J/A+A/432/1063 Analysis of inner solar corona in Extreme-UV (Lanzafame+, 2005)
ADAS analysis of the differential emission measure structure of the inner solar corona. II. A study of the 'quiet Sun' inhomogeneities from SOHO CDS-NIS spectra. Lanzafame A.C., Brooks D.H., Lang J. <Astron. Astrophys. 432, 1063 (2005)> =2005A&A...432.1063L
ADC_Keywords: Sun ; Spectra, ultraviolet ; Atomic physics Keywords: Sun: atmosphere - Sun: corona - Sun: UV radiation - Sun: abundances - atomic data - techniques: spectroscopic Abstract: We present a study of the differential emission measure (DEM) of a `quiet Sun' area observed in the extreme ultraviolet at normal incidence by the Coronal Diagnostic Spectrometer (CDS) on the SOHO spacecraft. The data used for this work were taken using the NISATS observing sequence. This takes the full wavelength ranges from both the NIS channels (308-381Å and 513-633Å) with the 2 arcsec by 240 arcsec slit, which is the narrowest slit available, yielding the best spectral resolution. In this work we contrast the DEM from subregions of 2*80arcsec2 with that obtained from the mean spectrum of the whole raster (20*240arcsec2). We find that the DEM maintains essentially the same shape in the subregions, differing by a constant factor between 0.5 and 2 from the mean DEM, except in areas were the electron density is below 2*107cm-3 and downflow velocities of 50km/s are found in the transition region. Such areas are likely to contain plasma departing from ionisation equilibrium, violating the basic assumptions underlying the DEM method. The comparison between lines of Li-like and Be-like ions may provide further evidence of departure from ionisation equilibrium. We find also that line intensities tend to be lower where velocities of the order of 30km/s or higher are measured in transition region lines. The DEM analysis is also exploited to improve the line identification performed by Brooks et al. (1999A&A...347..277B) and to investigate possible elemental abundance variations from region to region. We find that the plasma has composition close to photospheric in all the subregions examined. Description: Comparison of the observed intensities with those derived from the DEM for the mean spectrum. Lines used for the integral inversion are indicated with "i". Those compared with observations in the forward sense, i.e. by comparing the intensities predicted using the DEM with the observed intensities, are indicated with "f". File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table5.dat 110 180 Comparison of the observed intensities with those derived from the DEM for the mean spectrum.
See also: J/A+AS/113/237 : Ultraviolet Spectrum of the Sun (Samain, 1995) J/A+AS/131/431 : Accurate wavelengths in Sun spectrum (Allende Prieto+ 1998) Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1 A1 --- Blend Blend data (1) 2 A1 --- n_Blend [S] S when the record contains information about the blend 3- 4 A2 --- EL Element symbol (2) 6- 7 I2 --- Z1 ? Ion charge + 1 (2) 10- 16 F7.3 0.1nm lambda ? Adopted laboratory wavelength (2) 18 A1 --- r_lambda Reference for lambda (3) 21- 30 A10 --- Conf1 Lower level electronic configuration (2) 32- 37 A6 --- Term1 Lower level term (2) 38 A1 --- --- [-] 40- 49 A10 --- Conf2 Upper level electronic configuration (2) 51- 55 A5 --- Term2 Upper level term (2) 58- 61 F4.2 [K] logT ? Temperature (log) of peak of line formation (2) 64- 65 A2 --- n_lambdaObs [2x ] For Si 11 303.326 only 66- 72 F7.3 0.1nm lambdaObs ? Observed wavelength 77- 81 F5.1 mW/m2/sr IntTh Theoretical intensity 85- 89 F5.1 mW/m2/sr IntObs ? Observed intensity 93- 97 F5.1 mW/m2/sr e_IntObs ? Observational uncertainty 101-106 E6.2 --- Chi2 ? Chisquare 110 A1 --- Note Note (4)
Note (1): A same letter identifies the lines of the blend. Note (2): For data of blended lines (S), these quantities are not reported Note (3): The source for the adopted wavelengths, lambda, is denoted as follows: E = Edlen, 1983, Phys. Scripta, 28, p. 51 and p. 48, 1984, Phys. Scripta, 30, 135, 1985, Phys. Scripta, 31, 345, 1985, Phys. Scripta, 32, p. 59 and p. 86. F = Fawcett, 1975, Atomic Data and Nuclear Data Tables, 16, 138. J = Jupen et al., 1993MNRAS..264..627. K = Kelly, 1987, J. Phys. Chem. Ref. Data 16, Supp. 1. M = Moore, 1993, in Tables of Spectra of Hydrogen, Carbon, Nitrogen and Oxygen Atoms and Ions, ed. J.W. Gallacher, CRC Series in Evaluated Data in Atomic Physics (CRC Press). N = Martin et al.. 1995, NIST Database for Atomic Spectroscopy, Version 1.0. O = Wiese, 1985, Spectroscopic Data for Iron, ORNL No. 6089/V4 (Oak Ridge National Laboratory). S = Shirai et al., 1990, J. Chem. Phys. Ref. Data, 19, 127. Note (4): Note has the following meaning: i = the line has been used for the integral inversion f = the line has been compared with observations in the forward sense, i.e. by comparing the intensities predicted using the DEM with the observed intensities.
Acknowledgements: Alessandro Lanzafame, alanzafame(at)ct.astro.it References: Lanzafame et al, Paper I 2002A&A...384..242L
(End) Alessandro Lanzafame [Catania Univ.], Patricia Vannier [CDS] 30-Nov-2004
|The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line|