10,548 research outputs found
High-resolution CRIRES spectra of Terzan1: a metal-poor globular cluster toward the inner bulge
Containing the oldest stars in the Galaxy, globular clusters toward the bulge
can be used to trace its dynamical and chemical evolution. In the bulge
direction, there are ~50 clusters, but only about 20% have been subject of
high-resolution spectroscopic investigations. So far, the sample observed at
high resolution spans a moderate-to-high metallicity regime. In this sample,
however, very few are located in the innermost region (1.5\,Kpc and
). To constrain the chemical evolution enrichment of the
innermost region of Galaxy, accurate abundances and abundance patterns of key
elements based on high-resolution spectroscopy are necessary. Here we present
the results we obtained for Terzan 1, a metal-poor cluster located in the
innermost bulge region. Using the near-infrared spectrograph CRIRES at ESO/VLT,
we obtained high-resolution (R50,000) H-band spectra of 16 bright
giant stars in the innermost region () of Terzan1. Full spectral
synthesis techniques and equivalent width measurements of selected lines,
isolated and free of significant blending and/or contamination by telluric
lines, allowed accurate chemical abundances and radial velocities to be
derived. Fifteen out of 16 observed stars are likely cluster members, with an
average heliocentric radial velocity of +571.8\,km/s and mean iron
abundance of [Fe/H]=--1.260.03\,dex. For these stars we measured some
[/Fe] abundance ratios, finding average values of
[O/Fe]=+0.390.02\,dex, [Mg/Fe]=+0.420.02\,dex,
[Si/Fe]=+0.310.04\,dex, and [Ti/Fe]=+0.150.04\,dex The
enhancement (\,dex) found in the observed giant stars of Terzan1
is consistent with previous measurements on other, more metal-rich bulge
clusters, which suggests a rapid chemical enrichment.Comment: 7, pages, 6 figures, accepted for publication on A&
High resolution near-IR spectra of NGC 6624 and NGC 6569
We present the first abundances analysis based on high-resolution infrared
(IR) echelle spectra of NGC 6569 and NGC 6624, two moderately reddened globular
clusters located in the outer bulge of the Galaxy. We find
[Fe/H]=-0.790.02 dex and [Fe/H]=-0.690.02 dex for NGC 6569 and NGC
6624, respectively and an average -elements enhancement of
+0.430.02 dex and +0.390.02 dex, consistent with previous
measurements on other metal-rich Bulge clusters. We measure accurate radial
velocities of and
and velocity dispersions of and for NGC 6569 and NGC 6624, respectively. Finally, we find very low
isotopics ratio (7 in NGC 6624 and 5 in NGC
6569), confirming the presence extra-mixing mechanisms during the red giant
branch evolution phase.Comment: 7 pages, 3 figures, accepted for publication on MNRA
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