ULY_TGM | Define a TGM component |
ULY_TGM_EVAL | Evaluate a TGM model spectrum. |
ULY_TGM_EXTR | Compute a stellar template spectrum using TGM model |
ULY_TGM_INIT | Initialize a TGM component |
NAME: ULY_TGM PURPOSE: Define a TGM component USAGE: cmp = uly_tgm(MODEL_FILE=model_file, LSF=lsf_file, TG=t_guess, LG=l_guess, ZG=z_guess, TL=t_limits, LL=l_limits, ZL=z_limits, NAME=name, FIXPAR=fixpar, WL=lim_weight) KEYWORDS: MODEL_FILE Name of the FITS file containing the TGM model, by default use: /models/elodie32_flux_tgm.fits. LSF Name of the file containing a relative LSF to be injected in the template. TG [K] Guess value for the effective temperature (Teff), by default = 7000.0. If an array is passed, the analysis will be repeated starting from each element to find the optimal solution. LG [cm/s^2] Guess value for the surface gravity (Logg), by default = 2.0, it can also be given as an array to search the absolute minimum. ZG [dex] Guess value for the metallicity ([Fe/H]), by default = 0.0, it can also be given as an array to search the best minimum from the grid of guesses. TL [K], dblarr(2), limits for the Teff, by default = [3100.0,40000.0] see ULY_TGM_INIT. LL [dex],dblarr(2), limits for the Logg, by default = [-0.25, 5.9] see ULY_TGM_INIT. ZL [dex],dblarr(2), limits for the [Fe/H], by default = [-2.5, 1.0] see ULY_TGM_INIT. NAME A string, name of this component. By default a unique name is generated. FIXPAR An array used to fix some the atmosphere parameters, 0 means that the parameter is free, and 1 that it is fixed. A fixed parameter keeps its initial value. The parameters are specified in the following order: (Teff, Logg, [Fe/H]). WL Limits for the weight of the component [min_w, max_w]. The weight is in data units over component units. By default the weight is constrained to be positive. This constraint is applicable when multiple components are fitted (composite spectrum), it is ignored for a single component. /REBIN_COEF Computation mode, see the description below. DESCRIPTION: Return a TGM structure describing a TGM component that can be passed to program ULYSS. TGM stands for Temperature-Gravity-Metallicity: A TGM component specifies an interpolated stellar spectrum evaluated as a function of its atmospheric parameters (Teff, Logg and [Fe/H]) that was interpolated over a stellar spectral library (e.g. ELODIE 3.2) or over a grid of synthetic spectra. The file passed to ULY_TGM contains the coefficients of polynomials depending on the atmospheric parameter. Each wavelengh bin is represented separately, therefore the coefficients for each term of the development form a spectrum. Depending on the interpolator, there are 14 to about 25 terms. The first polynomial interpolator was presented in Prugniel and Soubiran 2001, A&A 369, 1048 for the ELODIE spectral libraries, it was updated in subsequent papers, in particular in Wu et al. 2011, A&A 525, 71. Interpolators for the MILES library were presented in Prugniel et al. 2011, A&A 531, 169, and Sharma et al. 2015, submitted. Other interpolators are available on the ULySS site. The interpolated spectra are evaluated using the interpolator, and then rebinned to the WCS of the spectrum to analyse. REBIN_COEF option: Rather than rebinning the interpolated spectrum, it first rebin the coefficients, and then compute the interpolated spectrum. This option is slightly less precise (because of the spline interpolation of the several coefficients), but is in some cases faster. This is the case when (i) a series of several spectra are fitted with the same CMP, and (ii) when the spectrum to analyse has a sampling much coarser than the interpolator. (Note that the impact on the precision of the interpolated spectrum is generally fully acceptable; it was the only available option before the release 1.3 of ULySS.) OUTPUT: TGM cmp struct, for detailed explanation please check uly_fit.pro REQUIRED FUNCTION: ULY_CMP_NAME EXAMPLE: Fit a CFLIB star: cmp = uly_tgm() star = uly_root+'/data/cflib_114642.fits' ulyss, star, cmp, lmin=3900.0, lmax=6800.0, /PLOT HISTORY: Creation Yue WU 2008/06/18
(See pgm/uly_tgm.pro)
NAME: ULY_TGM_EVAL PURPOSE: Evaluate a TGM model spectrum. USAGE: array = uly_tgm_eval(eval_data, para) ARGUMENTS: EVAL_DATA: The interpolated stellar spectrum model coefficients, it contains three dimensions of data, specifying to warm, hot and cold stellar regions respectively, in fact, they are the coefficients of the evaluating polynomial function. PARA: Input 3 atmospheric parameters (log(Teff), Logg, [Fe/H]), they will be passed to ULY_TGM_MODEL_PARAM to compute out the parameters which will be applied to the polynomial function for evaluating the model spectrum at this given stellar atmospheric parameters (Teff, log g and [Fe/H]). DESCRIPTION: Evaluate a TGM model spectrum which is interpolated as a function of atmospheric parameters (effective temperature, surface gravity and [Fe/H]). Each wavelength point is evaluated by using polynomials. This function is automatically called by the minimization routines: ULY_FIT, ULY_FIT_LIN to evaluate a TGM model (see ULY_TGM). OUTPUT: Evaluated stellar model spectrum REQUIRED FUNCTION: ULY_TGM_MODEL_PARAM, compute the parameters AUTHOR: Yue WU, 2008/06/18
(See pgm/uly_tgm_eval.pro)
NAME: ULY_TGM_EXTR PURPOSE: Compute a stellar template spectrum using TGM model USAGE: model = uly_tgm_extr([<spectrum>], <pars>, MODEL_FILE=<file>) DESCRIPTION: Compute a 1D stellar template spectrum by using TGM model at a given Teff, Log g and [Fe/H]. Rebin it with the same sampling as <spectrum> and with a compatible grid. If the natural wavelength range of the model is wider than the one of <spectrum> the returned spectrum has exactly the same sampling as <spectrum> (same range and same step). If instead the wavelength range of the model is narrower, the output spectrum will be truncated with respect to <spectrum> but its wavelength bins will match bins of <spectrum>. Note that although the model may be rebinned, its resolution is not matched to that of <spectrum>. If <spectrum> is omitted, i. e. if only one argument is given, the returned spectrum has the original sampling of the model. ARGUMENT: <spectrum> filename or spectrum structure serving as a reference for the velscale. <pars> array of parameters([Teff,Logg,[Fe/H]) used to evaluate the template spectrum. KEYWORD: MODEL_FILE = <file> Filename of the model to use, by default: uly_root + '/models/elodie32_flux_tgm.fits' RETURNS: A 1D stellar spectrum as a spect structure, see ULY_SPECT_ALLOC EXAMPLE: To compute a template spectrum at a given atmosphere parameters according to uly_root+'/data/cflib_114642.fits's velscale. model = uly_tgm_extr(uly_root+'/data/cflib_114642.fits', $ [6400., 4., 0.]) HISTORY: Yue WU 2008/08/20
(See pgm/uly_tgm_extr.pro)
NAME: ULY_TGM_INIT PURPOSE: Initialize a TGM component USAGE: cmp_new = uly_tgm_init (cmp, WAVERANGE=lamrange, $ VELSCALE=velscale, QUIET=quiet) ARGUMENTS: CMP: Component defined by using ULY_TGM, please check it for more details. KEYWORDS: WAVERANGE: Wavelength range used when the model will be evaluated with ULY_TGM_EVAL. VELSCALE: Size of one pixel in km/s. Used when the model will be evaluated and log-rebinned with ULY_TGM_EVAL. QUIET: verbosity control DESCRIPTION: This initialization function is automatically executed by ULY_FIT_INIT when a component has been defined by using ULY_TGM. A TGM model component can generate a spectrum at given stellar atmospheric parameters (Teff,log g and [Fe/H]). The name of this function is recorded as a member of cmp.init_fun in the TGM component structure (see ULY_FIT for a complete description of the component structure). ULY_TGM_INIT consists in loading the basic TGM model coefficients from a FITS file whose name is saved in *cmp.init_data (by default /models/elodie32_flux_tgm.fits), and also loads in the cmp structure the WCS. NOTE ULY_INIT_TGM is also called by ULY_TGM_EXTR where we use the keywords SAMPLING, WAVERANGE, STEP, which are more general because they can make either lin- or log-sampled spectra. This more general approach may be used in ULY_FIT_INIT in the future, when we will implement fitting in other than log- (not however that it is not fully general, because uneven sampling would not be supported). HISTORY: Creation Yue WU 2008/06/18
(See pgm/uly_tgm_init.pro)
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Last modified: Wed Feb 24 10:42:30 2016. |