- ID:
- ivo://CDS.VizieR/J/MNRAS/340/304
- Title:
- [X/Fe] of Galactic disc F and G dwarfs
- Short Name:
- J/MNRAS/340/304
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photospheric abundances are presented for 27 elements from carbon to europium in 181 F and G dwarfs from a differential local thermodynamic equilibrium (LTE) analysis of high-resolution and high signal-to-noise ratio spectra. Stellar effective temperatures (T_eff_) were adopted from an infrared flux method calibration of Stroemgren photometry. Stellar surface gravities (g) were calculated from Hipparcos parallaxes and stellar evolutionary tracks. Adopted T_eff_ and g values are in good agreement with spectroscopic estimates. Stellar ages were determined from evolutionary tracks. Stellar space motions (U, V, W) and a Galactic potential were used to estimate Galactic orbital parameters. These show that the vast majority of the stars belong to the Galactic thin disc.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/456/4488
- Title:
- XQ-100 survey neutral gas
- Short Name:
- J/MNRAS/456/4488
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 38 intervening damped Lyman {alpha} (DLA) systems identified towards 100 z>3.5 quasars, observed during the XQ-100 survey. The XQ-100 DLA sample is combined with major DLA surveys in the literature. The final combined sample consists of 742 DLAs over a redshift range approximately 1.6<z_abs_<5.0. We develop a novel technique for computing {Omega}_HI_^DLA^ as a continuous function of redshift, and we thoroughly assess and quantify the sources of error therein, including fitting errors and incomplete sampling of the high column density end of the column density distribution function. There is a statistically significant redshift evolution in {Omega}_HI_^DLA^ (>=3{sigma}) from z~2 to z~5. In order to make a complete assessment of the redshift evolution of {Omega}_HI_, we combine our high-redshift DLA sample with absorption surveys at intermediate redshift and 21-cm emission line surveys of the local universe. Although {Omega}_HI_^DLA^, and hence its redshift evolution, remains uncertain in the intermediate-redshift regime (0.1<z_abs_<1.6), we find that the combination of high-redshift data with 21-cm surveys of the local universe all yield a statistically significant evolution in {Omega}_HI_ from z~0 to z~5 (>=3{sigma}). Despite its statistical significance, the magnitude of the evolution is small: a linear regression fit between {Omega}_HI_ and z yields a typical slope of ~0.17x10^-3^, corresponding to a factor of ~4 decrease in {Omega}_HI_ between z=5 and z=0.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A138
- Title:
- XSL atmospheric parameters
- Short Name:
- J/A+A/627/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The X-shooter Spectral Library (XSL) is an empirical stellar library at medium spectral resolution covering the wavelength range from 3000 to 24800 angstrom. This library aims to provide a benchmark for stellar population studies. In this work, we present a uniform set of stellar atmospheric parameters, effective temperatures, surface gravities, and iron abundances for 754 spectra of 616 XSL stars. We used the full-spectrum fitting package ULySS with the empirical MILES library as reference to fit the ultraviolet-blue (UVB) and visible (VIS) spectra. We tested the internal consistency and we compared our results with compilations from the literature. The stars cover a range of effective temperature 2900<Teff<38000K, surface gravity 0<logg<5.7, and iron abundance -2.5<[Fe/H]<+1.0, with a couple of stars extending down to [Fe/H]=-3.9. The precisions of the measurements for the G- and K-type stars are 0.9%, 0.14, and 0.06 in Teff, log g and [Fe/H], respectively. For the cool giants with logg<1, the precisions are 2.1%, 0.21, and 0.22, and for the other cool stars these values are 1%, 0.14, and 0.10. For the hotter stars (Teff>6500K), these values are 2.6%, 0.20, and 0.10 for the three parameters.
- ID:
- ivo://CDS.VizieR/J/ApJ/832/121
- Title:
- 4-yr RV survey of red giant in eclipsing binaries
- Short Name:
- J/ApJ/832/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Given the potential of ensemble asteroseismology for understanding fundamental properties of large numbers of stars, it is critical to determine the accuracy of the scaling relations on which these measurements are based. From several powerful validation techniques, all indications so far show that stellar radius estimates from the asteroseismic scaling relations are accurate to within a few percent. Eclipsing binary systems hosting at least one star with detectable solar-like oscillations constitute the ideal test objects for validating asteroseismic radius and mass inferences. By combining radial velocity (RV) measurements and photometric time series of eclipses, it is possible to determine the masses and radii of each component of a double-lined spectroscopic binary. We report the results of a four-year RV survey performed with the echelle spectrometer of the Astrophysical Research Consortium's 3.5m telescope and the APOGEE spectrometer at Apache Point Observatory. We compare the masses and radii of 10 red giants (RGs) obtained by combining radial velocities and eclipse photometry with the estimates from the asteroseismic scaling relations. We find that the asteroseismic scaling relations overestimate RG radii by about 5% on average and masses by about 15% for stars at various stages of RG evolution. Systematic overestimation of mass leads to underestimation of stellar age, which can have important implications for ensemble asteroseismology used for Galactic studies. As part of a second objective, where asteroseismology is used for understanding binary systems, we confirm that oscillations of RGs in close binaries can be suppressed enough to be undetectable, a hypothesis that was proposed in a previous work.
- ID:
- ivo://CDS.VizieR/J/ApJ/830/10
- Title:
- >20yrs of HST obs. of Cepheids in SNIa host gal.
- Short Name:
- J/ApJ/830/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of an optical search conducted as part of the SH0ES project (Supernovae and H_0_ for the Equation of State of dark energy) for Cepheid variable stars using the Hubble Space Telescope (HST) in 19 hosts of Type Ia supernovae (SNe Ia) and the maser-host galaxy NGC4258. The targets include nine newly imaged SN Ia hosts using a novel strategy based on a long-pass filter that minimizes the number of HST orbits required to detect and accurately determine Cepheid properties. We carried out a homogeneous reduction and analysis of all observations, including new universal variability searches in all SNIa hosts, which yielded a total of 2200 variables with well-defined selection criteria, the largest such sample identified outside the Local Group. These objects are used in a companion paper to determine the local value of H_0_ with a total uncertainty of 2.4%.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/78
- Title:
- z=4.5 and z=5.7 LAEs properties with Spitzer
- Short Name:
- J/ApJ/813/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from a stellar population modeling analysis of a sample of 162 z=4.5 and 14 z=5.7 Ly{alpha} emitting galaxies (LAEs) in the Bootes field, using deep Spitzer/IRAC data at 3.6 and 4.5 {mu}m from the Spitzer Ly{alpha} Survey, along with Hubble Space Telescope NICMOS and WFC3 imaging at 1.1 and 1.6 {mu}m for a subset of the LAEs. This represents one of the largest samples of high-redshift LAEs imaged with Spitzer IRAC. We find that 30/162 (19%) of the z=4.5 LAEs and 9/14 (64%) of the z=5.7 LAEs are detected at >=3{sigma} in at least one IRAC band. Individual z=4.5 IRAC-detected LAEs have a large range of stellar mass, from 5x10^8^-10^11^ M_{sun}_. One-third of the IRAC-detected LAEs have older stellar population ages of 100 Myr^-1^ Gyr, while the remainder have ages <100 Myr. A stacking analysis of IRAC-undetected LAEs shows this population to be primarily low mass (8-20x10^8^ M_{sun}_) and young (64-570 Myr). We find a correlation between stellar mass and the dust-corrected ultraviolet-based star formation rate (SFR) similar to that at lower redshifts, in that higher mass galaxies exhibit higher SFRs. However, the z=4.5 LAE correlation is elevated 4-5 times in SFR compared to continuum-selected galaxies at similar redshifts. The exception is the most massive LAEs which have SFRs similar to galaxies at lower redshifts suggesting that they may represent a different population of galaxies than the traditional lower-mass LAEs, perhaps with a different mechanism promoting Ly{alpha} photon escape.
- ID:
- ivo://CDS.VizieR/J/AJ/151/120
- Title:
- z<1 3CR radio galaxies and quasars star formation
- Short Name:
- J/AJ/151/120
- Date:
- 16 Dec 2021 13:37:06
- Publisher:
- CDS
- Description:
- Using the Herschel Space Observatory we have observed a representative sample of 87 powerful 3CR sources at redshift z<1. The far-infrared (FIR, 70-500 {mu}m) photometry is combined with mid-infrared (MIR) photometry from the Wide-Field Infrared Survey Explorer and cataloged data to analyze the complete spectral energy distributions (SEDs) of each object from optical to radio wavelength. To disentangle the contributions of different components, the SEDs are fitted with a set of templates to derive the luminosities of host galaxy starlight, dust torus emission powered by active galactic nuclei (AGNs), and cool dust heated by stars. The level of emission from relativistic jets is also estimated to isolate the thermal host galaxy contribution. The new data are in line with the orientation-based unification of high-excitation radio-loud AGN, in that the dust torus becomes optically thin longwards of 30 {mu}m. The low-excitation radio galaxies and the MIR-weak sources represent an MIR- and FIR-faint AGN population that is different from the high-excitation MIR-bright objects; it remains an open question whether they are at a later evolutionary state or an intrinsically different population. The derived luminosities for host starlight and dust heated by star formation are converted to stellar masses and star-formation rates (SFR). The host-normalized SFR of the bulk of the 3CR sources is low when compared to other galaxy populations at the same epoch. Estimates of the dust mass yield a 1-100 times lower dust/stellar mass ratio than for the Milky Way, which indicates that these 3CR hosts have very low levels of interstellar matter and explains the low level of star formation. Less than 10% of the 3CR sources show levels of star formation above those of the main sequence of star-forming galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/4293
- Title:
- 0.1<z<0.8 galaxies gas-phase metallicity grad.
- Short Name:
- J/MNRAS/478/4293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxies at low-redshift typically possess negative gas-phase metallicity gradients (centres more metal-rich than their outskirts). Whereas, it is not uncommon to observe positive metallicity gradients in higher-redshift galaxies (z<0.6). Bridging these epochs, we present gas-phase metallicity gradients of 84 star-forming galaxies between 0.08<z<0.84. Using the galaxies with reliably determined metallicity gradients, we measure the median metallicity gradient to be negative (-0.039^+0.007^_-0.009_dex/kpc). Underlying this, however, is significant scatter: (8+/-3)% [7] of galaxies have significantly positive metallicity gradients, (38+/-5)% [32] have significantly negative gradients, (31+/-5)% [26] have gradients consistent with being flat. (The remaining (23+/-5)% [19] have unreliable gradient estimates.) We notice a slight trend for a more negative metallicity gradient with both increasing stellar mass and increasing star formation rate (SFR). However, given the potential redshift and size selection effects, we do not consider these trends to be significant. Indeed, once we normalize the SFR relative to that of the main sequence, we do not observe any trend between the metallicity gradient and the normalized SFR. This is contrary to recent studies of galaxies at similar and higher redshifts. We do, however, identify a novel trend between the metallicity gradient of a galaxy and its size. Small galaxies (rd<3kpc) present a large spread in observed metallicity gradients (both negative and positive gradients). In contrast, we find no large galaxies (rd > 3 kpc) with positive metallicity gradients, and overall there is less scatter in the metallicity gradient amongst the large galaxies. These large (well-evolved) galaxies may be analogues of present-day galaxies, which also show a common negative metallicity gradient.
- ID:
- ivo://CDS.VizieR/J/AJ/145/107
- Title:
- Zr, Ba, La, and Eu abundances in 19 open clusters
- Short Name:
- J/AJ/145/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We investigate cluster mean neutron-capture abundance trends as a function of cluster age and location in the Milky Way disk and compare them to results found in other studies in the literature. We find a statistically significant trend of increasing cluster [Ba/Fe] as a function of decreasing cluster age, in agreement with recent findings for other open cluster samples, supporting the increased importance of low-mass asymptotic giant branch stars to the generation of s-process elements. However, the other s-process elements, [La/Fe] and [Zr/Fe], do not show similar dependences, in contrast to theoretical expectations and the limited observational data from other studies. Conversely, cluster [Eu/Fe] ratios show a slight increase with increasing cluster age, although with marginal statistical significance. Ratios of [s/r]-process abundances, [Ba/Eu] and [La/Eu], however, show more clearly the increasing efficiency of s-process relative to r-process enrichment in open cluster chemical evolution, with significant increases among younger clusters. Last, cluster neutron-capture element abundances appear to be independent of Galactocentric distance. We conclude that a homogeneous analysis of a larger sample of open clusters is needed to resolve the apparent discrepant conclusions between different studies regarding s-process element abundance trends with age to better inform models of galactic chemical evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/822/42
- Title:
- z~3.3 star-forming galaxies NIR spectra
- Short Name:
- J/ApJ/822/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the relationship between stellar mass, star formation rate (SFR), ionization state, and gas-phase metallicity for a sample of 41 normal star-forming galaxies at 3<~z<~3.7. The gas-phase oxygen abundance, ionization parameter, and electron density of ionized gas are derived from rest-frame optical strong emission lines measured on near-infrared spectra obtained with Keck/Multi-Object Spectrograph for Infra-Red Exploration. We remove the effect of these strong emission lines in the broadband fluxes to compute stellar masses via spectral energy distribution fitting, while the SFR is derived from the dust-corrected ultraviolet luminosity. The ionization parameter is weakly correlated with the specific SFR, but otherwise the ionization parameter and electron density do not correlate with other global galaxy properties such as stellar mass, SFR, and metallicity. The mass-metallicity relation (MZR) at z~3.3 shows lower metallicity by ~0.7dex than that at z=0 at the same stellar mass. Our sample shows an offset by ~0.3dex from the locally defined mass-metallicity-SFR relation, indicating that simply extrapolating such a relation to higher redshift may predict an incorrect evolution of MZR. Furthermore, within the uncertainties we find no SFR-metallicity correlation, suggesting a less important role of SFR in controlling the metallicity at high redshift. We finally investigate the redshift evolution of the MZR by using the model by Lilly et al. (2013ApJ...772..119L), finding that the observed evolution from z=0 to z~3.3 can be accounted for by the model assuming a weak redshift evolution of the star formation efficiency.