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.

Chemical and dynamical analysis of Open Clusters from OCCASO data. The case of NGC 6705

2017 ◽  
Vol 13 (S334) ◽  
pp. 124-127
Author(s):  
Laia Casamiquela ◽  
Ricardo Carrera ◽  
Lola Balaguer-Núñez ◽  
Carme Jordi ◽  
Cristina Chiappini ◽  
...  
Keyword(s):  
High Resolution ◽  
Northern Hemisphere ◽  
Open Clusters ◽  
Radial Velocities ◽  
High Resolution Spectroscopy ◽  
Dynamical Analysis ◽  
Atmospheric Parameters ◽  
Chemical Abundances ◽  
Red Clump ◽  
Insight Into

AbstractThe OCCASO survey targets intermediate-age and old OCs visible from the Northern hemisphere. OCCASO provides homogeneous radial velocities, atmospheric parameters, and individual abundances from high-resolution spectroscopy (R>65,000) of Red Clump stars. We present a first insight into the homogeneously analyzed chemical abundances obtained fror 18 Northern OCs from OCCASO data. Our sample includes an interesting inner disk OC, NGC 6705, analyzed in the literature with inconclusive results about its α abundances. From OCCASO data this is an α-enhanced OC from the analysis of Si, Ca, Ti, Mg and O, despite its young age.

scholarly journals Masses and ages for metal-poor stars

2019 ◽  
Vol 627 ◽  
pp. A173 ◽  
Author(s):  
M. Valentini ◽  
C. Chiappini ◽  
D. Bossini ◽  
A. Miglio ◽  
G. R. Davies ◽  
...  
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Age Determination ◽  
High Resolution Spectroscopy ◽  
Chemical Abundances ◽  
Abundance Pattern ◽  
Halo Stars ◽  
Stellar Ages ◽  
First Results ◽  
Detailed Chemical

Context. Very metal-poor halo stars are the best candidates for being among the oldest objects in our Galaxy. Samples of halo stars with age determination and detailed chemical composition measurements provide key information for constraining the nature of the first stellar generations and the nucleosynthesis in the metal-poor regime. Aims. Age estimates are very uncertain and are available for only a small number of metal-poor stars. We present the first results of a pilot programme aimed at deriving precise masses, ages, and chemical abundances for metal-poor halo giants using asteroseismology and high-resolution spectroscopy. Methods. We obtained high-resolution UVES spectra for four metal-poor RAVE stars observed by the K2 satellite. Seismic data obtained from K2 light curves helped improve spectroscopic temperatures, metallicities, and individual chemical abundances. Mass and ages were derived using the code PARAM, investigating the effects of different assumptions (e.g. mass loss and [α/Fe]-enhancement). Orbits were computed using Gaia DR2 data. Results. The stars are found to be normal metal-poor halo stars (i.e. non C-enhanced), and an abundance pattern typical of old stars (i.e. α and Eu-enhanced), and have masses in the 0.80−1.0 M⊙ range. The inferred model-dependent stellar ages are found to range from 7.4 Gyr to 13.0 Gyr with uncertainties of ∼30%−35%. We also provide revised masses and ages for metal-poor stars with Kepler seismic data from the APOGEE survey and a set of M4 stars. Conclusions. The present work shows that the combination of asteroseismology and high-resolution spectroscopy provides precise ages in the metal-poor regime. Most of the stars analysed in the present work (covering the metallicity range of [Fe/H] ∼ −0.8 to −2 dex) are very old >9 Gyr (14 out of 19 stars), and all of the stars are older than >5 Gyr (within the 68 percentile confidence level).

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

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 High-resolution spectroscopy of the high-velocity hot post-AGB star IRAS 18379–1707 (LS 5112)

2019 ◽  
Vol 491 (4) ◽  
pp. 4829-4842 ◽  
Author(s):  
N P Ikonnikova ◽  
M Parthasarathy ◽  
A V Dodin ◽  
S Hubrig ◽  
G Sarkar
Keyword(s):  
High Resolution ◽  
Model Atmosphere ◽  
Emission Lines ◽  
High Resolution Spectroscopy ◽  
Atmospheric Parameters ◽  
Optical Counterpart ◽  
Chemical Abundances ◽  
Balmer Lines ◽  
Cno Abundances ◽  
First Time

ABSTRACT The high-resolution ($R\sim 48\, 000$) optical spectrum of the B-type supergiant LS 5112, identified as the optical counterpart of the post-AGB candidate IRAS 18379–1707 is analysed. We report the detailed identifications of the observed absorption and emission features in the wavelength range 3700–9200 Å for the first time. The absorption line spectrum has been analysed using non-LTE model atmosphere techniques to determine stellar atmospheric parameters and chemical composition. We estimate Teff = 18 000 ± 1000 K, log g = 2.25 ± 0.08, ξt = 10 ± 4 km s−1, and vsin i = 37 ± 6 km s−1, and the derived abundances indicate a metal-deficient ([M/H] ≈ −0.6) post-AGB star. Chemical abundances of eight different elements were obtained. The estimates of the CNO abundances in IRAS 18379–1707 indicate that these elements are overabundant with [(C + N + O)/S] = + 0.5 ± 0.2 suggesting that the products of helium burning have been brought to the surface as a result of third dredge-up on the AGB. From the absorption lines, we derived heliocentric radial velocity of Vr = −124.0 ± 0.4 km s−1. We have identified permitted emission lines of O i, N i, Na i, S ii, Si ii, C ii, Mg ii, and Fe iii. The nebula forbidden lines of [N i], [O i], [Fe ii], [N ii], [S ii], [Ni ii], and [Cr ii] have also been identified. The Balmer lines H α, H β, and H γ show P-Cygni behaviour clearly indicating post-AGB mass-loss process in the object with the wind velocity up to 170 km s−1.

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.

scholarly journals Open clusters in APOGEE and GALAH

2019 ◽  
Vol 623 ◽  
pp. A80 ◽  
Author(s):  
R. Carrera ◽  
A. Bragaglia ◽  
T. Cantat-Gaudin ◽  
A. Vallenari ◽  
L. Balaguer-Núñez ◽  
...  
Keyword(s):  
High Resolution ◽  
Stellar Evolution ◽  
Open Cluster ◽  
Open Clusters ◽  
Radial Velocities ◽  
High Resolution Spectroscopy ◽  
Galactic Disc ◽  
Chemical Abundances ◽  
Cross Matching ◽  
Detailed Chemical

Context. Open clusters are ideal laboratories to investigate a variety of astrophysical topics, from the properties of the Galactic disc to stellar-evolution models. Knowing their metallicity and possibly detailed chemical abundances is therefore important. However, the number of systems with chemical abundances determined from high-resolution spectroscopy remains small. Aims. Our aim is to increase the number of open clusters with radial velocities and chemical abundances determined from high-resolution spectroscopy using publicly available catalogues of surveys in combination with Gaia data. Methods. Open cluster stars have been identified in the APOGEE and GALAH spectroscopic surveys by cross-matching their latest data releases with stars for which high-probability astrometric membership has been derived in many clusters on the basis of the Gaia second data release. Results. Radial velocities were determined for 131 and 14 clusters from APOGEE and GALAH data, respectively. This is the first radial-velocity determination from high-resolution spectra for 16 systems. Iron abundances were obtained for 90 and 14 systems from APOGEE and GALAH samples, respectively. To our knowledge 66 of these clusters (57 in APOGEE and 9 in GALAH) do not have previous determinations in the literature. For 90 and 7 clusters in the APOGEE and GALAH samples, respectively, we also determined average abundances for Na, Mg, Al, Si, Ca, Cr, Mn, and Ni.

High-Resolution Spectroscopy of Cool Carbon-Rich and Metal-Poor Star HD 209621

2012 ◽  
Vol 21 (4) ◽  
Author(s):  
E. Matrozis ◽  
L. Začs ◽  
A. Barzdis
Keyword(s):  
High Resolution ◽  
Spectral Synthesis ◽  
High Resolution Spectroscopy ◽  
High Resolution Spectrum ◽  
Atmospheric Parameters ◽  
Atmospheric Models ◽  
Abundance Pattern ◽  
Element Abundances ◽  
First Time ◽  
Metal Poor Star

AbstractElement abundances for HD 209621 obtained earlier display significant discrepancies, especially in the case of CNO and neutron-capture elements. Therefore we performed a detailed analysis of chemical composition of this star using a new high-resolution spectrum. Atmospheric parameters and abundance pattern are updated, and the mechanism of nucleosynthesis is examined. Abundances for 11 elements are calculated for the first time. The method of atmospheric models and spectral synthesis was used. The following values of atmospheric parameters are derived: T

scholarly journals OCCASO – III. Iron peak and α elements of 18 open clusters. Comparison with chemical evolution models and field stars

2019 ◽  
Vol 490 (2) ◽  
pp. 1821-1842 ◽  
Author(s):  
L Casamiquela ◽  
S Blanco-Cuaresma ◽  
R Carrera ◽  
L Balaguer-Núñez ◽  
C Jordi ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Chemical Abundances ◽  
Homogeneous Sample ◽  
Giant Stars ◽  
Stellar Nucleosynthesis ◽  
Solar Abundances ◽  
Red Giant

ABSTRACT The study of open-cluster chemical abundances provides insights on stellar nucleosynthesis processes and on Galactic chemo-dynamical evolution. In this paper we present an extended abundance analysis of 10 species (Fe, Ni, Cr, V, Sc, Si, Ca, Ti, Mg, O) for red giant stars in 18 OCCASO clusters. This represents a homogeneous sample regarding the instrument features, method, line list and solar abundances from confirmed member stars. We perform an extensive comparison with previous results in the literature, and in particular with the Gaia FGK Benchmark stars Arcturus and $\mu$-Leo. We investigate the dependence of [X/Fe] with metallicity, Galactocentric radius (6.5 kpc < RGC < 11 kpc), age (0.3 Gyr < Age < 10 Gyr), and height above the plane (|z| < 1000 pc). We discuss the observational results in the chemo-dynamical framework, and the radial migration impact when comparing with chemical evolution models. We also use APOGEE DR14 data to investigate the differences between the abundance trends in RGC and |z| obtained for clusters and for field stars.

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