- ID:
- ivo://CDS.VizieR/J/MNRAS/370/2091
- Title:
- Abundances of HD 134439/40 and HD 211998
- Short Name:
- J/MNRAS/370/2091
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Abundances of 18 elements are determined for the common proper-motion pair, HD 134439 and HD 134440, which shows high [Mn/Fe] and low [alpha/Fe] ratios as compared to normal halo stars. Moreover, puzzling abundances are indicated from elements whose origins are normally considered to be from the same nucleosynthesis history. Particularly, we have found that [Mg/Fe] and [Si/Fe] are lower than [Ca/Fe] and [Ti/Fe] by 0.1-0.3dex. When elemental abundances are interpreted in term of their condensation temperatures (T_C_), obvious trends of [X/Fe] versus TC for alpha elements and probably iron-peak elements as well are shown. The hypothesis that these stars have formed from a dusty environment in dwarf spheroidal (dSph) galaxy provides a solution to the puzzling abundance pattern.
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- ID:
- ivo://CDS.VizieR/J/A+A/368/250
- Title:
- Abundances of HDE 341617
- Short Name:
- J/A+A/368/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detailed atmospheric abundances have been calculated for a sample of A-G supergiant stars with IR fluxes and/or high galactic latitudes. HD 172481 and HD 158616 show clear indications of being post-AGB stars that have experienced third dredge-up. HD 158616 is carbon-rich while the abundance pattern of HD 172481 and its large Li enhancement gives support to the hot bottom burning scenario that explains paucity of carbon-rich stars among AGB stars. HD 172324 is very likely a hot post-AGB star that shows a strong carbon deficiency. HD 725, HD 218753 and HD 331319 also appear to be evolved objects between the red giant and the AGB. HD 9167, HD 173638 with a few exceptions, reflect solar abundances and no signs of post red giant evolution. They are most likely young massive disk supergiants. Further analysis of proto-Planetary Nebula HDE 341617 reveals that He lines show signs of velocity stratification. The emission lines have weakened considerably since 1993. The envelope expands at 19km/s relative to the star. Atmospheric abundances, evolutionary tracks and isochrones are used to estimate masses and ages of all stars in the sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/123
- Title:
- Abundances of heavy ions in ICMEs from 1998-2011
- Short Name:
- J/ApJ/900/123
- Date:
- 20 Jan 2022 00:43:36
- Publisher:
- CDS
- Description:
- This statistical work studies the abundances and the charge states of the carbon, oxygen, and iron ions in 281 interplanetary coronal mass ejections (ICMEs) measured at 1 au by ACE spacecraft from 1998 to 2011. The Gaussian distribution test is applied, and the analysis of variance is used to quantify the similarity between two distributions of ionic charge states and abundances. The correlation coefficient is calculated to reveal the dependence of the abundances and the mean charge of heavy ions on the solar activity. The results show that the mean charge, the abundance, and the speed at 1 au are highly related to the sunspot number (SN). The O7+/O6+ shows statistical difference between the high speed and the low speed groups of ICMEs. Different from the cold materials inside ICMEs, the mean charge of carbon ions shows a positive relation to that of oxygen ions. The Mg/O in the studied ICMEs are much higher than that in the solar wind. Three types of charge distribution of C, O, and Fe ions are summarized. The fraction of each of the three types is related to the solar minimum or the solar maximum. The mean charge and the flux of oxygen ions show quasi-linear relations to the SN during solar minimum, and show fluctuations during maximum. The results reveal that the solar activity, which represents the solar magnetic field status by nature, controls the composition of heavy ions in ICMEs.
- ID:
- ivo://CDS.VizieR/J/AZh/79/867
- Title:
- Abundances of HII regions in blue galaxies
- Short Name:
- J/AZh/79/867
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New expression for the ionization correction factors (ICF) are used to find the nebular-gas compositions in HII regions in blue compact dwarf galaxies (BCD). The abundances of He, N, O, Ne, S, and Ar in 41 HII regions are determined.
- ID:
- ivo://CDS.VizieR/J/A+AS/129/563
- Title:
- Abundances of HR 4487, 14 Hyd and 3 Cen A
- Short Name:
- J/A+AS/129/563
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ussing CASLEO echelle spectrograms, elemental abundances are derived for the sharp-lined non-magnetic CP stars HR 4487, 14 Hya and 3 Cen A. The first two stars are members of the Mercury-Manganese subgroup and have abundances which are similar to other such peculiar stars. The third is a hotter related star. The detection of Mn II lines in its spectrum adds to this relationship.
- ID:
- ivo://CDS.VizieR/J/MNRAS/422/2969
- Title:
- Abundances of 19 K-type giants in moving groups
- Short Name:
- J/MNRAS/422/2969
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stellar parameters of 19 K-type giants and their abundances for 13 chemical elements (Al, Ba, Ca, Fe, K, Mg, Mn, Na, Ni, Sc, Si, Ti and V), selected from two moving groups, covering the metallicity range of -0.6<[Fe/H]<0.2, based on high-resolution spectra. Most of the elemental abundances show similar trends as in previous studies, except for Al, Na and Ba, which are seriously affected by evolution. The abundance ratios of [Na/Mg] increase smoothly with higher [Mg/H], and those of [Al/Mg] decrease slightly with increasing [Mg/H]. The abundance ratios of [Mg/Ba] show a distinction between these two moving groups, which is mainly induced by chemical evolution and also partly by kinematic effects. The inhomogeneous metallicity of each star from the moving groups demonstrates that these stars had different chemical origins before they were kinematically aggregated. This favours a dynamical resonant theory.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/5
- Title:
- Abundances of LAMOST giants from APOGEE DR12
- Short Name:
- J/ApJ/836/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this era of large-scale spectroscopic stellar surveys, measurements of stellar attributes ("labels," i.e., parameters and abundances) must be made precise and consistent across surveys. Here, we demonstrate that this can be achieved by a data-driven approach to spectral modeling. With The Cannon, we transfer information from the APOGEE survey to determine precise T_eff_, logg, [Fe/H], and [{alpha}/M] from the spectra of 450000 LAMOST giants. The Cannon fits a predictive model for LAMOST spectra using 9952 stars observed in common between the two surveys, taking five labels from APOGEE DR12 as ground truth T_eff_, logg, [Fe/H], [{alpha}/M], and K-band extinction A_k_. The model is then used to infer T_eff_, logg, [Fe/H], and [{alpha}/M] for 454180 giants, 20% of the LAMOST DR2 stellar sample. These are the first [{alpha}/M] values for the full set of LAMOST giants, and the largest catalog of [{alpha}/M] for giant stars to date. Furthermore, these labels are by construction on the APOGEE label scale; for spectra with S/N>50, cross-validation of the model yields typical uncertainties of 70K in T_eff_, 0.1 in logg, 0.1 in [Fe/H], and 0.04 in [{alpha}/M], values comparable to the broadly stated, conservative APOGEE DR12 uncertainties. Thus, by using "label transfer" to tie low-resolution (LAMOST R~1800) spectra to the label scale of a much higher-resolution (APOGEE R~22500) survey, we substantially reduce the inconsistencies between labels measured by the individual survey pipelines. This demonstrates that label transfer with The Cannon can successfully bring different surveys onto the same physical scale.
- ID:
- ivo://CDS.VizieR/III/27A
- Title:
- Abundances of late G/K dwarfs in solar neighborhood
- Short Name:
- III/27A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this investigation, a technique developed by Spinrad and Taylor for obtaining metal abundances of late-type stars, and used by them in an earlier investigation of evolved stars (see Cat. II/47), is applied to field dwarfs in the solar vicinity and to the Hyades. The colors determined from photoelectric spectrum-scanner observations are listed in the "raw_data.dat" file; the derived blocking factors are given in the "blocking.dat" file. These results were published as the Table 5 of the paper.
- ID:
- ivo://CDS.VizieR/J/AJ/145/52
- Title:
- Abundances of late K and M dwarfs in binary systems
- Short Name:
- J/AJ/145/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Knowledge of late K and M dwarf metallicities can be used to guide planet searches and constrain planet formation models. However, the determination of metallicities of late-type stars is difficult because visible wavelength spectra of their cool atmospheres contain many overlapping absorption lines, preventing the measurement of equivalent widths. We present new methods, and improved calibrations of existing methods, to determine metallicities of late K and M dwarfs from moderate resolution (1300<R<2000) visible and infrared spectra. We select a sample of 112 wide binary systems that contain a late-type companion to a solar-type primary star. Our sample includes 62 primary stars with previously published metallicities, as well as 50 stars with metallicities determined from our own observations. We use our sample to empirically determine which features in the spectrum of the companion are best correlated with the metallicity of the primary. We find ~120 features in K and M dwarf spectra that are useful for predicting metallicity. We derive metallicity calibrations for different wavelength ranges, and show that it is possible to get metallicities reliable to <0.10dex using either visible, J-, H-, or K-band spectra. We find that the most accurate metallicities derived from visible spectra requires the use of different calibrations for early-type (K5.5-M2) and late-type (M2-M6) dwarfs. Our calibrations are applicable to dwarfs with metallicities of -1.04<[Fe/H]<+0.56 and spectral types from K7 to M5. Lastly, we use our sample of wide binaries to test and refine existing calibrations to determine M dwarf metallicities. We find that the {zeta} parameter, which measures the ratio of TiO can CaH bands, is correlated with [Fe/H] for super-solar metallicities, and {zeta} does not always correctly identify metal-poor M dwarfs. We also find that existing calibrations in the K and H bands are quite reliable for stars with [Fe/H]>-0.5, but are less useful for more metal-poor stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/797/69
- Title:
- Abundances of late-type stars
- Short Name:
- J/ApJ/797/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of several absorption lines of neutral phosphorus (P, Z=15) in archival near-ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We derive phosphorus abundances or interesting upper limits in 14 late-type stars with metallicities spanning -3.8<[Fe/H]<-0.1. Previously, phosphorus had only been studied in Galactic stars with -1.0<[Fe/H]<+0.3. Iron lines reveal abundance offsets between the optical and ultraviolet regions, and we discuss and apply a correction factor to account for this offset. In stars with [Fe/H]>-1.0, the [P/Fe] ratio decreases toward the solar value with increasing metallicity, in agreement with previous observational studies. In stars with [Fe/H]<-1.0, $<[P/Fe]$>=+0.04+/-0.10, which overlaps with the [P/Fe] ratios found in several high-redshift damped Lyman-{alpha} systems. This behavior hints at a primary origin in massive stars.
