Mingantu Spectral Radioheliograph for Solar and Space Weather Studies

Yan, Yihua; Chen, Zhijun; Wang, Wei; Liu, Fei; Geng, Lihong; Chen, Linjie; Tan, Cuiyan; Chen, Xingyao; Su, Chao; Tan, Baolin

doi:10.3389/fspas.2021.584043

Cited by 28 publications

(19 citation statements)

References 43 publications

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“…The observed brightness temperature of the Sun has a gap near 1 GHz. Future work of calibrated observations to measure the brightness temperature and size in this frequency range (Yan et al 2021) could help to complete the spectrum.…”

Section: Discussionmentioning

confidence: 99%

Imaging of the Quiet Sun in the Frequency Range of 20–80 MHz

Zhang

Zucca

Kozarev

et al. 2022

ApJ

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Radio emission of the quiet Sun is considered to be due to thermal bremsstrahlung emission of the hot solar atmosphere. The properties of the quiet Sun in the microwave band have been well studied, and they can be well described by the spectrum of bremsstrahlung emission. In the meter-wave and decameter-wave bands, properties of the quiet Sun have rarely been studied due to the instrumental limitations. In this work, we use the LOw Frequency ARray telescope to perform high quality interferometric imaging spectroscopy observations of quiet Sun coronal emission at frequencies below 90 MHz. We present the brightness temperature spectrum and the size of the Sun in the frequency range of 20–80 MHz. We report on dark coronal regions with low brightness temperatures that persist with frequency. The brightness temperature spectrum of the quiet Sun is discussed and compared with the bremsstrahlung emission of a coronal model and previous quiet Sun observations.

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Section: Discussionmentioning

confidence: 99%

Imaging of the Quiet Sun in the Frequency Range of 20–80 MHz

Zhang

Zucca

Kozarev

et al. 2022

ApJ

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“…This physical regime may provide the main mass and energy conditions for the subsequent eruptions. We will continue to investigate the MGP mechanism in the solar and stellar coronal loops for atmospheric heating and eruptions in following work by using multi-wavelength observations, including radio broadband spectral imaging, such as MUSER [47], and the multi-wavelength EUV imaging, such as AIA/SDO [48], etc.…”

Section: Discussionmentioning

confidence: 99%

The Early Evolution of Solar Flaring Plasma Loops

Tan

2021

Universe

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Plasma loops are the elementary structures of solar flaring active regions and dominate the whole process of flaring eruptions. Standard flare models explain evolution and eruption after magnetic reconnection around the hot cusp-structure above the top of plasma loops very well; however, the early evolution of plasma loops before the onset of magnetic reconnection is poorly understood. Considering that magnetic gradients are ubiquitous in solar plasma loops, this work applies the magnetic-gradient pumping (MGP) mechanism to study the early evolution of flaring plasma loops. The results indicate that early evolution depends on the magnetic field distribution and the geometry of the plasma loops, which dominate the balance between the accumulation and dissipation of the energy around loop tops. Driven by MGP process, both of the density and temperature as well as the plasma β value around the looptop will increase in the early phase of the plasma loop’s evolution. In fact, the solar plasma loops will have two distinct evolutionary results: low, initially dense plasma loops with relatively strong magnetic fields tend to be stable for their maximum β value, which is always smaller than the critical value β<βc, while the higher, initially diluted solar plasma loops with relatively weak magnetic fields tend to be unstable for their β values, exceeding the critical value β>βc at a time of about one hour after the formation of the solar-magnetized plasma loop. The latter may produce ballooning instability and may finally trigger the following magnetic reconnection and eruptions. These physical scenarios may provide us with a new viewpoint to understand the nature and origin of solar flares.

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“…Based on the solar monitor 1 , the flare was a C6.7 class, and it started at about 05:40 UT, reached its maximum at around 05:51 UT. It was simultaneously measured by the IRIS (De Pontieu et al 2014), the New Vacuum Solar Telescope (NVST, Liu et al 2014), the Atmospheric Imaging Assembly (AIA, Lemen et al 2012) and the Helioseismic and Magnetic Imager (HMI, Schou et al 2012) for the Solar Dynamics Observatory (SDO, Pesnell et al 2012), the X-ray Telescope (XRT, Golub et al 2007) of the Hinode mission, as well as the Geostationary Operational Environmental Satellite (GOES-16, Loto'aniu et al 2017), the Fermi Gamma Ray Burst Monitor (GBM, Meegan et al 2009), the Mingantu Spectral Radioheliograph (MUSER, Yan et al 2021b), and the Nobeyama Radio Polarimeters (NoRP, Nakajima et al 1985), as listed in table 1.…”

Section: Observations and Instrumentsmentioning

confidence: 99%

“…The MUSER could provide the radio dynamic spectrum between 0.4 GHz and 2.0 GHz. It has forty 4.5-m reflector antennas distributed in three spiral arms, which can measure dual circular polarizations with a time resolution of 0.025 s (Yan et al 2009(Yan et al , 2021b. The NoRP and the Fermi/GBM observed the entire Sun with multiple channels in microwave and Xray ranges, respectively.…”

Section: Observations and Instrumentsmentioning

confidence: 99%

Simultaneous Observations of Chromospheric Evaporation and Condensation during a C-class Flare

Li,

Hong,

Ning

2021

Preprint

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We explored simultaneous observations of chromospheric evaporation and condensation during the impulsive phase of a C6.7 flare on 9 May 2019. The solar flare was simultaneously observed by multiple instruments, i.e., the New Vacuum Solar Telescope (NVST), the Interface Region Imaging Spectrograph, the Atmospheric Imaging Assembly (AIA), the Fermi, the Mingantu Spectral Radioheliograph, and the Nobeyama Radio Polarimeters. Using the single Gaussian fitting and the moment analysis technique, redshifted velocities at slow speeds of 15−19 km s −1 are found in the cool lines of C II and Si IV at one flare footpoint location. Red shifts are also seen in the Hα line-of-sight (LOS) velocity image measured by the NVST at double footpoints. Those red shifts with slow speeds can be regarded as the low-velocity downflows driven by the chromospheric condensation. Meanwhile, the converging motions from double footpoints to the loop top are found in the high-temperature EUV images, such as AIA 131 Å, 94 Å, and 335 Å. Their apparent speeds are estimated to be roughly 126−210 km s −1 , which could be regarded as the high-velocity upflows caused by the chromospheric evaporation. The nonthermal energy flux is estimated to be about 5.7×10 10 erg s −1 cm −2 . The characteristic timescale is roughly equal to 1 minute. All these observational results suggest an explosive chromospheric evaporation during the flare impulsive phase. While a HXR/microwave pulse and a type III radio burst are found simultaneously, indicating that the explosive chromospheric evaporation is driven by the nonthermal electron.

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Mingantu Spectral Radioheliograph for Solar and Space Weather Studies

Cited by 28 publications

References 43 publications

Imaging of the Quiet Sun in the Frequency Range of 20–80 MHz

Imaging of the Quiet Sun in the Frequency Range of 20–80 MHz

The Early Evolution of Solar Flaring Plasma Loops

Simultaneous Observations of Chromospheric Evaporation and Condensation during a C-class Flare

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