- ID:
- ivo://CDS.VizieR/J/A+A/371/1078
- Title:
- Elemental abundance of 4 normal B and A stars
- Short Name:
- J/A+A/371/1078
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Elemental abundances analysis of the superficially normal B and A stars {alpha} Dra (A0 III), {tau} Her (B5 IV), {gamma} Lyr (B9 III), and HR 7926 (B8 II-III) are performed consistent with previous studies of this series using spectrograms obtained with Reticon and CCD detectors. Comparisons of the first two analysis with those of the same stars performed earlier in this series which used mostly coadded photographic plates show the general consistency of the derived elemental abundances. A slight increase in the adopted effective temperature produces a corresponding increase in the derived abundances. In these stars the He/H ratios are found to be close to solar. Except for {gamma} Lyr the metals show for the most part marginally subsolar abundance values. But this star has Al, Ca, Sc, and Sr abundances that are substantially underabundant as well as other underabundant values.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/367/1329
- Title:
- Elemental abundances for 176 stars
- Short Name:
- J/MNRAS/367/1329
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed an abundance analysis for F- and G- dwarfs of the Galactic thick-disc component. A sample of 176 nearby (d<=150pc) thick-disc candidate stars was chosen from the Hipparcos catalogue and subjected to a high-resolution spectroscopic analysis. Using accurate radial velocities combined with the Hipparcos astrometry, kinematics (U, V and W) and Galactic orbital parameters were computed. We estimate the probability for a star to belong to the thin disc, the thick disc or the halo. With a probability P>=70 per cent taken as certain membership, we assigned 95 stars to the thick disc, 13 to the thin disc, and 20 to the halo. The remaining 48 stars in the sample cannot be assigned with reasonable certainty to one of the three components. Abundances of C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Ba, Ce, Nd and Eu have been obtained.
- ID:
- ivo://CDS.VizieR/J/MNRAS/364/272
- Title:
- Elemental abundances in Blanco 1
- Short Name:
- J/MNRAS/364/272
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectroscopy is used to determine the detailed chemical abundances of a group of eight F- and G-type stars in the young open cluster Blanco 1. An average [Fe/H] of +0.04+/-0.02 (internal error)+/-0.04 (external error) is found, considerably lower than a previous spectroscopic estimate for this cluster. The difference is due mainly to our adoption of significantly cooler temperatures that are consistent with both photometric and spectroscopic constraints. Blanco 1 exhibits subsolar [Ni/Fe](0.18+/-0.01+/-0.01), [Si/Fe](0.09+/-0.02+/-0.03), [Mg/Fe](0.14+/-0.02+/-0.03) and [Ca/Fe](0.09+/-0.03+/-0.03); ratios that are not observed among nearby field stars.
- ID:
- ivo://CDS.VizieR/J/AJ/118/1245
- Title:
- Elemental abundances in five stars in M54
- Short Name:
- J/AJ/118/1245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundances in five stars in M54, a globular cluster associated with the Sagittarius dwarf galaxy, have been determined using high-resolution echelle spectra. We find the cluster to have [Fe/H] = -1.55 and possibly halo-normal abundance patterns, although the [O/Fe] and [{alpha}/Fe] ratios lie between solar and the normal halo values. One star shows the combination of low oxygen and enhanced Na and Al, symptomatic of deep mixing of ON-cycle and other proton-capture products; a second star shows a lesser degree of O depletion unaccompanied by Na and Al excesses. In the cluster Eu is also enhanced, indicating that about 30% of the Ba in the cluster is due to the r-process. In general, M54 is similar to globulars of comparable metallicity in the inner Galactic halo, despite its clear association with the Sagittarius dwarf spheroidal.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/563
- Title:
- Elemental abundances in Hyades supercluster
- Short Name:
- J/MNRAS/415/563
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The existence of a kinematically defined moving group of stars centred at U=-40, V=-17km/s, referred to as the Hyades supercluster, has been suggested to be the debris of an originally large star-forming event, with its core being the present-day Hyades open cluster. Using high-resolution UV-Visual Echelle Spectrograph (UVES) spectra, we present the elemental abundances for a range of alpha, Fe-peak and neutron-capture elements for 26 proposed supercluster stars. Our results show that the sample stars display a heterogeneous abundance distribution, with a clump around [Fe/H]=+0.15. We also calculate stellar radial velocities and U, V, W space velocities. Enforcing strict chemical and kinematical membership criteria, we find that four supercluster stars share the Hyades open cluster abundances and kinematics, while many of the remaining stars fit the disc field kinematics and abundance range. We discuss our findings in the context of the Hyades supercluster being a dispersed star-forming remnant, a stellar stream of purely dynamical origin or a result of several processes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/386/2039
- Title:
- Elemental abundances of {alpha} Cir
- Short Name:
- J/MNRAS/386/2039
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Sydney University Stellar Interferometer to measure the angular diameter of alpha Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, alpha Cir being the brightest member of its class. We used the new and more accurate Hipparcos parallax to determine the radius to be 1.967+/-0.066R_{sun}_. We have constrained the bolometric flux from calibrated spectra to determine an effective temperature of 7420+/-170K . This is the first direct determination of the temperature of an roAp star. Our temperature is at the low end of previous estimates, which span over 1000K and were based on either photometric indices or spectroscopic methods. In addition, we have analysed two high-quality spectra of alpha Cir, obtained at different rotational phases and we find evidence for the presence of spots.
- ID:
- ivo://CDS.VizieR/J/A+A/420/673
- Title:
- Elemental abundances of CP2 star HR 5049
- Short Name:
- J/A+A/420/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A spectrum synthesis analysis for photospheric lines in the magnetic B star HR 5049 is presented, based on a high quality spectrogram obtained with the EMMI spectrograph attached to the NTT at ESO. It is found that light elements such as He, C and O are under-abundant. One of the most notable features is the deficiency of He by more than -2.0dex. Co and Cl are over-abundant by +3.5dex and +1.9dex, respectively. Other iron peak elements are over-abundant ranging from +0.47dex (Ti II) to +1.94 dex (Cr I). For rare earth elements, the lines of once-ionized species are generally weak, while the third spectra (especially those of Pr and Nd) are very prominent. Although rare earth elements show significant over-abundances ranging from +3.0dex to as large as +4.0dex, Ba has the solar abundance. The Nd-Pr abundance difference, which shows an apparent decreasing trend with increasing effective temperature among CP stars, is found to be unusually small in HR 5049.
- ID:
- ivo://CDS.VizieR/J/A+A/364/237
- Title:
- Elemental abundances of Deneb
- Short Name:
- J/A+A/364/237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study presents a detailed model atmosphere abundance analysis of Deneb which was performed using Kurucz LTE ATLAS9 model atmospheres. The atmospheric parameters were determined from Mg I/II and Fe I/II equilibrium, and by fitting the H{gamma} profile and optical region spectrophotometry. The compromise values which best satisfy these criteria are T_eff_ = 9000 K and log g = 1.45. The Mg I, Mg II, Si II, Ti II, Cr II, Fe I, and Fe II lines yield microturbulences of 3.60, 6.50, 8.50, 8.00, 11.90, 3.60, and 10.40 km/s, respectively. An average microturbulence of 7 km/s was used for the other atomic species.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1111
- Title:
- Elemental abundances of field red giants
- Short Name:
- J/AJ/130/1111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We summarize a selection process to identify red giants in the direction of the southern warp of the Galactic disk, employing VI_C_ photometry and multi-object spectroscopy.
- ID:
- ivo://CDS.VizieR/J/A+A/406/975
- Title:
- Elemental abundances of four A-B stars
- Short Name:
- J/A+A/406/975
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The superficially normal stars {theta} And (A2 V), {epsilon} Del (B6 III), {epsilon} Aqr (A1.5 V), and {iota} And (B9 V), which have rotationally broadened line profiles, are analyzed in a manner consistent with previous studies of this series using 2.4{AA}/mm spectrograms obtained with CCD detectors and S=N>=200. Their variable radial velocities strongly suggest they are spectroscopic binaries. As no evidence is seen for lines of their companions they are analyzed as single stars. Their derived abundances are generally near solar. But those for {theta} And suggest that it is possibly a fast rotating Am star.