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We firstly present the Solar Dynamics Observatory observations of four homologous flux ropes in active region (AR) 11745 on 2013 May 20-22. The four flux ropes are all above the neutral line of the AR, with endpoints anchoring at the same…

Solar and Stellar Astrophysics · Physics 2015-06-17 Ting Li , Jun Zhang

The mixture/interaction of anti-sunward-propagating Alfv\'enic fluctuations (AFs) and sunward-propagating Alfv\'enic fluctuations (SAFs) is believed to result in the decrease of the Alfv\'enicity of solar wind fluctuations with increasing…

Space Physics · Physics 2016-06-13 H. Li , C. Wang , J. W. Belcher , J. S. He , J. D. Richardson

We introduce an updated, time-dependent treatment to the split-tail ("croissant-like") heliosphere model with data-driven solar wind conditions at 1 au, to study the evolution of the heliosphere with solar-cycle variations in plasma speed,…

Solar and Stellar Astrophysics · Physics 2026-03-20 Chika Onubogu , M. Opher , E. Powell , S. Du , J. M. Sokół , J. D. Richardson , B. Van Der Holst

Using simultaneous high spatial (1.3 arc sec) and temporal (5 and 10 s) resolution H-alpha observations from the 15 cm Solar Tower Telescope at ARIES, we study the oscillations in the relative intensity to explore the possibility of sausage…

Astrophysics · Physics 2009-11-13 A. K. Srivastava , T. V. Zaqarashvili , W. Uddin , B. N. Dwivedi , Pankaj Kumar

Measurements of molecular hydrogen (H_2) column densities are presented for the first six rotational levels (J=0 to 5) for 73 extragalactic targets observed with FUSE. All of these have a final signal-to-noise ratio larger than \snlimit,…

Astrophysics · Physics 2009-11-11 B. P. Wakker

In collision-poor plasmas from space, e.g., solar wind or stellar outflows, the heat-flux carried by the strahl or beaming electrons is expected to be regulated by the self-generated instabilities. Recently, simultaneous field and particle…

Plasma Physics · Physics 2019-09-05 R. A. López , S. M. Shaaban , M. Lazar , S. Poedts , P. H. Yoon , A. Micera , G. Lapenta

We investigate the evolution of subsurface flows during the emergence and the active phase of sunspot regions using the time-distance helioseismology analysis of the full-disk Dopplergrams from the Helioseismic and Magnetic Imager (HMI)…

Solar and Stellar Astrophysics · Physics 2024-12-25 Alexander G. Kosovichev , Viacheslav M. Sadykov

We report on new spectro-polarimetric measurements with simultaneous filter imaging observation, revealing the frequent appearance of polarization signals indicating high-speed, probably supersonic, downflows that are associated with at…

We present an analysis of small-scale, periodic, solar-wind density enhancements (length-scales as small as \approx 1000 Mm) observed in images from the Heliospheric Imager (HI) aboard STEREO A. We discuss their possible relationship to…

Solar and Stellar Astrophysics · Physics 2010-09-30 Nicholeen M. Viall , Harlan E. Spence , Angelos Vourlidas , Russell Howard

We have developed a new automated small-scale magnetic flux rope (SSMFR) detection algorithm based on the Grad-Shafranov (GS) reconstruction technique. We have applied this detection algorithm to the Wind spacecraft in-situ measurements…

Solar and Stellar Astrophysics · Physics 2018-11-28 Qiang Hu , Jinlei Zheng , Yu Chen , Jakobus le Roux , Lulu Zhao

Unmanned aerial vehicles (UAVs) are finding use in applications that place increasing emphasis on robustness to external disturbances including extreme wind. However, traditional multirotor UAV platforms do not directly sense wind;…

We present new, third-epoch HST H-alpha and [S II] images of three HH jets (HH 1 and 2, HH 34, and HH 47) and compare these images with those from the previous epochs. The high-spatial resolution, coupled with a time-series whose cadence is…

Solar and Stellar Astrophysics · Physics 2015-05-27 P. Hartigan , A. Frank , J. M. Foster , B. H. Wilde , M. Douglas , P. A. Rosen , R. F. Coker , B. E. Blue , J. F. Hansen

We report the simultaneous extreme ultraviolet observation of magnetic reconnection inflow and outflow in a flare on 2010 August 18 observed by the Atmospheric Imaging Assembly on board the {\it Solar Dynamics Observatory}. We found that…

Solar and Stellar Astrophysics · Physics 2015-06-03 Shinsuke Takasao , Ayumi Asai , Hiroaki Isobe , Kazunari Shibata

We report on active region EUV dynamic events observed simultaneously at high-cadence with SUMER/SoHO and TRACE. Although the features appear in the TRACE Fe ix/x 171A images as jets seen in projection on the solar disk, the SUMER spectral…

Astrophysics · Physics 2009-11-13 M. S. Madjarska , J. G. Doyle , D. Innes , W. Curdt

Using a recently suggested magneto-morphological classification (MMC, Abramenko, 2021, MNRAS Vol 507) of solar active regions (ARs), we explored 3048 ARs, observed from12 May 1996 to 27 December 2021. Magnetograms were acquired with the…

Solar and Stellar Astrophysics · Physics 2026-01-21 Anastasiya Zhukova , Valentina Abramenko

Adverse space weather effects can often be traced to solar flares, prediction of which has drawn significant research interests. The Helioseismic and Magnetic Imager (HMI) produces full-disk vector magnetograms with continuous high cadence,…

Solar and Stellar Astrophysics · Physics 2017-07-26 Chang Liu , Na Deng , Jason T. L. Wang , Haimin Wang

Minimal observational evidence exists for fast transition region (TR) upflows in the presence of cool loops. Observations of such occurrences challenge notions of standard solar atmospheric heating models, as well as their description of…

Solar and Stellar Astrophysics · Physics 2016-01-13 N. B. Orange , D. L. Chesny , H. M. Oluseyi , K. Hesterly , M. Patel , P. R. Champey

The (sub)millimeter radiation of solar flares is poorly understood. Without spatial resolution, it cannot be compared easily to flare emissions in other wavelengths. The Atacama Large Millimeter-submillimeter Array (ALMA) offers sufficient…

Solar and Stellar Astrophysics · Physics 2023-02-01 I. Skokić , A. O. Benz , R. Brajša , D. Sudar , F. Matković , M. Bárta

We investigate the interaction between a shock-driven hot wind and a cold multi-cloud layer, for conditions commonly found in interstellar and circumgalactic gas. We present a method for identifying distinct clouds using a…

A hemispheric preference in the dominant sign of magnetic helicity has been observed in numerous features in the solar atmosphere: i.e., left-handed/right-handed helicity in the northern/southern hemisphere. The relative importance of…

Solar and Stellar Astrophysics · Physics 2020-11-25 Sung-Hong Park , K. D. Leka , Kanya Kusano