Results 31 to 40 of about 1,832,653 (172)

Risk Assessment of the Ground Magnetic Response to the March and April 2023 Geomagnetic Storms Using Geomagnetically Induced Currents Indices

Space Weather, Volume 23, Issue 4, April 2025.
Abstract We analyzed the solar origin and ground response during the severe geomagnetic storms (GSs) of 23–24 March (GS1) and 23–24 April 2023 (GS2) using Geomagnetically Induced Currents Indices (GIC indices) computed from geomagnetic field data. The GSs were initiated by erupting filaments and associated slow (fast) halo coronal mass ejections on 20 ...
Paul O. Amaechi, Honore Messanga, Frank O. Grodji, Andrew Akala, Irina Despirak, Chigomezyo M. Ngwira, Elijah Oyeyemi, Christine Amory‐Mazaudier   +7 more
wiley   +1 more source

Direct-imaging Discovery of a Substellar Companion Orbiting the Accelerating Variable Star HIP 39017

The Astronomical Journal
We present the direct-imaging discovery of a substellar companion (a massive planet or low-mass brown dwarf) to the young, γ Doradus ( γ Dor)-type variable star HIP 39017 (HD 65526). The companion’s SCExAO/CHARIS JHK (1.1–2.4 μ m) spectrum and Keck/NIRC2
Taylor L. Tobin, Thayne Currie, Yiting Li, Jeffrey Chilcote, Timothy D. Brandt, Brianna Lacy, Masayuki Kuzuhara, Maria Vincent, Mona El Morsy, Vincent Deo, Jonathan P. Williams, Olivier Guyon, Julien Lozi, Sebastien Vievard, Nour Skaf, Kyohoon Ahn, Tyler Groff, N. Jeremy Kasdin, Taichi Uyama, Motohide Tamura, Aidan Gibbs, Briley L. Lewis, Rachel Bowens-Rubin, Maïssa Salama, Qier An, Minghan Chen   +25 more
doaj   +1 more source

Decent Estimate of CME Arrival Time From a Data‐Assimilated Ensemble in the Alfvén Wave Solar Atmosphere Model (DECADE‐AWSoM)

Space Weather, Volume 23, Issue 1, January 2025.
Abstract Forecasting the arrival time of Earth‐directed coronal mass ejections (CMEs) via physics‐based simulations is an essential but challenging task in space weather research due to the complexity of the underlying physics and limited remote and in situ observations of these events. Data assimilation techniques can assist in constraining free model
Hongfan Chen, Nishtha Sachdeva, Zhenguang Huang, Bart van der Holst, Ward Manchester IV, Aniket Jivani, Shasha Zou, Yang Chen, Xun Huan, Gabor Toth   +9 more
wiley   +1 more source

SCExAO/CHARIS Multiwavelength High-contrast Imaging of the BD+45°598 Debris Disk

The Astronomical Journal
We present a multiwavelength (1.16–2.37 μ m) view of the debris disk around BD+45 ^° 598, using the Subaru Coronagraphic Extreme Adaptive Optics system paired with the Coronagraphic High Angular Resolution Imaging Spectrograph.
Maria Vincent, Kellen Lawson, Thayne Currie, Jonathan P. Williams, Olivier Guyon, Julien Lozi, Vincent Deo, Sébastien Vievard   +7 more
doaj   +1 more source

An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme-Adaptive Optics System [PDF]

, 2018
peer reviewedThe vector vortex is a coronagraphic imaging mode of the recently commissioned Subaru Coronagraphic Extreme-Adaptive Optics (SCExAO) platform on the 8-m Subaru Telescope.
Martinache, F., K. Liewer, D. Mawet, Lozi, Julien, Tamura, M., Hagelberg, Janis, Liewer, Kurt, Martinache, Frantz, Lozi, J., D. Defrere, M. Tamura, Currie, Thayne M., T. Currie, Tamura, Motohide, Serabyn, E., Kühn, J., Currie, Thayne, Liewer, K., Jovanovic, Nemanja, J. Hagelberg, Serabyn, Eugene, Singh, G., Currie, T., Kudo, Tomoyuki, Kudo, T., Defrere, Denis, J. Kühn, N. Jovanovic, T. Kudo, Mawet, D., Defrere, D., F. Martinache, E. Serabyn, G. Singh, Jovanovic, N., Hagelberg, J., Singh, Garima, Mawet, Dimitri, Guyon, Olivier, J. Lozi, Kühn, Jonas, Guyon, O., O. Guyon   +42 more
core   +1 more source

Jovian Sodium Nebula and Io Plasma Torus S+ and Brightnesses 2017–2023: Insights Into Volcanic Versus Sublimation Supply

Journal of Geophysical Research: Space Physics, Volume 129, Issue 3, March 2024.
Abstract We present first results derived from the largest collection of contemporaneously recorded Jovian sodium nebula and Io plasma torus in [S II] 6731 Å images assembled to date. The data were recorded by the Planetary Science Institute's Io Input/Output observatory and provide important context to Io geologic and atmospheric studies as well as ...
Jeffrey P. Morgenthaler, Carl A. Schmidt, Marissa F. Vogt, Nicholas M. Schneider, Max Marconi   +4 more
wiley   +1 more source

Collection, Collation, and Comparison of 3D Coronal CME Reconstructions

Space Weather, Volume 22, Issue 1, January 2024.
Abstract Predicting the impacts of coronal mass ejections (CMEs) is a major focus of current space weather forecasting efforts. Typically, CME properties are reconstructed from stereoscopic coronal images and then used to forward model a CME's interplanetary evolution.
C. Kay, E. Palmerio
wiley   +1 more source

Sequential coronagraphic low-order wavefront control [PDF]

, 2023
Coronagraphs are highly sensitive to wavefront errors, with performance degrading rapidly in the presence of low-order aberrations. Correcting these aberrations at the coronagraphic focal plane is key to optimal performance.
Walker, Samuel A. U., Cunnyngham, Ian, Guthery, Charlotte, Delorme, Jacques-Robert, Bottom, Michael   +4 more
core  

A Coronagraphic Pilot Study of the Circumstellar Environments around Red Supergiants: CD -31°4916’s Dust Morphology

The Astronomical Journal
Many mechanisms have been proposed to contribute to massive-star mass loss, but in general little is known about the physics involved. Studies of circumstellar environments around massive stars might help to determine which mechanisms are the most common.
Jamie R. Lomax, Emily M. Levesque, John P. Wisniewski, John H. Debes   +3 more
doaj   +1 more source

Focal plane wavefront control with model-based reinforcement learning

Astronomy & Astrophysics
Context. The direct imaging of potentially habitable exoplanets is one prime science case for high-contrast imaging (HCI) instruments on ground-based, extremely large telescopes.
Nousiainen J., Taskin I., Kasper M., Orban de Xivry G., Absil O.   +4 more
doaj   +1 more source