• Title/Summary/Keyword: chromosphere

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The Sun Observed by Fast Imaging Solar Spectrograph of the 1.6 meter New Solar Telescope at Big Bear

  • Chae, Jong-Chul;Park, Hyung-Min;Ahn, Kwang-Su;Yang, Hee-Su;Park, Young-Deuk;Nah, Ja-Kyoung;Jang, Bi-Ho;Cho, Kyung-Suk;Cao, Wenda;Gorceix, Nicholas;Goode, Philip R.
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.2
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    • pp.25-25
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    • 2010
  • With the aim of resolving important physical problems in the chromosphere of the Sun, we developed the Fast Imaging Solar Spectrograph for several years, and at last successfully installed it in the Coude room of the 1.6 meter New Solar Telescope at Big Bear in 2010 May. The instrument is an Echelle spectrograph with imaging capability based on slit scan, and can record two spectral bands (e.g., H alpha band and Ca II 8542 band) simultaneously. The early runs of the instrument produced data of high quality that are suited for the study of quiet Sun, filaments on the disk, prominences outside the limb, active regions and sunspots. We are ready to do good solar sciences using our own instrument, and will be able to do best sciences with the coming improvement of spatial resolution.

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Physics of Solar Flares

  • Magara, Tetsuya
    • Bulletin of the Korean Space Science Society
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    • pp.25.1-25.1
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    • 2010
  • This talk outlines the current understanding of solar flares, mainly focusing on magnetohydrodynamic (MHD) processes. A flare causes plasma heating, mass ejection, and particle acceleration that generates high-energy particles. The key physical processes related to a flare are: the emergence of magnetic field from the solar interior to the solar atmosphere (flux emergence), formation of current-concentrated areas (current sheets) in the corona, and magnetic reconnection proceeding in current sheets that causes shock heating, mass ejection, and particle acceleration. A flare starts with the dissipation of electric currents in the corona, followed by various dynamic processes which affect lower atmospheres such as the chromosphere and photosphere. In order to understand the physical mechanism for producing a flare, theoretical modeling has been developed, in which numerical simulation is a strong tool reproducing the time-dependent, nonlinear evolution of plasma before and after the onset of a flare. In this talk we review various models of a flare proposed so far, explaining key features of these models. We show observed properties of flares, and then discuss the processes of energy build-up, release, and transport, all of which are responsible for producing a flare. We come to a concluding view that flares are the manifestation of recovering and ejecting processes of a global magnetic flux tube in the solar atmosphere, which was disrupted via interaction with convective plasma while it was rising through the convection zone.

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Current Status and Improvement of the Fast Imaging Solar Spectrograph of the 1.6m telescope at Big Bear Solar Observatory

  • Park, Hyungmin;Chae, Jongchul;Song, Donguk;Yang, Heesu;Jang, Bi-Ho;Park, Young-Deuk;Nah, Jakyoung;Cho, Kyung-Suk;Ahn, Kwangsu
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.112.2-112.2
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    • 2012
  • For the study of fine-scale structure and dynamics in the solar chromosphere, the Fast Imaging Solar Spectrograph (FISS) was installed in 1.6m New Solar Telescope at Big Bear Solar Observatory in 2010. The instrument, installed at a vertical table of the Coude lab, is properly working and producing data for science. From the analysis of the data, however, we noticed that a couple of problems exist that deteriorate image quality : lower light level and poorer resolution of the CaII band data. After several tests, we found that the relay optics at the right position is crucial role for the spatial resolution of raster-scan images. By using resolution target, we re-aligned relay optics and other components of the spectrograph. Here we present the result of optical test and new data taken by the FISS.

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New Light Curves and Orbital Period Investigations of the Interacting Binary System UV Piscium

  • Jeong, Min-Ji;Han, Wonyong;Kim, Chun-Hwey;Yoon, Joh-Na;Kim, Hyoun-Woo
    • Journal of Astronomy and Space Sciences
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    • v.36 no.2
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    • pp.75-86
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    • 2019
  • UV Psc is a typical RS CVn type system undergoing dynamic chromosphere activity. We performed photometric observations of the system in 2015 and secured new BVR light curves showing well-defined photometric waves. In this paper, we analyzed the light curves using Wilson-Devinney binary code and investigated the orbital period of the system. The combination of our light curve synthesis with the spectroscopic solution developed by previous investigators yielded the absolute parameters as: $M_1=1.104{\pm}0.042M_{\odot}$, $R_1=1.165{\pm}0.025R_{\odot}$, and $L_1=1.361{\pm} 0.041L_{\odot}$ for the primary star, and $M_2=0.809{\pm}0.082M_{\odot}$, $R_2=0.858{\pm}0.018R_{\odot}$, and $L_2=0.339 {\pm}0.010L_{\odot}$ for the secondary star. The eclipse timing diagram for accurate CCD and photoelectric timings showed that the orbital period may vary either in a downward parabolic manner or a quasi-sinusoidal pattern. If the latter is adopted as a probable pattern for the period change, a more plausible account for the cyclic variation may be the light time effect caused by a circumbinary object rather than an Applegate-mechanism occurring via variable surface magnetic field strengths.

OBSERVATION SYSTEM OF SOLAR FLARE TELESCOPE (태양플레어망원경의 관측 시스템)

  • Park, Young-Deuk;Moon, Yong-Jae;Jang, Be-Ho;Sim, Kyung-Jin
    • Publications of The Korean Astronomical Society
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    • v.12 no.1
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    • pp.35-45
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    • 1997
  • SOFT($\underline{So}lar\;\underline{F}lare\;\underline{T}elescope$) installed at BOAO(Bohyunsan Optical Astronomy Observatory) is purposed for observing solar active regions using four refractors on single mount with a $400"\times300"$ field of view: Two refractors with a diameter of 15cm(f15) are observe the white light and $H\alpha$, and the other two refractors with a diameter of 20cm(f8) are observe the magnetic field distribution and Doppler shifts at the solar chromosphere. Three Lyot filters, one of the most important observational instruments, are installed on the optical rails for VMG, LMG, and $H\alpha$ that possible to very narrow pass band observation under high precision stability of temperature. From the combination of KD*P and quarter wave plate in the Lyot filter possible observe the magnetic fields strength and doppler shifts by using the characteristics of polarization components. In this paper, we introduce the basic characteristics, optical system, and monitor system of the SOFT.

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