- ID:
- ivo://CDS.VizieR/J/A+A/658/A47
- Title:
- Dwarf stars limb-darkening coefficients
- Short Name:
- J/A+A/658/A47
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Stellar models applied to large stellar surveys of the Milky Way need to be properly tested against a sample of stars with highly reliable fundamental stellar parameters. We have established a program aiming to deliver such a sample of stars. Here we present new fundamental stellar parameters of nine dwarf stars that will be used as benchmark stars for large stellar surveys. One of these stars is the solar-twin 18Sco, which is also one of the Gaia-ESO benchmarks. The goal is to reach a precision of 1% in effective temperatures (Teff). This precision is important for accurate determinations of the full set of fundamental parameters and abundances of stars observed by the surveys. We observed HD131156 (xi Boo), HD146233 (18 Sco), HD152391, HD173701, HD185395 (theta Cyg), HD186408 (16 Cyg A), HD186427 (16 Cyg B), HD190360 and HD207978 (15 Peg) using the high angular resolution optical interferometric instrument PAVO at the CHARA Array. We derived limb-darkening corrections from 3D model atmospheres and determined Teff directly from the Stefan-Boltzmann relation, with an iterative procedure to interpolate over tables of bolometric corrections. Surface gravities were estimated from comparisons to Dartmouth stellar evolution model tracks. We collected spectroscopic observations from the ELODIE spectrograph and estimated metallicities ([Fe/H]) from a 1D non-local thermodynamic equilibrium (NLTE) abundance analyses of unblended lines of neutral and singly ionized iron. For eight of the nine stars we measure the Teff less than 1%, and for one star better than 2%. We determined the median uncertainties in log g and [Fe/H] as 0.015dex and 0.05dex, respectively. This study presents updated fundamental stellar parameters of nine dwarf stars that can be used as new set of benchmarks. All fundamental stellar parameters were based on consistently combining interferometric observations, 3D limb-darkening modelling and spectroscopic analysis. The next paper in this series will extend our sample to giants in the metal-rich range.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/494/4110
- Title:
- DW Cnc H{alpha} and HeI RV curves
- Short Name:
- J/MNRAS/494/4110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present extensive radial velocity observations of the intermediate polar DW Cnc during its 2018-2019 low state. We show that the 86 min signal associated with the orbital period is strong in our radial velocity analysis, power spectrum search, and in our Doppler tomography. However, we find that the velocity modulation associated with the 70 min beat period and the 38 min spin cycle is dramatically weaker than that previously observed. We put forward two interpretations for this change. The first is that a sudden drop into a low state detected in 2018-2019 caused an episode of low mass transfer from the companion, thus inhibiting the lighthouse effect produced by the rebound emission. The second is that this is a consequence of a rare outburst detected in 2007 by Crawford et al. (2008, J. Am. Assoc. Var. Star Obs., 36, 60). We find this post-outburst hypothesis to be less likely. If the first scenario is correct, we predict that DW Cnc will recover its intermediate polar characteristics. A new ephemeris is presented by combining Patterson et al. (2004PASP..116..516P) radial velocities with ours.
5193. DX Eri variability
- ID:
- ivo://CDS.VizieR/J/A+A/309/787
- Title:
- DX Eri variability
- Short Name:
- J/A+A/309/787
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of nearly simultaneous monitoring of uvby light and HeI667.81nm line-profile variations of the equatorial Be star DX Eri in November 1991. They are analysed along with numerous uvby photometry in the period 1986-1995.
- ID:
- ivo://CDS.VizieR/J/ApJ/689/919
- Title:
- Dynamical evolution of globular clusters
- Short Name:
- J/ApJ/689/919
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We test the hypothesis that metal-poor globular clusters form within disk galaxies at redshifts z>3. We calculate the orbits of model clusters in the time-variable gravitational potential of a Milky Way-sized galaxy, using the outputs of a cosmological N-body simulation. We find that at present the orbits are isotropic in the inner 50kpc of the Galaxy and preferentially radial at larger distances. All clusters located outside 10kpc from the center formed in satellite galaxies, some of which are now tidally disrupted and some of which survive as dwarf galaxies. Mergers of the progenitors lead to a spheroidal spatial distribution of model clusters, although it is more extended than that of Galactic metal-poor clusters and has a somewhat shallower power-law slope of the number density profile, {gamma}~2.7. The combination of two-body relaxation, tidal shocks, and stellar evolution drives the evolution of the cluster mass function from an initial power law to a peaked distribution, in agreement with observations. However, not all initial conditions and not all evolution scenarios are consistent with the observed mass function of the Galactic globular clusters. We find that our best-fitting models require the average cluster density, M/R^3^_h_, to be constant initially for clusters of all mass and to remain constant with time. However, these models do not explain the observed decrease of the mean density with galactocentric distance. Both synchronous formation of all clusters at a single epoch (z=4) and continuous formation over a span of 1.6Gyr (between z=9 and 3) are consistent with the data. For both formation scenarios, we provide online catalogs of the main physical properties of model clusters.
- ID:
- ivo://nasa.heasarc/morbbincat
- Title:
- Dynamical Masses of Selected Orbital Binary Systems
- Short Name:
- MORBBINCAT
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Orbital binary stars are essential objects for determining dynamical and physical properties of stars through a combined analysis of photometric and astrometric data. The authors have compiled a set of orbital binaries with known trigonometric parallaxes and orbits of high quality, using data from current versions of the Observatorio Astronomico Ramon Maria Aller Catalog (OARMAC) of Orbits and Ephemerides of Visual Double Stars (Docobo et al. 2001, AcA, 51, 353) and the Sixth Catalog of Orbits of Visual Binary Stars (ORB6: Mason and Hartkopf 2007, IAUS 240, 575; Hartkopf et al. 2001, AJ, 122, 3472), as well as including updated information from the Washington Double Star (WDS) Catalog and SIMBAD. They constructed distributions of orbital binaries of the dynamical mass, period, semi-major axis, and eccentricity of systems, which characterize the set. Some problems related to the parametrization of orbital binaries are also discussed in the paper. To compile the orbit list, the authors combined data from both OARMAC and ORB6. At this stage, they maintained systems without parallaxes, but removed systems without a period or semi-major axis. The resulting list contained 3139 orbits for 2278 pairs: 1588 pairs have a single orbit, 548 pairs have two orbits, 120 pairs have three orbits, 19 pairs have four orbits, one pair has five orbits, and two pairs have seven orbits. Table 1 in the reference paper (not part of this HEASARC table) contains a compiled set of 3139 orbit solutions for visual binary stars. Separate entries are provided for different pairs in multiple systems. Several solutions per pair are possible. Each entry includes main orbital elements (Semi-major axis, period, eccentricity with corresponding uncertainties), indication of multiplicity and number of solutions, as well as visual magnitudes, spectral classes of the components, parallax and interstellar extinction estimate. Table 2 in the reference paper (on which this HEASARC table is based) contains a refined set of 652 solely binary systems with reliable orbits and determined parallaxes. One entry in this table corresponds to one system. Three mass estimates are provided: (1) The dynamical mass with its uncertainty derived from Kepler's third law and its trigonometric parallax, (2) a photometric mass estimated from the visual magnitudes, parallax and mass-luminosity relation, and (3) a spectroscopic mass based on the mass-spectrum relation introduced by Straizys and Kuriliene (1981, Ap&SS, 80, 353). Also provided for each system are the main orbital elements, the parallax, and the component magnitudes and spectral types. This table was created by the HEASARC in October 2014 based on the list of orbital binaries given in <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/546/A69">CDS Catalog J/A+A/546/A69</a> file table2.dat. Note that this table does not include the information on individual orbits which given listed in file table1.dat of this CDS catalog. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJ/771/85
- Title:
- Dynamical masses of z~2 quiescent galaxies
- Short Name:
- J/ApJ/771/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using stellar kinematics measurements, we investigate the growth of massive, quiescent galaxies from z~2 to today. We present X-Shooter spectra from the UV to NIR and dynamical mass measurements of five quiescent massive (>10^11^M_{sun}_) galaxies at z~2. This triples the sample of z>1.5 galaxies with well-constrained ({delta}{sigma}<100km/s) velocity dispersion measurements. From spectral population synthesis modeling we find that these galaxies have stellar ages that range from 0.5 to 2Gyr, with no signs of ongoing star formation. We measure velocity dispersions (290-450km/s) from stellar absorption lines and find that they are 1.6-2.1 times higher than those of galaxies in the Sloan Digital Sky Survey at the same mass. Sizes are measured using GALFIT from Hubble Space Telescope Wide Field Camera 3 H_160_ and UDS K-band images. The dynamical masses correspond well to the spectral energy distribution based stellar masses, with dynamical masses that are ~15% higher.
- ID:
- ivo://CDS.VizieR/J/MNRAS/363/769
- Title:
- Dynamical modelling of 4 early-type galaxies
- Short Name:
- J/MNRAS/363/769
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse long-slit spectra of four early-type galaxies which extend from ~1 to 3 effective radii: IC 1459; IC 3370; NGC 3379 and NGC 4105. We have extracted the full line-of-sight velocity distribution (in the case of NGC 3379 we also used data from the literature), which we model using the two-integral approach. Using two-integral modelling, we find no strong evidence for dark haloes, but the fits suggest that three-integral modelling is necessary. We also find that the inferred constant mass-to-light ratio in all the four cases is typical for early-type galaxies. Finally, we also discuss the constraints on the mass-to-light ratio, which can be obtained using X-ray haloes in the case of IC 1459, NGC 3379 and NGC 4105, and compare the estimated values with the predictions from the dynamical modelling.
- ID:
- ivo://CDS.VizieR/J/AZh/89/674
- Title:
- Dynamical parameters of open clusters
- Short Name:
- J/AZh/89/674
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Presented are the estimates of open cluster dynamical parameters: the cluster core density contrast, the stellar velocity dispersions allowing for influence of Galaxy external field and non-stationarity of the cluster, the oscillation periods of the cluster and the cluster core, the amplitudes of oscillations of a cluster virial factor and a radius of the cluster core. All the values were analytically received as a result solution of the gross dynamical equations for spherical and ellipsoidal cluster models.
- ID:
- ivo://CDS.VizieR/J/MNRAS/370/1223
- Title:
- Dynamical properties of 15 nearby galaxy groups
- Short Name:
- J/MNRAS/370/1223
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here, we present an investigation of the properties of 15 nearby galaxy groups and their constituent galaxies. The groups are selected from the Group Evolution Multiwavelength Study (GEMS) and all have X-ray as well as wide-field neutral hydrogen (HI) observations. Group membership is determined using a friends-of-friends algorithm on the positions and velocities from the 6-degree Field Galaxy Survey and NASA/IPAC Extragalactic Database. For each group we derive their physical properties using this membership, including: velocity dispersions (sigma_v_), virial masses (M_V_), total K-band luminosities [L_K_(Tot)] and early-type fractions (f_early_) and present these data for the individual groups.
- ID:
- ivo://CDS.VizieR/J/PAZh/26/301
- Title:
- Dynamical stability of triple stars
- Short Name:
- J/PAZh/26/301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The dynamic stability of 38 observed hierarchical triple stars with known orbital elements of the internal and external binary subsystems and component masses is considered. Four different criteria of dynamical stability are used. The observed stability parameters and their critical values are calculated by taking into account errors in the orbital elements and component masses.