scholarly journals Metallicities for 13 nearby open clusters from high-resolution spectroscopy of dwarf and giant stars

2008 ◽  
Vol 493 (1) ◽  
pp. 309-316 ◽  
Author(s):  
N. C. Santos ◽  
C. Lovis ◽  
G. Pace ◽  
J. Melendez ◽  
D. Naef
Keyword(s):  
High Resolution ◽  
Open Clusters ◽  
High Resolution Spectroscopy ◽  
Giant Stars

scholarly journals High-resolution spectroscopy of giant stars in the open clusters IC 4651 and IC 4725

2017 ◽  
Vol 95 (9) ◽  
pp. 862-868 ◽  
Author(s):  
Orlando J. Katime Santrich ◽  
Silvia Rossi
Keyword(s):  
High Resolution ◽  
Solar Spectrum ◽  
Open Clusters ◽  
High Resolution Spectroscopy ◽  
Local Thermal Equilibrium ◽  
Atmospheric Parameters ◽  
Chemical Abundances ◽  
Abundance Pattern ◽  
Giant Stars ◽  
Disk Structure

Open clusters are important astrophysical laboratories to study the stellar formation and evolution and to verify the disk structure of the Milky Way. We present calculations of stellar atmospheric parameters and s-process abundances for nine giant stars in the galactic open clusters IC 4651 and IC 4725. These objects have their memberships confirmed from dynamic studies and chemical analysis. The high-resolution spectra are available in the FEROS ESO archive. We have applied a line by line analysis relative to Juno solar spectrum to determine the stellar atmospheric parameters and chemical abundances of Y II, Zr I, La II, Ce II, and Nd II under the local thermal equilibrium hypothesis. The obtained results were compared to the literature values. The derived s-process abundance pattern agrees with the most recent behaviors reported for giant stars in galactic open clusters.

scholarly journals Stellar spectra analysis of giant stars: ARCTURUS

2020 ◽  
pp. 347-348
Author(s):  
Maria Rah
Keyword(s):  
High Resolution ◽  
Early Universe ◽  
Chemical Evolution ◽  
The Other ◽  
High Resolution Spectroscopy ◽  
Spectra Analysis ◽  
Stellar Spectra ◽  
Giant Stars ◽  
Low Metallicity ◽  
Red Giant

In this study, we analyzed the evolved red giant ARCTURUS using high-resolution spectroscopy that was taken by HARPS. The other names of this star is α Boo - Arcturus - HR 5340 - HD 124897 - HIP 69673. This evolved (log g = 1.66 dex) star shows low metallicity nature ([Fe/H] = -0.52), which could be employed to study the chemical evolution of the early universe.

High-resolution spectroscopy of red giants and ‘yellow stragglers’ in the southern open cluster NGC 2539

2020 ◽  
Vol 494 (1) ◽  
pp. 1470-1489
Author(s):  
Cintia F Martinez ◽  
N Holanda ◽  
C B Pereira ◽  
N A Drake
Keyword(s):  
High Resolution ◽  
Open Cluster ◽  
Open Clusters ◽  
Solar Neighborhood ◽  
Spectroscopic Binaries ◽  
High Resolution Spectroscopy ◽  
Red Giants ◽  
Light Elements ◽  
Abundance Pattern ◽  
Solar Metallicity

ABSTRACT We present a detailed high-resolution spectroscopic analysis of 12 red giant stars, in single and binaries or multiples systems, classified as members of the intermediate-age (631 Myr) open cluster NGC 2539. We used FEROS echelle spectra and the standard LTE analysis to derive the atmospheric parameters for the stars and the abundance ratios of light elements (Li, C, N), light odd-Z elements (Na, Al), α-elements (Mg, Si, Ca, Ti), Fe-group elements (Cr, Fe, Ni), and n-capture elements (Y, Zr, Ce, Nd, Eu). Our results show that the sample star of NGC 2539 has low projected rotational velocities and an almost solar metallicity, with a mean of [Fe/H] = −0.03 ± 0.07 dex. The abundance pattern displays for the analyzed stars are, in general, similar to those presented by solar neighborhood stars, including giant members of others open clusters. In particular, light elements and Na abundance pattern shows anomalies resulting from the appearance of enriched material on the stellar surface, produced by mechanisms like the first dredge-up and/or thermohaline and rotation-induced mixing. We also identified two of the spectroscopic binaries of our sample as ‘yellow stragglers’ and we determined the nature of their companions.

scholarly journals Galactic or extragalactic chemical tagging for NGC 3201?

2018 ◽  
Vol 614 ◽  
pp. A146 ◽  
Author(s):  
B. Dias ◽  
I. Araya ◽  
J. P. Nogueira-Cavalcante ◽  
L. Saker ◽  
A. Shokry
Keyword(s):  
High Resolution ◽  
Globular Cluster ◽  
High Resolution Spectroscopy ◽  
Low Resolution ◽  
Element Abundances ◽  
Giant Stars ◽  
Mass Size ◽  
Red Giant ◽  
Process Element ◽  
Size Relation

Context. The origin of the globular cluster (GC) NGC 3201 is under debate. Its retrograde orbit points to an extragalactic origin, but no further chemical evidence supports this idea. Light-element chemical abundances are useful to tag GCs and can be used to shed light on this discussion. Aims. Recently it was shown that the CN and CH indices are useful to identify GCs that are anomalous to those typically found in the Milky Way. A possible origin of anomalous clusters is the merger of two GCs and/or the nucleus of a dwarf galaxy. We aim to derive CN and CH band strengths for red giant stars in NGC3201 and compare these with photometric indices and high-resolution spectroscopy and discuss in the context of GC chemical tagging. Methods. We measure molecular band indices of S(3839) and G4300 for CN and CH, respectively from low-resolution spectra of red giant stars. Gravity and temperature effects are removed. Photometric indices are used to indicate further chemical information on C+N+O or s-process element abundances that are not derived from low-resolution spectra. Results. We found three groups in the CN–CH distribution. A main sequence (S1), a secondary less-populated sequence (S2), and a group of peculiar (pec) CN-weak and CH-weak stars, one of which was previously known. The three groups seem to have different C+N+O and/or s-process element abundances, to be confirmed by high-resolution spectroscopy. These are typical characteristics of anomalous GCs. The CN distribution of NGC 3201 is quadrimodal, which is more common in anomalous clusters. However, NGC 3201 does not belong to the trend of anomalous GCs in the mass-size relation. Conclusions. The globular cluster NGC 3201 shows signs that it can be chemically tagged as anomalous: it has an unusual CN–CH relation, indications that pec-S1-S2 is an increasing sequence of C+N+O or s-process element abundances, and a multi-modal CN distribution that seems to correlate with s-process element abundances. The non-anomalous characteristics are that it has a debatable Fe-spread and it does not follow the trend of mass size of all anomalous clusters. Three scenarios are postulated here: (i) if the sequence pec-S1-S2 has increasing C+N+O and s-process element abundances, NGC 3201 would be the first anomalous GC outside of the mass-size relation; (ii) if the abundances are almost constant, NGC 3201 would be the first non-anomalous GC with multiple CN–CH anti-correlation groups; or (iii) it would be the first anomalous GC without variations in C+N+O and s-process element abundances. In all cases, the definition of anomalous clusters and the scenario in which they have an extragalactic origin must be revised.

Using open clusters as tracers of the galactic disk history

2017 ◽  
Vol 13 (S334) ◽  
pp. 312-313
Author(s):  
Orlando J. Katime Santrich ◽  
Silvia Rossi ◽  
Yuri Abuchaim ◽  
Geraldo Gonçalves
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Spectroscopic Analysis ◽  
Galactic Disk ◽  
Dynamical Behavior ◽  
Open Clusters ◽  
Atmospheric Parameters ◽  
Giant Stars ◽  
Stellar Formation ◽  
Formation And Evolution

AbstractOpen clusters are important objects to study the galactic structure and its dynamical behavior as well as the stellar formation and evolution. We carried out a spectroscopic analysis to derive atmospheric parameters and chemical composition for 52 giant stars within 9 galactic open clusters. We have used the high-resolution spectra from FEROS, HARPS and UVES in the ESO archive. The methodology used is based on LTE-hypothesis. Abundances of C, N, O, Na, Mg, Al, Si, Ca, Ti, Cr, Ni, YII, LaII, CeII, and NdII were calculated. Although most of these clusters present spectroscopic analysis in the literature, some CNO and s-process abundances were not previously estimated or were calculated with high uncertainties. Several lines of such elements were identified and used to calculate new abundances and improve some previous one.

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