Search

Start Over Capability Type Simple Cone Search
221. Abundances of NGC 6362 member stars
ID:
ivo://CDS.VizieR/J/ApJ/824/73
Title:
Abundances of NGC 6362 member stars
Short Name:
J/ApJ/824/73
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first measure of Fe and Na abundances in NGC 6362, a low-mass globular cluster (GC) where first- and second-generation stars are fully spatially mixed. A total of 160 member stars (along the red giant branch (RGB) and the red horizontal branch (RHB)) were observed with the multi-object spectrograph FLAMES at the Very Large Telescope. We find that the cluster has an iron abundance of [Fe/H]=-1.09+/-0.01dex, without evidence of intrinsic dispersion. On the other hand, the [Na/Fe] distribution turns out to be intrinsically broad and bimodal. The Na-poor and Na-rich stars populate, respectively, the bluest and the reddest RGBs detected in the color-magnitude diagrams including the U filter. The RGB is composed of a mixture of first- and second-generation stars in a similar proportion, while almost all the RHB stars belong to the first cluster generation. To date, NGC 6362 is the least massive GC where both the photometric and spectroscopic signatures of multiple populations have been detected.
222. Abundances of NGC 6121 red giants
ID:
ivo://CDS.VizieR/J/A+A/490/625
Title:
Abundances of NGC 6121 red giants
Short Name:
J/A+A/490/625
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present abundance analysis based on high resolution spectra of 105 isolated red giant branch (RGB) stars in the Galactic Globular Cluster NGC 6121 (M4). The data have been collected with FLAMES+UVES, at the ESO/VLT@UT2 telescope. Spectroscopic data were coupled with high precision wide-field UBVI_C photometry from WFI@2.2m telescope and infrared JHK photometry from 2MASS. We derived an average [Fe/H]=-1.07+/-0.01, and an {alpha} enhancement of [{alpha}/Fe]=+0.39+/-0.05dex (internal errors). We confirm the presence of an extended Na-O anticorrelation, and find two distinct groups of stars with significantly different Na and O content. We find no evidence of a Mg-Al anticorrelation. By coupling our results with previous studies on the CN band strength, we find that the CN strong stars have higher Na and Al content and are more O depleted than the CN weak ones. The two groups of Na-rich, CN-strong and Na-poor, CN-weak stars populate two different regions along the RGB. In the U vs. U-B color magnitude diagram the RGB spread is present from the base of the RGB to the RGB-tip. Apparently, both spectroscopic and photometric results imply the presence of two stellar populations in M4. We briefly discuss the possible origin of these populations.
223. Abundances of NGC5897 red giants
ID:
ivo://CDS.VizieR/J/A+A/565/A23
Title:
Abundances of NGC5897 red giants
Short Name:
J/A+A/565/A23
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report for the first time on the chemical composition of the halo cluster NGC 5897 (R_{sun}_=12.5kpc), based on chemical abundance ratios for 27 {alpha}-, iron-peak, and neutron-capture elements in seven red giants. From our high-resolution, high signal-to-noise spectra obtained with theMagellan/MIKE spectrograph, we find a mean iron abundance from the neutral species of [Fe/H]=-2.04+/-0.01(stat.)+/-0.15(sys.), which is more metal-poor than implied by previous photometric and low-resolution spectroscopic studies. NGC 5897 is {alpha}-enhanced (to 0.34+/-0.01dex) and shows Fe-peak element ratios typical of other (metal-poor) halo globular clusters (GCs) with no overall, significant abundance spreads in iron nor in any other heavy element.
224. Abundances of non-type I PNe in LMC
ID:
ivo://CDS.VizieR/J/A+A/279/567
Title:
Abundances of non-type I PNe in LMC
Short Name:
J/A+A/279/567
Date:
21 Oct 2021
Publisher:
CDS
Description:
Spectroscopic observations, plasma diagnostics and chemical composition of 15 non-type I planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) are reported. Abundances of He, O, N, S, and Ar are determined and compared with recently obtained data for nebulae both in the Magellanic Clouds and in the Galaxy.
225. Abundances of non-variable red and blue HB stars
ID:
ivo://CDS.VizieR/J/AJ/140/1694
Title:
Abundances of non-variable red and blue HB stars
Short Name:
J/AJ/140/1694
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new detailed abundance study of field red horizontal branch (RHB) and blue horizontal branch (BHB) non-variable stars. High resolution and high signal-to-noise ratio echelle spectra of 11 RHB and 12 BHB were obtained with the McDonald 2.7m telescope, and the RHB sample was augmented by reanalysis of spectra of 25 stars from a recent survey. We derived stellar atmospheric parameters based on spectroscopic constraints and computed relative abundance ratios for 24 species of 19 elements.
226. Abundances of ONC X-ray PMS stars
ID:
ivo://CDS.VizieR/J/ApJ/660/1462
Title:
Abundances of ONC X-ray PMS stars
Short Name:
J/ApJ/660/1462
Date:
21 Oct 2021
Publisher:
CDS
Description:
Following the Chandra Orion Ultradeep Project (COUP) observation, we have studied the chemical composition of the hot plasma in a sample of 146 X-ray-bright pre-main-sequence stars in the Orion Nebula Cluster (ONC). We report measurements of individual element abundances for a subsample of 86 slightly absorbed and bright X-ray sources, using low-resolution X-ray spectra obtained from the Chandra ACIS instrument.
227. Abundances of open cluster stars
ID:
ivo://CDS.VizieR/J/MNRAS/428/2321
Title:
Abundances of open cluster stars
Short Name:
J/MNRAS/428/2321
Date:
21 Oct 2021
Publisher:
CDS
Description:
The first generation of large-scale chemical tagging surveys, in particular the High Efficiency and Resolution Multi-Element Spectrograph (HERMES)/Galactic Archaeology with HERMES million star survey, promises to vastly expand our understanding of the chemical and dynamical evolution of the Galaxy. This, however, is contingent on our ability to confidently perform chemical tagging on such a large data set. Chemical homogeneity has been observed across a range of elements within several Galactic open clusters, yet the level to which this is the case globally, and particularly in comparison to the scatter across clusters themselves, is not well understood. The patterns of elements in coeval cluster members, occupying a complex chemical abundance space, are rooted in the evolution, ultimately the nature of the very late stages, of early generations of stars. The current astrophysical models of such stages are not yet sufficient to explain all observations, combining with our significant gaps in the understanding of star formation, makes this a difficult arena to tackle theoretically. Here, we describe a robust pair-wise metric used to gauge the chemical difference between two stellar components. This metric is then applied to a data base of high-resolution literature abundance sources to derive a function describing the probability that two stars are of common evolutionary origin. With this cluster probability function, it will be possible to report a confidence, grounded in empirical observational evidence, with which clusters are detected, independent of the group finding methods. This formulation is also used to probe the role of chemical dimensionality, and that of individual chemical species, on the ability of chemical tagging to differentiate coeval groups of stars.
228. Abundances of 42 Pisces-Eridanus stream stars
ID:
ivo://CDS.VizieR/J/MNRAS/496/2422
Title:
Abundances of 42 Pisces-Eridanus stream stars
Short Name:
J/MNRAS/496/2422
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recently, a new cylindrical-shaped stream of stars, up to 700pc long, was discovered hiding in the Galactic disk using kinematic data enabled by the Gaia mission. This curious stream of stars, dubbed the Pisces-Eridanus stream, was initially thought to be as old as 1Gyr, yet its stars shared a rotation period distribution consistent with the 120-Myr-old Pleiades cluster. In this work, we explore the detailed chemical nature of this stellar stream. We carried out high-resolution spectroscopic follow-up of 42 Pisces-Eridanus stream stars using McDonald Observatory, and combined these data with information for 40 members observed with the low-resolution LAMOST spectroscopic survey. Together, these data enabled us to measure the abundance distribution of light/odd-Z (Li, C, Na, Al, Sc, V), {alpha} (Mg, Si, Ca, Ti), Fe-peak (Cr, Mn, Fe, Co, Ni, Zn), and neutron capture (Sr, Y, Zr, Ba, La, Nd, Eu) elements across the Pisces-Eridanus stream. We find that the stream is (1) near solar metallicity with [Fe/H] = -0.03 dex and (2) has a metallicity spread of 0.07 dex (or 0.04 dex when removing outliers). We also find that (3) the abundance of Li indicates that Pisces-Eridanus is ~120Myr old, consistent with the gyrochronology result. We find that (4) the stream has a [X/Fe] abundance spreads of 0.06<{sigma}_[X/Fe]_<0.20dex in most elements, and (5) no significant abundance gradients across its major axis except a potentially weak gradient in [Si/Fe]. These results together show that the Pisces-Eridanus stream is a uniquely close, young, chemically interesting laboratory for testing our understanding of star and planet formation.
229. Abundances of PNe in NGC 300
ID:
ivo://CDS.VizieR/J/A+A/552/A12
Title:
Abundances of PNe in NGC 300
Short Name:
J/A+A/552/A12
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained deep spectroscopy of 26 planetary nebulae (PNe) and 9 compact HII regions in the nearby spiral galaxy NGC 300, and analyzed them together with the giant HII regions observed by Bresolin et al. (2009ApJ...700..309B). We have determined the physical properties of all those objects and their content in He, N, O, Ne, S and Ar in a consistent way. We find that compact HII regions have abundances similar to those of giant HII regions, while PNe have systematically larger N/O ratios and similar Ne/O and Ar/O ratios. We demonstrate that this nitrogen enhancement in PNe cannot be due to second dredge-up in the progenitor stars, since their initial masses are around 2-2.5M_{sun}_. An extra mixing process is required, perhaps be driven by rotation. Concerning the radial abundance distribution, PNe behave differently from HII regions: In the central parts, they show an average O/H smaller by 0.15dex. Their abundance dispersion at any galactocentric radius is significantly larger than for HII regions and many of them have O/H values higher than HII regions at the same galactocentric distance, suggesting that oxygen production in the PN progenitors in NGC 300 is common. PN abundance gradients in O/H, Ne/H and Ar/He are significantly shallower than those of HII regions. We argue that this indicates a steepening of the metallicity gradient in NGC 300 during the last Gr, rather than the effect of radial stellar motions.
230. Abundances of PN towards Galactic bulge
ID:
ivo://CDS.VizieR/J/A+A/380/300
Title:
Abundances of PN towards Galactic bulge
Short Name:
J/A+A/380/300
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work we report spectrophotometric observations of a planetary nebula sample towards the galactic bulge. A total of 45 PNe was observed and their physical parameters (electron density and temperature) were derived. Ionic abundances were calculated using a three-level atom model and abundances were derived through ionisation correction factors. Results show low abundance objects at high galactic latitudes, indicating a possible vertical gradient inside the bulge. A few objects with low N/O ratio were found, which could have originated from old, low mass progenitors.

Limit your search

more »

more »

more »

more »

more »

more »