@article{00643dfbe58748ab8073997e9957f358,
title = "Frequently Occurring Reconnection Jets from Sunspot Light Bridges",
abstract = "Solid evidence of magnetic reconnection is rarely reported within sunspots, the darkest regions with the strongest magnetic fields and lowest temperatures in the solar atmosphere. Using the world's largest solar telescope, the 1.6 m Goode Solar Telescope, we detect prevalent reconnection through frequently occurring fine-scale jets in the Hα line wings at light bridges, the bright lanes that may divide the dark sunspot core into multiple parts. Many jets have an inverted Y-shape, shown by models to be typical of reconnection in a unipolar field environment. Simultaneous spectral imaging data from the Interface Region Imaging Spectrograph show that the reconnection drives bidirectional flows up to 200 km s-1, and that the weakly ionized plasma is heated by at least an order of magnitude up to ∼80,000 K. Such highly dynamic reconnection jets and efficient heating should be properly accounted for in future modeling efforts of sunspots. Our observations also reveal that the surge-like activity previously reported above light bridges in some chromospheric passbands such as the Hα core has two components: the ever-present short surges likely to be related to the upward leakage of magnetoacoustic waves from the photosphere, and the occasionally occurring long and fast surges that are obviously caused by the intermittent reconnection jets.",
keywords = "Sun: UV radiation, Sun: chromosphere, Sun: transition region, magnetic reconnection, sunspots",
author = "Hui Tian and Vasyl Yurchyshyn and Hardi Peter and Solanki, {Sami K.} and Young, {Peter R.} and Lei Ni and Wenda Cao and Kaifan Ji and Yingjie Zhu and Jingwen Zhang and Tanmoy Samanta and Yongliang Song and Jiansen He and Linghua Wang and Yajie Chen",
note = "Funding Information: BBSO operation is supported by NJIT, US NSF AGS-1250818, and NASA NNX13AG14G grants. The GST operation is partly supported by the Korea Astronomy and Space Science Institute (KASI), Seoul National University, and the Strategic Priority Research Program of CAS with grant No. XDB09000000. The authors thank the BBSO staff for their help during the observations. IRIS is a NASA Small Explorer mission developed and operated by LMSAL with mission operations executed at NASA Ames Research center and major contributions to downlink communications funded by ESA and the Norwegian Space Center. The authors are supported by NSFC grants 11790304, 41574166, 11573064, 11729301, 11573012, and 11790300, the Recruitment Program of Global Experts of China, the Max Planck Partner Group program, NASA grant NNX15AF48G, the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation program (grant agreement No. 695075), the BK21 plus program through the National Research Foundation (NRF) funded by the Ministry of Education of Korea, the ISSI Bern international team “Solar UV bursts—a new insight to magnetic reconnection,” the AFOSR FA9550-15-1-0322 and NSF AST-1614457 grants and KASI. Publisher Copyright: {\textcopyright} 2018. The American Astronomical Society. All rights reserved..",
year = "2018",
month = feb,
day = "20",
doi = "10.3847/1538-4357/aaa89d",
language = "English (US)",
volume = "854",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",
}