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We investigate the relationship between the main acceleration phase of coronal mass ejections (CMEs) and the particle acceleration in the associated flares as evidenced in RHESSI non-thermal X-rays for a set of 37 impulsive flare-CME…

Solar and Stellar Astrophysics · Physics 2012-05-14 S. Berkebile-Stoiser , A. M. Veronig , B. M. Bein , M. Temmer

Microflares are energetically smaller versions of solar flares, demonstrating the same processes of plasma heating and particle acceleration. However, it remains unclear down to what energy scales this impulsive energy release continues,…

Solar and Stellar Astrophysics · Physics 2024-02-09 Kristopher Cooper , Iain G. Hannah , Lindsay Glesener , Brian W. Grefenstette

Although flares from late-type main-sequence stars have been frequently detected in multi-wavelength, the associated dynamical process has been rarely reported so far. Here, we report follow-up observations of an X-ray transient triggered…

Solar and Stellar Astrophysics · Physics 2024-10-07 J. Wang , X. Mao , C. Gao , H. Y. Liu , H. L. Li , H. W. Pan , C. Wu , Y. Liu , G. W. Li , L. P. Xin , S. Jin , D. W. Xu , E. W. Liang , W. M. Yuan , J. Y. Wei

The thick-target model predicts that in flare foot points, we should observe lowering of HXR sources' altitude with increasing energy. The foot point of HXR sources result from the direct interaction of non-thermal electron beams with…

Solar and Stellar Astrophysics · Physics 2022-03-14 T. Mrozek , R. Falewicz , S. Kolomanski , M. Litwicka

X-ray observations of solar flares routinely reveal an impulsive high-energy and a gradual low-energy emission component, whose relationship is one of the key issues of solar flare study. The gradual and impulsive emission components are…

Solar and Stellar Astrophysics · Physics 2015-05-20 Jingnan Guo , Siming Liu , Lyndsay Fletcher , Eduard P. Kontar

Deriving a well-constrained differential emission measure (DEM) distribution for solar flares has historically been difficult, primarily because no single instrument is sensitive to the full range of coronal temperatures observed in flares,…

Solar and Stellar Astrophysics · Physics 2014-06-25 Amir Caspi , James M. McTiernan , Harry P. Warren

Emerging flux regions (EFRs) are known to exhibit various sporadic local heating events in the lower atmosphere. To investigate the characteristics of these events, especially to link the photospheric magnetic fields and atmospheric…

Solar and Stellar Astrophysics · Physics 2017-02-15 Shin Toriumi , Yukio Katsukawa , Mark C. M. Cheung

We present a new analytical technique, combining Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) high-resolution imaging and spectroscopic observations, to visualize solar flare emission as a function of spectral component…

Instrumentation and Methods for Astrophysics · Physics 2015-09-15 Amir Caspi , Albert Y. Shih , James M. McTiernan , Säm Krucker

Magnetic energy released in the corona by solar flares reaches the chromosphere where it drives characteristic upflows and downflows known as evaporation and condensation. These flows are studied here for the case where energy is…

Solar and Stellar Astrophysics · Physics 2015-06-22 D. W. Longcope

We have explored the relationship between hard X-ray (HXR) emissions and Doppler velocities caused by the chromospheric evaporation in two X1.6 class solar flares on 2014 September 10 and October 22, respectively. Both events display double…

Solar and Stellar Astrophysics · Physics 2015-11-04 Dong Li , Zongjun Ning , Qingmin Zhang

We present new constraints on the high-temperature emission measure of a non-flaring solar active region using observations from the recently flown Focusing Optics X-ray Solar Imager sounding rocket payload. FOXSI has performed the first…

In this paper, we discuss the temperature distribution and evolution of a microflare, simultaneously observed by Hinode XRT, EIS, and SDO AIA. We find using EIS lines that during peak emission the distribution is nearly isothermal and…

Solar and Stellar Astrophysics · Physics 2019-08-21 Urmila Mitra-Kraev , Giulio Del Zanna

Following a CME which started on 2002 November 26, RHESSI, the Ramaty High Energy Solar Spectroscopic Imager, observed for 12 hours an X-ray source above the solar limb, at altitudes between 0.1 and 0.3 RS above the photosphere. The GOES…

Solar and Stellar Astrophysics · Physics 2015-06-03 Pascal Saint-Hilaire , Sam Krucker , Robert P. Lin

We often find spectral signatures of chromospheric cold plasma ejections accompanied by flares in a wide range of spatial scales in the solar and stellar atmospheres. However, the relationship between physical quantities (such as mass,…

Solar and Stellar Astrophysics · Physics 2023-02-15 Yuji Kotani , Kazunari Shibata , Takako T. Ishii , Daiki Yamasaki , Kenichi Otsuji , Kiyoshi Ichimoto , Ayumi Asai

We analyzed and modeled an M1.2 non-eruptive solar flare on 2011 September 9. The flare exhibits a strong late-phase peak of the warm coronal emissions ($\sim$3~MK) of extreme-ultraviolet (EUV), with peak emission over 1.3 times that of the…

Solar and Stellar Astrophysics · Physics 2018-08-29 Yu Dai , Mingde Ding , Weiguo Zong , Kai E. Yang

High resolution spectra from the Hinode EUV Imaging Spectrometer (EIS) have revealed that coronal spectral line profiles are sometimes asymmetric, with a faint enhancement in the blue wing on the order of 100 km/s. These asymmetries could…

Solar and Stellar Astrophysics · Physics 2015-06-11 David H. Brooks , Harry P. Warren

With the elementary energy release events introduced in a previous paper (Liu & Fletcher 2009) we model the chromospheric evaporation in flaring loops. The thick-target hard X-ray (HXR) emission produced by electrons escaping from the…

Solar and Stellar Astrophysics · Physics 2014-11-20 Siming Liu , Feiran Han , Lyndsay Fletcher

Non-thermal and thermal parameters of 85 solar flares of GOES class B1 to M6 (background subtracted classes A1 to M6) have been compared to each other. The hard X-ray flux has been measured by RHESSI and a spectral fitting provided flux and…

Astrophysics · Physics 2009-11-11 Marina Battaglia , Paolo C. Grigis , Arnold O. Benz

Chromospheric evaporation is observed as Doppler blueshift during solar flares. It plays one of key roles in dynamics and energetics of solar flares, however, its mechanism is still unknown. In this paper we present a detailed analysis of…

Solar and Stellar Astrophysics · Physics 2016-08-31 V. M. Sadykov , A. G. Kosovichev , I. N. Sharykin , I. V. Zimovets , S. Vargas Dominguez

Wide-field EUV telescopes imaging in spectral bands sensitive to 1 MK plasma on the Sun often observe extended ray-like coronal structures stretching radially from active regions to distances of 1.5-2Rsun, which represent the EUV…

Solar and Stellar Astrophysics · Physics 2014-01-24 F. Goryaev , V. Slemzin , L. Vainshtein , D. R. Williams