Results 1 to 10 of about 221 (177)

Imaging exoplanets with coronagraphic instruments

Comptes Rendus. Physique, 2023
Exoplanetary science is a very active field of astronomy nowadays, with questions still opened such as how planetary systems form and evolve (occurrence, process), why such a diversity of exoplanets is observed (mass, radius, orbital parameters ...
Galicher, Raphaël, Mazoyer, Johan
doaj   +6 more sources

MEMS Deformable Mirrors for Space-Based High-Contrast Imaging [PDF]

Micromachines, 2019
Micro-Electro-Mechanical Systems (MEMS) Deformable Mirrors (DMs) enable precise wavefront control for optical systems. This technology can be used to meet the extreme wavefront control requirements for high contrast imaging of exoplanets with coronagraph
Rachel E. Morgan, Ewan S. Douglas, Gregory W. Allan, Paul Bierden, Supriya Chakrabarti, Timothy Cook, Mark Egan, Gabor Furesz, Jennifer N. Gubner, Tyler D. Groff, Christian A. Haughwout, Bobby G. Holden, Christopher B. Mendillo, Mireille Ouellet, Paula do Vale Pereira, Abigail J. Stein, Simon Thibault, Xingtao Wu, Yeyuan Xin, Kerri L. Cahoy   +19 more
doaj   +2 more sources

First Observations of the Brown Dwarf HD 19467 B with JWST

The Astrophysical Journal, 2023
We observed HD 19467 B with JWST’s NIRCam in six filters spanning 2.5–4.6 μ m with the long-wavelength bar coronagraph. The brown dwarf HD 19467 B was initially identified through a long-period trend in the radial velocity of the G3V star HD 19467.
Alexandra Z. Greenbaum, Jorge Llop-Sayson, Ben W.P. Lew, Geoffrey Bryden, Thomas L. Roellig, Marie Ygouf, B. J. Fulton, Daniel R. Hey, Daniel Huber, Sagnick Mukherjee, Michael Meyer, Jarron Leisenring, Marcia Rieke, Martha Boyer, Joseph J. Green, Doug Kelly, Karl Misselt, Eugene Serabyn, John Stansberry, Laurie E. U. Chu, Matthew De Furio, Doug Johnstone, Joshua E. Schlieder, Charles Beichman   +23 more
doaj   +1 more source

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

Hiding Dust around ϵ Eridani

The Astronomical Journal, 2023
With a Jupiter-like exoplanet and a debris disk with both asteroid and Kuiper Belt analogs, ϵ Eridani has a fascinating resemblance to our expectations for a young solar system.
Schuyler Grace Wolff, András Gáspár, George H. Rieke, Nicholas Ballering, Marie Ygouf   +4 more
doaj   +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