TY - JOUR A1 - Jiang, G. F. A1 - DePoy, D. L. A1 - Gal-Yam, A. A1 - Gaudi, B. S. A1 - Gould, A. A1 - Han, C. A1 - Lipkin, Y. A1 - Maoz, D. A1 - Ofek, E. O. A1 - Park, B. G. A1 - Pogge, R. W. A1 - Udalski, A. A1 - Kubiak, Marcin A1 - Szymanski, M. K. A1 - Szewczyk, O. A1 - Zerbrun, K. A1 - Wyrzykowski, L. A1 - Soszynski, I. A1 - Pietrzynski, G. A1 - Albrow, Michael D. A1 - Beaulieu, Jean-Philippe A1 - Caldwell, John A. R. A1 - Cassan, A. A1 - Coutures, C. A1 - Dominik, M. A1 - Donatowicz, J. A1 - Fouque, P. A1 - Greenhill, John A1 - Hill, K. A1 - Horne, Keith A1 - Jorgensen, S. F. A1 - Jorgensen, Uffe Grae A1 - Kane, Stephen R. A1 - Kubas, Daniel A1 - Martin, Ralph A1 - Menzies, J. W. A1 - Pollard, R. A1 - Sahu, K. C. A1 - Wambsganss, Joachim A1 - Watson, R. A1 - Williams, A. T1 - OGLE-2003-BLG-238 : Microlensing mass estimate of an isolated star N2 - Microlensing is the only known direct method to measure the masses of stars that lack visible companions. In terms of microlensing observables, the mass is given by M (c(2)/4G)(r) over tilde (E)theta(E) and so requires the measurement of both the angular Einstein radius theta(E) and the projected Einstein radius (r) over tilde (E). Simultaneous measurement of these two parameters is extremely rare. Here we analyze OGLE-2003-BLG-238, a spectacularly bright (I-min 10.3), high-magnification (A(max) 170) microlensing event. Pronounced finite-source effects permit a measurement of theta(E) = 650 muas. Although the timescale of the event is only t(E) 38 days, one can still obtain weak constraints on the microlens parallax: 4.4 AU < <(r)over tilde>(E) < 18 AU at the 1 σ level. Together these two parameter measurements yield a range for the lens mass of 0.36 M-&ODOT; < M < 1.48 M-&ODOT;. As was the case for MACHO- LMC-5, the only other single star (apart from the Sun) whose mass has been determined from its gravitational effects, this estimate is rather crude. It does, however, demonstrate the viability of the technique. We also discuss future prospects for single-lens mass measurements Y1 - 2004 SN - 0004-637X ER - TY - JOUR A1 - Kubas, Daniel A1 - Cassan, A. A1 - Beaulieu, Jean-Philippe A1 - Coutures, C. A1 - Dominik, M. A1 - Albrow, Michael D. A1 - Brillant, Stephane A1 - Caldwell, John A. R. A1 - Dominis, Dijana A1 - Donatowicz, J. A1 - Fendt, Christian A1 - Fouque, P. A1 - Jorgensen, Uffe Grae A1 - Greenhill, John A1 - Hill, K. A1 - Heinmüller, Janine A1 - Horne, Keith A1 - Kane, Stephen R. A1 - Marquette, Jean-Baptiste A1 - Martin, Ralph A1 - Menzies, J. W. A1 - Pollard, K. R. A1 - Sahu, K. C. A1 - Vinter, C. A1 - Wambsganss, Joachim A1 - Watson, R. A1 - Williams, A. A1 - Thurl, C. T1 - Full characterization of binary-lens event OGLE-2002-BLG-069 from PLANET observations N2 - We analyze the photometric data obtained by PLANET and OGLE on the caustic-crossing binary-lens microlensing event OGLE-2002-BLG-069. Thanks to the excellent photometric and spectroscopic coverage of the event, we are able to constrain the lens model up to the known ambiguity between close and wide binary lenses. The detection of annual parallax in combination with measurements of extended-source effects allows us to determine the mass, distance and velocity of the lens components for the competing models. While the model involving a close binary lens leads to a Bulge- Disc lens scenario with a lens mass of M = (0.51 ± 0.15) M-&ODOT; and distance of D-L = (2.9 ± 0.4) kpc, the wide binary lens solution requires a rather implausible binary black-hole lens ( M &GSIM; 126 M-&ODOT;). Furthermore we compare current state-of-the-art numerical and empirical models for the surface brightness profile of the source, a G5III Bulge giant. We find that a linear limb-darkening model for the atmosphere of the source star is consistent with the data whereas a PHOENIX atmosphere model assuming LTE and with no free parameter does not match our observations Y1 - 2005 SN - 0004-6361 ER - TY - JOUR A1 - Cassan, A. A1 - Beaulieu, Jean-Philippe A1 - Brillant, Stephane A1 - Coutures, C. A1 - Dominik, M. A1 - Donatowicz, J. A1 - Jorgensen, Uffe Grae A1 - Kubas, Daniel A1 - Albrow, Michael D. A1 - Caldwell, John A. R. A1 - Fouque, P. A1 - Greenhill, John A1 - Hill, K. A1 - Horne, Keith A1 - Kane, Stephen R. A1 - Martin, Ralph A1 - Menzies, J. W. A1 - Pollard, K. R. A1 - Sahu, K. C. A1 - Vinter, C. A1 - Wambsganss, Joachim A1 - Watson, R. A1 - Williams, A. A1 - Fendt, Christian A1 - Hauschildt, P. A1 - Heinmueller, Janine A1 - Marquette, Jean-Baptiste A1 - Thurl, C. T1 - Probing the atmosphere of the bulge G5III star OGLE-2002-BUL-069 by analysis of microlensed H alpha line N2 - We discuss high-resolution, time-resolved spectra of the caustic exit of the binary microlensing event OGLE 2002-BLG-069 obtained with UVES on the VLT. The source star is a G5III giant in the Galactic Bulge. During such events, the source star is highly magnified, and a strong differential magnification around the caustic resolves its surface. Using an appropriate model stellar atmosphere generated by the PHOENIX v2.6 code we obtain a model light curve for the caustic exit and compare it with a dense set of photometric observations obtained by the PLANET microlensing follow up network. We further compare predicted variations in the Halpha equivalent width with those measured from our spectra. While the model and observations agree in the gross features, there are discrepancies suggesting shortcomings in the model, particularly for the Halpha line core, where we have detected amplified emission from the stellar chromosphere after the source star's trailing limb exited the caustic. This achievement became possible by the provision of the very efficient OGLE-III Early Warning System, a network of small telescopes capable of nearly-continuous round-the-clock photometric monitoring, on-line data reduction, daily near-real-time modelling in order to predict caustic crossing parameters, and a fast and efficient response of a 8 m class telescope to a "Target-of-Opportunity" observation request Y1 - 2004 ER - TY - JOUR A1 - Sackett, Penny D. A1 - Albrow, Michael D. A1 - Beaulieu, Jean-Philippe A1 - Caldwell, John A. R. A1 - Coutures, C. A1 - Dominik, M. A1 - Greenhill, John A1 - Hill, K. A1 - Horne, Keith A1 - Jorgensen, Uffe Grae A1 - Kane, Stephen R. A1 - Kubas, Daniel A1 - Martin, Ralph A1 - Menzies, J. W. A1 - Pollard, K. R. A1 - Sahu, K. C. A1 - Wambsganß, Joachim A1 - Watson, R. A1 - Williams, A. T1 - PLANET II : a microlensing and transit search for extrasolar planets N2 - Due to their extremely small luminosity compared to the stars they orbit, planets outside our own Solar System are extraordinarily difficult to detect directly in optical light. Careful photometric monitoring of distant stars, however, can reveal the presence of exoplanets via the microlensing or eclipsing effects they induce. The international PLANET collaboration is performing such monitoring using a cadre of semi-dedicated telescopes around the world. Their results constrain the number of gas giants orbiting 1-7 AU from the most typical stars in the Galaxy. Upgrades in the program are opening regions of ''exoplanet discovery space'' - toward smaller masses and larger orbital radii - that are inaccessible to the Doppler velocity technique. Y1 - 2003 UR - http://arxiv.org/pdf/astro-ph/0211098 ER - TY - JOUR A1 - Beaulieu, Jean-Philippe A1 - Bennett, David P. A1 - Fouqué, Pascal A1 - Williams, Andrew A1 - Dominik, Martin A1 - Jorgensen, Uffe Grae A1 - Kubas, Daniel A1 - Cassan, Arnaud A1 - Coutures, Christian A1 - Greenhill, John A1 - Hill, Kym A1 - Menzies, John A1 - Sackett, Penny D. A1 - Albrow, Michael D. A1 - Brillant, Stephane A1 - Caldwell, John A. R. A1 - Calitz, Johannes Jacobus A1 - Cook, Kem H. A1 - Corrales Cosmeli, Esperanza de Santa Cecilia A1 - Desort, Morgan A1 - Dieters, Stefan A1 - Dominis, Dijana A1 - Donatowicz, Jadzia A1 - Hoffman, Martie A1 - Kane, Stephen R. A1 - Marquette, Jean-Baptiste A1 - Martin, Ralph A1 - Meintjes, Pieter A1 - Pollard, Karen R. A1 - Sahu, Kailash C. A1 - Vinter, Christian A1 - Wambsganss, Joachim A1 - Woller, Kristian A1 - Horne, Keith A1 - Steele, Iain A1 - Bramich, Daniel M. A1 - Burgdorf, Martin A1 - Snodgrass, Colin A1 - Bode, Mike A1 - Udalski, Andr T1 - Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing N2 - In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars ( the most common stars in our Galaxy), this model favours the formation of Earth-mass (M+) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (AU), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars(1-4). More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 AU from normal stars. Here we report the discovery of a 5.5(-2.7)(+5.5)M(+) planetary companion at a separation of 2.6(- 0.6)(+1.5) AU from a 0.22(-0.11)(+0.21)M(.) M-dwarf star, where M-. refers to a solar mass. (We propose to name it OGLE- 2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory. Y1 - 2006 UR - http://www.nature.com/nature/ U6 - https://doi.org/10.1038/Nature04441 SN - 0028-0836 ER - TY - JOUR A1 - Levermann, Anders A1 - Winkelmann, Ricarda A1 - Nowicki, S. A1 - Fastook, J. L. A1 - Frieler, Katja A1 - Greve, R. A1 - Hellmer, H. H. A1 - Martin, M. A. A1 - Meinshausen, Malte A1 - Mengel, Matthias A1 - Payne, A. J. A1 - Pollard, D. A1 - Sato, T. A1 - Timmermann, R. A1 - Wang, Wei Li A1 - Bindschadler, Robert A. T1 - Projecting antarctic ice discharge using response functions from SeaRISE ice-sheet models JF - Earth system dynamics N2 - The largest uncertainty in projections of future sea-level change results from the potentially changing dynamical ice discharge from Antarctica. Basal ice-shelf melting induced by a warming ocean has been identified as a major cause for additional ice flow across the grounding line. Here we attempt to estimate the uncertainty range of future ice discharge from Antarctica by combining uncertainty in the climatic forcing, the oceanic response and the ice-sheet model response. The uncertainty in the global mean temperature increase is obtained from historically constrained emulations with the MAGICC-6.0 (Model for the Assessment of Greenhouse gas Induced Climate Change) model. The oceanic forcing is derived from scaling of the subsurface with the atmospheric warming from 19 comprehensive climate models of the Coupled Model Intercomparison Project (CMIP-5) and two ocean models from the EU-project Ice2Sea. The dynamic ice-sheet response is derived from linear response functions for basal ice-shelf melting for four different Antarctic drainage regions using experiments from the Sea-level Response to Ice Sheet Evolution (SeaRISE) intercomparison project with five different Antarctic ice-sheet models. The resulting uncertainty range for the historic Antarctic contribution to global sea-level rise from 1992 to 2011 agrees with the observed contribution for this period if we use the three ice-sheet models with an explicit representation of ice-shelf dynamics and account for the time-delayed warming of the oceanic subsurface compared to the surface air temperature. The median of the additional ice loss for the 21st century is computed to 0.07 m (66% range: 0.02-0.14 m; 90% range: 0.0-0.23 m) of global sea-level equivalent for the low-emission RCP-2.6 (Representative Concentration Pathway) scenario and 0.09 m (66% range: 0.04-0.21 m; 90% range: 0.01-0.37 m) for the strongest RCP-8.5. Assuming no time delay between the atmospheric warming and the oceanic subsurface, these values increase to 0.09 m (66% range: 0.04-0.17 m; 90% range: 0.02-0.25 m) for RCP-2.6 and 0.15 m (66% range: 0.07-0.28 m; 90% range: 0.04-0.43 m) for RCP-8.5. All probability distributions are highly skewed towards high values. The applied ice-sheet models are coarse resolution with limitations in the representation of grounding-line motion. Within the constraints of the applied methods, the uncertainty induced from different ice-sheet models is smaller than that induced by the external forcing to the ice sheets. Y1 - 2014 U6 - https://doi.org/10.5194/esd-5-271-2014 SN - 2190-4979 SN - 2190-4987 VL - 5 IS - 2 SP - 271 EP - 293 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Bresnick, Anne R. A1 - Wolff-Long, Vicki L. A1 - Baumann, Otto A1 - Pollard, Thomas D. T1 - Phosphorylation of threonine-18 of the regulatory light chain dissociates the ATPase and motor properties of smooth muscle myosin II Y1 - 1995 SN - 006-2960 ER - TY - JOUR A1 - Seroussi, Helene A1 - Nowicki, Sophie A1 - Simon, Erika A1 - Abe-Ouchi, Ayako A1 - Albrecht, Torsten A1 - Brondex, Julien A1 - Cornford, Stephen A1 - Dumas, Christophe A1 - Gillet-Chaulet, Fabien A1 - Goelzer, Heiko A1 - Golledge, Nicholas R. A1 - Gregory, Jonathan M. A1 - Greve, Ralf A1 - Hoffman, Matthew J. A1 - Humbert, Angelika A1 - Huybrechts, Philippe A1 - Kleiner, Thomas A1 - Larourl, Eric A1 - Leguy, Gunter A1 - Lipscomb, William H. A1 - Lowry, Daniel A1 - Mengel, Matthias A1 - Morlighem, Mathieu A1 - Pattyn, Frank A1 - Payne, Anthony J. A1 - Pollard, David A1 - Price, Stephen F. A1 - Quiquet, Aurelien A1 - Reerink, Thomas J. A1 - Reese, Ronja A1 - Rodehacke, Christian B. A1 - Schlegel, Nicole-Jeanne A1 - Shepherd, Andrew A1 - Sun, Sainan A1 - Sutter, Johannes A1 - Van Breedam, Jonas A1 - van de Wal, Roderik S. W. A1 - Winkelmann, Ricarda A1 - Zhang, Tong T1 - initMIP-Antarctica BT - an ice sheet model initialization experiment of ISMIP6 JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union N2 - Ice sheet numerical modeling is an important tool to estimate the dynamic contribution of the Antarctic ice sheet to sea level rise over the coming centuries. The influence of initial conditions on ice sheet model simulations, however, is still unclear. To better understand this influence, an initial state intercomparison exercise (initMIP) has been developed to compare, evaluate, and improve initialization procedures and estimate their impact on century-scale simulations. initMlP is the first set of experiments of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6), which is the primary Coupled Model Intercomparison Project Phase 6 (CMIP6) activity focusing on the Greenland and Antarctic ice sheets. Following initMlP-Greenland, initMlP-Antarctica has been designed to explore uncertainties associated with model initialization and spin-up and to evaluate the impact of changes in external forcings. Starting from the state of the Antarctic ice sheet at the end of the initialization procedure, three forward experiments are each run for 100 years: a control run, a run with a surface mass balance anomaly, and a run with a basal melting anomaly beneath floating ice. This study presents the results of initMlP-Antarctica from 25 simulations performed by 16 international modeling groups. The submitted results use different initial conditions and initialization methods, as well as ice flow model parameters and reference external forcings. We find a good agreement among model responses to the surface mass balance anomaly but large variations in responses to the basal melting anomaly. These variations can be attributed to differences in the extent of ice shelves and their upstream tributaries, the numerical treatment of grounding line, and the initial ocean conditions applied, suggesting that ongoing efforts to better represent ice shelves in continental-scale models should continue. Y1 - 2019 U6 - https://doi.org/10.5194/tc-13-1441-2019 SN - 1994-0416 SN - 1994-0424 VL - 13 IS - 5 SP - 1441 EP - 1471 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Bindschadler, Robert A. A1 - Nowicki, Sophie A1 - Abe-Ouchi, Ayako A1 - Aschwanden, Andy A1 - Choi, Hyeungu A1 - Fastook, Jim A1 - Granzow, Glen A1 - Greve, Ralf A1 - Gutowski, Gail A1 - Herzfeld, Ute A1 - Jackson, Charles A1 - Johnson, Jesse A1 - Khroulev, Constantine A1 - Levermann, Anders A1 - Lipscomb, William H. A1 - Martin, Maria A. A1 - Morlighem, Mathieu A1 - Parizek, Byron R. A1 - Pollard, David A1 - Price, Stephen F. A1 - Ren, Diandong A1 - Saito, Fuyuki A1 - Sato, Tatsuru A1 - Seddik, Hakime A1 - Seroussi, Helene A1 - Takahashi, Kunio A1 - Walker, Ryan A1 - Wang, Wei Li T1 - Ice-sheet model sensitivities to environmental forcing and their use in projecting future sea level (the SeaRISE project) JF - Journal of glaciology N2 - Ten ice-sheet models are used to study sensitivity of the Greenland and Antarctic ice sheets to prescribed changes of surface mass balance, sub-ice-shelf melting and basal sliding. Results exhibit a large range in projected contributions to sea-level change. In most cases, the ice volume above flotation lost is linearly dependent on the strength of the forcing. Combinations of forcings can be closely approximated by linearly summing the contributions from single forcing experiments, suggesting that nonlinear feedbacks are modest. Our models indicate that Greenland is more sensitive than Antarctica to likely atmospheric changes in temperature and precipitation, while Antarctica is more sensitive to increased ice-shelf basal melting. An experiment approximating the Intergovernmental Panel on Climate Change's RCP8.5 scenario produces additional first-century contributions to sea level of 22.3 and 8.1 cm from Greenland and Antarctica, respectively, with a range among models of 62 and 14 cm, respectively. By 200 years, projections increase to 53.2 and 26.7 cm, respectively, with ranges of 79 and 43 cm. Linear interpolation of the sensitivity results closely approximates these projections, revealing the relative contributions of the individual forcings on the combined volume change and suggesting that total ice-sheet response to complicated forcings over 200 years can be linearized. Y1 - 2013 U6 - https://doi.org/10.3189/2013JoG12J125 SN - 0022-1430 VL - 59 IS - 214 SP - 195 EP - 224 PB - International Glaciological Society CY - Cambridge ER - TY - JOUR A1 - Nowicki, Sophie A1 - Bindschadler, Robert A. A1 - Abe-Ouchi, Ayako A1 - Aschwanden, Andy A1 - Bueler, Ed A1 - Choi, Hyeungu A1 - Fastook, Jim A1 - Granzow, Glen A1 - Greve, Ralf A1 - Gutowski, Gail A1 - Herzfeld, Ute A1 - Jackson, Charles A1 - Johnson, Jesse A1 - Khroulev, Constantine A1 - Larour, Eric A1 - Levermann, Anders A1 - Lipscomb, William H. A1 - Martin, Maria A. A1 - Morlighem, Mathieu A1 - Parizek, Byron R. A1 - Pollard, David A1 - Price, Stephen F. A1 - Ren, Diandong A1 - Rignot, Eric A1 - Saito, Fuyuki A1 - Sato, Tatsuru A1 - Seddik, Hakime A1 - Seroussi, Helene A1 - Takahashi, Kunio A1 - Walker, Ryan A1 - Wang, Wei Li T1 - Insights into spatial sensitivities of ice mass response to environmental change from the SeaRISE ice sheet modeling project II Greenland JF - Journal of geophysical research : Earth surface N2 - The Sea-level Response to Ice Sheet Evolution (SeaRISE) effort explores the sensitivity of the current generation of ice sheet models to external forcing to gain insight into the potential future contribution to sea level from the Greenland and Antarctic ice sheets. All participating models simulated the ice sheet response to three types of external forcings: a change in oceanic condition, a warmer atmospheric environment, and enhanced basal lubrication. Here an analysis of the spatial response of the Greenland ice sheet is presented, and the impact of model physics and spin-up on the projections is explored. Although the modeled responses are not always homogeneous, consistent spatial trends emerge from the ensemble analysis, indicating distinct vulnerabilities of the Greenland ice sheet. There are clear response patterns associated with each forcing, and a similar mass loss at the full ice sheet scale will result in different mass losses at the regional scale, as well as distinct thickness changes over the ice sheet. All forcings lead to an increased mass loss for the coming centuries, with increased basal lubrication and warmer ocean conditions affecting mainly outlet glaciers, while the impacts of atmospheric forcings affect the whole ice sheet. KW - Greenland KW - ice-sheet KW - sea-level KW - model KW - ensemble Y1 - 2013 U6 - https://doi.org/10.1002/jgrf.20076 SN - 2169-9003 VL - 118 IS - 2 SP - 1025 EP - 1044 PB - American Geophysical Union CY - Washington ER -