- ID:
- ivo://CDS.VizieR/J/A+A/613/A65
- Title:
- Spectroscopic parameters of O-type stars
- Short Name:
- J/A+A/613/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IACOB and OWN surveys are two ambitious complementary observational projects which have made available a large multi-epoch spectroscopic database of optical high resolution spectra of Galactic massive O-type stars. As a first step in the study of the full sample of (more than 350) O stars surveyed by the IACOB and OWN projects, we have performed the quantitative spectroscopic analysis of a subsample of 128 stars included in the modern grid of O-type standards for spectral classification. The sample comprises stars with spectral types in the range O3-O9.7 and covers all luminosity classes. We use the semi-automatized iacob-broad and iacob-gbat/fastwind tools to determine the complete set of spectroscopic parameters that can be obtained from the optical spectrum of O-type stars. A quality flag is assigned to the outcome of the iacob- gbat/fastwind analysis for each star, based on a visual evaluation of how the synthetic spectrum of the best fitting fastwind model reproduces the observed spectrum. We also benefit from the multi-epoch character of the IACOB and OWN surveys to perform a spectroscopic variability study of the complete sample, providing two different flags for each star accounting for spectroscopic binarity as well as variability of the main wind diagnostic lines.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/112/315
- Title:
- Spectroscopic parameters of Seyfert nuclei
- Short Name:
- J/ApJS/112/315
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have completed an optical spectroscopic survey of the nuclear regions (r<=200pc) of a large sample of nearby galaxies. Although the main objectives of the survey are to search for low-luminosity active galactic nuclei and to quantify their luminosity function, the database can be used for a variety of other purposes. This paper presents measurements of the spectroscopic parameters for the 418 emission-line nuclei, along with a compilation of the global properties of all 486 galaxies in the survey. Stellar absorption generally poses a serious obstacle to obtaining accurate measurement of emission lines in nearby galactic nuclei. We describe a procedure for removing the starlight from the observed spectra in an efficient and objective manner. The main parameters of the emission lines (intensity ratios, fluxes, profile widths, and equivalent widths) are measured and tabulated, as are several stellar absorption-line and continuum indices useful for studying the stellar population. Using standard nebular diagnostics, we determine the probable ionization mechanisms of the emission-line objects. The resulting spectral classifications provide extensive information on the demographics of emission-line nuclei in the nearby regions of the universe. This new catalog contains over 200 objects showing spectroscopic evidence for recent star formation and an equally large number of active galactic nuclei, including 46 that show broad H{alpha} emission. These samples will serve as the basis of future studies of nuclear activity in nearby galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A76
- Title:
- Spectroscopic parameters of stars (SPECIES). I.
- Short Name:
- J/A+A/615/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detection and subsequent characterisation of exoplanets are intimately linked to the characteristics of their host star. Therefore, it is necessary to study the star in detail in order to understand the formation history and characteristics of their companion(s). Our aims are to develop a community tool that allows the automated calculation of stellar parameters for a large number of stars, using high resolution echelle spectra and minimal photometric magnitudes, and introduce the first catalogue of these measurements in this work. We measured the equivalent widths of several iron lines and used them to solve the radiative transfer equation assuming local thermodynamic equilibrium in order to obtain the atmospheric parameters (Teff, [Fe/H], logg, and {xi}_t). We then used these values to derive the abundance of 11 chemical elements in the stellar photosphere (Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, Cu, and Zn). Rotation and macroturbulent velocity were obtained using temperature calibrators and synthetic line profiles to match the observed spectra isochrones, we were able to derive the mass, radius, and age for each star using a Bayesian approach. SPECIES obtains bulk parameters that are in good agreement with measured values from different existing catalogues, including when different methods are used to derive them. We find discrepancies in the chemical abundances for some elements with respect to other works, which could be produced by differences in Teff, or in the line list or the atomic line data used to derive them. We also obtained analytic relations to describe the correlations between different parameters, and we implemented new methods to better handle these correlations, which provides a better description of the uncertainties associated with the measurements.
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/4151
- Title:
- Spectroscopic properties for 107 stars
- Short Name:
- J/MNRAS/468/4151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results from the high-resolution spectral analysis of the 107 metal-rich (mostly [Fe/H]>=7.67dex) target stars from the Calan-Hertfordshire Extrasolar Planet Search programme observed with HARPS. Using our procedure of finding the best fit to the absorption line profiles in the observed spectra, we measure the abundances of Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu and Zn, and then compare them with known results from different authors. Most of our abundances agree with these works at the level of +/-0.05dex or better for the stars we have in common. However, we do find systematic differences that make direct inferences difficult. Our analysis suggests that the selection of line lists and atomic line data along with the adopted continuum level influence these differences the most. At the same time, we confirm the positive trends of abundances versus metallicity for Na, Mn, Ni and, to a lesser degree, Al. A slight negative trend is observed for Ca, whereas Si and Cr tend to follow iron. Our analysis allows us to determine the positively skewed normal distribution of projected rotational velocities with a maximum peaking at 3km/s. Finally, we obtained a Gaussian distribution of microturbulent velocities that has a maximum at 1.2km/s and a full width at half-maximum {Delta}v_1/2_=0.35km/s, indicating that metal-rich dwarfs and subgiants in our sample have a very restricted range in microturbulent velocity.
- ID:
- ivo://CDS.VizieR/J/ApJ/793/39
- Title:
- Spectroscopic properties of BOSS compact galaxies
- Short Name:
- J/ApJ/793/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive compact systems at 0.2<z<0.6 are the missing link between the predominantly compact population of massive quiescent galaxies at high redshift and their analogs and relics in the local volume. The evolution in number density of these extreme objects over cosmic time is the crucial constraining factor for the models of massive galaxy assembly. We select a large sample of ~200 intermediate-redshift massive compacts from the Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopy by identifying point-like Sloan Digital Sky Survey photometric sources with spectroscopic signatures of evolved redshifted galaxies. A subset of our targets have publicly available high-resolution ground-based images that we use to augment the dynamical and stellar population properties of these systems by their structural parameters. We confirm that all BOSS compact candidates are as compact as their high-redshift massive counterparts and less than half the size of similarly massive systems at z~0. We use the completeness-corrected numbers of BOSS compacts to compute lower limits on their number densities in narrow redshift bins spanning the range of our sample. The abundance of extremely dense quiescent galaxies at 0.2<z<0.6 is in excellent agreement with the number densities of these systems at high redshift. Our lower limits support the models of massive galaxy assembly through a series of minor mergers over the redshift range 0<z<2.
- ID:
- ivo://CDS.VizieR/J/ApJS/159/141
- Title:
- Spectroscopic properties of cool stars. I.
- Short Name:
- J/ApJS/159/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a uniform catalog of stellar properties for 1040 nearby F, G, and K stars that have been observed by the Keck, Lick, and AAT planet search programs. Fitting observed echelle spectra with synthetic spectra yielded effective temperature, surface gravity, metallicity, projected rotational velocity, and abundances of the elements Na, Si, Ti, Fe, and Ni, for every star in the catalog. Combining V-band photometry and Hipparcos parallaxes with a bolometric correction based on the spectroscopic results yielded stellar luminosity, radius, and mass. Interpolating Yonsei-Yale isochrones to the luminosity, effective temperature, metallicity, and {alpha}-element enhancement of each star yielded a theoretical mass, radius, gravity, and age range for most stars in the catalog.
- ID:
- ivo://CDS.VizieR/J/ApJ/863/102
- Title:
- Spectroscopic redshift catalog in A2142 field
- Short Name:
- J/ApJ/863/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the dynamics of the galaxy cluster A2142, we compile an extended catalog of 2239 spectroscopic redshifts of sources, including 237 newly measured redshifts, within 30 arcmin from the cluster center. With the {sigma}-plateau algorithm from the caustic method, we identify 868 members and a number of substructures in the galaxy distribution both in the outskirts, out to ~3.5Mpc from the cluster center, and in the central region. In the outskirts, one substructure overlaps a falling clump of gas previously identified in the X-ray band. These substructures suggest the presence of multiple minor mergers, which are responsible for the complex dynamics of A2142, and the absence of recent or ongoing major mergers. We show that the distribution of the galaxies in the cluster core and in several substructures is consistent with the mass distribution inferred from the weak-lensing signal. Moreover, we use spatially resolved X-ray spectroscopy to measure the redshift of different regions of the intracluster medium within ~3 arcmin from the cluster center. We find a ring of gas near the two X-ray cold fronts identified in previous analyses and measure a velocity of this ring of 810+/-330km/s larger than the cluster mean velocity. Our analysis suggests the presence of another ring surrounding the core, whose velocity is 660+/-300km/s larger than the cluster velocity. These X-ray features are not associated with any optical substructures, and support the core-sloshing scenario suggested in previous work.
- ID:
- ivo://CDS.VizieR/J/ApJ/741/122
- Title:
- Spectroscopic redshifts in A2142 and RXJ1720.1+2638
- Short Name:
- J/ApJ/741/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present evidence for the existence of substructure in the "relaxed appearing" cold front clusters Abell 2142 and RXJ1720.1+2638. The detection of these substructures was made possible by comprehensive multi-object optical spectroscopy obtained with the Hectospec and DEep Imaging Multi-Object Spectrograph instruments on the 6.5m MMT and 10m Keck II telescope, respectively. These observations produced 956 and 400 spectroscopically confirmed cluster members within a projected radius of 3Mpc from the centers of A2142 and RXJ1720.1+2638, respectively. The substructure manifests itself as local peaks in the spatial distribution of member galaxies and also as regions of localized velocity substructure. For both Abell 2142 and RXJ1720.1+2638, we identify group-scale substructures which, when considering the morphology of the cold fronts and the time since pericentric passage of a perturber estimated from the cold front radii, could plausibly have perturbed the cluster cores and generated the cold fronts observed in Chandra images. The results presented here are consistent with cold fronts being the result of merger activity and with cold fronts in relaxed appearing clusters being due to minor merger activity.
- ID:
- ivo://CDS.VizieR/J/ApJS/219/29
- Title:
- Spectroscopic redshifts in strong lens fields
- Short Name:
- J/ApJS/219/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectroscopic redshift catalog from a wide-field survey of the fields of 28 galaxy-mass strong gravitational lenses. We discuss the acquisition and reduction of the survey data, collected over 40 nights of 6.5m MMT and Magellan time, employing four different multiobject spectrographs. We determine that no biases are introduced by combining data sets obtained with different telescope and spectrograph combinations. Special care is taken to determine redshift uncertainties using repeat observations. The redshift catalog consists of 9768 new and unique galaxy redshifts. 82.4% of the catalog redshifts are between z=0.1 and z=0.7, and the catalog median redshift is z_med_=0.36. The data from this survey will be used to study the lens environments and line-of-sight structures to gain a better understanding of the effects of large-scale structure on lens statistics and lens-derived parameters.
- ID:
- ivo://CDS.VizieR/J/ApJ/764/135
- Title:
- Spectroscopic redshifts of BL Lac objects
- Short Name:
- J/ApJ/764/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on spectroscopic observations covering most of the 475 BL Lacs in the second Fermi Large Area Telescope (LAT) catalog of active galactic nuclei (AGNs). Including archival measurements (correcting several erroneous literature values) we now have spectroscopic redshifts for 44% of the BL Lacs. We establish firm lower redshift limits via intervening absorption systems and statistical lower limits via searches for host galaxies for an additional 51% of the sample leaving only 5% of the BL Lacs unconstrained. The new redshifts raise the median spectroscopic {overline}{Z} from 0.23 to 0.33 and include redshifts as large as z=2.471. Spectroscopic redshift minima from intervening absorbers have {overline}{Z}, showing a substantial fraction at large z and arguing against strong negative evolution. We find that detected BL Lac hosts are bright ellipticals with black hole masses M_{bullet}_~10^8.5^-10^9^, substantially larger than the mean of optical AGNs and LAT Flat Spectrum Radio Quasar samples. A slow increase in M_{bullet}_ with z may be due to selection bias. We find that the power-law dominance of the optical spectrum extends to extreme values, but this does not strongly correlate with the {gamma}-ray properties, suggesting that strong beaming is the primary cause of the range in continuum dominance.