Fabry-Perot Absorption Line Spectroscopy of the Galactic Bar. II. Stellar Metallicities - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




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Abstract: We measure the Ca II 8542 line strength in 3360 stars along threelines-of-sight in the Galactic bar: l,b ~ +-5.0,-3.5 and Baade-s Window,using Fabry-Perot FP absorption line spectroscopy. This is the first attemptto show that reliable absorption line strengths can be measured using FPspectroscopy. The Ca II 8542 line is a good indicator of metallicity and itscalibration to Fe-H is determined for globular cluster red giants in previousinvestigations. We derive such a calibration for the bulge giants and use it toinfer metallicities for our full red clump sample 2488 stars at all threelines-of-sight. We present the stellar metallicity distributions along themajor axis of the bar. We find the mean Fe-H = -0.09 +- 0.04 dex in Baade-sWindow, and find the distribution in this field to agree well with previousworks. We find gradients in the mean metallicity and its dispersion w.r.tBaade-s WIndow of -0.45 and -0.20 dex respectively at l = +5.5, and of -0.10dex and -0.20 dex at l = -5.0. We detect a signature of a possible tidal streamat l = +5.5, in both our velocity and metallicity distributions. Its radialvelocity indicates that it is not associated with the Sagittarius stream. Wealso measure the metallicity of a bulge globular cluster NGC 6522 in ourBaade-s Window field to be -0.90 +- 0.10 dex, in agreement with recentmeasurements of Zoccali et al. 2008. This agreement demonstrates thereliability of our metallicity measurements.



Autor: Naseem Rangwala, T. B. Williams

Fuente: https://arxiv.org/



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