Two-element interferometer for millimeter-wave solar flare observations, by Yu et al.

2023-08-29 0 views

Solar radio emission can be significantly influenced by Earth’s atmosphere when transmitting towards the Earth’s surface, due to atmospheric turbulence and the absorption of vapor and oxygen molecules etc. Consequently, antennas receive signals with a ‘dither’ component, indicating a noise signal exhibiting random variations. As a result, the sensitivity of observing systems distorts severely , especially for weaker radio bursts in the millimeter passband. Weak bursts can be usually observed […]

Data-constrained Solar Modeling with GX Simulator by G. Nita et al

2023-08-08 0 views

In the dynamic realm of modern solar physics, where vast and diverse data sets challenge understanding, a critical need emerges for advanced data-constrained 3D modeling that combines photospheric magnetic fields measurements and a wide range of contextual electromagnetic radiation observations, which includes radio, X-ray, and extreme ultraviolet (EUV) emissions. Bridging all these available observational data constraints is imperative to create a comprehensive understanding of solar activity and phenomena. Addressing this […]

Electron acceleration efficiency during the impulsive phase of a solar flare: X-ray and microwave observations by Kontar et al

2023-06-20 153 views

Solar flares are known to be prolific electron accelerators, yet identifying the mechanism(s) for such efficient electron acceleration in magnetic reconnection events at the Sun (and similar astrophysical settings) presents a major challenge in Astrophysics (e.g. Holman et al 2011). Accelerated electrons with energies above $\sim 20$ keV are revealed by hard X-ray (HXR) bremsstrahlung emission, while accelerated electrons with even higher energies usually manifest themselves through radio gyrosynchrotron emission. […]

Microwave imaging of quasi-periodic pulsations at flare current sheet by Yuankun Kou et al.

2023-01-03 282 views

Quasi-periodic pulsations (QPPs; also known as quasi-periodic oscillations, i.e., QPOs) are phenomena that electromagnetic emissions vary quasi-periodically with time. They appear in celestial transient events with different temporal/spatial scales, such as stellar flares, gamma ray bursts and fast radio bursts, and etc. The Sun is a normal but the closest star from us, where flares with QPPs appear frequently (e.g. Zimovets et al. 2021 as a review). In the standard […]

Magnetic Reconnection during the Post-impulsive Phase of a Long-duration Solar Flare
by S. Yu et al.

2020-10-27 238 views

Magnetic reconnection, a fundamental process in astrophysical environment plasma is believed to facilitate the release of energy stored in the magnetic field. However, where the magnetic reconnections occur, how and where the released magnetic energy is transported, and how it is converted to other forms remain unclear. Here, we report well-connected observational signatures of magnetic reconnection, plasma heating, and electron acceleration observed during the post-impulsive gradual phase of the X8.2-class […]

Microwave Spectral Imaging of an Erupting Magnetic Flux Rope During a Large Solar Flare
by B. Chen et al.*

2020-09-22 410 views

Magnetic flux ropes are believed to be the centerpiece of the three-part structure of coronal mass ejections. In the standard model of eruptive solar flares, flux rope eruption also induces the impulsive flare energy release through magnetic reconnection. Signatures of flare-associated flux ropes in the low solar corona have been frequently reported in extreme ultraviolet (EUV) wavelengths, particularly the so-called EUV “hot channel” structures (see, e.g., Cheng et al. 2017 […]

Exploring the potential of microwave diagnostics in SEP forecasting
by P. Zucca et al.*

2017-10-03 376 views

Solar energetic particles (SEPs), especially protons and heavy ions, may be a space-weather hazard when they impact spacecraft and the terrestrial atmosphere. Forecasting schemes have been developed, which use earlier signatures of particle acceleration to predict the arrival of solar protons and ions in the space environment of the Earth. The UMASEP (University of MAlaga Solar particle Event Predictor) scheme (Núñez 2011), forecasts the occurrence and the importance of an […]

Multi-Loop Structure of Nonthermal Microwave Sources in a Major Long-Duration Flare
by V. Grechnev et al.*

2017-05-23 602 views

Hard X-ray (HXR) and microwave observations of flares show only a few nonthermal sources. They are simple and compact, especially in impulsive flares, suggesting involvement of one to two loops. Hanaoka (1996) and Nishio et al. (1997) interpreted these observations in terms of double-loop flares. This view was later extended up to long-duration flares (Tzatzakis, Nindos, and Alissandrakis, 2008). A concept of a simple flare loop became dominant. However, observations […]

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