分类： 天文学 >> 天文学 提交时间： 2023-02-19
Hualin Xiao
Shane Maloney
Säm Krucker
Ewan Dickson
Paolo Massa
Erica Lastufka
Andrea Francesco Battaglia
Laszlo Etesi
Nicky Hochmuth
Frederic Schuller
Daniel F. Ryan
Olivier Limousin
Hannah Collier
Alexander Warmuth
Michele Piana
摘要： The Spectrometer/Telescope for Imaging X-rays (STIX) onboard Solar Orbiter observes solar X-ray emission in the range of 4 to 150 keV and produces spectra and images of solar flares over a wide range of flare magnitudes. During nominal operation, STIX continuously generates data. A constant data flow requires fully automated data processing pipelines to process and analyze and a data platform to manage, visualize, and distribute the data products to the scientific community. The STIX Data Center has been built to fulfill these needs. In this paper, we outline its main components to help the community better understand the tools and data it provides. Methods. The STIX Data Center is operated at the University of Applied Sciences and Arts Northwestern Switzerland (FHNW) and consists of automated processing pipelines and a data platform. The pipelines process STIX telemetry data, perform common analysis tasks and generate data products at different processing levels. They have been designed to operate fully automatically with minimal human intervention. The data platform provides web-based user interfaces and application programmable interfaces for searching and downloading STIX data products. The STIX Data Center has been operating successfully for more than two years. The platform facilitates instrument operations and provides vital support to STIX data users.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Ying Li
Qiao Li
De-Chao Song
Andrea Francesco Battaglia
Hualin Xiao
Säm Krucker
Udo Schühle
Hui Li
Weiqun Gan
M. D. Ding
摘要： The hydrogen Lyman-$\alpha$ (H {\sc i} Ly$\alpha$) emission during solar flares has rarely been studied in spatially resolved images and its physical origin has not been fully understood. In this paper, we present novel Ly$\alpha$ images for a C1.4 solar flare (SOL2021-08-20T22:00) from the Extreme Ultraviolet Imager aboard Solar Orbiter, together with multi-waveband and multi-perspective observations from the Solar Terrestrial Relations Observatory Ahead and the Solar Dynamics Observatory spacecraft. It is found that the Ly$\alpha$ emission has a good temporal correlation with the thermal emissions at 1--8 \AA\ and 5--7 keV, indicating that the flaring Ly$\alpha$ is mainly produced by a thermal process in this small event. However, nonthermal electrons play a minor role in generating Ly$\alpha$ at flare ribbons during the rise phase of the flare, as revealed by the hard X-ray imaging and spectral fitting. Besides originating from flare ribbons, the Ly$\alpha$ emission can come from flare loops, likely caused by plasma heating and also cooling that happen in different flare phases. It is also found that the Ly$\alpha$ emission shows fairly similar features with the He {\sc ii} 304 \AA\ emission in light curve and spatio-temporal variation along with small differences. These observational results improve our understanding of the Ly$\alpha$ emission in solar flares and also provide some insights for investigating the Ly$\alpha$ emission in stellar flares.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Paolo Massa
Gordon. J. Hurford
Anna Volpara
Matej Kuhar
Andrea Francesco Battaglia
Hualin Xiao
Diego Casadei
Emma Perracchione
Sara Garbarino
Sabrina Guastavino
Hannah Collier
Ewan C. M. Dickson
Daniel F. Ryan
Shane A. Maloney
Frederic Schuller
Alexander Warmuth
Anna Maria Massone
Federico Benvenuto
Michele Piana
Säm Krucker
摘要： Aims. To provide a schematic mathematical description of the imaging concept of the Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter. The derived model is the fundamental starting point for both the interpretation of STIX data and the description of the data calibration process. Methods. We describe the STIX indirect imaging technique which is based on spatial modulation of the X-ray photon flux by means of tungsten grids. We show that each of 30 STIX imaging sub-collimators measures a complex Fourier component of the flaring X-ray source corresponding to a specific angular frequency. We also provide details about the count distribution model, which describes the relationship between the photon flux and the measured pixel counts. Results. We define the image reconstruction problem for STIX from both visibilities and photon counts. We provide an overview of the algorithms implemented for the solution of the imaging problem, and a comparison of the results obtained with these different methods in the case of the SOL2022-03-31T18 flaring event.
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