Search

Start Over Capability Type Simple Cone Search
14131. Spectroscopy in Galactic globular clusters
ID:
ivo://CDS.VizieR/J/A+A/540/A27
Title:
Spectroscopy in Galactic globular clusters
Short Name:
J/A+A/540/A27
Date:
21 Oct 2021
Publisher:
CDS
Description:
Well determined radial velocities and abundances are essential for analyzing the properties of the Globular Cluster system of the Milky Way. However more than 50% of these clusters have no spectroscopic measure of their metallicity. In this context, this work provides new radial velocities and abundances for twenty Milky Way globular clusters which lack or have poorly known values for these quantities. The radial velocities and abundances are derived from spectra obtained at the CaII triplet using the FORS2 imager and spectrograph at the VLT, calibrated with spectra of red giants in a number of clusters with well determined abundances. For about half of the clusters in our sample we present signifiant revisions of the existing velocities or abundances, or both.
14132. Spectroscopy in lens fields
ID:
ivo://CDS.VizieR/J/ApJ/641/169
Title:
Spectroscopy in lens fields
Short Name:
J/ApJ/641/169
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results from our spectroscopic survey of strong gravitational lens environments. Six of the eight lens galaxies in our sample belong to a poor group of galaxies, three of which are newly discovered here (those associated with BRI 0952-0115, MG 1654+1346, and B2114+022).
14133. Spectroscopy in nearby group cores
ID:
ivo://CDS.VizieR/J/AJ/132/1796
Title:
Spectroscopy in nearby group cores
Short Name:
J/AJ/132/1796
Date:
21 Oct 2021
Publisher:
CDS
Description:
We used V and I CCD photometry to search for low surface brightness dwarf galaxies in the central (<0.5h^-1^Mpc) region of the groups NGC 6868, NGC 5846, HCG 42, and the poor cluster IC 4765. We used the exponential profile fit parameters to identify 80 low surface brightness dwarf galaxy candidates with 17mag<V<22mag (-16.7>MV>-11.4), V-I<1.5mag, {mu}_0_>22.5Vmag/arcsec^2^, h>1.5", and diameters larger than 1.2h^-1^kpc. Twenty of these galaxies are extended low surface brightness galaxies that were detected only on smoothed images, after masking all high surface brightness objects. The completeness in the sample detection is ~80% for V~<20 and 22.5Vmag/arcsec^2^<{mu}_0_<24.5Vmag/arcsec^2^. For galaxies with V>20mag and {mu}_0_>24.5Vmag/arcsec^2^, the completeness is below 50% but increases to ~80% when we search for galaxies in smoothed images.
14134. Spectroscopy in NGC 2360, NGC 3680, and NGC 5822
ID:
ivo://CDS.VizieR/J/AJ/148/83
Title:
Spectroscopy in NGC 2360, NGC 3680, and NGC 5822
Short Name:
J/AJ/148/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
Binary stars in open clusters are very useful targets in constraining the nucleosynthesis process. The luminosities of the stars are known because the distances of the clusters are also known, so chemical peculiarities can be linked directly to the evolutionary status of a star. In addition, binary stars offer the opportunity to verify a relationship between them and the straggler population in both globular and open clusters. We carried out a detailed spectroscopic analysis to derive the atmospheric parameters for 16 red giants in binary systems and the chemical composition of 11 of them in the open clusters NGC 2360, NGC 3680, and NGC 5822. We obtained abundances of C, N, O, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd. The atmospheric parameters of the studied stars and their chemical abundances were determined using high-resolution optical spectroscopy. We employ the local thermodynamic equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. The abundances of the light elements were derived using the spectral synthesis technique. We found that the stars NGC 2360-92 and 96, NGC 3680-34, and NGC 5822-4 and 312 are yellow straggler stars. We show that the spectra of NGC 5822-4 and 312 present evidence of contamination by an A-type star as a secondary star. For the other yellow stragglers, evidence of contamination is given by the broad wings of the H{alpha}. Detection of yellow straggler stars is important because the observed number can be compared with the number predicted by simulations of binary stellar evolution in open clusters. We also found that the other binary stars are not s-process enriched, which may suggest that in these binaries the secondary star is probably a faint main-sequence object. The lack of any s-process enrichment is very useful in setting constraints for the number of white dwarfs in the open cluster, a subject that is related to the birthrate of these kinds of stars in open clusters and also to the age of a cluster. Finally, rotational velocities were also determined and their values were compared with those already determined for field giant stars.
14135. Spectroscopy in Orion Nebula Cluster
ID:
ivo://CDS.VizieR/J/AJ/129/363
Title:
Spectroscopy in Orion Nebula Cluster
Short Name:
J/AJ/129/363
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from high-resolution spectra of 237 stars in the Orion Nebula cluster (ONC) obtained during two engineering runs with the Hectochelle multifiber echelle spectrograph on the 6.5m MMT. The ONC is the nearest populous young (age ~1Myr) cluster and is therefore an important object for studies of the evolution of protoplanetary disks. Using the high spectral resolution of Hectochelle, we are able to distinguish stellar accretion and wind emission-line profiles from nebular emission lines and identify accreting members of the cluster from H{alpha} profiles with greater accuracy than previously possible. We find 15 new members on the basis of Li {lambda}6707 absorption and H{alpha} emission. Line profiles of H{alpha} of some objects that are not too contaminated by nebular emission show features characteristic of mass inflow and ejection. We also present rotational velocities as part of an initial investigation into angular momentum evolution of very young stars, confirming a difference between classical T Tauri stars and weak-line T Tauri stars that had been found from period analysis. Finally, we present an initial study of the radial velocity dispersion of the brighter stars in the central cluster. The very small dispersion derived, 1.8km/s, is in good agreement with estimates from proper motions.
14136. Spectroscopy in Shapley supercluster
ID:
ivo://CDS.VizieR/J/MNRAS/381/1035
Title:
Spectroscopy in Shapley supercluster
Short Name:
J/MNRAS/381/1035
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new optical spectroscopy for 342 R<18 galaxies in the Shapley supercluster (and 198 supplementary galaxies), obtained from 8-h integrations with the AAOmega facility at the Anglo-Australian Telescope. We describe the observations and measurements of central velocity dispersion {sigma}, emission-line equivalent widths and absorption-line indices. The distinguishing characteristic of the survey is its coverage of a very wide baseline in velocity dispersion (90 per cent range {sigma}=40-230km/s), while achieving high signal-to-noise ratio throughout (median 60{AA}^-1^ at 5000{AA}). The data quality will enable estimates of Balmer-line ages to better than 20 per cent precision even for the faintest galaxies in the sample. Significant emission at H{alpha} was detected in ~30 per cent of the supercluster galaxies, including ~20 per cent of red-sequence members. Using line-ratio diagnostics, we find that the emission is LINER (low ionization nuclear emission region) like at high luminosity, but driven by star formation in low-luminosity galaxies. To characterize the absorption lines, we use the classical Lick indices in the spectral range 4000-5200{AA}. We introduce a new method for applying resolution corrections to the line-strength indices. We define a subset of galaxies with very low emission contamination, based on the H{alpha} line, and fit the index relations for this subset. The final sample analysed in this paper comprises 232 NFPS-selected galaxies meeting both the emission and the redshift criteria, of which 198 have measured velocity dispersions (i.e. are not unresolved).
14137. Spectroscopy in the 25 Ori group
ID:
ivo://CDS.VizieR/J/ApJ/661/1119
Title:
Spectroscopy in the 25 Ori group
Short Name:
J/ApJ/661/1119
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report here on the photometric and kinematic properties of a well-defined group of nearly 200 low-mass pre-main-sequence stars, concentrated within ~1{deg} of the early-B star 25 Ori, in the Orion OB1a subassociation. We refer to this stellar aggregate as the 25 Orionis group. The group also harbors the Herbig Ae/Be star V346 Ori and a dozen other early-type stars with photometry, parallaxes, and some with IR excess emission, indicative of group membership.
14138. Spectroscopy obs. of LeoA, Aqr & Sgr dwarf gal.
ID:
ivo://CDS.VizieR/J/ApJ/834/9
Title:
Spectroscopy obs. of LeoA, Aqr & Sgr dwarf gal.
Short Name:
J/ApJ/834/9
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Keck/DEIMOS spectroscopy of individual stars in the relatively isolated Local Group dwarf galaxies Leo A, Aquarius, and the Sagittarius dwarf irregular galaxy. The three galaxies-but especially Leo A and Aquarius-share in common delayed star formation histories (SFHs) relative to many other isolated dwarf galaxies. The stars in all three galaxies are supported by dispersion. We found no evidence of stellar velocity structure, even for Aquarius, which has rotating HI gas. The velocity dispersions indicate that all three galaxies are dark-matter-dominated, with dark-to-baryonic mass ratios ranging from 4.4_-0.8_^+1.0^ (SagDIG) to 9.6_-1.8_^+2.5^ (Aquarius). Leo A and SagDIG have lower stellar metallicities than Aquarius, and they also have higher gas fractions, both of which would be expected if Aquarius were further along in its chemical evolution. The metallicity distribution of Leo A is inconsistent with a closed or leaky box model of chemical evolution, suggesting that the galaxy was pre-enriched or acquired external gas during star formation. The metallicities of stars increased steadily for all three galaxies, but possibly at different rates. The [{alpha}/Fe] ratios at a given [Fe/H] are lower than that of the Sculptor dwarf spheroidal galaxy, which indicates more extended SFHs than Sculptor, consistent with photometrically derived SFHs. Overall, the bulk kinematic and chemical properties for the late-forming dwarf galaxies do not diverge significantly from those of less delayed dwarf galaxies, including dwarf spheroidal galaxies.
14139. Spectroscopy obs. of 20 Planck gal. cluster cand.
ID:
ivo://CDS.VizieR/J/ApJ/853/36
Title:
Spectroscopy obs. of 20 Planck gal. cluster cand.
Short Name:
J/ApJ/853/36
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Gemini and Keck spectroscopic redshifts and velocity dispersions for 20 clusters detected via the Sunyaev-Zel'dovich (SZ) effect by the Planck space mission, with estimated masses in the range 2.3x10^14^M_{sun}_<M_500_^Pl^<9.4x10^14^M_{sun}_. Cluster members were selected for spectroscopic follow-up with Palomar, Gemini, and Keck optical and (in some cases) infrared imaging. Seven cluster redshifts were measured for the first time with this observing campaign, including one of the most distant Planck clusters confirmed to date, at z=0.782+/-0.010, PSZ2 G085.95+25.23. The spectroscopic redshift catalogs of members of each confirmed cluster are included as online tables. We show the galaxy redshift distributions and measure the cluster velocity dispersions. The cluster velocity dispersions obtained in this paper were used in a companion paper to measure the Planck mass bias and to constrain the cluster velocity bias.
14140. Spectroscopy of Abell 222 and Abell 223
ID:
ivo://CDS.VizieR/J/A+A/394/395
Title:
Spectroscopy of Abell 222 and Abell 223
Short Name:
J/A+A/394/395
Date:
21 Oct 2021
Publisher:
CDS
Description:
This spectroscopic study of the neighboring massive clusters Abell 222 and Abell 223 is based on MOS using EMMI at the NTT. Photometry was obtained from WFI images taken with the ESO/MPG 2.2m telescope. Data for objects coincident with objects from Proust et al., 2000A&A...355..443P, is listed for comparison.

Limit your search

more »

more »

more »

more »

  • 218,086
  • 111

more »

more »