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The defining trait of magnetars, the most strongly magnetized neutron stars (NSs), is their transient activity in the X/$\gamma$-bands. In particular, many of them undergo phases of enhanced emission, the so-called outbursts, during which…

High Energy Astrophysical Phenomena · Physics 2022-09-14 Davide De Grandis , Roberto Turolla , Roberto Taverna , Elisa Lucchetta , Toby S. Wood , Silvia Zane

Solar eruptions may occur at different evolutionary stages of active regions, during which the photospheric motions manifest in various forms, including flux emergence, sunspot rotation, shearing, converging, and magnetic flux diffusion.…

Solar and Stellar Astrophysics · Physics 2025-09-25 Xinkai Bian , Chaowei Jiang , Yang Wang , Peng Zou , Xueshang Feng , Pingbing Zuo , Yi Wang

Dense plasma fragments were observed to fall back on the solar surface by the Solar Dynamics Observatory after an eruption on 7 June 2011, producing strong EUV brightenings. Previous studies investigated impacts in regions of weak magnetic…

Solar and Stellar Astrophysics · Physics 2016-11-15 A. Petralia , F. Reale , S. Orlando , P. Testa

Solar flares and coronal mass ejections, the primary space weather disturbances affecting the entire heliosphere and near-Earth environment, mainly emanate from sunspot regions harbouring high degrees of magnetic twist. However, it is not…

Solar and Stellar Astrophysics · Physics 2023-06-01 Shin Toriumi , Hideyuki Hotta , Kanya Kusano

The magnetar 1E~1547$-$5408 recently exhibited two periods of outburst, beginning on 2008 October 3 and 2009 January 22. Here we present an analysis of the persistent radiative evolution and a statistical study of the burst properties…

High Energy Astrophysical Phenomena · Physics 2015-05-28 Paul Scholz , Victoria M. Kaspi

Context: One aspect of understanding the dynamics of the quiet Sun is to quantify the evolution of the flux within small-scale magnetic features. These features are routinely observed in the quiet photosphere and were given various names,…

Solar and Stellar Astrophysics · Physics 2015-02-04 R. Attie , D. E. Innes

In this contribution we describe some recent observations of high-speed magnetized flows in the quiet Sun granulation. These observations were carried out with the Imaging Magnetograph eXperiment (IMaX) onboard the stratospheric balloon…

We have performed a three-dimensional magnetohydrodynamic simulation to study the emergence of a twisted magnetic flux tube from -20,000 km of the solar convection zone to the corona through the photosphere and the chromosphere. The middle…

Solar and Stellar Astrophysics · Physics 2015-06-03 S. Toriumi , T. Yokoyama

Magnetars, isolated neutron stars with magnetic field strengths typically $\gtrsim10^{14}$~G, exhibit distinctive months-long outburst epochs during which strong evolution of soft X-ray pulse profiles, along with nonthermal magnetospheric…

We present the timing and spectral analyses of the NICER, NuSTAR, and IXPE observations of the magnetar 1E 1841-045 covering 82 days following its August 2024 bursting activity as well as radio observations utilizing MeerKAT and Effelsberg.…

Radio pulsars are believed to have their emission powered by the loss of rotational kinetic energy. By contrast, magnetars show intense X-ray and gamma-ray radiation whose luminosity greatly exceeds that due to spin-down and is believed to…

High Energy Astrophysical Phenomena · Physics 2016-10-05 R. F. Archibald , V. M. Kaspi , S. P. Tendulkar , P. Scholz

The latitudinal distribution of starspots deviates from the solar pattern with increasing rotation rate. Numerical simulations of magnetic flux emergence and transport can help model the observed stellar activity patterns and the associated…

Solar and Stellar Astrophysics · Physics 2018-12-19 Emre Işık , Sami K. Solanki , Natalie A. Krivova , Alexander I. Shapiro

Magnetic field emerges at the surface of the Sun as sunspots and active regions. This process generates a poloidal magnetic field from a rising toroidal flux tube, it is a crucial but poorly understood aspect of the solar dynamo. The…

Solar and Stellar Astrophysics · Physics 2016-07-19 Aaron C. Birch , Hannah Schunker , Douglas C. Braun , Robert Cameron , Laurent Gizon , Björn Löptien , Matthias Rempel

In this article, the physical processes occurring in the convective layer and the photosphere of the Sun and their connection to the formation of active regions (ARs) and the development of the corresponding magnetic field are explored.…

Solar and Stellar Astrophysics · Physics 2024-02-22 Aidar M. Sadykov , Sergey A. Krasotkin

We report the discovery of isolated, small-scale emerging magnetic fields in a plage region with the Solar Optical Telescope aboard Hinode. Spectro-polarimetric observations were carried out with a cadence of 34 seconds for the plage region…

[Abridged] Bipolar magnetic regions are formed when loops of magnetic flux emerge at the solar photosphere. Our aim is to investigate the flux emergence process in a simulation of granular convection. In particular we aim to determine the…

Solar and Stellar Astrophysics · Physics 2012-08-09 Paul J Bushby , Vasilis Archontis

Despite decades of research, the fundamental processes involved in the initiation and acceleration of solar eruptions remain not fully understood, making them long-standing and challenging problems in solar physics. Recent high-resolution…

Solar and Stellar Astrophysics · Physics 2025-07-08 Satoshi Inoue , Takahiro Miyoshi , Keiji Hayashi , Huu Minh Triet Nguyen , Ju Jing , Wenda Cao , Haimin Wang

Sunspot proper motions and flares of a super active region NOAA 5395, which was the biggest and the most flare-active region in the 22nd sunspot cycle, were analyzed in details. We measured sunspot proper motions by using the H-alpha - 5.0…

Astrophysics · Physics 2009-10-30 Takako T. Ishii , Hiroki Kurokawa , Tsutomu T. Takeuchi

Solar flares and coronal mass ejections (CMEs), the most catastrophic eruptions in our solar system, have been known to affect terrestrial environments and infrastructure. However, because their triggering mechanism is still not…

Solar and Stellar Astrophysics · Physics 2015-06-11 K. Kusano , Y. Bamba , T. T. Yamamoto , Y. Iida , S. Toriumi , A. Asai

Young neutron stars born with magnetic fields $B\gtrsim 10^{16}$ G become hyperactive as the field inside the star evolves through ambipolar diffusion on a timescale $\sim 10^9$ s. We simulate this process numerically and find that it can…

High Energy Astrophysical Phenomena · Physics 2026-05-04 Ashley Bransgrove , Andrei M. Beloborodov , Yuri Levin