- ID:
- ivo://CDS.VizieR/J/A+A/619/A176
- Title:
- Chemical composition of Ruprecht 147
- Short Name:
- J/A+A/619/A176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ruprecht 147 (NGC 6774) is the closest old open cluster, with a distance of less than 300pc and an age of about 2.5Gyr. It is therefore well suited for testing stellar evolution models and for obtaining precise and detailed chemical abundance information. We combined photometric and astrometric information coming from literature and the Gaia mission with very high-resolution optical spectra of stars in different evolutionary stages to derive the cluster distance, age, and detailed chemical composition. We obtained spectra of six red giants using HARPS-N at the Telescopio Nazionale Galileo (TNG). We also used European Southern Observatory (ESO) archive spectra of 22 main sequence (MS) stars, observed with HARPS at the 3.6m telescope. The very high resolution (115000) and the large wavelength coverage (about 380-680nm) of the twin instruments permitted us to derive atmospheric parameters, metallicity, and detailed chemical abundances of 23 species from all nucleosynthetic channels. We employed both equivalent widths and spectrum synthesis. We also re-derived the cluster distance and age using Gaia parallaxes, proper motions, and photometry in conjunction with the PARSEC stellar evolutionary models. We fully analysed those stars with radial velocity and proper motion/parallax in agreement with the cluster mean values. We also discarded one binary not previously recognised, and six stars near the MS turn-off because of their high rotation velocity. Our final sample consists of 21 stars (six giants and 15 MS stars). We measured metallicity (the cluster average [Fe/H] is +0.08, rms=0.07) and abundances of light, alpha, Fe-peak, and neutron-capture elements. The Li abundance follows the expectations, showing a tight relation between temperature and abundance on the MS, at variance with M67, and we did not detect any Li-rich giant.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/324/435
- Title:
- Chemical composition of six K supergiants in the SMC
- Short Name:
- J/A+A/324/435
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of six SMC cool stars (K supergiants) are analysed by high resolution spectroscopy in order to investigate their chemical content, which should reflect that of the current interstellar medium within the SMC. The abundance of Na, Al, {alpha}-elements, Fe peak and heavy elements are derived through an LTE analysis of the lines, compared to a Galactic "standard" (the well-studied K giant Arcturus) and discussed in terms of chemical evolution of the SMC. The following results were obtained: 1. All the stars from this sample are metal deficient ([Fe/H] ranges from -0.59 to -0.89dex). The abundance varies little from star-to-star (0.10dex rms, comparable with the expected error due to uncertainties on the effective parameters of the stars), in agreement with the very small chemical composition variations among the H II regions within the SMC found by Pagel et al. (1978MNRAS.184..569P). 2. Sodium is not strongly enhanced in these stars, and the star-to-star scatter is larger than expected. 3. At variance with metal-poor stars in our Galaxy, the so-called {alpha}-elements do not seem to be enhanced. 4. Nickel displays a noticeable depletion with respect to iron ([Ni/Fe]=~-0.3dex), at variance with what is found in the SMC F supergiants and in Arcturus. 5. Except for PMMR 144, the s and r process elements heavier than Ba are enhanced in all of our stars by =~+0.4dex.
- ID:
- ivo://CDS.VizieR/J/A+A/305/551
- Title:
- Chemical composition of the s-Cepheids
- Short Name:
- J/A+A/305/551
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the base of photographic, Reticon and CCD spectra analysis we have derived the abundances for 8 s-Cepheids and V1162 Aql (before classified as s-Cepheid). The following results have been obtained: 1) all Cepheids (excluding only EU Tau) have solar-like abundances of {alpha}- and iron-group elements, 2) Na is over abundant for all program stars, 3) the carbon deficiency found for EU Tau, DT Cyg, V440 Per and nitrogen overabundance (DT Cyg), show that these s-Cepheids are not crossing the instability strip for first time, 4) s-process elements are slightly enhanced in the program stars, 5) V1162 Aql does not show any changes in C and N abundances. The most plausible explanation is that this star is a normal Cepheid (C{delta}), but it is firstly crossing the instability strip toward the giant branch. This conclusion is also confirmed by its position on the evolutionary diagram.
- ID:
- ivo://CDS.VizieR/J/AJ/134/926
- Title:
- Chemical composition of V2314 Oph
- Short Name:
- J/AJ/134/926
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated V2314 Oph using high-resolution (R=45000) spectral observations. The atmospheric parameters were determined using iron-line abundance analysis. We derived a mean effective temperature of Teff=7510K, mean surface gravity of logg=3.30, metallicity of [Fe/H]=-0.59, and rotation velocity of vsini=38km/s. The abundances of 19 chemical elements were determined.
- ID:
- ivo://CDS.VizieR/J/A+A/397/257
- Title:
- Chemical compositions of four barium stars
- Short Name:
- J/A+A/397/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical compositions of four barium stars are studied. We obtain their {alpha}, iron peak and neutron-capture (n-capture) process element abundances. The atomic data and measured equivalent widths (EWs) of the related spectral lines are given. The abundance errors caused by the combined effects of the uncertainties in oscillator strengths loggf-values, equivalent widths (EWs) and stellar atmospheric parameters (e.g. effective temperature Teff, surface gravity logg, and microturbulent velocity {xi_t_}) are the total abundance uncertainties. The individual and total abundance uncertainties caused by these factors are given.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/1095
- Title:
- Chemical compositions of 26 outer halo stars
- Short Name:
- J/ApJ/706/1095
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundances of 26 metal-poor dwarfs and giants are determined from high-resolution and high signal-to-noise ratio spectra obtained with the Subaru/High Dispersion Spectrograph. The sample is selected so that most of the objects have outer-halo kinematics. Self-consistent atmospheric parameters were determined by an iterative procedure based on spectroscopic analysis. Abundances of 13 elements, including {alpha}-elements (Mg, Si, Ca, Ti), odd-Z light elements (Na, Sc), iron-peak elements (Cr, Mn, Fe, Ni, Zn), and neutron-capture elements (Y, Ba), are determined by two independent data reduction and local thermodynamic equillibrium analysis procedures, confirming the consistency of the stellar parameters and abundances results.
- ID:
- ivo://CDS.VizieR/J/ApJS/197/29
- Title:
- Chemical compositions of 11 RR Lyrae
- Short Name:
- J/ApJS/197/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed abundance study of 11 RR Lyrae ab-type variables: AS Vir, BS Aps, CD Vel, DT Hya, RV Oct, TY Gru, UV Oct, V1645 Sgr, WY Ant, XZ Aps, and Z Mic. High-resolution and high signal-to-noise ratio echelle spectra of these variables were obtained with the 2.5m du Pont telescope at the Las Campanas Observatory. We obtained more than 2300 spectra, roughly 200 spectra per star, distributed more or less uniformly throughout the pulsational cycles. A new method has been developed to obtain the initial effective temperatures of our sample stars at a specific pulsational phase. We find that the abundance ratios are generally consistent with those of similar metallicity field stars in different evolutionary states and throughout the pulsational cycles for RR Lyrae stars. TY Gru remains the only n-capture enriched star among the RRab in our sample.
- ID:
- ivo://CDS.VizieR/J/A+A/463/265
- Title:
- Chemical compositions of 48 WR planetary nebulae
- Short Name:
- J/A+A/463/265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical compositions and other properties of planetary nebulae around central stars of spectral types [WC], [WO], and wels are compared with those of "normal" central stars, in order to clarify the evolutionary status of each type and their interrelation. We use plasma diagnostics to derive from optical spectra the plasma parameters and chemical compositions of 48 planetary nebulae. We also reanalyze the published spectra of a sample of 167 non-WR PN. The results as well as the observational data are compared in detail with those from other studies of the objects in common.
- ID:
- ivo://CDS.VizieR/III/58
- Title:
- Chemical elements in peculiar stellar spectra
- Short Name:
- III/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A systematic search of 27 journals, IAU Symposia, and Colloquia has yielded this catalogue of identifications of chemical species in peculiar spectra Ap, Bp and Am generally. Abundance surveys were only searched if they included element identification lists.
- ID:
- ivo://CDS.VizieR/J/ApJ/812/142
- Title:
- Chemical evolution in the LMC with a new model
- Short Name:
- J/ApJ/812/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a new network and a new model, we have studied chemical complexity in cold portions of dense clouds of the Large Magellanic Cloud (LMC). We varied the hydrogen number density between 1x10^5^ and 5x10^5^/cm3 and, for each density, we ran models for A_V_=3, 5, and 10. Then, for each density and visual extinction we varied the grain temperature between 10 and 50K in small intervals, while keeping the gas temperature constant at 20K. We used a gas-to-dust mass ratio based on a variety of observations and analyses, and scaled the elemental abundances of the LMC so that they are representative of so-called "low" metallic abundances. We found that although the LMC is metal-poor, it still shows a rich chemistry; almost all the major observed species in the gas phase of our Galaxy should be detectable using present-day observational facilities. We compared our model results with observed gas-phase abundances in some cold and dense sources, and found reasonably good agreement for most species. We also found that some observed results, especially for methanol, are better matched if these regions currently possess lower temperatures, or possessed them in the past. Finally, we discussed our simulated abundances for H_2_O ice with respect to total hydrogen, and CO_2_, CO, CH_3_OH, and NH_3_ ices with respect to water ice, and compared our values with those for two observed ices --CO_2_ and CO-- detected in front of young stellar objects in the LMC.
