Results 11 to 20 of about 3,877 (212)

An analytic expression for coronagraphic imaging through turbulence. Application to on-sky coronagraphic phase diversity [PDF]

Monthly Notices of the Royal Astronomical Society: Letters, 2017
Abstract The ultimate performance of coronagraphic high-contrast exoplanet imaging systems such as SPHERE or GPI is limited by quasi-static aberrations. These aberrations produce speckles that can be mistaken for planets in the image. In order to design instruments, correct quasi-static aberrations or analyse data, the expression of the ...
Herscovici-Schiller, Olivier, Mugnier, Laurent M., Sauvage, Jean-François   +2 more
openaire   +4 more sources

Parameter Distributions for the Drag‐Based Modeling of CME Propagation

Space Weather, Volume 20, Issue 9, September 2022., 2022
Abstract In recent years, ensemble modeling has been widely employed in space weather to estimate uncertainties in forecasts. We here focus on the ensemble modeling of Coronal Mass Ejections (CME) arrival times and arrival velocities using a drag‐based model, which is well‐suited for this purpose due to its simplicity and low computational cost ...
Gianluca Napoletano, Raffaello Foldes, Enrico Camporeale, Giancarlo de Gasperis, Luca Giovannelli, Evangelos Paouris, Ermanno Pietropaolo, Jannis Teunissen, Ajay Kumar Tiwari, Dario Del Moro   +9 more
wiley   +1 more source

Time‐of‐Arrival of Coronal Mass Ejections: A Two‐Phase Kinematics Approach Based on Heliospheric Imaging Observations

Space Weather, Volume 20, Issue 7, July 2022., 2022
Abstract The forecasting of the Time‐of‐Arrival (ToA) of coronal mass ejections (CMEs) to Earth does not yet meet most Space Weather users' requirements. The main physical reason is our incomplete understanding of CME propagation in the inner heliosphere.
Evangelos Paouris, Angelos Vourlidas
wiley   +1 more source

A Multi‐Purpose Heliophysics L4 Mission

Space Weather, Volume 19, Issue 9, September 2021., 2021
Abstract The Earth‐Sun Lagrangian point 4 is a meta‐stable location at 1 AU from the Sun, 60° ahead of Earth's orbit. It has an uninterrupted view of the solar photosphere centered on W60, the Earth's nominal magnetic field connection to the Sun. Such a mission on its own would serve as a solar remote sensing observatory that would oversee the entire ...
A. Posner, C. N. Arge, J. Staub, O. C. StCyr, D. Folta, S. K. Solanki, R. D. T. Strauss, F. Effenberger, A. Gandorfer, B. Heber, C. J. Henney, J. Hirzberger, S. I. Jones, P. Kühl, O. Malandraki, V. J. Sterken   +15 more
wiley   +1 more source

A Quarter Century of Wind Spacecraft Discoveries

Reviews of Geophysics, Volume 59, Issue 2, June 2021., 2021
Abstract The Wind spacecraft, launched on November 1, 1994, is a critical element in NASA’s Heliophysics System Observatory (HSO)—a fleet of spacecraft created to understand the dynamics of the Sun‐Earth system. The combination of its longevity (>25 years in service), its diverse complement of instrumentation, and high resolution and accurate ...
Lynn B. Wilson III, Alexandra L. Brosius, Natchimuthuk Gopalswamy, Teresa Nieves‐Chinchilla, Adam Szabo, Kevin Hurley, Tai Phan, Justin C. Kasper, Noé Lugaz, Ian G. Richardson, Christopher H. K. Chen, Daniel Verscharen, Robert T. Wicks, Jason M. TenBarge   +13 more
wiley   +1 more source

CME Magnetic Structure and IMF Preconditioning Affecting SEP Transport

Space Weather, Volume 19, Issue 4, April 2021., 2021
Abstract Coronal mass ejections (CMEs) and solar energetic particles (SEPs) are two phenomena that can cause severe space weather effects throughout the heliosphere. The evolution of CMEs, especially in terms of their magnetic structure, and the configuration of the interplanetary magnetic field (IMF) that influences the transport of SEPs are currently
Erika Palmerio, Emilia K. J. Kilpua, Olivier Witasse, David Barnes, Beatriz Sánchez‐Cano, Andreas J. Weiss, Teresa Nieves‐Chinchilla, Christian Möstl, Lan K. Jian, Marilena Mierla, Andrei N. Zhukov, Jingnan Guo, Luciano Rodriguez, Patrick J. Lowrance, Alexey Isavnin, Lucile Turc, Yoshifumi Futaana, Mats Holmström   +17 more
wiley   +1 more source

Assessing the Projection Correction of Coronal Mass Ejection Speeds on Time‐of‐Arrival Prediction Performance Using the Effective Acceleration Model

Space Weather, Volume 19, Issue 2, February 2020., 2021
Abstract White light images of coronal mass ejections (CMEs) are projections on the plane‐of‐sky (POS). As a result, CME kinematics are subject to projection effects. The error in the true (deprojected) speed of CMEs is one of the main causes of uncertainty to Space Weather forecasts, since all estimates of the CME time‐of‐arrival (ToA) at a certain ...
Evangelos Paouris, Angelos Vourlidas, Athanasios Papaioannou, Anastasios Anastasiadis   +3 more
wiley   +1 more source

Deriving CME Density From Remote Sensing Data and Comparison to In‐Situ Measurements

Journal of Geophysical Research: Space Physics, Volume 126, Issue 1, January 2021., 2021
Abstract We determine the three‐dimensional geometry and deprojected mass of 29 well‐observed coronal mass ejections (CMEs) and their interplanetary counterparts (ICMEs) using combined Solar Terrestrial Relations Observatory ‐ Solar and Heliospheric Observatory white‐light data.
M. Temmer, L. Holzknecht, M. Dumbović, B. Vršnak, N. Sachdeva, S. G. Heinemann, K. Dissauer, C. Scolini, E. Asvestari, A. M. Veronig, S. J. Hofmeister   +10 more
wiley   +1 more source

Speckle temporal stability in XAO coronagraphic images [PDF]

Astronomy & Astrophysics, 2012
Context. The major source of noise limiting high-contrast imaging is caused by quasi-static speckles. Speckle noise originates from wavefront errors caused by various independent sources, and evolves on different timescales depending on their nature. An understanding of how quasi-static speckles originate from instrumental errors is paramount to the ...
Martinez, P., Loose, C., Aller Carpentier, E., Kasper, M.   +3 more
openaire   +3 more sources

NICMOS Imaging of a Damped Lyman-alpha Absorber at z=1.89 toward LBQS 1210+1731 : Constraints on Size and Star Formation Rate [PDF]

, 2000
We report results of a high-resolution imaging search (in rest frame H-$\alpha$ and optical continuum) for the galaxy associated with the damped Lyman-$\alpha$ (DLA) absorber at $z=1.892$ toward the $z_{em}=2.543$ quasar LBQS 1210+1731, using HST/NICMOS.
Buell T. Jannuzi, Glenn Schneider, Hershey J. L., John M. Hill, Krist J., Le Brun V., Lisa J. Storrie‐Lombardi, Marcia J. Rieke, Matteucci F., Moller P., Ray J. Weymann, Rodger I. Thompson, Steidel C. C., Varsha P. Kulkarni   +13 more
core   +2 more sources