【学术报告】
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报告题目：Structure of Sunspots

报告人: Dr. Debi Prasad Choudhary

报告人单位：Department of Physics and Astronomy, San Fernando Observatory, California State University Northridge

报告时间：2017年5月3日（周三）上午 9:30-10:30

报告地点：小学校会议室

报告语言：英文

报告摘要： 

Sunspots are main ingredient of solar cycle and site of major eruptive events. Understanding the structure of these objects is an important aspect studying our nearest star. We have observed several sunspots using the Spectropolarimeter in near-Infrared and Optical wavelength ranges at the Dunn Solar Telescope during 29 July to 4 August 2013. The data consists of full Stokes profiles in the Ca II 854.2 nm and Fe I 1.56 micron lines. The inversion of these Stokes spectra provides the magnetic, thermal and velocity structure at photospheric and chromospheric heights of sunspots. In this lecture, we present the results on the 3D thermal structure in the super- penumbral canopy of a round sunspot, derived by a novel approach for the inversion of Ca II IR spectra. Tracing individual fibrils in the super-penumbral canopy, we find that about half of them form only short loops of a a few Mm length that return to the photosphere in the close surroundings of the sunspot instead of connecting to more remote magnetic network at the outer end of the moat flow. We also find indications for standing shocks at the inner foot points of the flow channels that are compatible with a supersonic siphon flow scenario.

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4月25日