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ISSN 1063-7737, Astronomy Letters, 2008, Vol. 34, No. 1, pp. 33­51. c Pleiades Publishing, Inc., 2008. Original Russian Text c S.V. Shestov, S.A. Bozhenkov, I.A. Zhitnik, S.V. Kuzin, A.M. Urnov, I.L. Beigman, F.F. Goryayev, I.Yu. Tolstikhina, 2008, published in Pis'ma v Astronomicheski Zhurnal, 2008, Vol. 34, No. 1, pp. 38­57. i

Solar EUV Spectra Obtained during the SPIRIT Experiment Onboard the ° CORONAS-F Satellite: A Catalog of Lines in the Range 176­207 A
S. V. Shestov1, 2 * , S. A. Bozhenkov3 , I. A. Zhitnik1 , S. V. Kuzin1 , A. M. Urnov1, 2 ** , I. L. Beigman1, 2 , F. F. Goryayev1 , and I. Yu. Tolstikhina
1 2

1

Lebedev Physical Institute, Russian Academy of Sciences, Leninskii pr. 53, Moscow, 119991 Russia Moscow Institute of Physics and Technology, Institutskii per. 9, Dolgoprudnyi, Moscow oblast, 141700 Russia 3 Institute of Plasma Physics, Juelich Research Center, Germany
Received April 28, 2007

° Abstract--We present a catalog of 65 spectral lines in the range 176­207 A recorded by the RES spectroheliograph in active regions and flares during the SPIRIT experiment onboard the CORONASF satellite. We have identified 51 lines. The relative intensities of lines recorded during the M6.5 (GOES) flare of September 16, 2001, are given. The data processing technique is discussed. PACS numbers : 95.55.Fw; 95.75.Fg; 96.60.P-; 96.60.Tf; 95.85.Mt; 95.30.Ky DOI: 10.1134/S1063773708010052 Key words: CORONAS-F, SPIRIT, EUV spectrum, catalog of lines in solar flares and active regions.

the spectra of active regions and flares recorded in the ° 176­207 A channel of the RES spectroheliograph. This paper is a continuation of the paper by ° The spectral range 180­210 A is of great interBeigman et al. (2005), which is devoted to processing est in spectroscopically diagnosing the solar coronal and identifying the extreme ultraviolet (EUV) spectra obtained with the RES spectroheliograph of the plasma. This range contains many spectral lines of SPIRIT instrumentation onboard the CORONAS-F multiply charged ions formed in a wide temperature satellite (see Zhitnik et al. 2005). The RES spectro- range, 8 â 105 -3 â 107 K. Since there is a number of heliograph includes two channels to obtain monochro- spectral lines of iron ions at various ionization stages ° matic EUV (176­207 and 280­330 A) solar im- (from Fe VIII to Fe XXIV), the emitting plasma can ages and X-ray channels to image the Sun in the be diagnosed by abundance-insensitive methods. The ° monochromatic MgXII 8.42 A line. A detailed de- sensitivity of Fe XII­Fe XV line ratios to density alplasma density to be determined in scription of the RES channels and their basic charac- lows the emitting 12 the range 108 -10 cm-3 (Brickhouse et al. 1995). teristics are given in Kuzin et al. (1997) and Zhitnik et al. (2006). The overall objectives of the SPIRIT The Sun was observed in the spectral range 186­ experiments and the first results of observations are 201 A by the RES-C spectroheliograph onboard the ° presented in Zhitnik et al. (2002). A brief overview CORONAS-I satellite (see Zhitnik et al. 1998). The of the observational data and preliminary results of RES-C data were used both to determine the plasma modeling active plasma structures in the solar corona density in active regions and to identify spectral lines based on EUV spectra and X-ray images are provided in this range and to refine atomic parameters (Zhitnik in Zhitnik et al. (2006) and Urnov et al. (2007). The et al. 1999). The solar observations in the spectral specifications of the RES EUV channels, the data range 176­207 A were continued by the RES spec° processing technique, and a full catalog of spectral troheliograph of the SPIRIT instrumentation. ° lines in the range 280­330 A compiled from the Here (see Table 1), we present a catalog of spectral observations of the X3.4 flare of December 28, 2001, ° lines in the range 176­207 A compiled from the specand the compact active region NOAA 9765 are given trum for the M5.6 (GOES) flare of September 16, in Beigman et al. (2005). In this paper, we analyze 2001, at 03 : 39-03 : 53-04 : 18 UT. The flare spec* trum was recorded on September 16, 2001, at 03 : E-mail: sshestov@dgap.mipt.ru ** E-mail: urnov@sci.lebedev.ru 59 UT with an exposure time of 37 s. We also used the
33

INTRODUCTION


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° Table 1. Parameters of the observed lines in the range 176­207 A N 1 2 3 4 5 6 7 ° , A 176.09 176.34 176.71 176.93 177.24 178.02 179.24 I ,arb.units 1070 ± 128 956 ± 132 822 ± 128 2625 ± 162 6900 ± 234 3799 ± 178 1409 ± 141 2365 ± 157 15381 ± 1500 823 ± 85 170 ± 51 3225 ± 112 ... 230 ± 54 324 ± 51 130 ± 66 2386 ± 120 2742 ± 107 434 ± 55 1726 ± 81 112 ± 40 1044 ± 81 4780 ± 130 ,pixels 2.68 ± 0.24 2.21 ± 0.24 2.14 ± 0.25 2.23 ± 0.09 2.62 ± 0.06 2.83 ± 0.09 3.06 ± 0.24 3.13 ± 0.15 ... 2.20 ± 0.16 2.24 ± 0.50 3.00 ± 0.07 ... 2.41 ± 0.41 1.93 ± 0.21 2.04 ± 0.91 3.02 ± 0.12 3.14 ± 0.08 1.77 ± 0.16 2.49 ± 0.08 1.77 ± 0.49 2.43 ± 0.14 2.82 ± 0.05 Ion Ni XV ... Ni XV Ca XV + b Fe X Fe XI + b Ni XV SIX 8 9 179.75 180.42 Fe XI Fe XI Fe X 10 11 12 13 14 15 181.11 181.87 182.17 182.3 182.71 183.41 Fe XI Ca XV Fe XI Fe X ... Ar XIV Ca XIV 16 17 18 19 20 183.81 184.03 184.52 184.77 185.20 ... ... Fe X Fe XI Fe VIII Ni XVI 21 22 186.23 186.60 Fe XII Ca XIV Fe VIII 23 186.87 Fe XII Fe XII SXI 24 25 187.38 187.92 109 ± 67 746 ± 134 8198 ± 245


° C , A .11 ... .74 .93 .24 .06 .27 .28 .76 .41 .41 .14 .90 .17 .31 ... .45 .46 ... ... .54 .80 .21 .23 .24 .61 .60 .88 .85 .84 ... .92 .97 .23 .30 .19

I ... ... ... .95 .24 .05 .27 ... .75 .41

II ... ... ... ... .24 ... .28 ... ... .38

.14 .91 .17 ... ... .45 ... ... ... .54 .80 .21 ... .60

.13 ... .17 ... ... ... ... ... ... .53 .80 .22 ... .62

.87

.87

2.71 ± 1.36 4.26 ± 0.66 3.42 ± 0.08

... Fe XXI Ar XIV Fe XI Fe XI Fe XII

... .95

... .96

26

188.25

.23

.21

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SOLAR EUV SPECTRA Table 1. (Contd.) N 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 ° , A 188.50 188.66 188.78 189.06 189.39 189.69 190.00 I ,arb.units 911 ± 230 313 ± 170 474 ± 167 1059 ± 139 102 ± 42 193 ± 47 848 ± 33 585 ± 96 190.35 191.00 378 ± 59 238 ± 77 809 ± 110


35

,pixels 2.92 ± 0.70 1.69 ± 0.63 2.46 ± 0.81 4.39 ± 0.48 1.97 ± 0.61 1.95 ± 0.35 3.62 ± 0.16 2.42 ± 0.28 2.85 ± 0.76 2.55 ± 0.30 ... 2.89 ± 0.06 2.05 ± 0.34

Ion ?Fe XII SXI Ar XI ?Fe XI+ b ... Fe XI Fe X Fe XII SXI Ar XI Fe XII SXI Fe XXIV Fe XII ... Ca XVII Fe XI Fe XII Fe XI Ca XIV ?Ni XVI ?Ar XIV ... Fe XII Fe XII Fe XIII Fe XII ... Fe XIII ... Fe XI S VIII Fe XII

° C , A .45 .68 .81 .13 ... .72 .04 .07 .36 .95 .05 .27 .03 .39 ... .82 .83 .52 .52 .87 .02 .40 ... .12 .18 .54 .64 ... .43 ... .55 .55 .58 ... .02 ...

I ... ... ... .14 ... ... .04

II .49 .66 .82 .19 ... .72 .05 ... ... ... .26 ... .39 ... .88 .81

.37 .04

191.25 192.03 192.39 192.61 192.82

.27 .03 .40 ... .86

11396 ± 1000 5659 ± 164 661 ± 123 4851 ± 186 1722 ± 51


2.94 ± 0.06 ... 3.08 ± 0.96 2.63 ± 1.14 2.25 ± 0.32 ... ... ... ... ... ... ...

193.54

11488 ± 1500 1344 ± 466 533 ± 428 647 ± 114 478 ± 150 17628 ± 1500 8176 ± 610 445 ± 200 2197 ± 250 947 ± 100 4426 ± 400

.51

.51

193.83 193.99 194.35 194.66 195.19

.87 .05 .41 ... .13

.87 .03 .40 ... .12

196.62

.52 .63 .01 .44 ... .55

.52 .64 ... ... ... .56

197.07 197.42 197.83 198.53

52 53 54

199.24 200.01 200.41

1601 ± 150 11864 ± 1000 565 ± 40

... ... ...

... Fe XIII ...

... .02 .37

... .02 ...

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36 Table 1. (Contd.) N 55 56 ° , A 200.67 201.15 I ,arb.units 569 ± 40 21866 ± 2000

SHESTOV et al.

,pixels ... ...

Ion ... Fe XIII Fe XII

° C , A ... .13 .14 .74 .76 .71 .04 .71 .61 .63 .16 .83 .80 .26 .65 .95 ...

I ... .13

II ... .12

57

201.72

2518 ± 250

...

Fe XII Fe XII Ar XIII

.74

.76

58 59

202.08 202.63

40323 ± 4000 1600 ± 200

... ...

Fe XIII ?Fe XI S VIII Fe XI

.05 ... ... ... .18 .82

.04 ... ... ... .16 .82

60 61

203.19 203.84

8065 ± 500 52795 ± 5000

... ...

Fe XIII Fe XIII Fe XIII

62 63 64 65

204.26 204.63 204.95 206.32


6052 ± 1000 2180 ± 200 7782 ± 800 12380 ± 1000

... ... ... ...

Fe XIII Fe XVII Fe XIII + b ...

.25 .65 .94 .25

.26 .67 .95 .26

° Note. Notation: N is the line number; is the measured wavelength; I is the line intensity; is the line width (1 pixel is 0.025 A); ion is the identified ion; C is the fractional part of the wavelength of the identified line from the CHIANTI database (Landi et al. 2006); I is the fractional part of the line wavelength from the spectral catalog of flares by Dere (1978); II is the fractional part of the line wavelength from the spectral catalog of active regions by Brosius et al. (1998); marks the lines that are clearly seen only in the flare spectrum; +b denotes the line intensity attributable to an unidentified blend; denotes the intensities of blended lines estimated from the branching ratios; ? means that questions remain in the line identification. The lines given under the same number are unresolvable. For further explanations, see the text.

spectra of active regions (NOAA 9650, 9653, 9655, 9659, 9660, 9665, 9695, 9697, 9698, 9715, 9716, 9725) recorded on October 14­17, November 22, and December 5, 2001, with various exposure times. The spectra of active regions were used to check the line identifications and the spectral sensitivity calibration of the spectroheliograph (see Table 2). DATA PROCESSING AND CALIBRATION One-Dimensional Spectrum Construction The spectroheliogram is a sequence of monochromatic images of the full solar disk compressed in

the dispersion direction. The primary data processing consists in subtracting the background on the spectroheliogram, rotating the image, and constructing the source's one-dimensional spectrum. The primary spectroheliogram processing technique for the ° 280­330 A channel as an example was described by Beigman et al. (2005). Figure 1a shows the spec° troheliogram for the 176­207 A channel recorded on September 16, 2001, at 03 : 59 UT. Figure 1b shows the same spectroheliogram after the background subtraction; the arrow indicates the dispersion direction. The one-dimensional spectrum is a spectroheliASTRONOMY LETTERS Vol. 34 No. 1 2008


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ogram section in the dispersion direction and a convolution of the source's emission spectrum with the spatial distribution of its intensity along the dispersion axis. Thus, information about the source's spatial intensity distribution along the dispersion axis is generally required to reconstruct and interpret the one-dimensional spectrum. However, the spatial distribution is unimportant if the source's size in this direction is smaller than the width of the point spread function that corresponds to the source's 1 size of R . Solar flares and most active regions 5 meet this requirement. Figure 2a shows the spectroheliogram recorded on September 16, 2001, at 03 : 59 UT; the dispersion direction is horizontal and the wavelength increases to the right. The dashed line represents the one-dimensional spectrum that corresponds to the M5.6 (GOES) flare. The most intense lines are labeled. Figure 2b shows a magnified portion ° of the spectroheliogram near = 193 A, where we see relatively "cold" Fe XII lines, which are intense on the entire solar disk, and "hot" flare regions identified as

Ca XVII and Fe XXIV lines. In this paper, the onedimensional spectrum was averaged over five pixels in a direction perpendicular to the dispersion direction. In this direction, the width of the point spread function is 2 pixels; 1 pixel corresponds to 5 . 4. The subsequent spectroheliogram processing procedure consists in the wavelength calibration of the one-dimensional spectrum obtained (based on reference lines), the determination of its parameters-- the intensity (given the spectral sensitivity of the instrument) and width, and the identification of spectral lines. Based on a geometrical model of the spectroheliograph, Beigman et al. (2005) showed that the wavelength could be expressed by a second-degree polynomial of the line position (in pixels) in the onedimensional spectrum. The polynomial coefficients can be determined using reference lines for the spectral region under consideration. In this channel, the following reference lines were used to determine the wavelengths:

° 177.24 A (FeX 3s2 3p ° 184.54 A (FeX 3s2 3p

5 5 3 3 2 2

2 2 4 4 3 3

P3/2 - 3s2 3p4 (3 P )3d P3/2 - 3s2 3p4 (1 D)3d S S
3/2 3/2

2

P3/2 ), S
1/2

2 4 4

),

° 192.39 A (FeXII 3s2 3p ° 193.52 A (FeXII 3s2 3p

- 3s2 3p2 (3 P )3d - 3s2 3p2 (3 P )3d
3 3

P1/2 ), P3/2 ),

° 200.02 A (FeXIII 3s2 3p ° 204.95 A (FeXIII 3s2 3p

P1 - 3s2 3p3d P2 - 3s2 3p3d

D2 ), D1 ).

The accuracy of determining the wavelengths by this ° method is 0.04 A. To test the technique, Fig. 3 compares the experimental and theoretical wavelengths. The spectral sensitivity of the instrument is determined mainly by the wavelength dependence of the multilayer mirror reflectance. The mirror reflectance was measured before the flight of the instrument; the normalized reflectance is shown in Fig. 4. To check the calibration accuracy of the spectral sensitivity, we used line intensity ratios insensitive to emitting plasma parameters. The results are presented in Table 2. Most of the experimentally measured ratios agree with the theoretical values with an accuracy of 30%, which corresponds to the accuracy of measuring the mirror reflectance.
ASTRONOMY LETTERS Vol. 34 No. 1 2008

Line Parameter Determination
To determine the positions and parameters of spectral lines, we fitted the spectrum in the chosen narrow wavelength range. This method proved to be efficient in analyzing strongly blended spectra (Brooks et al. 1999; Thomas and Neupert 1994; Lang et al. 1990; Brosius et al. 1998, 2000; Beigman et al. 2005). The emission intensity distribution in the chosen wavelength region 1 ­2 can generally be written as
N

i() = P + Q +
i=1

Ai

(1)

â exp -

1 2

- i

i 0

2

,

= [1 ,2 ],


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SHESTOV et al.

° Table 2. SPIRIT line intensity ratios in the range 176­207 A Lines SXI 188.68/191.27 , % Fe X 177.24/184.54 , % Fe X 184.54/190.04b , % Fe XI 178.06b/182.17 , % Fe XI 192.83b/188.23 , % Fe XI 189.13/189.72 , % Fe XII 192.39/193.51 , % Fe XII 192.39/195.12 , % Fe XII 193.51/195.12 , % Fe XIII 197.43/204.95b , % Fe XIII 197.43/201.13b , % Fe XIII 201.13b/204.95b , % Fe XIII 200.02/204.26 , % Fe XIII 200.02/203.16 , % Fe XIII 203.82/200.02 , % 1 0.39 56 2.52 5 1.91 7 1.18 6 0.80 4 ... ... 0.42 5 0.32 9 0.78 10 0.18 17 0.10 20 1.79 11 1.83 15 1.44 18 4.94 28 2 ... ... 2.76 9 1.49 7 0.93 20 0.36 8 0.55 105 0.52 13 0.36 14 0.69 15 0.19 16 0.10 20 1.90 11 1.82 15 1.21 21 5.35 26 3 0.39 49 2.90 9 ... ... 0.69 9 0.28 4 1.00 32 0.50 14 0.33 15 0.65 14 0.16 18 0.08 25 1.91 11 1.61 17 1.76 15 5.54 25 4 ... ... 3.15 9 ... ... 1.00 13 0.38 8 ... ... 0.48 6 0.24 8 0.50 14 0.19 16 0.10 20 1.86 11 1.65 17 1.44 18 6.57 21 5 0.59 32 2.60 6 1.42 8 0.95 14 0.36 3 1.43 50 0.54 15 0.38 13 0.71 14 0.19 16 0.09 23 2.31 9 2.00 14 1.31 20 5.39 26 6 ... ... 2.55 6 1.56 8 0.85 7 0.37 3 1.26 37 0.59 15 0.40 15 0.68 15 0.17 18 0.09 23 1.77 11 1.85 15 1.38 20 4.61 30 5.40 4.55


Mean 0.46

Theory 0.57


Ratio 0.81

2.64

1.93

1.37

1.56

3.21

0.49

0.89

0.27

3.30

0.34

0.21

1.62

1.04

1.30


0.8

0.45

0.42

1.07

0.29

0.26



1.12

0.65

0.61



1.07

0.18

0.65

0.28

0.09

0.24

0.38

1.92

3.35


0.57

1.79

1.56

1.15

1.42

1.68



0.85

1.19

Note. The data are given for the flare (1) and the active regions (2­6). Mean--the value obtained by averaging 2­6 values; theory-- the theoretical value based on CHIANTI data (Landi et al. 2006); --based on data by Brickhouse et al. (1995); --based on data by Landi (2002); ratio -- the mean-to-theory ratio; b marks a blended line; is the measurement error.

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60.20° ± 0.02°

()

(b)

Fig. 1. (a) Original spectroheliogram recorded on September 16, 2001, at 03 : 59 UT. (b) The same spectroheliogram after the background subtraction; the arrow indicates the dispersion direction on the spectroheliogram.

()

Fe XI 180.4 å

Fe XII 186.9 å

Fe XI 188.3 å

Fe XIII 202.1 å

Fe XIII 203.8 å

(b)

Fe XXIV 192.0 å Ca XVII 192.8 å

Fe XII 192.4, 193.5, 195.1å

Fig. 2. (a) Spectroheliogram recorded on September 16, 2001, at 03 : 59 UT; the dispersion axis is horizontal. The dashed line represents the one-dimensional spectrum that corresponds to the M5.6 (GOES) flare. Some of the spectral lines are labeled. ° (b) A magnified portion of the spectroheliogram near = 193 A.

where P and Q describe the local background, N is the number of spectral lines, Ai , i , and i are 0 the peak intensity, wavelength, and width of spectral line i, respectively. The line shape is assumed to be Gaussian; the total line intensity can be calculated using the formula (2) Ii = 2Ai i . In fitting, the parameters P , Q, Ai , i , and i are 0 chosen using the 2 test (see, e.g., William et al. 2001; Brandt 1998). The error distribution is assumed to be normal and the standard deviation for each
ASTRONOMY LETTERS Vol. 34 No. 1 2008

point is given by the Poisson formula: = i(). The method allows the error in the parameters to be estimated and yields an estimate for the quality of the fit. In most cases, the error in the line parameters is determined precisely by the fitting procedure, despite the error introduced at the background subtraction step and the detector noise. However, there was a defocusing in the RES channel under consideration, causing a broadening of the lines and and a distortion of their shapes near the long-wavelength edge of the range (see Fig. 5a). Because of asymmetry in the line profiles,


40
0.10

SHESTOV et al.
1.0 0.8 Reflectance 180 185 190 195 Wavelength, å 200 205
l1

0.05 exper ­ theor, å

0.6 0.4 0.2 0

0

­ 0.05

­ 0.10 175

165 170 175 180 185 190 195 200 205 Wavelength, å

Fig. 3. Difference between the experimental and theoretical wavelengths for the flare of September 16, 2001.

Fig. 4. Normalized multilayer mirror reflectance versus wavelength.

the Gaussian fitting method in our case is applicable ° for wavelengths < 196 A, where the asymmetry ° in the profile is minor. For > 196 A, we used a different technique to determine the line parameters: the intensities were summed over the entire line profile: Ij =
l0

(3) The match between the experimental and theoretical (CHIANTI) line ratios. We checked the identification of the flare and active region spectra based on density-insensitive line ratios. Table 2 gives the experimental line intensity ratios along with the CHIANTI theoretical ones. The catalog of spectral lines compiled from the spectrum of the M5.6 (GOES) flare recorded on September 16, 2001, at 03 : 59 UT is given in Table 1. The table contains the measured wavelengths of the spectral lines, their parameters (intensities and widths), and suggested identifications; based on it, we make a comparison with the wavelengths from the CHIANTI catalog and from the spectral catalogs of flares (Dere 1978) and active regions (Brosius et al. 1998). The RES flare spectrum is shown in Figs. 6­ 8; the observed lines are marked by vertical bars. Below, we provide explanations in the identification of individual lines. The following notation is used: "+"-- the line is observed; "-"--the line is not observed; "b"--the line is blended; "l"--the line that does not ° fall within the recorded wavelength range 176­207 A; "u"--there remain questions in the line identification discussed in the text. S VIII (logT = 5.9). 2s2 2p5 2 P - 2s2p6 2 S . ° Jlow - Jup , A Note 1/2 - 1/2 202.61 +b 3/2 - 1/2 198.55 +b
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i()d.

(3)

The "effective" peak intensity of such a line was calculated from the formula Aj = Ij / 2j , where j is the "reduced" line width dependent on wavelength j (see Fig. 5b). Below in the texts and the tables, we use the total line intensities I obtained from Eqs. (2) and (3), while the peak intensities A and A are used to estimate the contribution from weak or blended lines. LINE IDENTIFICATION The line identification method used here corresponds to that applied by Beigman et al. (2005). The line identification was based on the following criteria: (1) The coincidence of wavelengths with previously recorded ones. The CHIANTI package, version 5.2 (Landi et al. 2006), was used as the wavelength standard. We also made a comparison with the spectral catalog of flares (see Dere 1978) and active regions (Brosius et al. 1998). (2) The presence of a multiplet structure in the experimental spectrum.


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1.0 Relative intensity 0.8 0.6 0.4 0.2 0 ­12

4.5 () Line width, pixel 4.0 3.5 3.0 2.5 2.0 1.5 12 173.03 182.87 192.99 Wavelength, å 203.37 (b)

1

2

4 3 8

­8

­4 0 4 Coordinate, pixel

° Fig. 5. (a) Change of the line profile with increasing wavelength in the range 176­207 A: 1, 177.24 ° (b) Increase in the line width toward the long-wavelength edge of the range 176­207 4, 203.82 A. experimental data; the solid line represents the linear fit = -7.73(±1.4) + 0.055(± 0.008).

° ° ° A; 2, 192.39 A; 3, 201.12 A; ° The squares indicate the A.

2000 Intensity, arb. units 1500 500 1000 500 0 176 177 178 179 0 180 181 181 182 Wavelengths, å

183

184

185

186

Fig. 6. Spectrum of the September 16, 2001 flare. The vertical bars mark the lines included in Table 1.

° The S VIII 202.61 A line is blended with the ° (3s2 3p4 1 D2 - 3s2 3p3 (2 D)3d 1 P1 ) Fe XI 202.71 A ° line. The S VIII 198.55 A line is blended with the ° (3s2 3p4 1 D2 - 3s2 3p3 (2 D)3d 3 P1 ) Fe XI 198.55 A 2P ° and Fe XII 198.58 A (3s2 3p3 1/2 - 2 3p2 (1 D )3d 2 P 3s 3/2 ) lines. The S VIII line intensity ratio I (198.55)/I (202.61) calculated from the branching ratio using the CHIANTI package is insensitive to density and temperature and is 2.2. SIX (logT = 6.0). 2s2 2p ° 179.28 A.
41

SXI (logT = 6.3). 2s2 2p

23

P - 2s2p

33

S.

° Jlow - Jup , A Note 0-1 1-1 2-1 186.84 +b 188.68 191.27 + +

D2 - 2s2p

51

P1 =

The experimental intensity ratio I (188.68)/ I (191.27) is close to the theoretical one (see Table 2). ° ° Consequently, the S XI 188.68 A and S XI 191.27 A lines are unblended. The intensity of the blended ° S XI 186.84 A line was estimated from the intensity of ° the S XI 191.27 A line and the branching ratio (Landi et al. 2006) ISXI (186.84) = 0.19ISXI (191.27) = 0.19(810 ± 111) = 156 ± 21. (4)

° The SIX 179.28 A line is blended with the Ni XV 2 3p2 3 P - 3s2 3p3d 3 D ) line. ° 179.27 A(3s 2 3
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SHESTOV et al.

1000 Intensity, arb. units 1000 500 500

0 186

187

188

189

190

0 191 192 191 Wavelengths, å

193

194

195

196

Fig. 7. Spectrum of the September 16, 2001 flare (the continuation of Fig. 6). The vertical bars mark the lines included in Table 1.

600 500 400 300 200 100 0 196

ntensity, arb. units

1500 1000 500 0 201 201 202 203 204 205 206 Wavelengths, å

197

198

199

200

Fig. 8. Spectrum of the September 16, 2001 flare (the end of Fig. 6). The vertical bars mark the lines included in Table 1.

° The experimental intensity of the 186.87 A line is 4780 ± 130. Thus, the contribution from the ° S XI 186.84 A line is 3% and is at the level of ° the error in the 186.87 A line intensity, while the 2 3p3 2 D 2 23 2 ° Fe XII 186.88 A(3s 5/2 - 3s 3p ( P )3d F7/2 ) and 3s 3p
2

Ar XI (log T = 6.3). 2s2 2p

43

P - 2s2p

53

P.

° Jlow - Jup , A Note 1-0 0-1 1-1 2-1 1-2 2-2 187.09 - - - +

190.98 +b 189.58

Fe XII
2 (3 2

186.85

° A

(3s 3p

2

3

2

D3/2 -

P )3d F5/2 ) lines make a major contribution.

184.52 +b 194.10 188.81

2s 2p

2

21

D2 - 2s2p

21

° P1 = 190.36 A.

° The spectrum exhibits the 190.35 A line with an intensity of 378 ± 59. The theoretical S XI line ratio I (190.36)/I (191.27) is sensitive to density and reaches values >0.3 at log ne > 11 cm-3 . Thus, the ° ° 190.35 A line can be identified as S XI 190.36 A.

° The Ar XI 190.98 A line is blended with the ° (3s2 3p3 2 P3/2 - 3s2 3p2 (3 P ) â Fe XII 191.05 A ° 3d 2 D5/2 ) line. The blending of Ar190.98 A is con° firmed by the absence of the Ar XI 189.58 A line in the experimental spectrum whose intensity should ° account for 0.79 of the Ar XI 190.98 A intensity (based on CHIANTI data; Landi et al. 2006).
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° The Ar XI 184.52 A line is blended with the ° Fe X 184.54 A (3s2 3p5 2 P3/2 - 3s2 3p4 (1 D)3d 2 S1/2 ) line. Estimating the contribution from the ° Ar XI 184.52 A line based on the intensity of ° by assuming that the latter is unAr XI 190.98 A blended yields I
Ar XI

(184.52) = 1.45IAr XI (190.98) 1.45(238 ± 77) = 345 ± 112.

(5)

° The intensity of the 184.54 A line on the spectroheliogram is Itotal (184.54) = 2737 ± 107. Consequently, ° the contribution from Ar XI 184.52 A does not exceed 13%. Ar XIII (log T = 6.5). 2s2 2p2 3 P - 2s2p3 3 P . ° Jlow - Jup , A Note 1-0 0-1 1-1 2-1 1-2 2-2 205.95 - - -l - -l

° The Ar XIV 183.45 A line is blended with the ° Ca XIV 183.46 A(2s2 2p3 4 S3/2 - 2s2p4 4 P1/2 ) line. ° The Ar XIV 191.40 A line is not observed, although, judging by the branching ratio (Landi et al. 2006), it should be approximately twice as strong as ° the Ar XIV 183.45 A line. Consequently, the observed ° ° 183.45 A line is determined by the Ca XIV 183.46 A emission. ° The Ar XIV 187.97 A line is blended with the ° 2s2 2p2 1 D2 - 2s2p3 3 D1 ) line. The Fe XXI 187.92 A( ° Ar XIV 180.29 A line is not observed. Let us estimate ° its intensity based on the intensity of Ar XIV 187.97 A by assuming that there is no blending and on the branching ratio (Landi et al. 2006) by taking into account the calibration factor, (6) IAr XIV (180.29) = 0.63 â 0.18 â IAr XIV (187.97) 0.11(746 ± 134) = 82 ± 15, AAr 1 I 2 2
XIV

201.71 +b 205.80 211.01 205.29 210.47

(180.29)

(7)

Ar XIV

(180.29) = 16 ± 3.

The peak intensity is at the noise level; besides, it ° should be noted that the Ar XIV 187.97 A line is blended. 2s2 2p 2 P - 2s2p2 2 S . ° Jlow - Jup , A Note 1/2 - 1/2 194.40 + 3/2 - 1/2 203.35 +b ° The Ar XIV 194.40 A line is observed. The in° tensity of Ar XIV 203.35 A is estimated from the ° 194.40 line to be 80; however, the 203.35 A line is not observed due to the presence of strong close Fe XII and Fe XIII lines. Ca XIV (log T = 6.6). 2s2 2p3 4 S - 2s2p4 4 P . ° Jlow - Jup , A Note 3/2 - 1/2 183.46 +b 3/2 - 3/2 186.61 +b 3/2 - 5/2 193.87 +

° The Ar XIII 201.71 A line is blended with the ° strong Fe XII 201.74 A (3s2 3p3 2 P1/2 - 2 3p2 (1 D )3d 2P ° and Fe XII 201.76 A 3s 1/2 ) 2 3p3 2 P 2 3p2 (1 D )3d 2 S (3s 3/2 - 3s 1/2 ) lines. Since the ° line is not observed in the experiAr XIII 205.80 A mental spectrum, an upper limit for the intensity of ° Ar XIII 201.72 A can be estimated from the branching ° ratio. The intensity of Ar XIII 205.80 A should be a ° factor of 1.33 higher than that of Ar XIII 201.71 A (CHIANTI), which, given the calibration factor, corresponds to the same intensity, i.e., IAr XIII (205.80) ° IAr XIII (201.71). The intensity of 205.80 A cannot exceed 200 and, thus, the contribution from ° ° Ar XIII 201.71 A to the experimental 201.72 A line does not exceed 10%. Ar XIV (log T = 6.5). 2s2 2p 2 P - 2s2p2 2 P . ° Jlow - Jup , A Note 1/2 - 1/2 183.45 +b 3/2 - 1/2 191.40 -u 1/2 - 3/2 180.29 - 3/2 - 3/2 187.97 +b
ASTRONOMY LETTERS Vol. 34 No. 1 2008

° The Ca XIV 183.46 A line is blended with the ° (2s2 2p 2 P1/2 - 2s2p2 2 P1/2 ) line. Ar XIV 183.45 A However, as follows from the discussion of the Ar XIV identification, the line is determined mainly by the ° Ca XIV 183.46 A emission. ° The Ca XIV 186.61 A line is blended with the ° Fe VIII 186.60 A (3p6 3d 2 D3/2 - 3p5 3d2 (3 F ) 2 F5/2 )


44

SHESTOV et al.

° line. The intensity of Ca XIV 186.61 A is estimated ° and 193.87 A lines to be 710 ± 60. ° from the 183.46 A Ca XV (log T = 6.6). 2s2 2p
23

Fe VIII (log T = 5.6). 3p6 3d 2 D - 3p5 3d2 (1 S ) 2 P . ° Jlow - Jup , A Note 3/2 - 1/2 192.01 +b 3/2 - 3/2 196.65 +b 5/2 - 3/2 197.36 +b ° The 197.36 A line is blended with the Fe XIII ° line. 197.43 A ° The Fe VIII 196.65 A line is blended with the ° and Fe XIII 196.64 A lines. ° Fe XII 196.54 A ° The Fe VIII 192.01 A line is blended with the ° line. strong Fe XXIV 192.03 A Let us estimate the intensities of these lines ° based on the Fe VIII 187.24 A line, which is not observed in the spectrum. The line ratios are sensitive to density and temperature; modeling for various conditions in the emitting plasma shows that I (197.36)/I (187.24) 3.0, I (196.65)/I (187.24) 0.3, and I (192.01)/I (187.24) 0.6. Thus, the lines of this term do not contribute noticeably to the corresponding spectral lines and are not given in Table 1. 3p6 3d 2 D - 3p5 3d2 (3 F ) 2 F . ° Jlow - Jup , A Note 3/2 - 5/2 186.60 +b 5/2 - 5/2 187.24 - 5/2 - 7/2 185.21 +b ° The Fe VIII 186.60 A line is blended with the ° (2s2 2p3 4 S3/2 - 2s2p4 4 P3/2 ) line. Ca XIV 186.61 A ° The intensity of the 186.60 A line can be estimated from the total intensity of the two lines and the inten° sity of Ca XIV 186.61 A: I (Fe186.60) = Itotal (186.60) - I (Ca186.61) = (1044 ± 81) - (710 ± 60) = 334 ± 125. ° The Fe VIII 187.24 A line is not observed. Let us ° estimate its intensity via Fe VIII 186.60 A based on the branching ratio (CHIANTI) and disregarding the ° Fe VIII 186.60 A blending: IFe
VIII

P - 2s2p

33

P.

° Jlow - Jup , A Note 1-0 0-1 1-1 2-1 1-2 2-2 177.26 +b 171.60 -l - -l +

176.93 +b 182.87 176.02 181.90

° The Ca XV 176.93 A line is observed in the experimental spectrum, but it is blended with an unknown line. Let us estimate its intensity based on ° ° the Ca XV 182.87 A line. The 182.87 A line is not observed separately in the experimental spectrum. Based on a branching ratio of 1.72 from CHIANTI and an upper error threshold of 20, we obtain ICa
XV

(176.93) 1.72ICa XV (182.87) = 1.72 2 â 2 â 20 = 173.

(8)

At the same time, the experimental line intensity is I (176.93) = 2627 ± 162. This discrepancy can be explained by the blending with an unknown line. ° The Ca XV 177.26 A line is blended with the ° line. Indeed, the intensity of strong Fe X 177.24 A ° Ca XV 177.24 A accounts for 0.3-0.5 of the intensity ° of Ca XV 181.90 A. Since the intensity of the latter ° is 170, the intensity of the 177.24 A line does not ° exceed 110, and the contribution to the 177.24 A line ° line is does not exceed 2%. Therefore, the 177.24 A ° identified in Table 1 as Fe X 177.24 A. Ca XVII (log T = 6.8). 2s ° 192.82 A.
21

S0 - 2s2p 1 P1 =

° The Ca XVII 192.82 A line is blended with the ° (3s2 3p4 3 P1 - 3s2 3p3 (2 D)3d 3 P2 ) Fe XI 192.83 A ° line. The intensity of Ca XVII 192.82 A was estimated ° from the intensity of Fe XI 192.83 A, see the expression from William et al. (2001): I
Ca XVII

(187.24) = 0.046IFe 48 ± 4.

VIII

(186.60)

(10)

= Itotal (192.82 + 192.83)

(9)

- IFe XI (192.83) = 4851 ± 186.

This corresponds to the peak intensity at the noise level 1 IFe VIII (187.24) (11) AFe VIII (187.24) 2.51 â 2
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45

= 10 ± 1. ° The Fe VIII 185.21 A line is blended with the ° Ni XVI 185.23 A (3s2 3p 2 P1/2 - 3s2 3d 2 D3/2 ) line. An estimate based on the intensity of the ° Fe VIII 186.60 A line shows that I (185.21) 1.5I (186.60) = 500 ± 188. Fe X (log T = 6.0). 3s2 3p5 2 P - 3s2 3p4 (3 P )3d 2 P . ° Jlow - Jup , A Note 1/2 - 1/2 180.41 +b 3/2 - 1/2 175.44 3/2 - 3/2 177.24 -l 1/2 - 3/2 182.31 -u +
600 Intensity, arb. units

400

200 17 31 0 181.5 182.0 182.5 Wavelengths, å 183.0

° The Fe X 180.41 A line is blended with the ° Fe XI 180.41 A (3s2 3p4 3 P2 - 3s2 3p3 (4 S )3d 3 D3 ) ° line. Estimating the intensity of Fe X 180.41 A based ° on Fe X 177.24 A yields I (180.41) < 0.4I (177.24) = 2700. ° The Fe X 182.31 A line is not observed, because ° it lies near the strong Fe XI 182.17 A (3s2 3p4 3 P1 - 2 3p3 (4 S )3d 3 D ) line. Estimating the intensity of 3s 2 ° ° Fe X 182.31 A based on the intensity of Fe X 177.24 A and the branching ratio (CHIANTI) yields I
Fe X

° Fig. 9. Fe X 182.31 A line in the active region of October 15, 2001, at 23 : 53; the exposure time is 150 s. The vertical bars mark the observed lines; the fractional part of the wavelength is indicated.

° line is blended with the Fe XII 190.07 A 2 3p3 4 S 2 3p2 (1 S ) â 3d 2 D (3s 3/2 - 3s 3/2 ) line. The ° was estimated from the intensity of Fe XII 190.07 A ° intensity of Fe X 184.54 A and the branching ratio (CHIANTI): IFe X (190.04) = 0.31IFe X (184.54) = 0.31(2737 ± 107) = 848 ± 33, I
Fe XII

(13)

(182.31) = 0.025IFe X (177.24) = 0.025(6903 ± 234) = 173 ± 6,

(12)

° while the intensity of the nearby Fe XI 182.17 A line ° line is I (182.17) = 3219 ± 112. The Fe X 182.31 A was included in Table 1, because its parameters in the spectra of active regions recorded with an exposure time of 150 s can be determined with a good accuracy (see Fig. 9). 3s2 3p5 2 P - 3s2 3p4 (1 D)3d 2 S ° Jlow - Jup , A Note 1/2 - 1/2 190.04 +b 3/2 - 1/2 184.54 +

(190.07) = Itotal (190.04 + 0.07) - IFe X (190.04) = 585 ± 96.
43

(14)

Fe XI (log T = 6.1). 3s2 3p

P - 3s2 3p3 (4 S )3d 3 D.

° Jlow - Jup , A Note 0-1 1-1 2-1 1-2 2-2 2-3 181.14 + - +

180.60 +u 176.56 182.17

178.06 +b 180.41 +b

The intensity ratio I (177.24)/I (184.54) is only slightly sensitive to density (see Brickhouse et al. 1995) and is fairly close to its theoretical value (see ° Table 2). Consequently, the Fe X 184.54 A line is unblended. The experimental intensity ratio I (184.54)/ I (190.04) (Table 2) is more than 27 smaller than the ° experimental one, suggesting that the Fe X 190.04 A
ASTRONOMY LETTERS Vol. 34 No. 1 2008

° The Fe XI 176.56 A line is not observed in the experimental spectrum. Estimating its intensity based ° on the 181.14 A line intensity and the branching ratio (CHIANTI) yields IFe XI (176.56) = 0.033IFe XI (181.14) = 0.033(822 ± 84) = 27 ± 3, (15)


46

SHESTOV et al.

2000 Flare Active region Intensity, arb. units 1500 .03 .39 .82 .52

3s2 3p

43

P - 3s2 3p3 (2 D)3d 3 P . ° Jlow - Jup , A Note 1-0 0-1 1-1 2-1 1-2 2-2 182.48 -u 189.72 + -

1000

189.13 +u 184.70

500

192.83 +b 188.23 +b

0 192 193 Wavelength, å 194

° Fig. 10. Comparison of the Fe XXIV 192.03 A line in an active region with that in a flare. The vertical bars mark the observed lines; the fractional part of the wavelength is indicated.

which corresponds to the peak intensity 1 AFe XI (176.56) IFe XI (176.56) = 5 ± 1. 2 2 (16) We see that the peak intensity is below the noise level. ° The Fe XI 180.60 A line is located in the wing ° of the strong Fe XI 180.41 A line. As a result, the ° cannot be determined. Let intensity of Fe XI 180.60 A ° us estimate the intensity of Fe XI 180.60 A based on ° and the branching the intensity of Fe XI 181.14 A ratio: (17) IFe XI (180.60) = 0.71IFe XI (181.14) = 0.71(822 ± 84) = 584 ± 60. At the same time, the intensity of the nearby line is I (180.41) = 14 415 ± 1255. ° The Fe XI 180.41 A line is blended with the ° Fe X 180.41 A (3s2 3p5 2 P1/2 - 3s2 3p4 (3 P )3d 2 P1/2 ) line. However, as follows from the discussion to ° ° Fe X 180.41 A, the contribution from Fe XI 180.41 A reaches 80%. The experimental intensity ratio I (178.06)/ I (182.17) differs significantly from the theoretical one ° (Table 2), suggesting that the Fe XI 178.06 A line is blended with an unknown line. ° 3s2 3p4 1 D2 - 3s2 3p3 (2 D)3d 1 F3 = 179.76 A. ° The 179.76 A line is observed. 2 3p4 1 D - 3s2 3p3 (2 D )3d 1 D = 184.80 A. ° 3s 2 2 ° The 184.80 A line is observed.

° The Fe XI 188.23 A line is blended with the ° (3s2 3p4 3 P2 - 3s2 3p3 (2 D)3d 1 P1 ) Fe XI 188.30 A ° and Fe XII 188.19 A (3s2 3p3 2 P1/2 - 3s2 3p2 (3 P )3d 2D lines. T he line intensity ratio 3/2 ) I (188.23)/I (188.30) is sensitive to density and lies within the range 2.0-2.7, reaching its maximum at log ne = 8 cm-3 and its minimum at log ne = 11 cm-3 . The Fe XII and Fe XI line intensity ratio is sensitive to many parameters (the spatial distributions of temperature and density in the emitting volume); our calculations based on various densities (log ne = 8-11 cm-3 ) and various model distributions of differential emission measure yield a line intensity ratio I (Fe XI)/I (Fe XII) = 10-200, dropping below 30 only at log ne > 10 cm-3 . Hence, the intensities of the blend components can be estimated as I (188.23) = 0.69Itotal 6570, I (188.30) = 0.29Itotal 2380,and I (188.19) = 0.02Itotal 165. The experimental intensity ratio I (192.83)/ I (188.23) (Table 2) differs from the theoretical one by 13 for active regions and even more significantly ° for a flare. This suggests that the Fe XI 192.83 A ° line is blended with the "hot" Ca XVII 192.82 A (2s2 1 S0 - 2s2p 1 P1 ) line; the temperature for the maximum Ca XVII abundance is log T = 6.8, while log T = 6.1 for Fe XI (CHIANTI). The intensity ° of Fe XI 192.83 A is roughly estimated from the ° intensity of Fe XI 188.23 A (without blending) and the branching ratio (Landi et al. 2006) to be (18) IFe XI (192.83) = 0.21IFe XI (188.23) = 0.21(8202 ± 245) = 1722 ± 51. The experimental intensity ratio I (189.13)/ I (189.72) (Table 2) matches its theoretical value, within the measurement error limits. However, the ° intensity of Fe XI 189.13 A cannot be determined accurately for the September 16, 2001 flare spectrum, ° because the unidentified 189.03 A line is unresolvable. These two lines are attributed in Table 1 to the ° 189.06 A line.
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° The Fe XI 184.70 A line is not observed. Let us estimate its intensity based on the intensity of ° Fe XI 189.72 A and the branching ratio (Landi et al. 2006): IFe XI (184.70) = 0.084IFe XI (189.72) = 0.084(193 ± 47) = 16 ± 4, (19)

° Fe XI 202.63 A (3s2 3p4 1 D2 - 3s2 3p3 (2 D)3d 3 P2 ) lines. Fe XII (log T = 6.2). 3s2 3p3 4 S - 3s2 3p2 (1 S )3d 2 D. ° Jlow - Jup , A Note 3/2 - 3/2 190.07 +b 3/2 - 5/2 186.24 +

which gives the peak intensity at the noise level 1 AFe XI (184.70) IFe XI (184.70) = 3 ± 1. 2 2 (20) 3s2 3p
43

P - 3s2 3p3 (2 D)3d 1 P . ° Jlow - Jup , A Note 0-1 1-1 2-1 193.52 +b 192.90 -

188.30 +b

° The Fe XI 193.52 A line is blended with the ° Fe XII 193.52 A(3s2 3p3 4 S3/2 - 3s2 3p2 (3 P )3d 4 P3/2 ) line. ° The Fe XI 188.30 A line is blended with the ° Fe XI 188.23 A (3s2 3p4 3 P2 - 3s2 3p3 (2 D)3d 3 P2 ) 2P ° and Fe XII 188.19 A (3s2 3p3 1/2 - 2 3p2 (3 P )3d 2 D -3s 3/2 ) lines. See the discussion to ° line. the Fe XI 188.23 A ° 3s2 3p4 1 S0 - 3s2 3p3 (2 P )3d 1 P1 = 184.41A. ° The 184.41 A line is observed in the experimental spectrum. 3s2 3p4 1 D - 3s2 3p3 (2 D)3d 3 P . ° Jlow - Jup , A Note 2-1 2-2 The Fe XI S VIII 198.55 Fe XII 195.58 3d 2 P3/2 ) lines. The Fe XI S VIII 202.61 Fe XI 202.71 lines. 3s2 3p4 1 D2 198.55 +b 202.63 +b

° The intensity of the Fe XII 186.24 A line is 112 ± ° line is blended with the 40. The Fe XII 190.07 A ° Fe X 190.04 A (3s2 3p5 2 P1/2 - 3s2 3p4 (1 D)3d 2 S1/2 ) line. The Fe XII line intensity ratio I (190.07)/I (186.24) = 1.1-1.9 is sensitive to density, reaching its maximum at log ne = 8 cm-3 and its minimum at log ne = 11 cm-3 . Consequently, the ° intensity of Fe XII 190.07 A is 185 ± 100. However, ° estimating the intensity of this line via Fe X 190.04 A (see the discussion) using Eq. (14) yields IFe XII (190.07) = 585 ± 96. 3s2 3p3 2 P - 3s2 3p2 (3 P )3d 2 D. ° Jlow - Jup , A Note 1/2 - 3/2 188.19 +b 3/2 - 3/2 190.49 - 3/2 - 5/2 191.05 +b ° The Fe XII 188.19 A line is blended with the ° Fe XI 188.23 A (3s2 3p4 3 P2 - 3s2 3p3 (2 D)3d 3 P2 ) ° and Fe XI 188.30 A (3s2 3p4 3 P2 - 3s2 3p3 (2 D) â 1 P ) lines. See the discussion to the Fe XI 188.23 A ° 3d 1 line. ° The Fe XII 191.05 A line is blended with the ° 2s2 2p4 3 P0 - 2s2p5 3 P1 ) line. Ar XI 190.98 A( 3s2 3p3 4 S - 3s2 3p2 (3 P )3d 4 P . ° Jlow - Jup , A Note 3/2 - 1/2 192.39 + 3/2 - 3/2 193.52 +b 3/2 - 5/2 195.12 +b ° The Fe XII 193.52 A line is blended with the ° Fe XI 193.52 A (3s2 3p4 3 P0 - 3s2 3p3 (2 D)3d 1 P1 ) ° line. The Fe XII 195.12 A line is blended with the ° (3s2 3p3 2 D3/2 - 3s2 3p2 (1 D) â Fe XII 195.18 A â3d 2 D3/2 ) line. The experimental intensity ratios I (192.39)/I (193.52), I (192.39)/I (195.12), and I (193.52)/I (195.12) are close to the theoretical ones

° 198.55 A line is blended with the ° (2s2 2p5 2 P3/2 - 2s2p6 2 S1/2 ) and A ° A (3s2 3p3 2 P1/2 - 3s2 3p2 (1 D) â

° 202.63 A line is blended with the ° A (2s2 2p5 2 P1/2 - 2s2p6 2 S1/2 ) and ° A (3s2 3p4 1 D2 - 3s2 3p3 (2 D)3d 1 P1 )

° - 3s2 3p3 (2 D)3d 1 P1 = 202.71 A. ° The Fe XI 202.71 A line is blended with the ° S VIII 202.61 A (2s2 2p5 2 P1/2 - 2s2p6 2 S1/2 ) and
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SHESTOV et al.

° (Table 2), suggesting that the Fe XII 193.52 A and ° lines are weakly blended. 195.12 A 3s2 3p3 2 D - 3s2 3p2 (1 D)3d 2 D. ° Jlow - Jup , A Note 3/2 - 3/2 195.18 +b 5/2 - 3/2 196.92 3/2 - 5/2 194.90 - -

5/2 - 5/2 196.64 +b ° The Fe XII 195.18 A line is blended with the ° Fe XII 195.12 A(3s2 3p3 4 S3/2 - 3s2 3p2 (3 P )3d 4 P5/2 ) line; as follows from Table 2, the contribution from ° Fe XII 195.18 A to the total intensity is minor. ° The Fe XII 196.64 A line is blended with the ° 3s2 3p2 1 D2 - 3s2 3p3d 1 F3 ) line. Fe XIII 196.54 A( 3s2 3p
32

not exceed 10% (see the discussion of the correspond° ing line). Thus, the intensity of Fe XII 201.74 A can be estimated as 1300. ° The intensity of the 204.38 A line is ° 0.008I (201.74) = 20, when the Fe XII 201.74 A ° line line blending is disregarded. The Fe 204.38 A is not observed on the spectroheliogram. ° The Fe XII 198.58 A line is blended with the ° (3s2 3p4 1 D2 - 3s2 3p3 (2 D)3d 3 P1 ) Fe XI 198.55 A ° and S VIII 198.55 A (2s2 2p5 2 P3/2 - 2s2p6 2 S1/2 ) lines. ° The Fe XII 201.14 A line is blended with the ° 3s2 3p2 3 P1 - 3s2 3p3d 3 D1 ) line. Fe XIII 201.13 A( 3S 2 3P 3 2 P - 3s2 3p2 (1 D)3d 2 S . ° Jlow - Jup , A Note 1/2 - 1/2 199.19 3/2 - 1/2 201.76 - +

D - 3s2 3p2 (3 P )3d 2 F . ° Jlow - Jup , A Note 3/2 - 5/2 186.85 +b 5/2 - 5/2 188.45 +u 5/2 - 7/2 186.88 +b

° ° The Fe XII 186.85 A and Fe XII 186.88 A lines are ° unresolvable and are blended with the S XI 186.84 A (2s2 2p2 3 P0 - 2s2p3 3 S1 ) line. However, the total ° contribution from S XI 186.84 Ais 3%. ° The spectroheliogram exhibits the 188.50 A line with an intensity of 900 ± 200. The Fe XII line intensity ratio I (188.45)/I (186.85 + 186.88) is sensitive to density and lies within the range 0.01-0.02. ° The intensity of Fe XII 188.45 A estimated in this way will not exceed 100 and the identification of this line remains questionable. 3s2 3p3 2 P - 3s2 3p2 (1 D)3d 2 P . ° Jlow - Jup , A Note 1/2 - 1/2 201.74 +b 3/2 - 1/2 204.38 - 1/2 - 3/2 198.58 +b 3/2 - 3/2 201.14 +b ° The 201.74 A line is blended with the Fe XII ° and Ar XIII 201.71 A lines. The Fe XII line ° 201.76 A intensity ratio is I (201.74)/I (201.76) = 1.1-2.5 and ° the contribution from the Ar XIII 201.71 A line does

° The Fe XII 201.76 A lineisblended with theFe XII ° 201.74 A (3s2 3p3 2 P1/2 - 3s2 3p2 (1 D) â 3d 2 P1/2 ) line. The intensity ratio I (201.76)/I (201.74) for these lines is weakly sensitive to temperature and density and lies within the range 0.4-0.9. The intensity of ° Fe XII 199.19 A calculated via the branching ratio ° should account for 0.006 of the Fe XII 201.76 A line ° line intensity and be 15, when the Fe XII 201.76 A blending is disregarded. Fe XIII (log T = 6.2). 3s2 3p2 1 D2 - 3s2 3p3d 1 F3 ° = 196.54 A. ° The 196.54 A line is blended with the Fe XII ° 195.64 A(3s2 3p3 2 D5/2 - 3s2 3p2 (1 D)3d 2 D5/2 ) line. The intensity ratio for these two lines is sensitive to both emitting plasma temperature and density. Modeling based on the CHIANTI package for various combinations of temperature and density shows that the ratio lies within the range 0.3­3.0. 3s2 3p2 3 P - 3s2 3p3d 3 D. ° Jlow - Jup , A Note 0-1 1-1 2-1 1-2 2-2 2-3 197.43 +b 201.13 +b 204.95 +b 200.02 +

203.80 +b 203.83 +b
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° The Fe XIII 197.43 A line is blended with the ° Fe VIII 197.36 A (3p6 3d 2 D5/2 - 3p5 3d2 (1 S ) 2 P3/2 ) line. ° The Fe XIII 201.13 A line is blended with the ° 3s2 3p3 2 P3/2 - 3s2 3p2 (1 D)3d 2 P3/2 ) Fe XII 201.14 A( line. The experimental intensity ratio I (197.43)/ I (201.13) (Table 2) is smaller than the theoretical ° one by 15 , which confirms the Fe XIII 201.13 A line blending. The experimental intensity ratios I (197.43)/ I (204.95) and I (201.13)/I (204.95) (Table 2) are smaller than the theoretical ones by 47 and 17 , respectively, which can be explained by the blending ° of Fe XIII 204.95 A with an unknown line. ° ° The Fe XIII 203.80 A and Fe XIII 203.83 A lines are unresolvable. The intensity ratios I (200.02)/ I (204.26), I (200.02)/I (203.16), and I (203.80 + 203.83)/I (200.02) are weakly sensitive to density (Brickhouse et al. 1995; Landi 2002) and their experimental values (Table 2) are close to the ° theoretical ones. Consequently, the Fe XIII 200.02 A ° and line as well as the pair of the Fe XIII 203.80 A ° 203.83 A lines are unblended. 2 3p2 3 P - 3s2 3p3d 3 P . 3s ° Jlow - Jup , A Note 1-0 0-1 1-1 2-1 1-2 2-2 203.16 202.04 205.92 209.92 209.62 213.77 + + - -l -l -l

Given the calibration factor attributable to the spectral sensitivity of the instrument, this corresponds to the peak intensity below the noise threshold: AFe
XIII

0.18 (205.92) IFe 3 2 = 2 ± 0.2.

XII

(204.74)

(22)

3s2 3p

23

P - 3s2 3p3d 1 D. ° Jlow - Jup , A Note 1-2 2-2 204.26 208.20 + -l

The intensity ratio I (200.02)/I (204.26) is weakly sensitive to density (Brickhouse et al. 1995; Landi 2002) and its experimental value (Table 2) is close to the theoretical one. Consequently, the ° Fe XIII 204.26 A line is unblended. Fe XVII (log T = 6.9). 2p5 3s 1 P1 - 2p5 3p 1 S0 = ° 204.65 A. ° The Fe XVII 204.65 A line is observed. Fe XXI (log T = 7.1). 2s2 2p
21

D - 2s2p

33

D.

° Jlow - Jup , A Note 2-1 2-2 2-3 187.93 +b 187.70 - 178.90 -u

The intensity ratio I (200.02)/I (203.16) is weakly ° The Fe XXI 187.93 A line is blended with the sensitive to density (Brickhouse et al. 1995; Lan- Ar XIV 187.97 A(2s2 2p 2 P - 2s2p2 2 P ) line. ° 3/2 3/2 di 2002) and its experimental value (Table 2) is close to the theoretical one. Consequently, the Fe XXIV (log T = 7.2). 1s2 2s 2 S - 1s2 2p 2 P . ° Fe XIII 203.16 A line is unblended. ° The Fe XIII 202.04 A line is observed. The line in° Jlow - Jup , A Note tensity ratios I (197.43)/I (202.04), I (200.02)/ I (202.04), I (203.16)/I (202.04), I (204.26)/I (202.04), 1/2 - 1/2 255.11 -l and I (203.80 + .82)/I (202.04) are in good agreement 1/2 - 3/2 192.03 + with the theory (Landi et al. 2006). ° The Fe XIII 205.92 A line is not observed in the experimental spectrum. Its intensity based on ° The identification of Fe XXIV 192.03 A is con° Fe XIII 202.04 A and the branching ratio (CHIANTI) firmed by our comparison of the intensities of this line is in an active region and in a flare. We see from Fig. 10 (21) that the Fe XXIV 192.03 A line has a statistically IFe XIII (205.92) = 0.002IFe XIII (202.04) ° 82 ± 7. significant intensity only in the flare spectrum.
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50

SHESTOV et al.

Ni XV (log T = 6.4). 3s2 3p

23

P - 3s2 3p3d 3 D.

Ni XVI (log T = 6.4). 3s2 3p 2 P - 3s2 3d 2 D. ° Jlow - Jup , A Note 1/2 - 3/2 185.23 +b 3/2 - 3/2 195.28 - 3/2 - 5/2 194.02 +u ° The Ni XVI 185.23 A line is blended with the ° (3p6 3d 2 D5/2 - 3p5 3d2 (3 F ) 2 F7/2 ) Fe VIII 185.21 A line. ° The spectrum exhibits the 193.99 A line that can ° The Fe VIII 193.97 A ° be identified as Ni XVI 194.02 A. line is another possible candidate that can contribute ° to the 193.99 A line. However, our estimate obtained ° via Fe VIII 185.21 A for various densities and when the blending of the latter is disregarded shows that ° the intensity of Fe VIII 193.97 A is 50. Thus, ° the experimental 193.99 A line can be identified as ° Ni XVI 194.02 A. CONCLUSIONS Based on data from the RES spectroheliograph of the SPIRIT experiment onboard CORONAS-F, we compiled a catalog of 65 spectral lines in the range ° 176­207 A, the overwhelming majority of which belong to the Fe X­Fe XIII ions. The spectrum of the M5.6 (GOES) flare of September 16, 2001, recorded by the spectroheliograph at 03 : 59 UT was taken as the basis. The accuracy of determining the wave° lengths is 40 mA and the calibration accuracy of the relative intensities is 30%. We suggested identifications for 51 lines and estimated the degree of blending. To check the identifications, we compared density-insensitive line intensity ratios with their calculated values. We also used the spectra for the active regions NOAA 9650, 9653, 9655, 9659, 9660, 9665, 9695, 9697, 9698, 9715, 9716, and 9725. Two of the 65 lines are observed only in the flare. A total of 165 lines whose formation temperature spans the range 5 â 104 -2 â 107 K are observed in ° ° the EUV 176­207 A and 280­330 A channels of the RES spectroheliograph. The presence of many lines of individual multiply charged ions and extensive experimental information (more than ten thousand EUV spectroheliograms were recorded over the period of CORONAS-F operation; about 15 X (GOES) flares at various phases of their evolution were observed) provide wide scope for diagnosing the various plasma structures in the solar corona as they develop.
ASTRONOMY LETTERS Vol. 34 No. 1 2008

° Jlow - Jup , A Note 0-1 1-1 2-1 1-2 2-2 2-3 171.60 176.11 180.06 174.99 178.89 -l + - -l -

179.27 +b

° The Ni XV 179.27 A line is blended with the ° 2s2 2p4 1 D2 - 2s2p5 1 P1 ) line. SIX 179.28 A( 3s2 3p
23

P - 3s2 3p3d 3 P . ° Jlow - Jup , A Note 1-0 0-1 1-1 2-1 1-2 2-2 173.85 176.74 181.53 185.73 184.88 189.24 -l + - - - -

° ° The Ni XV 181.53 A and 185.73 A lines are not observed. Let us estimate their intensities based on ° the Ni XV 176.74 A line intensity and the branching ratios (CHIANTI): INi
XV

(181.53) = 0.035INi

XV

(176.74)

(23)

= 0.035(823 ± 128) = 29 ± 4, INi
XV

(185.73) = 0.095INi XV (176.74) = 0.095(823 ± 128) = 78 ± 12. 1 INi 2.51 â 2 = 6 ± 1, 1 INi 2.51 â 2 = 16 ± 2.

(24)

These correspond to the peak intensities ANi
XV

(181.53)

XV

(181.53)

(25)

ANi

XV

(185.73)

XV

(185.73)

(26)

The peak line intensities probably correspond to the noise level.


SOLAR EUV SPECTRA

51

This is the second paper of the series (the first paper by Beigman et al. (2005) gives a catalog of ° spectral lines in the range 280­330 A) devoted to flare plasma diagnostics based on data from the RES EUV spectroheliograph onboard the CORONAS-F satellite. At present, we are determining the physical conditions in the emission source based on the spectra obtained, in particular, the distribution of differential emission measure in temperature; we plan to publish our results in the third paper of this series. ACKNOWLEDGMENTS We wish to thank G. Del Zanna for help. This work was supported by the Russian Foundation for Basic Research (project nos. 05-02-16658, 06-02-16298, 05-02-17415), Programs nos. 10 and 16 of the Russian Academy of Sciences, and Program no. 16 of the Presidium of the Russian Academy of Sciences. REFERENCES
1. I. L. Beigman, S. A. Bozhenkov, I. A. Zhitnik, et al., Pis'ma Astron. Zh. 31, 39 (2005) [Astron. Lett. 31,37 (2005)]. 2. S. Brandt, Data Analysis. Statistical and Computational Methods for Scientists and Engineers (Springer, Berlin, 1998). 3. N. S. Brickhouse, J. C. Raymond, and B. W. Smith, Astrophys. J., Suppl Ser. 97, 551 (1995). 4. D. H. Brooks, G. A. Fishbacher, A. Fludra, et al., Astron. Astrophys. 347, 277 (1999). 5. J. W. Brosius, J. M. Davila, and R. J. Thomas, Astrophys. J., Supp. Ser. 119, 225 (1998).

6. J. W. Brosius, R. J. Thomas, and J. M. Davila), Astrophys. J. 543, 1016 (2000). 7. K. P. Dere, Astrophys. J. 221, 1062 (1978). 8. S. V. Kuzin, I. A. Zhitnik, A. A. Pertsov, et al.), J. Xray Sci. Technol. 7, 233 (1997). 9. E. Landi, Astron. Astrophys. 382, 1106 (2002). 10. E. Landi, G. Del Zanna, P.R. Young, et al., Astrophys. J., Suppl. Ser. 162, 261 (2006). 11. J. Lang, H. E. Mason, and R. W. McWhirter, Sol. Phys. 129, 31 (1990). 12. R. J. Thomas and W. M. Neupert, Astrophys. J. 91, 461 (1994). 13. A. M. Urnov, S. V. Shestov, S. A. Bogachev, et al., Pis'ma Astron. Zh. 33, 446 (2007) [Astron. Lett. 33, 396 (2007)]. 14. H. W. William, S. A. Teukolsky, and B. P. Flannery, Numerical Recipes in Fortran 77. The Art if Scientific Computing (Cambridge Univ. Press, Cambridge, 2001). 15. I. A. Zhitnik, O. I. Bougaenko, J.-P. Delaboudiniere, et al., Solar Variability: From Core to Outer Frontiers, Praha, 2002, Ed. by A. Wilson, ESA SP-506, Vol. 2, p. 915. 16. I. A. Zhitnik, S. V. Kuzin, V. N. Oraevsky, et al., Pis'ma Astron. Zh. 24, 943 (1998) [Astron. Lett. 24, 819 (1998)]. 17. I. A. Zhitnik, S. V. Kuzin, I. I. Sobel'man, Astron. Vestn. 39, 495 (2005) [Sol. Syst. Res. 39, 442 (2005)]. 18. I. A. Zhitnik, S. V. Kuzin, A. M. Urnov, et al., Mon. Not. R. Astron. Soc. 308, 228 (1999). 19. I. A. Zhitnik, S. V. Kuzin, A. M. Urnov, et al., Astron. Vestn. 40, 299 (2006) [Sol. Syst. Res. 40, 272 (2006)].

Translated by V. Astakhov

ASTRONOMY LETTERS

Vol. 34 No. 1 2008