- ID:
- ivo://CDS.VizieR/J/A+A/558/A106
- Title:
- Chemical abundances for 83 transit hosts
- Short Name:
- J/A+A/558/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precise stellar parameters are crucial in exoplanet research for correctly determining of the planetary parameters. For stars hosting a transiting planet, determining of the planetary mass and radius depends on the stellar mass and radius, which in turn depend on the atmospheric stellar parameters. Different methods can provide different results, which leads to different planet characteristics. In this paper, we use a uniform method to spectroscopically derive stellar atmospheric parameters, chemical abundances, stellar masses, and stellar radii for a sample of 90 transit hosts. Surface gravities are also derived photometrically using the stellar density as derived from the light curve. We study the effect of using these different surface gravities on the determination of the chemical abundances and the stellar mass and radius. A spectroscopic analysis based on Kurucz models in LTE was performed through the MOOG code to derive the atmospheric parameters and the chemical abundances. The photometric surface gravity was determined through isochrone fitting and the use of the stellar density, directly determined from the light curve. Stellar masses and radii are determined through calibration formulae. Spectroscopic and photometric surface gravities differ, but this has very little effect on the precise determination of the stellar mass in our spectroscopic analysis. The stellar radius, and hence the planetary radius, is most affected by the surface gravity discrepancies. For the chemical abundances, the difference is, as expected, only noticable for the abundances derived from analyzing of lines of ionized species.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/775/L27
- Title:
- Chemical abundances in a metal-poor RGB star
- Short Name:
- J/ApJ/775/L27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present chemical abundances for 27 elements ranging from oxygen to erbium in the metal-poor ([Fe/H]=-1.67) bulge red giant branch star 2MASS 18174532-3353235. The results are based on equivalent width and spectrum synthesis analyses of a high-resolution (R~30000) spectrum obtained with the Magellan-MIKE spectrograph. While the light (Z<~30) element abundance patterns match those of similar metallicity bulge and halo stars, the strongly enhanced heavy element abundances are more similar to "r-II" halo stars (e.g., CS 22892-052) typically found at [Fe/H]<~-2.5. We find that the heaviest elements (Z>=56) closely follow the scaled-solar r-process abundance pattern. We do not find evidence supporting significant s-process contributions; however, the intermediate mass elements (e.g., Y and Zr) appear to have been produced through a different process than the heaviest elements. The light and heavy element abundance patterns of 2MASS 18174532-3353235 are in good agreement with the more metal-poor r-process enhanced stars CS 22892-052 and BD +17{deg}3248. 2MASS 18174532-3353235 also shares many chemical characteristics with the similar metallicity but comparatively {alpha}-poor Ursa Minor dwarf galaxy giant COS 82. Interestingly, the Mo and Ru abundances of 2MASS 18174532-3353235 are also strongly enhanced and follow a similar trend recently found to be common in moderately metal-poor main-sequence turn-off halo stars.
- ID:
- ivo://CDS.VizieR/J/AZh/79/909
- Title:
- Chemical abundances in barium stars
- Short Name:
- J/AZh/79/909
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used high-resolution spectra to compute model atmospheres to derive the atmospheric abundances of moderate barium stars. Comparing our results with analogous data for normal red giants, we find that the moderate barium stars appear to not differ systematically from normal red giants. Their chemical abundance anomalies show the same patterns and can be interpreted in terms of evolutionary effects: the evolutionary stage, mass, luminosity, and metallicity of the objects.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A12
- Title:
- Chemical abundances in Galactic PNe
- Short Name:
- J/A+A/567/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new low-resolution (R~800) optical spectra of 22 Galactic PNe with Spitzer spectra. These data are combined with recent optical spectroscopic data available in the literature to construct representative samples of compact (and presumably young) Galactic disc and bulge PNe with Spitzer spectra. Attending to the nature of the dust features seen in their Spitzer spectra, Galactic disc and bulge PNe are classified according to four major dust types (oxygen chemistry or OC, carbon chemistry or CC, double chemistry or DC, featureless or F) and subtypes (amorphous and crystalline, and aliphatic and aromatic). Nebular gas abundances of He, N, O, Ne, S, Cl, and Ar, as well as plasma parameters (e.g. Ne, Te) are homogeneously derived and we study the median chemical abundances and nebular properties in Galactic disc and bulge PNe depending on their Spitzer dust types and subtypes. A comparison of the derived median abundance patterns with AGB nucleosynthesis predictions show mainly that i) DC PNe, both with amorphous and crystalline silicates, display high-metallicity (solar/supra-solar) and the highest He abundances and N/O ratios, suggesting relatively massive (~3-5M_{sun}_) hot bottom burning AGB stars as progenitors; ii) PNe with O-rich and C-rich unevolved dust (amorphous and aliphatic) seem to evolve from subsolar metallicity (z~0.008) and lower mass (<3M_{sun}_) AGB stars; iii) a few O-rich PNe and a significant fraction of C-rich PNe with more evolved dust (crystalline and aromatic, respectively) display chemical abundances similar to DC PNe, suggesting that they are related objects. A comparison of the derived nebular properties with predictions from models combining the theoretical central star evolution with a simple nebular model is also presented. Finally, a possible link between the Spitzer dust properties, chemical abundances, and evolutionary status is discussed.
- ID:
- ivo://CDS.VizieR/III/193
- Title:
- Chemical Abundances in Late-Type Stars
- Short Name:
- III/193
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue includes chemical abundances determinations (from Li to Eu) and atmospheric parameters (Teff, logg, microturbulent velocity) obtained from re-analyses of 1108 Late-Type Stars. It contains field stars of the Galaxy, of open and globular cluster stars, and stars belonging to the LMC and the SMC. Almost all of these stars are referenced in the Cayrel de Strobel et al.'s [Fe/H] catalog (see cat. <III/200>). Most of the abundance results are very reliable within 0.2dex when using different sources of equivalent widths taken from the literature for a given star.
- ID:
- ivo://CDS.VizieR/J/MNRAS/378/318
- Title:
- Chemical abundances in Leo I and II dSph
- Short Name:
- J/MNRAS/378/318
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained calcium abundances and radial velocities for 102 red giant branch (RGB) stars in the Leo I dwarf spheroidal galaxy (dSph) and 74 RGB stars in the Leo II dSph using the low-resolution spectrograph (LRIS) on the Keck I 10-m telescope. We report on the calcium abundances [Ca/H] derived from the strengths of the Ca ii triplet absorption lines at 8498, 8542 and 8662{AA} in the stellar spectra using a new empirical Ca II triplet calibration to [Ca/H].
- ID:
- ivo://CDS.VizieR/J/A+A/440/321
- Title:
- Chemical abundances in 43 metal-poor stars
- Short Name:
- J/A+A/440/321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Ni and Ba for 43 metal-poor field stars in the solar neighbourhood, most of them subgiants or turn-off-point stars, with iron abundances [Fe/H] ranging from -0.4 to -3.0. About half of this sample has not been analysed spectroscopically in detail before. Effective temperatures were estimated from uvby photometry, and surface gravities primarily from Hipparcos parallaxes. The analysis is differential relative to the Sun, and carried out with plane-parallel MARCS models. Various sources of error are discussed and found to contribute a total error of about 0.1-0.2dex for most elements, while relative abundances, such as [Ca/Fe], are most probably more accurate. For the oxygen abundances, determined in an NLTE analysis of the 7774{AA} triplet lines, the errors may be somewhat larger.
- ID:
- ivo://CDS.VizieR/J/AJ/161/183
- Title:
- Chemical abundances in 52 M-giant stars
- Short Name:
- J/AJ/161/183
- Date:
- 18 Jan 2022
- Publisher:
- CDS
- Description:
- We measured ^35^Cl abundances in 52-M giants with metallicities in the range -0.5<[Fe/H]<0.12. Abundances and atmospheric parameters were derived using infrared spectra from CSHELL on the NASA Infrared Telescope Facility and from optical echelle spectra. We measured Cl abundances by fitting a H^35^Cl molecular feature at 3.6985{mu}m with synthetic spectra. We also measured the abundances of O, Ca, Ti, and Fe using atomic absorption lines. We find that the [Cl/Fe] ratio for our stars agrees with chemical evolution models of Cl, and the [Cl/Ca] ratio is broadly consistent with the solar ratio over our metallicity range. Both indicate that Cl is primarily made in core-collapse supernovae with some contributions from Type Ia supernovae. We suggest that other potential nucleosynthesis processes, such as the {nu}-process, are not significant producers of Cl. Finally, we also find our Cl abundances are consistent with HII and planetary nebular abundances at a given oxygen abundance, although there is scatter in the data.
- ID:
- ivo://CDS.VizieR/J/ApJ/824/5
- Title:
- Chemical abundances in NGC 5024 (M53)
- Short Name:
- J/ApJ/824/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Fe, Ca, Ti, Ni, Ba, Na, and O abundances for a sample of 53 red giant branch stars in the globular cluster (GC) NGC 5024 (M53). The abundances were measured from high signal-to-noise medium resolution spectra collected with the Hydra multi-object spectrograph on the Wisconsin-Indiana-Yale-NOAO 3.5m telescope. M53 is of interest because previous studies based on the morphology of the cluster's horizontal branch suggested that it might be composed primarily of first generation (FG) stars and differ from the majority of other GCs with multiple populations, which have been found to be dominated by the second generation (SG) stars. Our sample has an average [Fe/H]=-2.07 with a standard deviation of 0.07dex. This value is consistent with previously published results. The alpha-element abundances in our sample are also consistent with the trends seen in Milky Way halo stars at similar metallicities, with enhanced [Ca/Fe] and [Ti/Fe] relative to solar. We find that the Na-O anti-correlation in M53 is not as extended as other GCs with similar masses and metallicities. The ratio of SG to the total number of stars in our sample is approximately 0.27 and the SG generation is more centrally concentrated. These findings further support that M53 might be a mostly FG cluster and could give further insight into how GCs formed the light element abundance patterns we observe in them today.
- ID:
- ivo://CDS.VizieR/J/A+A/360/509
- Title:
- Chemical abundances in 7 red giants
- Short Name:
- J/A+A/360/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundances of about fifteen elements from oxygen to europium are measured in seven red giants of the two open clusters NGC 2360 and NGC 2447. The effective temperatures of the giants are determined spectroscopically by taking advantage of their known masses (~2M_{sun}_ in NGC 2360 and ~3M_{sun}_ in NGC 2447) and bolometric magnitudes. The average iron abundances we obtain for the two clusters are [Fe/H]=0.07 for NGC 2360 and [Fe/H]=0.03 for NGC 2447.
