- ID:
- ivo://CDS.VizieR/J/AJ/149/59
- Title:
- Abundances of {rho} Pup
- Short Name:
- J/AJ/149/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated the chemical composition of {rho} Pup using high-resolution spectral observations taken from the Very Large Telescope and the IUE archives and also spectra obtained at the 1.8m telescope of the Bohyunsan observatory in Korea. The abundances of 56 chemical elements and the upper limits of Li and Be abundances were determined. The abundance pattern of {rho} Pup was found to be similar to that of Am-type stars. The possibility of the influence of the accretion of interstellar gas and dust on the abundance patterns of B--F-type stars is discussed. The plots of the relative abundances of chemical elements in the atmospheres of {rho} Pup and {delta} Sct versus the second ionization potentials of these elements show the correlations. The discontinuities at 13.6 and 24.6eV--the ionization potentials of hydrogen and helium, respectively, are also exhibited in these plots. These discontinuities can be explained by interaction of the atoms of interstellar gas, mainly hydrogen and helium atoms, with the atoms of stellar photospheres (so-called charge-exchange reactions). Note that only the jumps near 13.6 and 24.6eV were pointed out in previous investigations of relative abundances versus the second ionization potentials for Am-type stars. The dependencies of the relative abundances of chemical elements on the second ionization potentials of these elements were investigated using the published abundance patterns of B-F-type stars. The correlations of relative and absolute abundances of chemical elements, second ionization potentials, and projected rotational velocities are clearly detected for stars with effective temperatures between 7000 and 12000K. If the correlation of relative abundances and second ionization potentials can be explained by the accretion of interstellar gas on the stellar surfaces, the investigation of these correlations can provide valuable information on the density and velocities of interstellar gas in different regions of the Galaxy and also on the influence of this phenomenon on stellar evolution. The dependencies of the relative abundances of chemical elements on the condensation temperatures of these elements were also found in the atmospheres of {rho} Pup, {delta} Sct, and other B--F-type stars. Ten possible {lambda} Boo-type stars were detected. The effective temperatures of these objects are between 10900 and 14000K.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/465/815
- Title:
- Abundances of Sgr dSph stars
- Short Name:
- J/A+A/465/815
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Sagittarius dwarf spheroidal galaxy is the nearest neighbor of the Milky Way. Moving along a short period quasi-polar orbit within the Halo, it is being destroyed by the tidal interaction with our Galaxy, losing its stellar content along a huge stellar stream. We study the detailed chemical composition of 12 giant stars in the Sagittarius dwarf Spheroidal main body, together with 5 more in the associated globular cluster Terzan 7, by means of high resolution VLT-UVES spectra. Abundances are derived for up to 21 elements from O to Nd, by fitting lines EW or line profiles against ATLAS 9 model atmospheres and SYNTHE spectral syntheses calculated ad-hoc. Temperatures are derived from (V-I)_0_ or (B-V)_0_ colors and gravities from FeI-FeII ionization equilibrium. The metallicity of the observed stars is between [Fe/H]=-0.9 and 0. We detected a highly peculiar "chemical signature", with undersolar alpha elements, Na, Al , Sc, V, Co, Ni, Cu, and Zn, among others, and overabundant La, Ce, and Nd. Many of these abundance ratios (in particular light-odd elements and iron peak ones) are strongly at odds with what is observed within the Milky Way, so they may be a very useful tool for recognizing populations originating within the Sagittarius dwarf. This can be clearly seen in the case of the globular Palomar 12, which is believed to have been stripped from Sagittarius: the cluster shows precisely the same chemical "oddities", thus finally confirming its extragalactic origin.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/94
- Title:
- Abundances of solar twins from Keck/HIRES
- Short Name:
- J/ApJ/839/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The six planets of the Kepler-11 system are the archetypal example of a population of surprisingly low-density transiting planets revealed by the Kepler mission. We have determined the fundamental parameters and chemical composition of the Kepler-11 host star to unprecedented precision using an extremely high-quality spectrum from Keck-HIRES (R~67000, S/N per pixel ~260 at 600nm). Contrary to previously published results, our spectroscopic constraints indicate that Kepler-11 is a young main-sequence solar twin. The revised stellar parameters and new analysis raise the densities of the Kepler-11 planets by between 20% and 95% per planet, making them more typical of the emerging class of "puffy" close-in exoplanets. We obtain photospheric abundances of 22 elements and find that Kepler-11 has an abundance pattern similar to that of the Sun with a slightly higher overall metallicity. We additionally analyze the Kepler light curves using a photodynamical model and discuss the tension between spectroscopic and transit/TTV-based estimates of stellar density.
- ID:
- ivo://CDS.VizieR/J/A+A/327/587
- Title:
- Abundances of 9 solar-type stars
- Short Name:
- J/A+A/327/587
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Line identifications, measured equivalent widths and derived chemical abundances in 9 solar-type dwarf stars, which are identified by their Bright Star (HR, (Cat. <V/50>)) numbers.
- ID:
- ivo://CDS.VizieR/J/A+A/530/A15
- Title:
- Abundances of 94 stars
- Short Name:
- J/A+A/530/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Abundances of Mn, Cu, Zn, Y, and Ba are determined for a sample of stars previously studied by Nissen & Schuster (2010, Cat. J/A+A/511/L10). Equivalent widths of atomic lines are measured from high resolution VLT/UVES and NOT/FIES spectra and used to derive abundance ratios from an LTE analysis based on MARCS model atmospheres. The analysis is made relative to two thick-disk stars, HD22879 and HD76932, such that very precise differential values are obtained.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/27
- Title:
- Abundances of 11 stars in Carina II and III
- Short Name:
- J/ApJ/889/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first detailed elemental abundances in the ultra-faint Magellanic satellite galaxies Carina II (Car II) and Carina III (CarIII). With high-resolution Magellan/MIKE spectroscopy, we determined the abundances of nine stars in Car II, including the first abundances of an RR Lyrae star in an ultra-faint dwarf galaxy (UFD), and two stars in Car III. The chemical abundances demonstrate that both systems are clearly galaxies and not globular clusters. The stars in these galaxies mostly display abundance trends matching those of other similarly faint dwarf galaxies: enhanced but declining [{alpha}/Fe] ratios, iron-peak elements matching the stellar halo, and unusually low neutron-capture element abundances. One star displays a low outlying [Sc/Fe]=-1.0. We detect a large Ba scatter in Car II, likely due to inhomogeneous enrichment by low-mass asymptotic giant branch star winds. The most striking abundance trend is for [Mg/Ca] in Car II, which decreases from +0.4 to -0.4 and indicates clear variation in the initial progenitor masses of enriching core-collapse supernovae. So far, the only UFDs displaying a similar [Mg/Ca] trend are likely satellites of the Large Magellanic Cloud. We find two stars with [Fe/H]<=-3.5 whose abundances likely trace the first generation of metal-free Population III stars and are well fit by Population III core-collapse supernova yields. An appendix describes our new abundance uncertainty analysis that propagates line-by-line stellar parameter uncertainties.
- ID:
- ivo://CDS.VizieR/J/AJ/129/303
- Title:
- Abundances of stars in M3 and M13
- Short Name:
- J/AJ/129/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a detailed abundance analysis for 21 elements in a sample of 27 stars with a wide range in luminosity from luminous giants to stars near the main-sequence turnoff in the globular cluster M13 ([Fe/H]=-1.50dex) and in a sample of 13 stars distributed from the tip to the base of the red giant branch (RGB) in the globular cluster M3 ([Fe/H]=-1.39dex). The analyzed spectra, obtained with HIRES at the Keck Observatory, are of high dispersion (R={lambda}/{Delta}{lambda}=35000).
- ID:
- ivo://CDS.VizieR/J/ApJ/854/184
- Title:
- Abundances of stars in 3 open clusters
- Short Name:
- J/ApJ/854/184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Single stars in open clusters with known distances are important targets in constraining the nucleosynthesis process since their ages and luminosities are also known. In this work, we analyze a sample of 29 single red giants of the open clusters NGC2360, NGC3680, and NGC5822 using high-resolution spectroscopy. We obtained atmospheric parameters, abundances of the elements C, N, O, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd, as well as radial and rotational velocities. We employed the local thermodynamic equilibrium atmospheric models of Kurucz and the spectral analysis code moog. Rotational velocities and light-element abundances were derived using spectral synthesis. Based on our analysis of the single red giants in these three open clusters, we could compare, for the first time, their abundance pattern with that of the binary stars of the same clusters previously studied. Our results show that the abundances of both single and binary stars of the open clusters NGC 2360, NGC 3680, and NGC 5822 do not have significant differences. For the elements created by the s-process, we observed that the open clusters NGC2360, NGC3680, and NGC5822 also follow the trend already raised in the literature that young clusters have higher s-process element abundances than older clusters. Finally, we observed that the three clusters of our sample exhibit a trend in the [Y/Mg]-age relation, which may indicate the ability of the [Y/Mg] ratio to be used as a clock for the giants.
- ID:
- ivo://CDS.VizieR/J/ApJ/701/1053
- Title:
- Abundances of 8 stars in the Draco dSph
- Short Name:
- J/ApJ/701/1053
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an abundance analysis based on high-resolution spectra of eight stars selected to span the full range in metallicity in the Draco dwarf spheroidal (dSph) galaxy. We find that [Fe/H] for the sample stars ranges from -1.5 to -3.0dex. Combining our sample with previously published work for a total of 14 luminous Draco giants, we show that the abundance ratios [Na/Fe], [Mg/Fe], and [Si/Fe] for the Draco giants overlap those of Galactic halo giants at the lowest [Fe/H] probed, but are significantly lower for the higher Fe-metallicity Draco stars. Using a toy model we compare the behavior of the abundance ratios within the sample of Draco giants with those from the literature of Galactic globular clusters, and the Carina and Sgr dSph galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/732/55
- Title:
- Abundances of stars with planets
- Short Name:
- J/ApJ/732/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precise abundances of 18 elements have been derived for 10 stars known to host giant planets from high signal-to-noise ratio, high-resolution echelle spectroscopy. Internal uncertainties in the derived abundances are typically <~0.05dex. The stars in our sample have all been previously shown to have abundances that correlate with the condensation temperature (T_c_) of the elements in the sense of increasing abundances with increasing T_c_; these trends have been interpreted as evidence that the stars may have accreted H-depleted planetary material. Our newly derived abundances also correlate positively with T_c_, although slopes of linear least-square fits to the [m/H]-T_c_ relations for all but two stars are smaller here than in previous studies. When considering the refractory elements (T_c_>900K) only, which may be more sensitive to planet formation processes, the sample can be separated into a group with positive slopes (four stars) and a group with flat or negative slopes (six stars). The four stars with positive slopes have very close-in giant planets (three at 0.05AU) and slopes that fall above the general Galactic chemical evolution trend. We suggest that these stars have accreted refractory-rich planet material but not to the extent that would increase significantly the overall stellar metallicity. The flat or negative slopes of the remaining six stars are consistent with recent suggestions of a planet formation signature, although we show that the trends may be the result of Galactic chemical evolution.
