- ID:
- ivo://CDS.VizieR/J/A+AS/129/237
- Title:
- G and K dwarfs abundances
- Short Name:
- J/A+AS/129/237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table presents the abundances of all 47 dwarf stars analysed in the paper. We give abundances relative to the Sun in the standard notation of [X/H]=log(X/H)_star_-log(X/H)_{sun}_. The 5 K dwarf stars and 3 stars in common with Barbuy & Grenon (1990) appear at the end of the table. The label of each column indicates the ion the quoted abundances are derived from. For each star we give the abundance, [X/H], the line-to-line scatter (if more than one line is used) and the number of lines used. The stars are ordered in the same way as in Table 1 in the paper, ie. the K dwarf stars and the stars in common with Barbuy & Grenon (1990) are found at the end.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/336/879
- Title:
- G and K dwarfs UBV(RI)c and ubvy photometry
- Short Name:
- J/MNRAS/336/879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K dwarfs have lifetimes older than the present age of the Galactic disc, and are thus ideal stars for investigating the chemical evolution of the disc. We have developed several photometric metallicity indicators for K dwarfs, based on a sample of accurate spectroscopic metallicities for 34 disc and halo G and K dwarfs. The photometric metallicities lead us to develop a metallicity index for K dwarfs based only on their position in the colour-absolute-magnitude diagram. Metallicities have been determined for 431 single K dwarfs drawn from the Hipparcos catalogue, selecting the stars by absolute magnitude and removing multiple systems. The sample is essentially a complete reckoning of the metal content in nearby K dwarfs. We use stellar isochrones to mark the stars by mass, and select a subset of 220 of the stars, which is complete within a narrow mass interval. We fit the data with a model of the chemical evolution of the solar cylinder. We find that only a modest cosmic scatter is required to fit our age-metallicity relation. The model assumes two main infall episodes for the formation of the halo-thick disc and thin disc, respectively. The new data confirm that the solar neighbourhood formed on a long time-scale of the order of 7Gyr.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A116
- Title:
- G and K giant stars stellar parameters
- Short Name:
- J/A+A/574/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained precise radial velocities for a sample of 373 G and K type giants at Lick Observatory regularly over more than 12 years. Planets have been identified around 15 of these giant stars, and an additional 20 giant stars host planet candidates. We are interested in the occurrence rate of substellar companions around giant stars as a function of stellar mass and metallicity. We probe the stellar mass range from approximately 1 to beyond 3M_{sun}_, which is not being explored by main-sequence samples. We fit the giant planet occurrence rate as a function of stellar mass and metallicity with a Gaussian and an exponential distribution, respectively.
- ID:
- ivo://CDS.VizieR/III/10B
- Title:
- G5 and later stars in a North Galactic Pole region
- Short Name:
- III/10B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is an objective-prism survey of late-type stars in a region of 396 square degrees surrounding the north galactic pole. The objective-prism spectra employed have a dispersion of 58 nm/mm at H-{gamma} and extend into the ultraviolet region. The catalog contains the magnitudes and spectral classes of 4027 stars of class G5 and later, complete to a limiting photographic magnitude of 13.0. The spectral classification of the stars is based on the Yerkes system. The catalog includes the serial numbers of the stars corresponding to the numbers on the identification charts in Upgren (1984), BD and HD numbers, B magnitudes, spectral classes, and letters designating the subregion and identification chart on which each star is located. This survey was undertaken to determine the space densities at varying distances from the galactic plane. Accurate separation of the surveyed stars of G5 and later into giants and dwarfs was achieved through the use of the UV region as well as conventional methods of classification. The resulting catalog of 4027 stars is probably complete over the region to a limiting photographic magnitude of 13.0. The region covered by the survey is the same as that discussed by Slettebak and Stock (1959) and is in the approximate range RA 11:30 to 13:00, Declination +25 to +50 (B1950.0). The catalog includes all M and Carbon stars previously published by Upgren (1960). For a discussion of the classification criteria, the combining of multiple classifications (each spectral image was classified twice), the determination of magnitudes, and additional details about the catalog, the source reference should be consulted. Corrections, accurate positions, more identifications, and remarks have been added in Nov. 2015 by B. Skiff in the file "positions.dat"; see the "History" section below for details.
- ID:
- ivo://CDS.VizieR/J/A+A/462/875
- Title:
- Garching-Bonn Deep Survey (GaBoDS) IX
- Short Name:
- J/A+A/462/875
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of the present work is the construction of a mass-selected galaxy cluster sample based on weak gravitational lensing methods. This sample will be subject to spectroscopic follow-up observations. We apply the mass aperture statistics (S-statistics) and a new derivative of it (the P-statistics) to 19 square degrees of high quality, single colour wide field imaging data obtained with the WFI@MPG/ESO 2.2m telescope. For the statistics a family of filter functions is used that approximates the expected tangential radial shear profile and thus allows for the efficient detection of mass concentrations. The exact performance of the P-statistics still needs to be evaluated by means of simulations.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A68
- Title:
- Gas accretion in nearby spiral galaxies
- Short Name:
- J/A+A/567/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We quantify the gas accretion rate from minor mergers onto star-forming galaxies in the local Universe using HI observations of 148 nearby spiral galaxies (WHISP sample). We developed a dedicated code that iteratively analyses HI data-cubes, finds dwarf gas-rich satellites around larger galaxies, and estimates an upper limit to the gas accretion rate. We found that 22% of the galaxies have at least one detected dwarf companion. We made the very stringent assumption that all satellites are going to merge in the shortest possible time, transferring all their gas to the main galaxies. This leads to an estimate of the maximum gas accretion rate of 0.28M_{sun}_/yr, about five times lower than the average star formation rate of the sample. Given the assumptions, our accretion rate is clearly an overestimate. Our result strongly suggests that minor mergers do not play a significant role in the total gas accretion budget in local galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A133
- Title:
- Gas and dust in star-forming region rho OphA
- Short Name:
- J/A+A/608/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate to what degree local physical and chemical conditions are related to the evolutionary status of various objects in star-forming media. rho Oph A displays the entire sequence of low-mass star formation in a small volume of space. Using spectrophotometric line maps of H_2_, H_2_O, NH_3_, N_2_H^+^, O_2_, OI, CO, and CS, we examine the distribution of the atomic and molecular gas in this dense molecular core. The physical parameters of these species are derived, as are their relative abundances in rho Oph A. Using radiative transfer models, we examine the infall status of the cold dense cores from their resolved line profiles of the ground state lines of H_2_O and NH_3_, where for the latter no contamination from the VLA 1623 outflow is observed and line overlap of the hyperfine components is explicitly taken into account. The stratified structure of this photon dominated region (PDR), seen edge-on, is clearly displayed. Polycyclic aromatic hydrocarbons (PAHs) and OI are seen throughout the region around the exciting star S1. At the interface to the molecular core 0.05pc away, atomic hydrogen is rapidly converted into H_2_, whereas OI protrudes further into the molecular core. This provides oxygen atoms for the gas-phase formation of O_2_ in the core SM1, where X(O_2_)~5x10^-8^. There, the ratio of the O_2_ to H_2_O abundance [X(H_2_O)~5x10^-9^] is significantly higher than unity. Away from the core, O_2_ experiences a dramatic decrease due to increasing H_2_O formation. Outside the molecular core, on the far side as seen from S1, the intense radiation from the 0.5pc distant early B-type star HD147889 destroys the molecules. Towards the dark core SM1, the observed abundance ratio X(O_2_)/X(H_2_O)>1, which suggests that this object is extremely young, which would explain why O_2_ is such an elusive molecule outside the solar system.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A131
- Title:
- Gas and dust in the star-forming region rho OphA
- Short Name:
- J/A+A/578/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using mapping observations of the very dense rho Oph A core, we examined standard 1D and non-standard 3D methods to analyse data of far-infrared and submillimeter continuum radiation. The resulting dust surface density distribution can be compared to that of the gas. The latter was derived from the analysis of accompanying molecular line emission, observed with Herschel from space and with APEX from the ground. As a gas tracer we used N_2_H^+^, which is believed to be much less sensitive to freeze-out than CO and its isotopologues. Radiative transfer modelling of the N_2_H^+^(J=3-2) and (J=6-5) lines with their hyperfine structure explicitly taken into account provides solutions for the spatial distribution of the column density N(H2), hence the surface density distribution of the gas. The gas-to-dust mass ratio is varying across the map, with very low values in the central regions around the core SM1. The global average, =88, is not far from the canonical value of 100, however. In rho Oph A, the exponent beta of the power-law description for the dust opacity exhibits a clear dependence on time, with high values of 2 for the envelope-dominated emission in starless Class-1 sources to low values close to 0 for the disk-dominated emission in ClassIII objects. beta assumes intermediate values for evolutionary classes in between. Since beta is primarily controlled by grain size, grain growth mostly occurs in circumstellar disks. The spatial segregation of gas and dust, seen in projection toward the core centre, probably implies that, like C^18^O, also N_2_H^+^ is frozen onto the grains.
- ID:
- ivo://CDS.VizieR/J/A+A/374/394
- Title:
- Gas and stars kinematics in disc galaxies
- Short Name:
- J/A+A/374/394
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ionized gas and stellar kinematical parameters have been measured along the major axis of 20 nearby disc galaxies. We discuss the properties of each sample galaxy, distinguishing between those characterized by regular or peculiar kinematics. In early-type disc galaxies, ionized gas tends to rotate faster than stars and to have a lower velocity dispersion (V_g_>V_*_ and {sigma}_g_<{sigma}_*_), whereas in late-type spirals, gas and stars show almost the same rotation velocities and velocity dispersions (V_g_=~V_*_ and {sigma}_g_=~{sigma}_*_). Incorporating the early-type disc galaxies studied by Bertola et al. (1995ApJ...448L..13B), Fisher (1997, Cat. <J/AJ/113/950>) and Corsini et al. (1999, Cat. <J/A+A/342/671>), we have compiled a sample of some 40 galaxies for which the major-axis radial profiles of both the stellar and gaseous components have been measured. The value of {sigma}_*_ measured at R_e_/4 turns out to be strongly correlated with the galaxy morphological type, while {sigma}_g_ is not and sometimes takes values above the range expected from thermal motions or small-scale turbulence.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/398
- Title:
- Gas and stellar metallicities in HII galaxies
- Short Name:
- J/MNRAS/421/398
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the gas and stellar metallicities in a sample of HII galaxies from the Sloan Digital Sky Survey, which possibly contains the largest homogeneous sample of HII galaxy spectra to date. We eliminated all spectra with an insufficient signal-to-noise ratio, without strong emission lines and without the [OII] {lambda}3727{AA} line, which is necessary for the determination of the gas metallicity. This excludes galaxies with redshift ~<0.033. Our final sample contains ~700 spectra of HII galaxies.