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81. Abundances of 4 red giants in Pal 1
ID:
ivo://CDS.VizieR/J/ApJ/740/106
Title:
Abundances of 4 red giants in Pal 1
Short Name:
J/ApJ/740/106
Date:
21 Oct 2021
Publisher:
CDS
Description:
Detailed chemical abundances for 21 elements are presented for four red giants in the anomalous outer halo globular cluster Palomar 1 (R_GC_=17.2kpc, Z=3.6kpc) using high-resolution (R=36000) spectra from the High Dispersion Spectrograph on the Subaru Telescope. Pal 1 has long been considered unusual because of its low surface brightness, sparse red giant branch, young age, and its possible association with two extragalactic streams of stars. This paper shows that its chemistry further confirms its unusual nature. The mean metallicity of the four stars, [Fe/H]=-0.60+/-0.01, is high for a globular cluster so far from the Galactic center, but is low for a typical open cluster. The [{alpha}/Fe] ratios, though in agreement with the Galactic stars within the 1{sigma} errors, agree best with the lower values in dwarf galaxies. No signs of the Na/O anticorrelation are detected in Pal 1, though Na appears to be marginally high in all four stars. Pal 1's neutron-capture elements are also unusual: its high [Ba/Y] ratio agrees best with dwarf galaxies, implying an excess of second-peak over first-peak s-process elements, while its [Eu/{alpha}] and [Ba/Eu] ratios show that Pal 1's contributions from the r-process must have differed in some way from normal Galactic stars. Therefore, Pal 1 is unusual chemically, as well in its other properties. Pal 1 shares some of its unusual abundance characteristics with the young clusters associated with the Sagittarius dwarf galaxy remnant and the intermediate-age LMC clusters, and could be chemically associated with the Canis Majoris overdensity; however, it does not seem to be similar to the Monoceros/Galactic Anticenter Stellar Stream.
82. Abundances of 11 stars in Carina II and III
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.
83. Abundances of 3 supergiants in Sextans A
ID:
ivo://CDS.VizieR/J/AJ/127/2723
Title:
Abundances of 3 supergiants in Sextans A
Short Name:
J/AJ/127/2723
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the abundance analyses of three isolated A-type supergiant stars in the dwarf irregular galaxy Sextans A (=DDO 75) from high-resolution spectra obtained with the Ultraviolet-Visual Echelle Spectrograph (UVES) on the Kueyen telescope (UT2) of the ESO Very Large Telescope (VLT). Detailed model atmosphere analyses have been used to determine the stellar atmospheric parameters and the elemental abundances of the stars.
84. Abundances of the eclipsing binary ZZ Boo
ID:
ivo://CDS.VizieR/J/AJ/144/35
Title:
Abundances of the eclipsing binary ZZ Boo
Short Name:
J/AJ/144/35
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigated ZZ Boo using a high-resolution (R=80000) spectrum obtained at the BOES echelle spectrograph attached to a 1.8m telescope at the Bohuynsan observatory in Korea. The atmospheric parameters of the components were found using the published photometrical observations and the abundance analysis of iron lines: the flux ratio of the components F_A_/F_B_=1.12+/-0.15, the effective temperatures of the components T_eff_=6860+/-20K and 6930+/-20K, the surface gravities log g=3.72+/-0.10 and 3.84+/-0.10, the metallicities [Fe/H]=-0.10+/-0.08 and -0.03+/-0.10, and the projected rotation velocities vsin i=11.9+/-0.4km/s and 19.3+/-0.8km/s for the primary and secondary components, respectively. The pointed errors are the formal errors of the methods used; the systematic errors of the temperatures, gravities, metallicities, and projected rotational velocities can be as high as 250-300K, 0.3dex, 0.15dex, and 4km/s, respectively. The abundances of 24 and 22 chemical elements were determined in the atmospheres of the components. The abundance pattern of the primary component shows the solar or slightly undersolar abundances of all elements. CNO abundances are close to solar values. The abundance pattern of this component resembles those of {lambda} Boo type stars. The abundances of light elements, except oxygen, in the atmosphere of the secondary component are practically solar. The abundances of barium and two detected lanthanides are close to the solar values; the overabundance of oxygen is 0.9dex. The abundances of two components are evidently different. The comparison of relative abundances with the condensation temperatures and second ionization potentials of the elements confirms the difference in abundance patterns and allows discussion of the different accretion scenarios for two components of this binary system.
85. Abundances of the halo PN BoBn 1
ID:
ivo://CDS.VizieR/J/ApJ/723/658
Title:
Abundances of the halo PN BoBn 1
Short Name:
J/ApJ/723/658
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have performed a comprehensive chemical abundance analysis of the extremely metal-poor ([Ar/H]<-2) halo planetary nebula (PN) BoBn 1 based on International Ultraviolet Explorer archive data, Subaru/High-Dispersion Spectrograph spectra, VLT/UVES archive data, and Spitzer/IRS spectra. We have detected over 600 lines in total and calculated ionic and elemental abundances of 13 elements using detected optical recombination lines (ORLs) and collisionally excited lines (CELs). The estimations of C, N, O, and Ne abundances from the ORLs and Kr, Xe, and Ba from the CELs are done the first for this nebula, empirically and theoretically. We have detected five fluorine and several slow neutron capture elements (the s-process). The amounts of [F/H], [Kr/H], and [Xe/H] suggest that BoBn 1 is the most F-rich among F-detected PNe and is a heavy s-process element rich PN. We have confirmed dust in the nebula that is composed of amorphous carbon and polycyclic aromatic hydrocarbons with a total mass of 5.8x10^-6^M_{sun}_. The photoionization models built with non-LTE theoretical stellar atmospheres indicate that the progenitor was a 1-1.5M_{sun}_ star that would evolve into a white dwarf with an ~0.62M_{sun}_ core mass and ~0.09M_{sun}_ ionized nebula. We have measured a heliocentric radial velocity of +191.6+/-1.3km/s and expansion velocity 2V_exp_ of 40.5+/-3.3km/s from an average over 300 lines.
86. Abundances of the Ret II brightest red giant members
ID:
ivo://CDS.VizieR/J/ApJ/830/93
Title:
Abundances of the Ret II brightest red giant members
Short Name:
J/ApJ/830/93
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present chemical abundances derived from high-resolution Magellan/Magellan Inamori Kyocera Echelle spectra of the nine brightest known red giant members of the ultra-faint dwarf galaxy Reticulum II (Ret II). These stars span the full metallicity range of Ret II (-3.5<[Fe/H]< -2). Seven of the nine stars have extremely high levels of r-process material ([Eu/Fe]~1.7), in contrast to the extremely low neutron-capture element abundances found in every other ultra-faint dwarf galaxy studied to date. The other two stars are the most metal-poor stars in the system ([Fe/H]< -3), and they have neutron-capture element abundance limits similar to those in other ultra-faint dwarf galaxies. We confirm that the relative abundances of Sr, Y, and Zr in these stars are similar to those found in r-process halo stars, but they are ~0.5dex lower than the solar r-process pattern. If the universal r-process pattern extends to those elements, the stars in Ret II display the least contaminated known r-process pattern. The abundances of lighter elements up to the iron peak are otherwise similar to abundances of stars in the halo and in other ultra-faint dwarf galaxies. However, the scatter in abundance ratios is large enough to suggest that inhomogeneous metal mixing is required to explain the chemical evolution of this galaxy. The presence of low amounts of neutron-capture elements in other ultra-faint dwarf galaxies may imply the existence of additional r-process sites besides the source of r-process elements in Ret II. Galaxies like Ret II may be the original birth sites of r-process enhanced stars now found in the halo.
87. Abundances of two very metal-poor stars
ID:
ivo://CDS.VizieR/J/ApJ/819/103
Title:
Abundances of two very metal-poor stars
Short Name:
J/ApJ/819/103
Date:
21 Oct 2021
Publisher:
CDS
Description:
From high resolution (R~=45000), high signal-to-noise ratio (S/N>400) spectra gathered with the Immersion Grating Infrared Spectrograph (IGRINS) in the H and K photometric bands, we have derived elemental abundances of two bright, well-known metal-poor halo stars: the red giant HD 122563 and the subgiant HD 140283. Since these stars have metallicities approaching [Fe/H]=-3, their absorption features are generally very weak. Neutral-species lines of Mg, Si, S and Ca are detectable, as well as those of the light odd-Z elements Na and Al. The derived IR-based abundances agree with those obtained from optical-wavelength spectra. For Mg and Si the abundances from the infrared transitions are improvements to those derived from shorter wavelength data. Many useful OH and CO lines can be detected in the IGRINS HD 122563 spectrum, from which derived O and C abundances are consistent to those obtained from the traditional [OI] and CH features. IGRINS high resolutions H- and K-band spectroscopy offers promising ways to determine more reliable abundances for additional metal-poor stars whose optical features are either not detectable, or too weak, or are based on lines with analytical difficulties.
88. Abundances of various elements in 20 Peg
ID:
ivo://CDS.VizieR/J/AZh/79/841
Title:
Abundances of various elements in 20 Peg
Short Name:
J/AZh/79/841
Date:
21 Oct 2021
Publisher:
CDS
Description:
Atmosphere study of the giant 20 Peg was investigated using high-resolution spectra.
89. Abundances of very metal-poor stars in Sagittarius
ID:
ivo://CDS.VizieR/J/ApJ/855/83
Title:
Abundances of very metal-poor stars in Sagittarius
Short Name:
J/ApJ/855/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
Sagittarius (Sgr) is a massive disrupted dwarf spheroidal galaxy in the Milky Way halo that has undergone several stripping events. Previous chemical studies were restricted mainly to a few, metal-rich ([Fe/H]>~-1) stars that suggested a top-light initial mass function (IMF). Here we present the first high-resolution, very metal-poor ([Fe/H]=-1 to -3) sample of 13 giant stars in the main body of Sgr. We derive abundances of 13 elements, namely C, Ca, Co, Fe, Sr, Ba, La, Ce, Nd, Eu, Dy, Pb, and Th, that challenge the interpretation based on previous studies. Our abundances from Sgr mimic those of the metal-poor halo, and our most metal-poor star ([Fe/H]~-3) indicates a pure r-process pollution. Abundances of Sr, Pb, and Th are presented for the first time in Sgr, allowing for age determination using nuclear cosmochronology. We calculate ages of 9+/-2.5Gyr. Most of the sample stars have been enriched by a range of asymptotic giant branch (AGB) stars with masses between 1.3 and 5M_{sun}_. SgrJ190651.47-320147.23 shows a large overabundance of Pb (2.05dex) and a peculiar abundance pattern best fit by a 3M_{sun}_ AGB star. Based on star-to-star scatter and observed abundance patterns, a mixture of low- and high-mass AGB stars and supernovae (15-25M_{sun}_) is necessary to explain these patterns. The high level (0.29+/-0.05dex) of Ca indicates that massive supernovae must have existed and polluted the early ISM of Sgr before it lost its gas. This result is in contrast with a top-light IMF with no massive stars polluting Sgr.
90. Abundance study of LMC post-AGB stars
ID:
ivo://CDS.VizieR/J/A+A/554/A106
Title:
Abundance study of LMC post-AGB stars
Short Name:
J/A+A/554/A106
Date:
21 Oct 2021
Publisher:
CDS
Description:
The photospheric abundances of evolved solar-type stars of different metallicities serve as probes into stellar evolution theory. Stellar photospheres of post-asymptotic giant branch (post-AGB) stars bear witness to the internal chemical enrichment processes, integrated over their entire stellar evolution. Here we study post-AGB stars in the Large Magellanic Cloud (LMC). With their known distances, these rare objects are ideal tracers of AGB nucleosynthesis and dredge-up phenomena.

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