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تسجيل مستخدم جديدThe diffuse interstellar band around 8620 {AA} I. Methods and application to the GIBS data set
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We developed a set of procedures to automatically detect and measure the DIB around 8620 {AA} (the Gaia DIB) for a wide range of temperatures. The DIB profile is fit with a Gaussian function. Specifically, the DIB feature is extracted from the spectra of late-type stars by subtracting the corresponding synthetic spectra. For early-type stars we applied a specific model based on the Gaussian process that needs no prior knowledge of the stellar parameters. The method was tested on $sim$5000 spectra from the Giraffe Inner Bulge Survey (GIBS). After validation, we obtained 4194 reasonable fitting results from the GIBS database. An EW versus $E(J,{-},K_{rm S})$ relation is derived as $E(J,{-},K_{rm S}),{=},1.875,({pm},0.152),{times},{rm EW},{-},0.011,({pm},0.048)$, according to $E(B,{-},V)/{rm EW},{=},2.721$, which is highly consistent with previous results toward similar sightlines. After a correction based on the VVV database for both EW and reddening, the coefficient derived from individual GIBS fields, $E(J,{-},K_{rm S})/{rm EW},{=},1.884,{pm},0.225$, is also in perfect agreement with literature values. Based on a subsample of 1015 stars toward the Galactic center within $-3^{circ},{<},b,{<},3^{circ}$ and $-6^{circ},{<},l,{<},3^{circ}$, we determined a rest-frame wavelength of the Gaia DIB as 8620.55 {AA}. A Gaussian profile is proved to be a proper and stable assumption for the Gaia DIB as no intrinsic asymmetry is found.
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