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Start Over Subject population ii stars Publisher CDS
91. UBVRcIc photometry of FHB and metal-poor stars
ID:
ivo://CDS.VizieR/J/ApJS/168/128
Title:
UBVRcIc photometry of FHB and metal-poor stars
Short Name:
J/ApJS/168/128
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report broadband UBV and/or BVR_C_I_C_ CCD photometry for a total of 1857 stars in the thick-disk and halo populations of the Galaxy. The majority of our targets were selected as candidate field horizontal-branch or other A-type stars (FHB/A, N=576), or candidate low-metallicity stars (N=1221), from the HK and Hamburg/ESO objective-prism surveys. Similar data for a small number of additional stars from other samples are also reported.
92. VI light curves of Galactic Bulge Cepheids
ID:
ivo://CDS.VizieR/J/AcA/61/285
Title:
VI light curves of Galactic Bulge Cepheids
Short Name:
J/AcA/61/285
Date:
21 Oct 2021
Publisher:
CDS
Description:
The fourteenth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains Cepheid variables detected in the OGLE-II and OGLE-III fields toward the Galactic bulge. The catalog is divided into two main categories: 32 classical Cepheids (21 single-mode fundamental-mode F, four first-overtone 1O, two double-mode F/1O, three double-mode 1O/2O and two triple-mode 1O/2O/3O pulsators) and 335 type II Cepheids (156 BL Her, 128 W Vir and 51 RV Tau stars). Six of the type II Cepheids likely belong to the Sagittarius Dwarf Spheroidal Galaxy. The catalog data include the time-series photometry collected in the course of the OGLE survey, observational parameters of the stars, finding charts, and cross-identifications with the General Catalogue of Variable Stars.
93. VR photometry of type II Cepheids
ID:
ivo://CDS.VizieR/J/AJ/128/1748
Title:
VR photometry of type II Cepheids
Short Name:
J/AJ/128/1748
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 1256 new photometric observations of 36 Cepheids with periods longer than 8 days. The majority are likely type II Cepheids, but we have included about a dozen classical Cepheids for comparison purposes, a few stars of uncertain type, and one putative RV Tauri star. We discuss the appearance of the light curves, the Fourier parameters, and the light-curve stability in terms of differentiation between type I and type II Cepheids. Although we encounter the same difficulties as previous investigators in using these parameters for this purpose, we are able to identify some stars of particular interest, including several likely type I Cepheids at large distances from the Galactic plane. Six stars with especially large period changes are identified and discussed.
94. VR photometry of type II Cepheids. III
ID:
ivo://CDS.VizieR/J/AJ/130/832
Title:
VR photometry of type II Cepheids. III
Short Name:
J/AJ/130/832
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 741 new photometric observations for 22 Cepheids with periods between 3 and 8 days. Many of the stars are probable type II Cepheids, but we have included some type I Cepheids for comparison.
95. WISE J072543.88-235119.7 line abundances
ID:
ivo://CDS.VizieR/J/A+A/582/A74
Title:
WISE J072543.88-235119.7 line abundances
Short Name:
J/A+A/582/A74
Date:
21 Oct 2021
Publisher:
CDS
Description:
The lithium abundance in turnoff stars of the old population of our Galaxy is remarkably constant in the metallicity interval -2.8<[Fe/H]<-2.0, defining a plateau. The Li abundance of these turnoff stars is clearly lower than the abundance predicted by the primordial nucleosynthesis in the frame of the standard Big Bang nucleosynthesis. Different scenarios have been proposed for explaining this discrepancy, along with the very low scatter of the lithium abundance around the plateau. The recently identified very high velocity star, WISE.J0725.2351 appears to belong to the old Galactic population, and appears to be an extreme halo star on a bound, retrograde Galactic orbit. In this paper, we study the abundance ratios and, in particular the lithium abundance, in this star. The available spectra (ESO-Very Large Telescope) are analyzed and the abundances of Li, C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Fe, Co, Ni, Sr and Ba are determined.
96. WISE view of RV Tauri stars
ID:
ivo://CDS.VizieR/J/MNRAS/453/133
Title:
WISE view of RV Tauri stars
Short Name:
J/MNRAS/453/133
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed study based on infrared (IR) photometry of all Galactic RV Tauri stars from the General Catalogue of Variable Stars (GCVS). RV Tauri stars are the brightest among the Population II Cepheids. They are thought to evolve away from the asymptotic giant branch (AGB) towards the white dwarf domain. IRAS detected several RV Tauri stars because of their large IR excesses and it was found that they occupy a specific region in the [12]-[25], [25]-[60] IRAS two-colour diagram. We used the all sky survey of Wide-field Infrared Survey Explorer to extend these studies and compare the IR properties of all RV Tauri stars in the GCVS with a selected sample of post-AGB objects with the goal to place the RV Tauri pulsators in the context of post-AGB evolution. Moreover, we correlated the IR properties of both the RV Tauri stars and the comparison sample with other observables like binarity and the presence of a photospheric chemical anomaly called depletion. We find that Galactic RV Tauri stars display a range of IR properties and we differentiate between disc sources, objects with no IR excess and objects for which the spectral energy distribution (SED) is uncertain. We obtain a clear correlation between disc sources and binarity. RV Tauri stars with a variable mean magnitude are exclusively found among the disc sources. We also find evidence for disc evolution among the binaries. Furthermore our studies show that the presence of a disc seems to be a necessary but not sufficient condition for the depletion process to become efficient.
97. Yields for Z=1e-5 intermediate-mass stars
ID:
ivo://CDS.VizieR/J/A+A/645/A10
Title:
Yields for Z=1e-5 intermediate-mass stars
Short Name:
J/A+A/645/A10
Date:
21 Oct 2021
Publisher:
CDS
Description:
Observed abundances of extremely metal-poor (EMP) stars in the Halo hold clues for the understanding of the ancient universe. Interpreting these clues requires theoretical stellar models at the low-Z regime. We provide the nucleosynthetic yields of intermediate-mass Z=10^-5^ stars between 3 and 7.5M_{sun}_, and quantify the effects of the uncertain wind rates. We expect these yields can be eventually used to assess the contribution to the chemical inventory of the early universe, and to help interpret abundances of selected C-enhanced EMP stars. By comparing our models and other existing in the literature, we explore evolutionary and nucleosynthetic trends with wind prescriptions and with initial metallicity. We compare our results to observations of CEMP-s stars belonging to the Halo. The yields of intermediate-mass EMP stars reflect the effects of very deep second dredge-up (for the most massive models), superimposed with the combined signatures of hot-bottom burning and third dredge-up. We confirm the reported trend that models with initial metallicity Zini<=0.001 give positive yields of ^12^C, ^15^N, ^16^O, and ^26^Mg. The ^20^Ne, ^21^Ne, and ^24^Mg yields, which were reported to be negative at Zini=0.0001, become positive for Z=10^-5^. The results using two different prescriptions for mass-loss rates differ widely in terms of the duration of the thermally-pulsing (Super) AGB phase, overall efficiency of the third dredge-up episode, and nucleosynthetic yields. The most efficient of the standard wind rates frequently used in the literature seems to favour agreement between our yield results and observational data. Regardless of the wind prescription, all our models become N-enhanced EMP stars.

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