A Confined Two-peaked Solar Flare Observed by EAST and SDO

The solar flare is one of the most violent explosions,and can disturb the near-Earth space weather.Except for commonly single-peaked solar flares in soft X-ray,some special flares show intriguing a two-peak feature that is deserved much more attentions.Here,we reported a confined two-peaked solar flare and analyzed the associated eruptions using high-quality observations from Educational Adaptive-optics Solar Telescope and Solar Dynamics Observatory.Before the flare,a magnetic flux rope(MFR)formed through partially tether-cutting reconnection between two sheared arches.The flare occurred after the MFR eruption that was confined by the overlying strong field.Interestingly,a small underlying filament immediately erupted,which was possibly destabilized by the flare ribbon.The successive eruptions were confirmed by the analysis of the emission measure and the reconnection fluxes.Therefore,we suggest that the two peaks of the confined solar flare are corresponding to two episodes of magnetic reconnection during the successive eruptions of the MFR and the underlying filament.

The Educational Adaptive-optics Solar Telescope at the Shanghai Astronomy Museum

The Educational Adaptive-optics Solar Telescope(EAST)at the Shanghai Astronomy Museum has been running routine astronomical observations since 2021.It is a 65-cm-aperture Gregorian solar telescope for scientific education,outreach,and research.The telescope system is designed in an“open”format so that the solar tower architecture can be integrated with it,and visitors can watch the observations live from inside the tower.Equipped with adaptive optics,a high-resolution imaging system,and an integral field unit spectro-imaging system,this telescope can obtain high-resolution solar images in the TiO and Hαbands,and perform spectral image reconstruction using 400 optical fibers at selected wavelengths.It can be used not only in public education and scientific outreach but also in solar physics research.

Adaptive optics based on machine learning: a review

Adaptive optics techniques have been developed over the past half century and routinely used in large ground-based telescopes for more than 30 years.Although this technique has already been used in various applications,the basic setup and methods have not changed over the past 40 years.In recent years,with the rapid development of artificial in-telligence,adaptive optics will be boosted dramatically.In this paper,the recent advances on almost all aspects of adapt-ive optics based on machine learning are summarized.The state-of-the-art performance of intelligent adaptive optics are reviewed.The potential advantages and deficiencies of intelligent adaptive optics are also discussed.

EAST-Educational Adaptive-optics Solar Telescope

For the public having a better understanding of solar activities,the Educational Adaptive-optics Solar Telescope(EAST)was built in July 2021 and is located at the Shanghai Astronomy Museum.The EAST consists of a 65 cm aperture solar telescope with a 177-element adaptive optics system and two-channel high resolution imaging system at the Hαand TiO bands,in addition to three full disk solar telescopes at CaK,Hαand TiO bands equipped on the tube of the main telescope.In this paper,the configuration of the EAST is described.Its performance and on-sky observational results are presented.The EAST,to our knowledge,is the most advanced solar telescope for the popularization of science in the world.Due to its excellent performance,the data acquired by the EAST can also be used for research on solar physics and space weather prediction.

Ground-layer adaptive optics for the New Vacuum Solar Telescope:Instrument description and first results

Ground-layer adaptive optics(GLAO)has shown its potential for use in solar observation owing to its wide field-of-view(FOV)correction.A high-order GLAO system that consists of a multiple direction Shack-Hartmann wavefront sensor(WFS),a realtime controller with a multi-CPU processor,and a 151-element deformable mirror was developed for the 1-m New Vacuum Solar Telescope at Yunnan Observatories,Chinese Academy of Sciences.A hexagonal microlens with 9×8 subapertures is employed in the WFS.The detection FOV is 42′′×37′′,in which 9(3×3)guide regions are extracted for multiple direction wavefront sensing with a frame rate of up to 2200 Hz.To our knowledge,this is the first professional solar GLAO system used as a regularly operating instrument for scientific observations.Its installation and adjustment were performed in the summer of 2021.In this article,a detailed account of the GLAO system and its first light results and a comprehensive analysis of the performance of the GLAO system are provided.The results show that this system can effectively improve the imaging quality after compensating for the wavefront aberration due to ground-layer turbulence.

First light of the 1.8-m solar telescope–CLST

Large-aperture solar telescopes play an important role in solar observations and research,and require high temporal and spatial resolution[1].To solve some fundamental problems such as the solar dynamo,coronal heating,and the triggering of major solar eruptions,the spatial resolution for solar-atmosphere observation should reach at least 0.1 arcsec[2].

First light of solar multi-conjugate adaptive optics at the 1-m new vacuum solar telescope

Observations play a leading role in any branches of astronomy, including solar physics. In order to solve fundamental problems, such as solar dynamo [1], coronal heating [2] and the triggering of major solar eruptions [3], solar observations with spatial resolution better than 0.1 arcsec are required. Such a goal cannot be achieved without the help of adaptive optics （AO）, which eliminates the wavefront distortion caused by atmosphere turbulence [4,5]. However, solar observations are performed over an extended field of view （FoV）. Flare trigger mechanisms operate rapidly and on the smallest spatial scales and their location within the FoV is difficult to predict.