students in Thailand: The Role of Emotional Attachment in an Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Teo, Timothy

    2016-01-01

    The aim of this study is to examine the factors that influenced the use of Facebook among university students. Using an extended technology acceptance model (TAM) with emotional attachment (EA) as an external variable, a sample of 498 students from a public-funded Thailand university were surveyed on their responses to five variables hypothesized…

  1. Measuring effectiveness of a university by a parallel network DEA model

    NASA Astrophysics Data System (ADS)

    Kashim, Rosmaini; Kasim, Maznah Mat; Rahman, Rosshairy Abd

    2017-11-01

    Universities contribute significantly to the development of human capital and socio-economic improvement of a country. Due to that, Malaysian universities carried out various initiatives to improve their performance. Most studies have used the Data Envelopment Analysis (DEA) model to measure efficiency rather than effectiveness, even though, the measurement of effectiveness is important to realize how effective a university in achieving its ultimate goals. A university system has two major functions, namely teaching and research and every function has different resources based on its emphasis. Therefore, a university is actually structured as a parallel production system with its overall effectiveness is the aggregated effectiveness of teaching and research. Hence, this paper is proposing a parallel network DEA model to measure the effectiveness of a university. This model includes internal operations of both teaching and research functions into account in computing the effectiveness of a university system. In literature, the graduate and the number of program offered are defined as the outputs, then, the employed graduates and the numbers of programs accredited from professional bodies are considered as the outcomes for measuring the teaching effectiveness. Amount of grants is regarded as the output of research, while the different quality of publications considered as the outcomes of research. A system is considered effective if only all functions are effective. This model has been tested using a hypothetical set of data consisting of 14 faculties at a public university in Malaysia. The results show that none of the faculties is relatively effective for the overall performance. Three faculties are effective in teaching and two faculties are effective in research. The potential applications of the parallel network DEA model allow the top management of a university to identify weaknesses in any functions in their universities and take rational steps for improvement.

  2. Predoctoral Program Models in Dentistry for the Handicapped: The University of Tennessee Program.

    ERIC Educational Resources Information Center

    Wessels, Kenneth E.

    1980-01-01

    A model program in dentistry for the handicapped offered at the University of Tennessee and supported by a Robert Wood Johnson Foundation grant is described. The program includes didactic instruction, observation and seminar, and clinical practice. (JMF)

  3. BUILDING MODEL ANALYSIS APPLICATIONS WITH THE JOINT UNIVERSAL PARAMETER IDENTIFICATION AND EVALUATION OF RELIABILITY (JUPITER) API

    EPA Science Inventory

    The open-source, public domain JUPITER (Joint Universal Parameter IdenTification and Evaluation of Reliability) API (Application Programming Interface) provides conventions and Fortran-90 modules to develop applications (computer programs) for analyzing process models. The input ...

  4. Consistency of the tachyon warm inflationary universe models

    SciTech Connect

    Zhang, Xiao-Min; Zhu, Jian-Yang, E-mail: zhangxm@mail.bnu.edu.cn, E-mail: zhujy@bnu.edu.cn

    2014-02-01

    This study concerns the consistency of the tachyon warm inflationary models. A linear stability analysis is performed to find the slow-roll conditions, characterized by the potential slow-roll (PSR) parameters, for the existence of a tachyon warm inflationary attractor in the system. The PSR parameters in the tachyon warm inflationary models are redefined. Two cases, an exponential potential and an inverse power-law potential, are studied, when the dissipative coefficient Γ = Γ{sub 0} and Γ = Γ(φ), respectively. A crucial condition is obtained for a tachyon warm inflationary model characterized by the Hubble slow-roll (HSR) parameter ε{sub H}, and the conditionmore » is extendable to some other inflationary models as well. A proper number of e-folds is obtained in both cases of the tachyon warm inflation, in contrast to existing works. It is also found that a constant dissipative coefficient (Γ = Γ{sub 0}) is usually not a suitable assumption for a warm inflationary model.« less

  5. Matter-Induced Neutrino Oscillation in Double Universal Seesaw Model

    NASA Astrophysics Data System (ADS)

    Sogami, I. S.; Shinohara, T.; Egawa, Y.

    1992-04-01

    The Mikheyev-Smirnov-Wolfenstein effect is investigated in an extended gauge field theory in which the universal seesaw mechanism is applied singly to the charged fermion sectors to lower their masses below the electroweak energy scale and doubly to the neutral fermion sector to make neutrinos superlight. At the first seesaw approximation, neutrinos are proved to have a distinctive spectrum consisting of doubly degenerate states with smaller mass m_{S} and a singlet state with larger mas m_{L}. The lepton mixing matrix is determined definitely in terms of the masses of charged leptons and down quarks, with a very small vacuum mixing angle sin theta = 0.043 +/- 0.004. The Schrödinger-like equation describing the spatial evolution of stationary neutrino flux is solved for globally-rotated-flavor wave functions. Comparison of its nonadiabatic solution with experimental results leads to an estimation m_{L}(2) - m_{S}(2) = (6 +/- 2) x 10(-6) eV(2) for the squared mass difference and a capture rate prediction of 74 +/- 12 SNU for the SAGE gallium experiment.

  6. Stability of the Einstein static universe in open cosmological models

    SciTech Connect

    Canonico, Rosangela; Parisi, Luca; INFN, Sezione di Napoli, GC di Salerno, Via Ponte Don Melillo, I-84081 Baronissi

    2010-09-15

    The stability properties of the Einstein static solution of general relativity are altered when corrective terms arising from modification of the underlying gravitational theory appear in the cosmological equations. In this paper the existence and stability of static solutions are considered in the framework of two recently proposed quantum gravity models. The previously known analysis of the Einstein static solutions in the semiclassical regime of loop quantum cosmology with modifications to the gravitational sector is extended to open cosmological models where a static neutrally stable solution is found. A similar analysis is also performed in the framework of Horava-Lifshitz gravitymore » under detailed balance and projectability conditions. In the case of open cosmological models the two solutions found can be either unstable or neutrally stable according to the admitted values of the parameters.« less

  7. A box full of chocolates: The rich structure of the nearby stellar halo revealed by Gaia and RAVE

    NASA Astrophysics Data System (ADS)

    Helmi, Amina; Veljanoski, Jovan; Breddels, Maarten A.; Tian, Hao; Sales, Laura V.

    2017-02-01

    Context. The hierarchical structure formation model predicts that stellar halos should form, at least partly, via mergers. If this was a predominant formation channel for the Milky Way's halo, imprints of this merger history in the form of moving groups or streams should also exist in the vicinity of the Sun. Aims: We study the kinematics of halo stars in the Solar neighbourhood using the very recent first data release from the Gaia mission, and in particular the TGAS dataset, in combination with data from the RAVE survey. Our aim is to determine the amount of substructure present in the phase-space distribution of halo stars that could be linked to merger debris. Methods: To characterise kinematic substructure, we measured the velocity correlation function in our sample of halo (low-metallicity) stars. We also studied the distribution of these stars in the space of energy and two components of the angular momentum, in what we call "integrals of motion" space. Results: The velocity correlation function reveals substructure in the form of an excess of pairs of stars with similar velocities, well above that expected for a smooth distribution. Comparison to cosmological simulations of the formation of stellar halos indicates that the levels found are consistent with the Galactic halo having been built solely via accretion. Similarly, the distribution of stars in the space of integrals of motion is highly complex. A strikingly high fraction (from 58% up to more than 73%) of the stars that are somewhat less bound than the Sun are on (highly) retrograde orbits. A simple comparison to Milky Way-mass galaxies in cosmological hydrodynamical simulations suggests that less than 1% have such prominently retrograde outer halos. We also identify several other statistically significant structures in integrals of motion space that could potentially be related to merger events.

  8. Spitzer Trigonometric Parallaxes of L, T, and Y Dwarfs: Complementing Gaia's Optically-selected Census of Nearby Stars

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, J. Davy; Smart, Richard; Marocco, Federico; Martin, Emily; Faherty, Jacqueline; Tinney, Christopher; Cushing, Michael; Beichman, Charles; Gelino, Christopher; Schneider, Adam; Wright, Edward; Lowrance, Patrick; Ingalls, James

    2018-05-01

    We now find ourselves at a moment in history where a parallax-selected census of nearby objects from the hottest A stars to the coldest Y dwarfs is almost a reality. With the release of Gaia DR2 in April of this year, we will be able to extract a volume-limited sample of stars out to 20 pc down to a spectral type of L5. Extending the census to colder types is much more difficult but nonetheless possible and essential. Ground-based astrometric monitoring of some of these colder dwarfs can be done with deep infrared detections on moderate to large (4+ meter) telescopes, but given the amount of time needed, only a portion of the colder objects believed to lie within 20 pc has been monitored. Our prior Spitzer observations have already enabled direct distance measures for T6 through Y dwarfs, but many 20-pc objects with spectral types between L5 and T5.5 have still not been astrometrically monitored, leaving a hole in our knowledge of this important all-sky sample. Spitzer Cycle 14 observations of modest time expenditure can rectify this problem by providing parallaxes for the 150+ objects remaining. Analysis of the brown dwarfs targeted by Spitzer is particularly important because it will provide insight into the low-mass cutoff of star formation, the shape of the mass function as inferred from the observed temperature distribution, the binary fraction of near-equal mass doubles, and the prevalence of extremely young (low-gravity) and extremely old (low metallicity) objects within the sample - all of which can be used to test and further refine model predictions of the underlying mass function.

  9. Astrometry and exoplanets in the Gaia era: a Bayesian approach to detection and parameter recovery

    NASA Astrophysics Data System (ADS)

    Ranalli, P.; Hobbs, D.; Lindegren, L.

    2018-06-01

    The Gaia mission is expected to make a significant contribution to the knowledge of exoplanet systems, both in terms of their number and of their physical properties. We develop Bayesian methods and detection criteria for orbital fitting, and revise the detectability of exoplanets in light of the in-flight properties of Gaia. Limiting ourselves to one-planet systems as a first step of the development, we simulate Gaia data for exoplanet systems over a grid of S/N, orbital period, and eccentricity. The simulations are then fit using Markov chain Monte Carlo methods. We investigate the detection rate according to three information criteria and the Δχ2. For the Δχ2, the effective number of degrees of freedom depends on the mission length. We find that the choice of the Markov chain starting point can affect the quality of the results; we therefore consider two limit possibilities: an ideal case, and a very simple method that finds the starting point assuming circular orbits. We use 6644 and 4402 simulations to assess the fraction of false positive detections in a 5 yr and in a 10 yr mission, respectively; and 4968 and 4706 simulations to assess the detection rate and how the parameters are recovered. Using Jeffreys' scale of evidence, the fraction of false positives passing a strong evidence criterion is ≲0.2% (0.6%) when considering a 5 yr (10 yr) mission and using the Akaike information criterion or the Watanabe-Akaike information criterion, and <0.02% (<0.06%) when using the Bayesian information criterion. We find that there is a 50% chance of detecting a planet with a minimum S/N = 2.3 (1.7). This sets the maximum distance to which a planet is detectable to 70 pc and 3.5 pc for a Jupiter-mass and Neptune-mass planets, respectively, assuming a 10 yr mission, a 4 au semi-major axis, and a 1 M⊙ star. We show the distribution of the accuracy and precision with which orbital parameters are recovered. The period is the orbital parameter that can be determined

  10. American Association of University Women: Branch Operations Data Modeling Case

    ERIC Educational Resources Information Center

    Harris, Ranida B.; Wedel, Thomas L.

    2015-01-01

    A nationally prominent woman's advocacy organization is featured in this case study. The scenario may be used as a teaching case, an assignment, or a project in systems analysis and design as well as database design classes. Students are required to document the system operations and requirements, apply logical data modeling concepts, and design…

  11. An Equilibrium Flow Model of a University Campus.

    ERIC Educational Resources Information Center

    Oliver, Robert M.; Hopkins, David S. P.

    This paper develops a simple deterministic model that relates student admissions and enrollments to the final demand for educated students. It includes the effects of dropout rates and student-teacher ratios on student enrollments and faculty staffing levels. Certain technological requirements are assumed known and given. These, as well as the…

  12. Towards a universal model for carbon dioxide uptake by plants

    DOE PAGES

    Wang, Han; Prentice, I. Colin; Keenan, Trevor F.; ...

    2017-09-04

    Gross primary production (GPP) - the uptake of carbon dioxide (CO 2) by leaves, and its conversion to sugars by photosynthesis - is the basis for life on land. Earth System Models (ESMs) incorporating the interactions of land ecosystems and climate are used to predict the future of the terrestrial sink for anthropogenic CO 2. ESMs require accurate representation of GPP. However, current ESMs disagree on how GPP responds to environmental variations, suggesting a need for a more robust theoretical framework for modelling. Here in this work, we focus on a key quantity for GPP, the ratio of leaf internalmore » to external CO 2 (χ). χ is tightly regulated and depends on environmental conditions, but is represented empirically and incompletely in today's models. We show that a simple evolutionary optimality hypothesis predicts specific quantitative dependencies of χ on temperature, vapour pressure deficit and elevation; and that these same dependencies emerge from an independent analysis of empirical χ values, derived from a worldwide dataset of >3,500 leaf stable carbon isotope measurements. A single global equation embodying these relationships then unifies the empirical light-use efficiency model with the standard model of C 3 photosynthesis, and successfully predicts GPP measured at eddy-covariance flux sites. This success is notable given the equation's simplicity and broad applicability across biomes and plant functional types. Finally, it provides a theoretical underpinning for the analysis of plant functional coordination across species and emergent properties of ecosystems, and a potential basis for the reformulation of the controls of GPP in next-generation ESMs.« less

  13. Towards a universal model for carbon dioxide uptake by plants

    SciTech Connect

    Wang, Han; Prentice, I. Colin; Keenan, Trevor F.

    Gross primary production (GPP) - the uptake of carbon dioxide (CO 2) by leaves, and its conversion to sugars by photosynthesis - is the basis for life on land. Earth System Models (ESMs) incorporating the interactions of land ecosystems and climate are used to predict the future of the terrestrial sink for anthropogenic CO 2. ESMs require accurate representation of GPP. However, current ESMs disagree on how GPP responds to environmental variations, suggesting a need for a more robust theoretical framework for modelling. Here in this work, we focus on a key quantity for GPP, the ratio of leaf internalmore » to external CO 2 (χ). χ is tightly regulated and depends on environmental conditions, but is represented empirically and incompletely in today's models. We show that a simple evolutionary optimality hypothesis predicts specific quantitative dependencies of χ on temperature, vapour pressure deficit and elevation; and that these same dependencies emerge from an independent analysis of empirical χ values, derived from a worldwide dataset of >3,500 leaf stable carbon isotope measurements. A single global equation embodying these relationships then unifies the empirical light-use efficiency model with the standard model of C 3 photosynthesis, and successfully predicts GPP measured at eddy-covariance flux sites. This success is notable given the equation's simplicity and broad applicability across biomes and plant functional types. Finally, it provides a theoretical underpinning for the analysis of plant functional coordination across species and emergent properties of ecosystems, and a potential basis for the reformulation of the controls of GPP in next-generation ESMs.« less

  14. Universal etiology, multifactorial diseases and the constitutive model of disease classification.

    PubMed

    Fuller, Jonathan

    2018-02-01

    Infectious diseases are often said to have a universal etiology, while chronic and noncommunicable diseases are said to be multifactorial in their etiology. It has been argued that the universal etiology of an infectious disease results from its classification using a monocausal disease model. In this article, I will reconstruct the monocausal model and argue that modern 'multifactorial diseases' are not monocausal by definition. 'Multifactorial diseases' are instead defined according to a constitutive disease model. On closer analysis, infectious diseases are also defined using the constitutive model rather than the monocausal model. As a result, our classification models alone cannot explain why infectious diseases have a universal etiology while chronic and noncommunicable diseases lack one. The explanation is instead provided by the Nineteenth Century germ theorists. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. A New Model of Governance: One University's Journey.

    PubMed

    Brooks, Beth A; Scanlan, Therese

    2015-01-01

    In the nearly 50 years, since the Medicare Program established funding for nursing education in the United States, there has been a steady migration away from hospital-controlled programs toward those which function as wholly owned subsidiaries within larger health care systems. Private sector health care organizations in particular are under increasing pressure to adapt at the risk of losing all of their funding. However, accomplishing this presents multiple challenges for today's nursing education programs in terms of their regulatory compliance, accreditation, autonomy, and, above all, governance model. The authors outline the journey toward, and specific challenges involved in creating, implementing and administering a new governance model, which sustains the overall mission and vision of the education institution while functioning seamlessly within a modern corporate health care system.

  16. Exploring the common molecular basis for the universal DNA mutation bias: Revival of Loewdin mutation model

    SciTech Connect

    Fu, Liang-Yu; Center for Bioinformatics, Huazhong Agricultural University, Wuhan 430070; Wang, Guang-Zhong

    2011-06-10

    Highlights: {yields} There exists a universal G:C {yields} A:T mutation bias in three domains of life. {yields} This universal mutation bias has not been sufficiently explained. {yields} A DNA mutation model proposed by Loewdin 40 years ago offers a common explanation. -- Abstract: Recently, numerous genome analyses revealed the existence of a universal G:C {yields} A:T mutation bias in bacteria, fungi, plants and animals. To explore the molecular basis for this mutation bias, we examined the three well-known DNA mutation models, i.e., oxidative damage model, UV-radiation damage model and CpG hypermutation model. It was revealed that these models cannot providemore » a sufficient explanation to the universal mutation bias. Therefore, we resorted to a DNA mutation model proposed by Loewdin 40 years ago, which was based on inter-base double proton transfers (DPT). Since DPT is a fundamental and spontaneous chemical process and occurs much more frequently within GC pairs than AT pairs, Loewdin model offers a common explanation for the observed universal mutation bias and thus has broad biological implications.« less

  17. Universal Responses of Cyclic-Oxidation Models Studied

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2003-01-01

    Oxidation is an important degradation process for materials operating in the high-temperature air or oxygen environments typical of jet turbine or rocket engines. Reaction of the combustion gases with the component material forms surface layer scales during these oxidative exposures. Typically, the instantaneous rate of reaction is inversely proportional to the existing scale thickness, giving rise to parabolic kinetics. However, more realistic applications entail periodic startup and shutdown. Some scale spallation may occur upon cooling, resulting in loss of the protective diffusion barrier provided by a fully intact scale. Upon reheating, the component will experience accelerated oxidation due to this spallation. Cyclic-oxidation testing has, therefore, been a mainstay of characterization and performance ranking for high-temperature materials. Models simulate this process by calculating how a scale spalls upon cooling and regrows upon heating (refs. 1 to 3). Recently released NASA software (COSP for Windows) allows researchers to specify a uniform layer or discrete segments of spallation (ref. 4). Families of model curves exhibit consistent regularity and trends with input parameters, and characteristic features have been empirically described in terms of these parameters. Although much insight has been gained from experimental and model curves, no equation has been derived that can describe this behavior explicitly as functions of the key oxidation parameters.

  18. Short arc orbit determination and imminent impactors in the Gaia era

    NASA Astrophysics Data System (ADS)

    Spoto, F.; Del Vigna, A.; Milani, A.; Tommei, G.; Tanga, P.; Mignard, F.; Carry, B.; Thuillot, W.; David, P.

    2018-06-01

    Short-arc orbit determination is crucial when an asteroid is first discovered. In these cases usually the observations are so few that the differential correction procedure may not converge. We developed an initial orbit computation method, based on systematic ranging, which is an orbit determination technique that systematically explores a raster in the topocentric range and range-rate space region inside the admissible region. We obtained a fully rigorous computation of the probability for the asteroid that could impact the Earth within a few days from the discovery without any a priori assumption. We tested our method on the two past impactors, 2008 TC3 and 2014 AA, on some very well known cases, and on two particular objects observed by the European Space Agency Gaia mission.

  19. Three-dimensional structure of the Upper Scorpius association with the Gaia first data release

    NASA Astrophysics Data System (ADS)

    Galli, Phillip A. B.; Joncour, Isabelle; Moraux, Estelle

    2018-06-01

    Using new proper motion data from recently published catalogues, we revisit the membership of previously identified members of the Upper Scorpius association. We confirmed 750 of them as cluster members based on the convergent point method, compute their kinematic parallaxes, and combined them with Gaia parallaxes to investigate the 3D structure and geometry of the association using a robust covariance method. We find a mean distance of 146 ± 3 ± 6 pc and show that the morphology of the association defined by the brightest (and most massive) stars yields a prolate ellipsoid with dimensions of 74 × 38 × 32 pc3, while the faintest cluster members define a more elongated structure with dimensions of 98 × 24 × 18 pc3. We suggest that the different properties of both populations are an imprint of the star formation history in this region.

  20. Characterizing Accreting Double White Dwarf Binaries with the Laser Interferometer Space Antenna and Gaia

    NASA Astrophysics Data System (ADS)

    Breivik, Katelyn; Kremer, Kyle; Bueno, Michael; Larson, Shane L.; Coughlin, Scott; Kalogera, Vassiliki

    2018-02-01

    We demonstrate a method to fully characterize mass-transferring double white dwarf (DWD) systems with a helium-rich (He) white dwarf (WD) donor based on the mass–radius (M–R) relationship for He WDs. Using a simulated Galactic population of DWDs, we show that donor and accretor masses can be inferred for up to ∼60 systems observed by both Laser Interferometer Space Antenna (LISA) and Gaia. Half of these systems will have mass constraints {{Δ }} {M}{{D}} ≲ 0.2 {M}ȯ and {{Δ }} {M}{{A}} ≲ 2.3 {M}ȯ . We also show how the orbital frequency evolution due to astrophysical processes and gravitational radiation can be decoupled from the total orbital frequency evolution for up to ∼50 of these systems.

  1. Evidence for Unresolved Exoplanet-hosting Binaries in Gaia DR2

    NASA Astrophysics Data System (ADS)

    Evans, Daniel F.

    2018-05-01

    This note describes an effort to detect additional stellar sources in known transiting exoplanet (TEP) systems, which are unresolved or barely resolved in the Gaia Data Release 2 (DR2) catalogue. The presence of multiple unresolved stars in photometric and spectroscopic observations of a transiting planetary system biases measurements of the planet's radius, mass, and atmospheric conditions. In addition to the effect on individual planetary systems, the presence of unresolved stars across the sample of known exoplanets biases our overall understanding of planetary systems, due to the systematic underestimation of both masses and radii. This work uses the Astrometric Goodness of Fit in the Along-Scan direction (GOF_AL) and the Astrometric Excess Noise as indicators of poorly-resolved binaries. Many known close binaries in the exoplanet host star sample have highly significant GOF_AL and Astrometric Excess Noise values, such as WASP-20AB with Astrometric Excess Noise significant at $4720\\sigma$ and GOF_AL=124.

  2. LISA verification binaries with updated distances from Gaia Data Release 2

    NASA Astrophysics Data System (ADS)

    Kupfer, T.; Korol, V.; Shah, S.; Nelemans, G.; Marsh, T. R.; Ramsay, G.; Groot, P. J.; Steeghs, D. T. H.; Rossi, E. M.

    2018-06-01

    Ultracompact binaries with orbital periods less than a few hours will dominate the gravitational wave signal in the mHz regime. Until recently, 10 systems were expected have a predicted gravitational wave signal strong enough to be detectable by the Laser Interferometer Space Antenna (LISA), the so-called `verification binaries'. System parameters, including distances, are needed to provide an accurate prediction of the expected gravitational wave strength to be measured by LISA. Using parallaxes from Gaia Data Release 2 we calculate signal-to-noise ratios (SNR) for ≈50 verification binary candidates. We find that 11 binaries reach a SNR≥20, two further binaries reaching a SNR≥5 and three more systems are expected to have a SNR≈5 after four years integration with LISA. For these 16 systems we present predictions of the gravitational wave amplitude (A) and parameter uncertainties from Fisher information matrix on the amplitude (A) and inclination (ι).

  3. Animal Models for Influenza Viruses: Implications for Universal Vaccine Development

    PubMed Central

    Margine, Irina; Krammer, Florian

    2014-01-01

    Influenza virus infections are a significant cause of morbidity and mortality in the human population. Depending on the virulence of the influenza virus strain, as well as the immunological status of the infected individual, the severity of the respiratory disease may range from sub-clinical or mild symptoms to severe pneumonia that can sometimes lead to death. Vaccines remain the primary public health measure in reducing the influenza burden. Though the first influenza vaccine preparation was licensed more than 60 years ago, current research efforts seek to develop novel vaccination strategies with improved immunogenicity, effectiveness, and breadth of protection. Animal models of influenza have been essential in facilitating studies aimed at understanding viral factors that affect pathogenesis and contribute to disease or transmission. Among others, mice, ferrets, pigs, and nonhuman primates have been used to study influenza virus infection in vivo, as well as to do pre-clinical testing of novel vaccine approaches. Here we discuss and compare the unique advantages and limitations of each model. PMID:25436508

  4. The Gaia-ESO Survey: A globular cluster escapee in the Galactic halo

    NASA Astrophysics Data System (ADS)

    Lind, K.; Koposov, S. E.; Battistini, C.; Marino, A. F.; Ruchti, G.; Serenelli, A.; Worley, C. C.; Alves-Brito, A.; Asplund, M.; Barklem, P. S.; Bensby, T.; Bergemann, M.; Blanco-Cuaresma, S.; Bragaglia, A.; Edvardsson, B.; Feltzing, S.; Gruyters, P.; Heiter, U.; Jofre, P.; Korn, A. J.; Nordlander, T.; Ryde, N.; Soubiran, C.; Gilmore, G.; Randich, S.; Ferguson, A. M. N.; Jeffries, R. D.; Vallenari, A.; Allende Prieto, C.; Pancino, E.; Recio-Blanco, A.; Romano, D.; Smiljanic, R.; Bellazzini, M.; Damiani, F.; Hill, V.; de Laverny, P.; Jackson, R. J.; Lardo, C.; Zaggia, S.

    2015-03-01

    A small fraction of the halo field is made up of stars that share the light element (Z ≤ 13) anomalies characteristic of second generation globular cluster (GC) stars. The ejected stars shed light on the formation of the Galactic halo by tracing the dynamical history of the clusters, which are believed to have once been more massive. Some of these ejected stars are expected to show strong Al enhancement at the expense of shortage of Mg, but until now no such star has been found. We search for outliers in the Mg and Al abundances of the few hundreds of halo field stars observed in the first eighteen months of the Gaia-ESO public spectroscopic survey. One halo star at the base of the red giant branch, here referred to as 22593757-4648029 is found to have [ Mg/Fe ] = -0.36 ± 0.04 and [ Al/Fe ] = 0.99 ± 0.08, which is compatible with the most extreme ratios detected in GCs so far. We compare the orbit of 22593757-4648029 to GCs of similar metallicity andfind it unlikely that this star has been tidally stripped with low ejection velocity from any of the clusters. However, both chemical and kinematic arguments render it plausible that the star has been ejected at high velocity from the anomalous GC ω Centauri within the last few billion years. We cannot rule out other progenitor GCs, because some may have disrupted fully, and the abundance and orbital data are inadequate for many of those that are still intact. Based on data acquired by the Gaia-ESO Survey, programme ID 188.B-3002. Observations were made with ESO Telescopes at the La Silla Paranal Observatory.Appendix A is available in electronic form at http://www.aanda.org

  5. An Ultraviolet Excess in the Superluminous Supernova Gaia16apd Reveals a Powerful Central Engine

    SciTech Connect

    Nicholl, M.; Berger, E.; Blanchard, P. K.

    Since the discovery of superluminous supernovae (SLSNe) in the last decade, it has been known that these events exhibit bluer spectral energy distributions than other supernova subtypes, with significant output in the ultraviolet. However, the event Gaia16apd seems to outshine even the other SLSNe at rest-frame wavelengths below ∼3000 Å. Yan et al. have recently presented HST UV spectra and attributed the UV flux to low iron-group abundance in the outer ejecta, and hence reduced line blanketing. Here, we present UV and optical light curves over a longer baseline in time, revealing a rapid decline at UV wavelengths despite amore » typical optical evolution. Combining the published UV spectra with our own optical data, we demonstrate that Gaia16apd has a much hotter continuum than virtually any SLSN at maximum light, but it cools rapidly thereafter and is indistinguishable from the others by ∼10–15 days after peak. Comparing the equivalent widths of UV absorption lines with those of other events, we show that the excess UV continuum is a result of a more powerful central power source, rather than a lack of UV absorption relative to other SLSNe or an additional component from interaction with the surrounding medium. These findings strongly support the central-engine hypothesis for hydrogen-poor SLSNe. An explosion ejecting M {sub ej} = 4.8(0.2/ κ ) M {sub ⊙}, where κ is the opacity in cm{sup 2} g{sup −1}, and forming a magnetar with spin period P = 2 ms, and B = 2 × 10{sup 14} G (lower than other SLSNe with comparable rise times) can consistently explain the light curve evolution and high temperature at peak. The host metallicity, Z = 0.18 Z {sub ⊙}, is comparable to other SLSNe.« less

  6. Quasar lenses and pairs in the VST-ATLAS and Gaia

    NASA Astrophysics Data System (ADS)

    Agnello, A.; Schechter, P. L.; Morgan, N. D.; Treu, T.; Grillo, C.; Malesani, D.; Anguita, T.; Apostolovski, Y.; Rusu, C. E.; Motta, V.; Rojas, K.; Chehade, B.; Shanks, T.

    2018-04-01

    We report on discovery results from a quasar lens search in the ATLAS-DR3 public footprint. Spectroscopic follow-up campaigns, conducted at the 2.6 m Nordic Optical Telescope (La Palma) and 3.6 m New Technology Telescope (La Silla) in 2016, yielded seven pairs of quasars exhibiting the same lines at the same redshift and monotonic flux ratios with wavelength (hereafter NIQs, nearly identical quasar pairs). Magellan spectra of A0140-1152 (01h40m03{^s.}0-11d52m19{^s.}0, zs = 1.807) confirm it as a lens with deflector at zl = 0.277 and Einstein radius θE = (0.73 ± 0.02) arcsec. Follow-up imaging of the NIQ A2213-2652 (22h13m38{^s.}4-26d52m27{^s.}1) reveals the deflector galaxy and confirms it as a lens. We show the use of spatial resolution from the Gaia mission to select lenses and list additional systems from a WISE-Gaia-ATLAS search, yielding three additional lenses (02h35m27{^s.}4-24d33m13{^s.}2, 02h59m33s-23d38m01{^s.}8, 01h46m32{^s.}9-11d33m39{^s.}0). The overall sample consists of 11 lenses/NIQs, plus three lenses known before 2016, over the ATLAS-DR3 footprint (≈3500 deg2). Finally, we discuss future prospects for objective classification of pair/NIQ/contaminant spectra.

  7. Variability of extragalactic sources: its contribution to the link between ICRF and the future Gaia Celestial Reference Frame

    NASA Astrophysics Data System (ADS)

    Taris, F.; Damljanovic, G.; Andrei, A.; Souchay, J.; Klotz, A.; Vachier, F.

    2018-03-01

    Context. The first release of the Gaia catalog is available since 14 September 2016. It is a first step in the realization of the future Gaia reference frame. This reference frame will be materialized by the optical positions of the sources and will be compared with and linked to the International Celestial Reference Frame, materialized by the radio position of extragalactic sources. Aim. As in the radio domain, it can be reasonably postulated that quasar optical flux variations can alert us to potential changes in the source structure. These changes could have important implications for the position of the target photocenters (together with the evolution in time of these centers) and in parallel have consequences for the link of the reference systems. Methods: A set of nine optical telescopes was used to monitor the magnitude variations, often at the same time as Gaia, thanks to the Gaia Observation Forecast Tool. The Allan variances, which are statistical tools widely used in the atomic time and frequency community, are introduced. Results: This work describes the magnitude variations of 47 targets that are suitable for the link between reference systems. We also report on some implications for the Gaia catalog. For 95% of the observed targets, new information about their variability is reported. In the case of some targets that are well observed by the TAROT telescopes, the Allan time variance shows that the longest averaging period of the magnitudes is in the range 20-70 d. The observation period by Gaia for a single target largely exceeds these values, which might be a problem when the magnitude variations exhibit flicker or random walk noises. Preliminary computations show that if the coordinates of the targets studied in this paper were affected by a white-phase noise with a formal uncertainty of about 1 mas (due to astrophysical processes that are put in evidence by the magnitude variations of the sources), it would affect the precision of the link at the

  8. Toward University Modeling Instruction—Biology: Adapting Curricular Frameworks from Physics to Biology

    PubMed Central

    Manthey, Seth; Brewe, Eric

    2013-01-01

    University Modeling Instruction (UMI) is an approach to curriculum and pedagogy that focuses instruction on engaging students in building, validating, and deploying scientific models. Modeling Instruction has been successfully implemented in both high school and university physics courses. Studies within the physics education research (PER) community have identified UMI's positive impacts on learning gains, equity, attitudinal shifts, and self-efficacy. While the success of this pedagogical approach has been recognized within the physics community, the use of models and modeling practices is still being developed for biology. Drawing from the existing research on UMI in physics, we describe the theoretical foundations of UMI and how UMI can be adapted to include an emphasis on models and modeling for undergraduate introductory biology courses. In particular, we discuss our ongoing work to develop a framework for the first semester of a two-semester introductory biology course sequence by identifying the essential basic models for an introductory biology course sequence. PMID:23737628

  9. Toward university modeling instruction--biology: adapting curricular frameworks from physics to biology.

    PubMed

    Manthey, Seth; Brewe, Eric

    2013-06-01

    University Modeling Instruction (UMI) is an approach to curriculum and pedagogy that focuses instruction on engaging students in building, validating, and deploying scientific models. Modeling Instruction has been successfully implemented in both high school and university physics courses. Studies within the physics education research (PER) community have identified UMI's positive impacts on learning gains, equity, attitudinal shifts, and self-efficacy. While the success of this pedagogical approach has been recognized within the physics community, the use of models and modeling practices is still being developed for biology. Drawing from the existing research on UMI in physics, we describe the theoretical foundations of UMI and how UMI can be adapted to include an emphasis on models and modeling for undergraduate introductory biology courses. In particular, we discuss our ongoing work to develop a framework for the first semester of a two-semester introductory biology course sequence by identifying the essential basic models for an introductory biology course sequence.

  10. Merging universal and indicated prevention programs: the Fast Track model. Conduct Problems Prevention Research Group.

    PubMed

    2000-01-01

    Fast Track is a multisite, multicomponent preventive intervention for young children at high risk for long-term antisocial behavior. Based on a comprehensive developmental model, this intervention includes a universal-level classroom program plus social-skill training, academic tutoring, parent training, and home visiting to improve competencies and reduce problems in a high-risk group of children selected in kindergarten. The theoretical principles and clinical strategies utilized in the Fast Track Project are described to illustrate the interplay between basic developmental research, the understanding of risk and protective factors, and a research-based model of preventive intervention that integrates universal and indicated models of prevention.

  11. Out of This World: A University Partnership Model for Functional Clothing Design

    NASA Technical Reports Server (NTRS)

    Dunne, Lucy E.; Simon, Cory

    2013-01-01

    University collaborations with external partners can be difficult to initiate, especially in early-stage or emerging topics. External collaborators may be reluctant to commit the level of funding required to ensure that the topic is given adequate attention, and low-stakes mechanisms are relatively rare. Here, we present a successful model for collaboration between universities and NASA, which uses existing project-based coursework as a vehicle for exploration of emerging topics. This model leverages existing structures, reducing the financial and intellectual commitment of both University and NASA research partners, and facilitating pilot investigations for exploration of potential areas for more in-depth research. We outline the logistical structure and benefits for University and NASA partners over 1.5 years of collaboration.

  12. The Robust Learning Model (RLM): A Comprehensive Approach to a New Online University

    ERIC Educational Resources Information Center

    Neumann, Yoram; Neumann, Edith F.

    2010-01-01

    This paper outlines the components of the Robust Learning Model (RLM) as a conceptual framework for creating a new online university offering numerous degree programs at all degree levels. The RLM is a multi-factorial model based on the basic belief that successful learning outcomes depend on multiple factors employed together in a holistic…

  13. A Model for Projection of Instructional Activity in a Multi-Campus University.

    ERIC Educational Resources Information Center

    Tallman, B. M.; Newton, R. D.

    This report is concerned with the development of a model for projecting instructional activity and its application within The Pennsylvania State University. Inasmuch as models of this type have been developed at a number of institutions of higher education, the effort described in this report does not constitute an extension of fundamental…

  14. A Universal Model for Evaluating Basic Electronic Courses in Terms of Field Utilization of Training.

    ERIC Educational Resources Information Center

    Air Force Occupational Measurement Center, Lackland AFB, TX.

    The main purpose of the Air Force project was to develop a universal model to evaluate usage of basic electronic principles training. The criterion used by the model to evaluate electronic theory training is a determination of the usefulness of the training vis-a-vis the performance of assigned tasks in the various electronic career fields. Data…

  15. Making of a Corporate University Model: Transition from Traditional Training to Learning Management System

    ERIC Educational Resources Information Center

    Ilyas, Mohammed

    2017-01-01

    Today organizations have adopted a corporate university model to meet their training requirements, a model that adds value to the business in terms of revenue and profit, improvement in customer retention, improved employee productivity, cost reduction and retention of talented employees. This paper highlights the radical change and an evolution…

  16. A Developmental Sequence Model to University Adjustment of International Undergraduate Students

    ERIC Educational Resources Information Center

    Chavoshi, Saeid; Wintre, Maxine Gallander; Dentakos, Stella; Wright, Lorna

    2017-01-01

    The current study proposes a Developmental Sequence Model to University Adjustment and uses a multifaceted measure, including academic, social and psychological adjustment, to examine factors predictive of undergraduate international student adjustment. A hierarchic regression model is carried out on the Student Adaptation to College Questionnaire…

  17. Testing an Instructional Model in a University Educational Setting from the Student's Perspective

    ERIC Educational Resources Information Center

    Betoret, Fernando Domenech

    2006-01-01

    We tested a theoretical model that hypothesized relationships between several variables from input, process and product in an educational setting, from the university student's perspective, using structural equation modeling. In order to carry out the analysis, we measured in sequential order the input (referring to students' personal…

  18. University Library Strategy Development: A Conceptual Model of Researcher Performance to Inform Service Delivery

    ERIC Educational Resources Information Center

    Maddox, Alexia; Zhao, Linlin

    2017-01-01

    This case study presents a conceptual model of researcher performance developed by Deakin University Library, Australia. The model aims to organize research performance data into meaningful researcher profiles, referred to as researcher typologies, which support the demonstration of research impact and value. Three dimensions shaping researcher…

  19. The ethical and pedagogical effects of modeling "not-so-universal" precautions.

    PubMed

    Aultman, Julie M; Borges, Nicole J

    2011-01-01

    We sought to understand current medical students' levels of training and knowledge, and their attitudes regarding universal precautions practices and underlying professional and ethical issues. A total of 54 US medical students at two schools were interviewed to determine the level of understanding and training students receive about universal precautions, their feelings about the effectiveness (or ineffectiveness) of universal precautions, the frequency and kinds of universal precautions used by healthcare professionals as observed by medical students, and students' perspectives about the lack of or inconsistent use of universal precautions. Pre-clinical students focused on safe-sex practices among students and professionals, as well as simple, important acts to protect oneself against infection and disease, such as hand-washing. Clinical students, on the other hand, had more exposure to observing and practicing universal precautions, thus presented us with more, in-depth responses pertaining to inconsistent and ineffective use of universal precautions among peers and role models. Several themes were noted from students' responses. This study confirms previously acquired data that universal precautions are not consistently or appropriately used by healthcare professionals, it is a significant and novel study in that it reveals a hidden, ethical, and clinical problem in medical education.

  20. Newtonian self-gravitating system in a relativistic huge void universe model

    SciTech Connect

    Nishikawa, Ryusuke; Nakao, Ken-ichi; Yoo, Chul-Moon, E-mail: ryusuke@sci.osaka-cu.ac.jp, E-mail: knakao@sci.osaka-cu.ac.jp, E-mail: yoo@gravity.phys.nagoya-u.ac.jp

    We consider a test of the Copernican Principle through observations of the large-scale structures, and for this purpose we study the self-gravitating system in a relativistic huge void universe model which does not invoke the Copernican Principle. If we focus on the the weakly self-gravitating and slowly evolving system whose spatial extent is much smaller than the scale of the cosmological horizon in the homogeneous and isotropic background universe model, the cosmological Newtonian approximation is available. Also in the huge void universe model, the same kind of approximation as the cosmological Newtonian approximation is available for the analysis of themore » perturbations contained in a region whose spatial size is much smaller than the scale of the huge void: the effects of the huge void are taken into account in a perturbative manner by using the Fermi-normal coordinates. By using this approximation, we derive the equations of motion for the weakly self-gravitating perturbations whose elements have relative velocities much smaller than the speed of light, and show the derived equations can be significantly different from those in the homogeneous and isotropic universe model, due to the anisotropic volume expansion in the huge void. We linearize the derived equations of motion and solve them. The solutions show that the behaviors of linear density perturbations are very different from those in the homogeneous and isotropic universe model.« less