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We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than…

Solar and Stellar Astrophysics · Physics 2016-02-15 Bruce H. McClintock , Aimee A. Norton

We perform a series of radiative magnetohydrodynamic simulations to understand the amplification mechanism of the exceptionally strong horizontal magnetic field in delta-type sunspots. In the simulations, we succeed in reproducing the…

Solar and Stellar Astrophysics · Physics 2020-09-02 H. Hotta , S. Toriumi

During the rising phase of Solar Cycle 24 tremendous activity occurred on the Sun with fast and compact emergence of magnetic flux leading to bursts of flares (C to M and even X-class). We investigate the violent events occurring in the…

Solar and Stellar Astrophysics · Physics 2015-06-18 C. H. Mandrini , B. Schmieder , P. Démoulin , Y. Guo , G. D. Cristiani

White-light flares (WLFs), first observed in 1859, refer to a type of solar flares showing an obvious enhancement of the visible continuum emission. This type of enhancement often occurs in most energetic flares, and is usually interpreted…

Solar and Stellar Astrophysics · Physics 2020-04-22 Yongliang Song , Hui Tian , Xiaoshuai Zhu , Yajie Chen , Mei Zhang , Jingwen Zhang

We attempt to understand the white-light flare (WLF) that was observed on 2012 March 9 with a newly constructed multi-wavelength solar telescope called the Optical and Near-infrared Solar Eruption Tracer (ONSET). We analyzed WLF…

Solar and Stellar Astrophysics · Physics 2012-11-09 Q. Hao , Y. Guo , Y. Dai , M. D. Ding , Z. Li , X. Y. Zhang , C. Fang

Sunspots are of basic interest in the study of the Sun. Their relevance ranges from them being an activity indicator of magnetic fields to being the place where coronal mass ejections and flares erupt. They are therefore also an important…

Solar and Stellar Astrophysics · Physics 2018-05-24 Illa R. Losada , Jörn Warnecke , Kolja Glogowski , Markus Roth , Axel Brandenburg , Nathan Kleeorin , Igor Rogachevskii

Solar flares and coronal mass ejections (CMEs), especially the larger ones, emanate from active regions (ARs). With the aim to understand the magnetic properties that govern such flares and eruptions, we systematically survey all flare…

Solar and Stellar Astrophysics · Physics 2017-01-11 Shin Toriumi , Carolus J. Schrijver , Louise K. Harra , Hugh Hudson , Kaori Nagashima

We study the visibility of sunspots and its influence on observed values of sunspot region parameters. We use Virtual Observatory tools provided by AstroGrid to analyse a sample of 6862 sunspot regions. By studying the distributions of…

Astrophysics · Physics 2008-02-12 S. Dalla , L. Fletcher , N. A. Walton

We report a solar jet phenomenon associated with successive flares on November 10th 2014. These explosive events were involved with the satellite spots' emergence around a delta-type sunspot in the decaying active region NOAA 12205. The…

Solar and Stellar Astrophysics · Physics 2017-10-11 Takahito Sakaue , Akiko Tei , Ayumi Asai , Satoru Ueno , Kiyoshi Ichimoto , Kazunari Shibata

Context: Solar active regions (ARs) are key manifestations of the Sun's magnetic activity, displaying diverse spatial and temporal characteristics. Their formation and evolution play a crucial role in understanding the solar dynamo and…

Solar and Stellar Astrophysics · Physics 2025-08-06 M. Švanda , J. Jurčák , M. Schmassmann

We analyze the correlation between starspots and superflares on solar-type stars using observations from the Kepler mission. The analysis shows that the observed fraction of stars with superflares decreases as the rotation period increases…

Solar and Stellar Astrophysics · Physics 2017-06-21 Hiroyuki Maehara , Yuta Notsu , Shota Notsu , Kosuke Namekata , Satoshi Honda , Takako T. Ishii , Daisaku Nogami , Kazunari Shibata

Solar flares and coronal mass ejections are among the most prominent manifestations of the magnetic activity of the Sun. The strongest events of them tend to occur in active regions (ARs) that are large, complex, and dynamically evolving.…

Solar and Stellar Astrophysics · Physics 2022-08-17 Shin Toriumi

On 2016 September 20, the Interface Region Imaging Spectrograph observed an active region during its earliest emerging phase for almost 7 hours. The Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory observed…

Solar and Stellar Astrophysics · Physics 2018-03-14 Hui Tian , Xiaoshuai Zhu , Hardi Peter , Jie Zhao , Tanmoy Samanta , Yajie Chen

Solar active regions (ARs) are areas on the Sun with very strong magnetic fields where various activities take place. Prominences are one of the typical solar features in the solar atmosphere, whose eruptions often lead to solar flares and…

Solar and Stellar Astrophysics · Physics 2024-02-22 T. Zhang , Q. Hao , P. F. Chen

Charged particles, generated in solar flares, sometimes can get extremely high energy, above the 500 MeV level, and produce abrupt ground level enhancements (GLEs) on the ground-based detectors of cosmic rays. The initial flares are strong…

Solar and Stellar Astrophysics · Physics 2024-04-11 Regina A. Suleymanova , Leonty I. Miroshnichenko , Valentina I. Abramenko

Lyman break galaxies (LBGs) display a range in structures (from single/compact to clumpy/extended) that is different from typical local star-forming galaxies. Recently, we have introduced a sample of rare, nearby (z<0.3) starbursts that…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 R. A. Overzier , T. M. Heckman , D. Schiminovich , A. Basu-Zych , T. Goncalves , D. C. Martin , R. M. Rich

The sub-arcsec bright points (BP) associated with the small scale magnetic fields in the lower solar atmosphere are advected by the evolution of the photospheric granules. We measure various quantities related to the horizontal motions of…

Solar and Stellar Astrophysics · Physics 2012-05-28 LP. Chitta , A. A. van Ballegooijen , L. Rouppe van der Voort , E. E. DeLuca , R. Kariyappa

We present the observed H$\alpha$ flux and derived star formation rates (SFRs) for a fall sample of low$-$surface$-$brightness galaxies (LSBGs). The sample is selected from the fall sky region of the 40$\%$ ALFALFA {\ion{H}{1}} survey $-$…

Solar active region (AR) 12673 produced 4 X-class, 27 M-class, and numerous lower class flares during its passage across the visible solar disk in September 2017. Our study is to answer the questions why this AR was so flare-productive and…

Solar and Stellar Astrophysics · Physics 2017-11-08 Shuhong Yang , Jun Zhang , Xiaoshuai Zhu , Qiao Song

Strongly star-forming galaxies are prolific in producing the young and most massive star clusters (YMCs) still forming today. This work investigates the star cluster luminosity functions (CLFs, dN/dL ~ L^{-alpha}) of 26 starburst and…

Astrophysics of Galaxies · Physics 2022-05-04 Z. Randriamanakoto , P. Vaisanen , P. Ranaivomanana , R. Ramphul , E. Kankare , S. Mattila , S. D. Ryder , J. Kotilainen