• 제목/요약/키워드: sun: chromosphere

검색결과 24건 처리시간 0.019초

SPECTROSCOPIC OBSERVATION OF THE SOLAR ACTIVE REGIONS IN HeI 10830 ${\AA}$ LINE

  • TOHMURA ICHIROH;KITAI REIZABURO;SUEMATSU YOSHINORI;SOLTAU DIRK
    • 천문학회지
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    • 제29권spc1호
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    • pp.333-335
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    • 1996
  • Here we report the results from spectroscopic observations of soloar active regions in the HeI 10830 ${\AA}$ line at the German Vacuum Tower Telescope(VTT) in Tenerife during the August 199:3 International EFR(Emerging Flux Region) Campaign. Four active regions in various stages of their evolution, i.e., NOAA7558, 7560, 7561, and 7562, were ovserved on 10 August 1993. From the observed HeI 10830 ${\AA}$ spectra in these active regions, spectroscopic quantities such as equivalent width(EW), doppler shift, doppler width, etc., were derived(see Figure l(a)) and the correlation between them were studied(see Figure l(b)). Our main results are as follows: (I)In NOAA7562, which is a young and evolving EFR, the EW is large, while it is small around a simple and roundish spot of NOAA7558. (2)In these active regions, redshift in the 10830 line is dominant when the EW is larger. (3)As the doppler width increases, the line tends to shift redward. (4)When the EW is smaller, it seems to exist another component which have dynamic characteristics different from the redshifting component. In NOAA7560 and NOAA7561, regions which have several small spots, the values of the EW are intermediate. Results (2) and (3) may suggest the possible existence of downflow above active regions, if the HeI 10830 ${\AA}$line is formed in the upper chromopshere, and it is consistent with the earlyer result from the SMM extreme-ultraviolet observation by Klimchuk(1987, Astrophys. J., 323, 368) (to be submitted. to Astronomy and Astrophysics; an extended abstract)

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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.
    • 천문학회보
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    • 제35권2호
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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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Generation of He I 1083 nm Images from SDO/AIA 19.3 and 30.4 nm Images by Deep Learning

  • Son, Jihyeon;Cha, Junghun;Moon, Yong-Jae;Lee, Harim;Park, Eunsu;Shin, Gyungin;Jeong, Hyun-Jin
    • 천문학회보
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    • 제46권1호
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    • pp.41.2-41.2
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    • 2021
  • In this study, we generate He I 1083 nm images from Solar Dynamic Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images using a novel deep learning method (pix2pixHD) based on conditional Generative Adversarial Networks (cGAN). He I 1083 nm images from National Solar Observatory (NSO)/Synoptic Optical Long-term Investigations of the Sun (SOLIS) are used as target data. We make three models: single input SDO/AIA 19.3 nm image for Model I, single input 30.4 nm image for Model II, and double input (19.3 and 30.4 nm) images for Model III. We use data from 2010 October to 2015 July except for June and December for training and the remaining one for test. Major results of our study are as follows. First, the models successfully generate He I 1083 nm images with high correlations. Second, the model with two input images shows better results than those with one input image in terms of metrics such as correlation coefficient (CC) and root mean squared error (RMSE). CC and RMSE between real and AI-generated ones for the model III with 4 by 4 binnings are 0.84 and 11.80, respectively. Third, AI-generated images show well observational features such as active regions, filaments, and coronal holes. This work is meaningful in that our model can produce He I 1083 nm images with higher cadence without data gaps, which would be useful for studying the time evolution of chromosphere and coronal holes.

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Doppler Shifts of the $H{\alpha}$ Line and the Ca II 854.2 nm Line in a Quiet Region of the Sun Observed with the FISS/NST

  • 채종철;박형민;양희수;박영득;조경석;안광수
    • 천문학회보
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    • 제37권2호
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    • pp.113.1-113.1
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    • 2012
  • The characteristics of Doppler shifts in a quiet region of the Sun are investigated by comparing between the $H{\alpha}$ line and the Caii infrared line at 854.2 nm. A small area of $16^{\prime\prime}{\times}40^{\prime\prime}$ was observed for about half an hour with the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST) at Big Bear Solar Observatory. The observed area contains a network region and an internetwork region, and identified in the network region are $H{\alpha}$ fibrils, Caii fibrils and bright points. We infer the Doppler velocity from each line profile at a point with the lambdameter method as a function of half wavelength separation ${\Delta}{\lambda}$. It is confirmed that the bisector of the spatially-averaged Caii line profile has an inverse C-shape of with a significant peak redshift of +1.8 km/s. In contrast, the bisector of the spatially-averaged $H{\alpha}$ line profile has a different shape; it is almost vertically straight or, if not, has a C-shape with a small peak blueshift of -0.5 km/s. In both the lines, the bisectors of bright network points are much different from those of other features in that they are significantly redshifted not only at the line centers, but also at the wings. We also find that the spatio-temporal fluctuation of Doppler shift inferred from the Caii line is correlated with those of the $H{\alpha}$ line. The strongest correlation occurs in the internework region, and when the inner wings rather than the line centers are used to determine Doppler shift. In this region, the RMS value of Doppler shift fluctuation is the largest at the line center, and monotonically decreases with ${\Delta}{\lambda}$. We discuss the physical implications of our results on the formation of the $H{\alpha}$ line and Caii 854.2 nm line in the quiet region chromosphere.

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