- ID:
- ivo://CDS.VizieR/J/MNRAS/367/1329
- Title:
- Elemental abundances for 176 stars
- Short Name:
- J/MNRAS/367/1329
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed an abundance analysis for F- and G- dwarfs of the Galactic thick-disc component. A sample of 176 nearby (d<=150pc) thick-disc candidate stars was chosen from the Hipparcos catalogue and subjected to a high-resolution spectroscopic analysis. Using accurate radial velocities combined with the Hipparcos astrometry, kinematics (U, V and W) and Galactic orbital parameters were computed. We estimate the probability for a star to belong to the thin disc, the thick disc or the halo. With a probability P>=70 per cent taken as certain membership, we assigned 95 stars to the thick disc, 13 to the thin disc, and 20 to the halo. The remaining 48 stars in the sample cannot be assigned with reasonable certainty to one of the three components. Abundances of C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Ba, Ce, Nd and Eu have been obtained.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/130/1111
- Title:
- Elemental abundances of field red giants
- Short Name:
- J/AJ/130/1111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We summarize a selection process to identify red giants in the direction of the southern warp of the Galactic disk, employing VI_C_ photometry and multi-object spectroscopy.
- ID:
- ivo://CDS.VizieR/J/AJ/159/46
- Title:
- Elemental abundances of 416 stars in 5 dSphs of M31
- Short Name:
- J/AJ/159/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep spectroscopy from Keck/DEIMOS (DEep Imaging Multi-Object Spectrograph) of Andromeda I, III, V, VII, and X, all of which are dwarf spheroidal satellites (dSphs) of M31. The sample includes 256 spectroscopic members across all five dSphs. We confirm previous measurements of the velocity dispersions and dynamical masses, and we provide upper limits on bulk rotation. Our measurements confirm that M31 satellites obey the same relation between stellar mass and stellar metallicity as Milky Way (MW) satellites and other dwarf galaxies in the Local Group. The metallicity distributions show trends with stellar mass that are similar to those of MW satellites, including evidence in massive satellites for external influence, like pre-enrichment or gas accretion. We present the first measurements of individual element ratios, like [Si/Fe], in the M31 system, as well as measurements of the average [{alpha}/Fe] ratio. The trends of [{alpha}/Fe] with [Fe/H] also follow the same galaxy mass-dependent patterns as MW satellites. Less massive galaxies have more steeply declining slopes of [{alpha}/Fe] that begin at lower [Fe/H]. Finally, we compare the chemical evolution of M31 satellites to M31's Giant Stellar Stream and smooth halo. The properties of the M31 system support the theoretical prediction that the inner halo is composed primarily of massive galaxies that were accreted early. As a result, the inner halo exhibits higher [Fe/H] and [{alpha}/Fe] than surviving satellite galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/894/53
- Title:
- ELM Survey South. I. RVs for 6 new ELM WDs
- Short Name:
- J/ApJ/894/53
- Date:
- 22 Oct 2021 08:25:16
- Publisher:
- CDS
- Description:
- We begin the search for extremely low mass (M<=0.3M_{sun}_, ELM) white dwarfs (WDs) in the southern sky based on photometry from the VST ATLAS and SkyMapper surveys. We use a similar color selection method as the Hypervelocity star survey. We switched to an astrometric selection once Gaia Data Release 2 became available. We use the previously known sample of ELM white dwarfs to demonstrate that these objects occupy a unique parameter space in parallax and magnitude. We use the SOAR 4.1m telescope to test the Gaia-based selection, and identify more than two dozen low mass white dwarfs, including six new ELM white dwarf binaries with periods as short as 2h. The better efficiency of the Gaia-based selection enables us to extend the ELM Survey footprint to the southern sky. We confirm one of our candidates, J0500-0930, to be the brightest (G=12.6mag) and closest (d=72pc) ELM white dwarf binary currently known. Remarkably, the Transiting Exoplanet Survey Satellite (TESS) full-frame imaging data on this system reveals low-level (<0.1%) but significant variability at the orbital period of this system (P=9.5hr), likely from the relativistic beaming effect. TESS data on another system, J0642-5605, reveals ellipsoidal variations due to a tidally distorted ELM WD. These demonstrate the power of TESS full-frame images in confirming the orbital periods of relatively bright compact object binaries.
- ID:
- ivo://CDS.VizieR/J/A+A/379/305
- Title:
- Envelope Tomography of LPV stars
- Short Name:
- J/A+A/379/305
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table provides the heliocentric radial velocities (between parenthesis) for 81 Mira and semi-regular variables monitored at the Observatoire de Haute Provence with the ELODIE spectrograph. The different types of cross-correlation functions (CCFs) obtained with the K0 III- and M4 V-templates are coded as defined in the paper (see also Note 1 below).
- ID:
- ivo://CDS.VizieR/J/ApJ/740/60
- Title:
- Equivalent widths for NGC2419 and NGC7099 RGB stars
- Short Name:
- J/ApJ/740/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 2419 is a massive outer halo Galactic globular cluster (GC) whose stars have previously been shown to have somewhat peculiar abundance patterns. We have observed seven luminous giants that are members of NGC 2419 with Keck/HIRES at reasonable signal-to-noise ratio. One of these giants is very peculiar, with an extremely low [Mg/Fe] and high [K/Fe] but normal abundances of most other elements. The abundance pattern does not match the nucleosynthetic yields of any supernova model. The other six stars show abundance ratios typical of inner halo Galactic GCs, represented here by a sample of giants in the nearby GC M30. Although our measurements show that NGC 2419 is unusual in some respects, its bulk properties do not provide compelling evidence for a difference between inner and outer halo GCs.
- ID:
- ivo://CDS.VizieR/J/ApJ/760/86
- Title:
- Equivalent widths for 13 NGC2419 RGB stars
- Short Name:
- J/ApJ/760/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new Keck/HIRES observations of six red giants in the globular cluster (GC) NGC 2419. Although the cluster is among the most distant and most luminous in the Milky Way, it was considered chemically ordinary until very recently. Our previous work showed that the near-infrared Ca II triplet line strength varied more than expected for a chemically homogeneous cluster, and that at least one star had unusual abundances of Mg and K. Here, we confirm that NGC 2419 harbors a population of stars, comprising about one-third of its mass, that is depleted in Mg by a factor of eight and enhanced in K by a factor of six with respect to the Mg-normal population. Although the majority, Mg-normal population appears to have a chemical abundance pattern indistinguishable from ordinary, inner-halo GCs, the Mg-poor population exhibits dispersions of several elements. The abundances of K and Sc are strongly anti-correlated with Mg, and some other elements (Si and Ca among others) are weakly anti-correlated with Mg. These abundance patterns suggest that the different populations of NGC 2419 sample the ejecta of diverse supernovae in addition to asymptotic giant branch ejecta. However, the abundances of Fe-peak elements except Sc show no star-to-star variation. We find no nucleosynthetic source that satisfactorily explains all of the abundance variations in this cluster. Because NGC 2419 appears like no other GC, we reiterate our previous suggestion that it is not a GC at all, but rather the core of an accreted dwarf galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/91
- Title:
- Equivalent widths of giants in the GC NGC3201
- Short Name:
- J/ApJ/887/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Space Telescope (HST) UV Legacy Survey of Galactic Globular Clusters (GCs) has investigated multiple stellar populations by means of the "chromosome map" (ChM) diagnostic tool that maximizes the separation between stars with different chemical compositions. One of the most challenging features revealed by ChM analysis is the apparent inhomogeneity among stars belonging to the first population, a phenomenon largely attributed to He variations. However, this explanation is not supported by uniformity in the p-capture elements of these stars. The HST survey has revealed that the GC NGC 3201 shows exceptionally wide coverage in the {Delta}_F275W,F814W_ parameter of the ChM. We present a chemical abundance analysis of 24 elements in 18 giants belonging to the first population of this GC and having a wide range in {Delta}_F275W,F814W_. As far as the p-capture elements are concerned, the chemical abundances are typical of first-generation (1G) stars, as expected from the location of our targets in the ChM. Based on radial velocities and chemical abundance arguments, we find that the three stars with the lowest {Delta}_F275W,F814W_ values are binary candidates. This suggests that at least those stars could be explained with binarity. These results are consistent with evidence inferred from multiband photometry that evolved blue stragglers (BSs) populate the bluest part of the 1G sequence in the ChM. The remaining 15 spectroscopic targets show a small range in the overall metallicity by ~0.10dex, with stars at higher {Delta}_F275W,F814W_ values having higher absolute abundances. We suggest that a small variation in metals and binarity governs the color spread of the 1G in the ChM and that evolved BSs contribute to the bluest tail of the 1G sequence.
- ID:
- ivo://CDS.VizieR/J/ApJ/798/110
- Title:
- Equivalent widths of LAMOST metal-poor stars
- Short Name:
- J/ApJ/798/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on early results from a pilot program searching for metal-poor stars with LAMOST and follow-up high-resolution observation acquired with the MIKE spectrograph attached to the Magellan II telescope. We performed detailed abundance analysis for eight objects with iron abundances [Fe/H]<-2.0, including five extremely metal-poor (EMP; [Fe/H]<-3.0) stars with two having [Fe/H]<-3.5. Among these objects, three are newly discovered EMP stars, one of which is confirmed for the first time with high-resolution spectral observations. Three program stars are regarded as carbon-enhanced metal-poor (CEMP) stars, including two stars with no enhancement in their neutron-capture elements, which thus possibly belong to the class of CEMP-no stars; one of these objects also exhibits significant enhancement in nitrogen, and is thus a potential carbon and nitrogen-enhanced metal-poor star. The [X/Fe] ratios of the sample stars generally agree with those reported in the literature for other metal-poor stars in the same [Fe/H] range. We also compared the abundance patterns of individual program stars with the average abundance pattern of metal-poor stars and find only one chemically peculiar object with abundances of at least two elements (other than C and N) showing deviations larger than 0.5 dex. The distribution of [Sr/Ba] versus [Ba/H] agrees that an additional nucleosynthesis mechanism is needed aside from a single r-process. Two program stars with extremely low abundances of Sr and Ba support the prospect that both main and weak r-processes may have operated during the early phase of Galactic chemical evolution. The distribution of [C/N] shows that there are two groups of carbon-normal giants with different degrees of mixing. However, it is difficult to explain the observed behavior of the [C/N] of the nitrogen-enhanced unevolved stars based on current data.
- ID:
- ivo://CDS.VizieR/J/ApJ/751/102
- Title:
- Equivalent widths of 9 RGB in Carina dSph
- Short Name:
- J/ApJ/751/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detailed abundances of 23 chemical elements in nine bright red giant branch stars in the Carina dwarf spheroidal galaxy are presented based on high-resolution spectra gathered at the Very Large Telescope (VLT) and Magellan telescopes. A spherical model atmospheres analysis is applied using standard methods (local thermodynamic equilibrium and plane-parallel radiative transfer) to spectra ranging from 380 to 680nm. Stellar parameters are found to be consistent between photometric and spectroscopic analyses, both at moderate and high resolution. The stars in this analysis range in metallicity from -2.9<[Fe/H]<-1.3, and adopting the ages determined by Lemasle et al. (Cat. J/A+A/538/A100), we are able to examine the chemical evolution of Carina's old and intermediate-aged populations.
