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**Last modified: **Tue Jan 4 12:52:37 2011.

PROJECT: CHIANTI CHIANTI is an Atomic Database Package for Spectroscopic Diagnostics of Astrophysical Plasmas. It is a collaborative project involving the Naval Research Laboratory (USA), the University of Florence (Italy), the University of Cambridge and the Rutherford Appleton Laboratory (UK). NAME: INTEGRAL_CALC PURPOSE: To compute the atomic data integral for use in column or volume emission measure work. CATEGORY: Scientific analysis EXPLANATION: Defining G(T) = 0.83 * Fr(T) * N_j * A_ji / N_e where Fr(T) is the ionisation fraction (e.g., from Arnaud & Rothenflug), N_j the relative population of level j, A_ji the A-value for the j->i transition and N_e the electron density. The 0.83 is the ratio of hydrogen to free electrons, which is constant above around 10^4 K. This function is sharply-peaked at a temperature T_mem (the temperature of maximum emission, which can be different from the temperature of maximum ionisation, T_max) and so an oft-used approximation is to take G(T) constant in the range log T_mem - 0.15 to log T_mem + 0.15 and zero outside. The value of the constant, which we call C_lambda here, is then given by C_lambda = integral { G(T) dT } -------------------- T_mem * (10^0.15 - 10^-0.15) If EM(s) is the column emission measure, F the flux (erg cm-2 s-1) in a line lambda, Ab the abundance of the element and DE (erg) the energy for the transition, then: F = DE * Ab * C_lambda * EM(s) If we are dealing with intensities I (erg cm-2 s-1 sr-1) then: 4pi * I = DE * Ab * C_lambda * EM(s) This program extracts the ionisation balance and emissivities from the CHIANTI database and calculates C_lambda for all lines in the specified wavelength interval WRANGE by integrating over 0.02 dex temperature intervals. The C_lambda functions for all the lines in the selected wavelength range WRANGE are displayed as well as the temperature of maximum emission (T_mem), DE*C_lambda and 4pi/(DE*C_lambda). These latter two quantities are useful for the emission measure analysis. Any combination of the displayed lines can then be blended and the corresponding quantities for the blend will be displayed. The function Fr(T) * N_j * A_ji can also be plotted at this stage. CALLING SEQUENCE: INTEGRAL_CALC, IZ, ION, [WRANGE=WRANGE, /CHOOSE, DENS=DENS] EXAMPLES: INTEGRAL_CALC, 26, 13, WRANGE=[200,205], /CHOOSE INTEGRAL_CALC, 14, 10, WRANGE=[250,270], DENS=10. INPUTS: IZ: The atomic number of the ion ION: The spectroscopic number of the ion (e.g., 12 = XII) OPTIONAL INPUTS: DENS: The density at which the emissivities are calculated (default=10.) WRANGE: Wavelength range for which C_lambda functions are calculated. If not given, then the 10 strongest lines are printed. INDEX: Particular elements in the emissivity structure can be selected with INDEX. This allows integral_calc to be run 'silently'. The output is contained in the OUTSTR structure. If index is given as, e.g., [7,8], then the C_lambda functions for these two lines are summed and output. PATH: Directly specify the directory path where the Chianti data for the ion is found ABUND_FILE The name of a CHIANTI abundance file. This is used for calculating the proton to electron ratio. Default is !abund_file. IONEQ_FILE The name of a CHIANTI ion balance file. This is used for calculating the proton to electron ratio and evaluating the T_max of the ion. Default is !ioneq_file. RADTEMP The blackbody radiation field temperature (default 6000 K). RPHOT Distance from the centre of the star in stellar radius units. I.e., RPHOT=1 corresponds to the star's surface. (Default is infinity, i.e., no photoexcitation.) KEYWORDS: CHOOSE: Allow ion balance calculations to be selected manually (see choose_ioneq.pro routine). OPTIONAL OUTPUTS: OUTSTR: A structure with the following tags .tmem - the T_mem for the line(s) .dec - total( de * c_lambda ) .pidec - 4 * pi / total( de * c_lambda ) Only output when INDEX is specified. COMMON BLOCKS: None. CALLS: EMISS_CALC, CH_GET_FILE, READ_IONEQ, GET_IEQ HISTORY: Ver.1: PRY, 28-JUN-97. Ver.2: PRY, 7-OCT-97. Added TEMPI and GOFT, for plotting. Ver.3: PRY, 31-JUL-98. Added PATH. Ver.4: PRY, 6-APR-99. Added INDEX, OUTSTR. Removed TEMPI and GOFT (these can be got from the g_of_t routine). Ver.5: PRY, 9-Dec-01. Modified for v.4 of CHIANTI. V.6, 21-May-2002, Giulio Del Zanna (GDZ) generalized directory concatenation to work for Unix, Windows and VMS. V.7, 06-Aug-02 GDZ Changed the use of CHIANTI system variables. V.8, 6-Feb-2006, Peter Young Integration is now performed on d(logT) intervals, rather than dT intervals following problems identified by Luca Teriaca. VERSION : 8, 06-Feb-06

**(See em/integral_calc.pro)**