- ID:
- ivo://CDS.VizieR/J/A+AS/141/491
- Title:
- Chemical composition of halo and disk stars
- Short Name:
- J/A+AS/141/491
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 3. Atmospheric parameters, space velocities, distances, masses and ages of the program stars. Table 4. Atomic line data including wavelength, excitation energy of the lower level, the logarithm of the oscillator strength (the experimental or theoretical value, the corrected value and the differential value from standard stars) and the adopted enhancement factor of the Unsold approximation to the van der Waals damping constant. The last column gives the equivalent width in the spectrum of HD 142373 representing a typical metallicity of the sample of stars. Uncertain EWs marked by (:) and strong lines with EW>100m{AA} are not used in the abundance determination for this star. Table 5. Abundance ratios for the program stars. The oxygen abundance is derived from the 7774{AA} triplet but scaled to results from the forbidden [OI] line at 6300{AA}.
Number of results to display per page
Search Results
- 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/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/A+A/634/A136
- Title:
- Chemical sulfur abundances of 719 FGK stars
- Short Name:
- J/A+A/634/A136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Elemental abundances are of prime importance to help us reconstruct the origin and evolution of stars and galaxies in our Universe. Sulfur abundances have not been as heavily studied as other elements, so some details regarding its behaviour are still unclear. We aim to investigate [S/Fe] ratios in stars of the solar neighbourhood in order to analyse the chemical evolution of sulfur and probe for possible differences in abundances of planet host and non-planet host stars. We use the code MOOG to perform spectral synthesis and derive v*sin(i) values and [S/Fe] ratios for 719 FGK stars with high-resolution (R~115000) and high-quality spectra from the HARPS-GTO program. We find the best fit and corresponding parameter values by performing chi-square minimisation of the deviation between synthetic profiles and observational spectra. Our results reveal that sulfur behaves as a typical alpha-element, with low abundances in young thin disk stars and high abundances in old thick disk stars, following what was expected from our understanding of the Galactic chemical evolution (GCE). Nevertheless, further studies into the abundances of sulfur in very metal-poor stars are required as our sample only derived sulfur abundances to stars with metallicity as low as [Fe/H]=-1.13dex. High-alpha metal rich stars are more enhanced in sulfur compared to their thin disk counterparts at the same metallicity. We compare our results to GCE models from other authors in the [S/Fe] vs. [Fe/H] plane. The [S/Fe]-age relationship is a good proxy for time, just like it is the case with other alpha-elements. We report no differences in the abundances of sulfur between stars with and without planetary companions in the metallicity range [Fe/H]>=-0.3dex.
- ID:
- ivo://CDS.VizieR/J/AJ/125/197
- Title:
- CN abundances of the 47 Tuc main sequence
- Short Name:
- J/AJ/125/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a deep spectroscopic survey for star-to-star CN variations along the main sequence (MS) of the globular cluster 47 Tuc with ESO's Very Large Telescope. We find a significant bimodal distribution in the S(3839) index for main-sequence stars in the mass range ~0.85 to 0.65M_{sun}_, or from the main-sequence turnoff down to ~2.5 mag below the main-sequence turnoff. An anticorrelation of CN and CH is evident on the MS. The result is discussed in the context of the ability of faint MS stars to alter their surface composition through internal evolutionary effects. We argue against internal stellar evolution as the only origin for the abundance spread in 47 Tuc; an external origin such as pollution seems to be more likely.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A44
- Title:
- 3D-corrected oxygen abundances for halo stars
- Short Name:
- J/A+A/624/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measurable amounts of Be could have been synthesised primordially if the Universe were non-homogeneous or in the presence of late decaying relic particles. We investigate the Be abundance in the extremely metal-poor star 2MASS J1808-5104 ([Fe/H]=-3.84) with the aim of constraining inhomogeneities or the presence of late decaying particles. High resolution, high signal-to-noise ratio (S/N) UV spectra were acquired at ESO with the Kueyen 8.2m telescope and the UVES spectrograph. Abundances were derived using several model atmospheres and spectral synthesis code. We measured log(Be/H)=-14.3 from a spectrum synthesis of the region of the Be line. Using a conservative approach, however we adopted an upper limit two times higher, i.e. log(Be/H)<-14.0. We measured the O abundance from UV-OH lines and find [O/H]=-3.46 after a 3D correction. Our observation reinforces the existing upper limit on primordial Be. There is no observational indication for a primordial production of 9Be. This places strong constraints on the properties of putative relic particles. This result also supports the hypothesis of a homogeneous Universe, at the time of nucleosynthesis. Surprisingly, our upper limit of the Be abundance is well below the Be measurements in stars of similar [O/H]. This may be evidence that the Be-O relation breaks down in the early Galaxy, perhaps due to the escape of spallation products from the gas clouds in which stars such as 2MASS J1808-5104 have formed.
- ID:
- ivo://CDS.VizieR/J/ApJ/681/1524
- Title:
- Detailed abundances for 28 metal-poor stars
- Short Name:
- J/ApJ/681/1524
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an abundance analysis for a sample of stars with -4<[Fe/H]<-2. The data were obtained with the HIRES spectrograph at Keck Observatory. The set includes 28 stars, with effective temperature ranging from 4800 to 6600K. For 13 stars with [Fe/H]<-2.6, including nine with [Fe/H]<-3.0 and one with [Fe/H]=-4.0, these are the first reported detailed abundances. For the most metal-poor star in our sample, CS 30336-049, we measure an abundance pattern that is very similar to stars in the range [Fe/H]~-3.5, including a normal C+N, abundance. We also find that it has very low but measurable Sr and Ba, indicating some neutron-capture activity even at this low of a metallicity. We explore this issue further by examining other very neutron capture-deficient stars and find that, at the lowest levels, [Ba/Sr] exhibits the ratio of the main r-process. We also report on a new r-process-enhanced star, CS 31078-018. This star has [Fe/H]=-2.85, [Eu/Fe]=1.23, and [Ba/Eu]=-0.51. CS 31078-018 exhibits an "actinide boost," i.e., much higher [Th/Eu] than expected and at a similar level to CS 31082-001. Our spectra allow us to further constrain the abundance scatter at low metallicities, which we then use to fit to the zero-metallicity Type II supernova yields of Heger & Woosley (2008arXiv0803.3161H). We find that supernovae with progenitor masses between 10 and 20M_{sun}_ provide the best matches to our abundances.
- ID:
- ivo://CDS.VizieR/J/ApJ/612/447
- Title:
- Draco 119 and HD 88609 equivalent widths
- Short Name:
- J/ApJ/612/447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the abundance analysis of new high signal-to-noise ratio (S/N) spectra of the most metal-poor ([Fe/H]=-2.95) star currently known to be a member of a dwarf galaxy, the Draco dSph red giant D119. No absorption lines for elements heavier than Ni are detected in two Keck HIRES spectra covering the 3850-6655{AA} wavelength range, a phenomenon not previously noted in any other metal-poor star. We present upper limits for several heavy-element abundances. The most stringent limits, based on the nondetection of SrII and BaII lines, indicate that the total s- and r-process enrichment of D119 is at least 100times smaller than Galactic stars of similar metallicity. The light-element abundances are consistent with the star having formed out of material enriched primarily by massive Type II supernovae (M>20-25M_{Sun}_). If this is the case, we are forced to conclude that massive, metal-poor Type II supernovae did not contribute to the r-process in the proto-Draco environment. We compare the abundance pattern observed in D119 to current predictions of prompt enrichment and pair-instability supernovae and find that the model predictions fail by an order of magnitude or more for many elements.
- ID:
- ivo://CDS.VizieR/J/A+A/354/899
- Title:
- Elemental abundance analyses IV.
- Short Name:
- J/A+A/354/899
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new CASLEO echelle spectrograms, we extended our elemental abundances of the sharp-lines Mercury-Manganese star {mu} Lep, 14 Hya, {kappa} Cnc, HR 4487, 28 Her, and HR 7245, the closely related star 3 CenA, and 7 Sex an A0V star with population I abundances, but with Population II star space motion. The {lambda}{lambda}4500-6200 region contains a sufficient number of lines to derive high-quality abundances of these stars. For most stars, the new spectra provide additional lines for the analyses which improve their quality as well as help fill in the periodic table.
- ID:
- ivo://CDS.VizieR/J/AN/329/4
- Title:
- Elemental abundance analyses of nu Her & 41 Cyg
- Short Name:
- J/AN/329/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This series of high quality elemental abundance analyses of mostly Main Sequence normal and peculiar B, A, and F stars defines their properties and provides data for the comparison with analyses of somewhat similar stars and with theoretical predictions. Most use high dispersion and high S/N (greater than or equal to 200) spectrograms obtained with CCD detectors at the long camera of the 1.22-m Dominion Astrophysical Observatory telescope's coude spectrograph. Here we expand the range of stars examined to include two relatively quiescent F supergiants. nu Her (F2 II) and 41 Cyg (F5 Ib-II) are analyzed as consistently as possible with previous studies. These LTE fine analyses use the ATLAS9 and the WIDTH9 programs of R.L. Kurucz. High signal-to-noise spectrograms and high quality atomic data were employed. The derived values of these photometrically constant stars are somewhat different with the abundances of nu Her being somewhat metal-poor and those of 41 Cyg being crudely solar-like. Our analyses indicate that the basic results of Luck and Wepfer who also studied nu Her and 41 Cyg are not likely to be significantly changed by new studies of all their stars.
