- ID:
- ivo://CDS.VizieR/J/A+A/582/A97
- Title:
- SSP in NIR. II. Synthesis models
- Short Name:
- J/A+A/582/A97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present unresolved single stellar population synthesis models in the near-infrared (NIR) range. The extension to the NIR is important for the study of early-type galaxies, since these galaxies are predominantly old and therefore emit most of their light in this wavelength range. The models are based on a library of empirical stellar spectra, the NASA infrared telescope facility (IRTF) spectral library. Integrating these spectra along theoretical isochrones, while assuming an initial mass function (IMF), we have produced model spectra of single age-metallicity stellar populations at a resolution R~2000. These models can be used to fit observed spectral of globular clusters and galaxies, to derive their age distribution, chemical abundances and IMF. The models have been tested by comparing them to observed colours of elliptical galaxies and clusters in the Magellanic Clouds. Predicted absorption line indices have been compared to published indices of other elliptical galaxies. The comparisons show that our models are well suited for studying stellar populations in unresolved galaxies. They are particularly useful for studying the old and intermediate-age stellar populations in galaxies, relatively free from contamination of young stars and extinction by dust. These models will be indispensable for the study of the upcoming data from JWST and extremely large telescopes, such as the E-ELT.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/502/817
- Title:
- SSP models for star clusters in tidal fields
- Short Name:
- J/A+A/502/817
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Evolutionary synthesis models are the primary means of constructing spectrophotometric models of stellar populations, and deriving physical parameters from observations compared with these models. One of the basic assumptions of evolutionary synthesis models has been the time-independence of the stellar mass function, apart from the successive removal of high-mass stars by stellar evolution. However, dynamical simulations of star clusters in tidal fields have demonstrated that the mass function can be changed by the preferential removal of low-mass stars from clusters. We combine the results of dynamical simulations of star clusters in tidal fields with our evolutionary synthesis code GALEV. We extend the models to consider the total cluster disruption time as additional parameter.
- ID:
- ivo://CDS.VizieR/J/A+A/312/745
- Title:
- SSRS groups of galaxies redshift neighbourhood
- Short Name:
- J/A+A/312/745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Southern Sky Redshift Survey (SSRS) includes 13 groups of 5 or more members with velocities >=2000km/s. By measuring redshifts and accumulating data from the literature, we increase the total number of known group members from 89 to 218. We also measured new redshifts for 59 foreground/background galaxies superimposed on the group neighborhoods. The velocity dispersions of the groups are remarkably stable.
17724. SS 433 UBVRI light curves
- ID:
- ivo://CDS.VizieR/J/other/PZ/31.5
- Title:
- SS 433 UBVRI light curves
- Short Name:
- J/other/PZ/31.5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- After 33 years of extensive studies of SS 433, we have learnt much about this unique system with moving emission lines in the spectrum. The orbital inclination is known from spectroscopic observations of moving lines; the distance is derived from radio interferometry of relativistic jets; the mass ratio of its components is determined from X-ray observations of jets' eclipses. In 2005, the accretion donor was detected as an A4-A8 giant, and its contribution to eclipse light was measured spectroscopically. In the present paper, the A-type star was detected via multicolor photometry on the basis of its Balmer jump. A method is proposed to estimate the interstellar reddening, able to measure the individual law of interstellar absorption for SS 433 from spectrophotometry.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A109
- Title:
- Ssynthetic spectra of supernovae models
- Short Name:
- J/A+A/621/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observational surveys are now able to detect an increasing number of transients, such as core-collapse supernovae (SN) and powerful non-terminal outbursts (SN impostors). Dedicated spectroscopic facilities can follow up these events shortly after detection. Here we investigate the properties of these explosions at early times.We use the radiative transfer code CMFGEN to build an extensive library of spectra simulating the interaction of supernovae and their progenitor's winds/circumstellar medium (CSM).We consider a range of progenitor mass-loss rates (dM/dt=5x10^-4^ to 10^-2^ M_{sun}/yr), abundances (solar, CNO-processed, and He-rich), and SN luminosities (L=1.9x10^8^ to 2.5x10^10^L_{sun}_). The models simulate events ~=1-day after explosion, and we assume a fixed location of the shock front as R_in_=8.6x10^13^cm. We show that the large range of massive star properties at the pre-SN stage causes a diversity of early-time interacting SN and impostors. We identify three main classes of early-time spectra consisting of relatively high-ionisation (e.g. HeII and OVI), medium-ionisation (e.g. CIII and NIII), and low-ionisation lines (e.g. HeI and FeII/III). They are regulated by L and the CSM density. Given a progenitor wind velocity v_inf_, our models also place a lower limit of dM/dt>~5x10^-4^(v_inf_=150km/s)M_{sun}_/yr for detection of CSM interaction signatures in observed spectra. Early-time SN spectra should provide clear constraints on progenitors by measuring H, He, and CNO abundances if the progenitors come from single stars. The connections are less clear considering the effects of binary evolution. Nevertheless, our models provide a clear path for linking the final stages of massive stars to their post-explosion spectra at early times, and guiding future observational follow-up of transients with facilities such as the Zwicky Transient Facility.
- ID:
- ivo://CDS.VizieR/J/ApJ/716/1336
- Title:
- Stability analysis of single-planet
- Short Name:
- J/ApJ/716/1336
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the dynamical stability of planetary systems consisting of one hypothetical terrestrial-mass planet (1 or 10M_{earth}_) and one massive planet (10M{earth}-10M_jup_). We consider masses and orbits that cover the range of observed planetary system architectures (including non-zero initial eccentricities), determine the stability limit through N-body simulations, and compare it to the analytic Hill stability boundary. We show that for given masses and orbits of a two-planet system, a single parameter, which can be calculated analytically, describes the Lagrange stability boundary (no ejections or exchanges) but diverges significantly from the Hill stability boundary. However, we do find that the actual boundary is fractal, and therefore we also identify a second parameter which demarcates the transition from stable to unstable evolution. We show the portions of the habitable zones (HZs) of {rho} CrB, HD 164922, GJ 674, and HD 7924 that can support a terrestrial planet. These analyses clarify the stability boundaries in exoplanetary systems and demonstrate that, for most exoplanetary systems, numerical simulations of the stability of potentially habitable planets are only necessary over a narrow region of the parameter space. Finally, we also identify and provide a catalog of known systems that can host terrestrial planets in their HZs.
- ID:
- ivo://CDS.VizieR/J/A+A/375/661
- Title:
- Stability of VLBI reference frame
- Short Name:
- J/A+A/375/661
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The file table 2 gives the results of various tests and noise measurements performed on time serie of extragalactic radio source coordinates. Systematic and random behaviours in time serie of individual determinations of cooordinates for 283 sources over 1987-1999 are investigated. The random variability of the source coordinates is characterized by the {chi}^2^ test (Bevington, 1969, p.187) and the "goodness of fit (gof)" (Bevington, 1969, p.188). The Allan variance method (Allan, 1966, Proc. IEEE, vol. 54, 221) is used to investigate spectral characteristics of the time series. The source structure index (Fey & Charlot, 1997ApJS..111...95F, 2000, Cat. <J/ApJS/128/17>) qualifies the level of position disturbance expected at the date of the map (1 for the less disturbed, 4 for the most disturbed). The estimation of "linear rates" in the coordinates is a qualifier of the systematic parts of the source instability. This table contains the 283 best observed sources and is divided in three parts, with the left hand side giving general information and counts, the middle part giving statistics in the source local frame, and the right hand side giving statistics in the equatorial frame.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/140
- Title:
- Stacked spectra of SDSS star forming galaxies
- Short Name:
- J/ApJ/765/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relation between galaxy stellar mass and gas-phase metallicity is a sensitive diagnostic of the main processes that drive galaxy evolution, namely cosmological gas inflow, metal production in stars, and gas outflow via galactic winds. We employed the direct method to measure the metallicities of ~200000 star-forming galaxies from the Sloan Digital Sky Survey that were stacked in bins of (1) stellar mass and (2) both stellar mass and star formation rate (SFR) to significantly enhance the signal-to-noise ratio of the weak [OIII]{lambda}4363 and [OII]{lambda}{lambda}7320,7330 auroral lines required to apply the direct method. These metallicity measurements span three decades in stellar mass from log(M_*_/M_{sun}_)=7.4-10.5, which allows the direct method mass-metallicity relation to simultaneously capture the high-mass turnover and extend a full decade lower in mass than previous studies that employed more uncertain strong line methods. The direct method mass-metallicity relation rises steeply at low mass (O/H{prop.to}M_*_^1/2^) until it turns over at log(M_*_/M_{sun}_)=8.9 and asymptotes to 12+log(O/H)=8.8 at high mass. The direct method mass-metallicity relation has a steeper slope, a lower turnover mass, and a factor of two to three greater dependence on SFR than strong line mass-metallicity relations. Furthermore, the SFR-dependence appears monotonic with stellar mass, unlike strong line mass-metallicity relations. We also measure the N/O abundance ratio, an important tracer of star formation history, and find the clear signature of primary and secondary nitrogen enrichment. N/O correlates tightly with oxygen abundance, and even more so with stellar mass.
17729. STAGES master catalog
- ID:
- ivo://CDS.VizieR/J/MNRAS/393/1275
- Title:
- STAGES master catalog
- Short Name:
- J/MNRAS/393/1275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an overview of the Space Telescope A901/2 Galaxy Evolution Survey (STAGES). STAGES is a multiwavelength project designed to probe physical drivers of galaxy evolution across a wide range of environments and luminosity. A complex multicluster system at z~0.165 has been the subject of an 80-orbit F606W Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) mosaic covering the full 0.5x0.5deg^2^ (~5x5Mpc^2^) span of the supercluster. Extensive multiwavelength observations with XMM-Newton, GALEX, Spitzer, 2dF, Giant Metrewave Radio Telescope and the 17-band COMBO-17 photometric redshift survey complement the HST imaging. Our survey goals include simultaneously linking galaxy morphology with other observables such as age, star formation rate, nuclear activity and stellar mass. In addition, with the multiwavelength data set and new high-resolution mass maps from gravitational lensing, we are able to disentangle the large-scale structure of the system. By examining all aspects of an environment we will be able to evaluate the relative importance of the dark matter haloes, the local galaxy density and the hot X-ray gas in driving galaxy transformation.
- ID:
- ivo://CDS.VizieR/J/A+A/557/A26
- Title:
- STAGGER-grid of 3D stellar models. I.
- Short Name:
- J/A+A/557/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the STAGGER-grid, a comprehensive grid of time-dependent, three-dimensional (3D), hydrodynamic model atmospheres for late-type stars with realistic treatment of radiative transfer, covering a wide range in stellar parameters. All our models were generated with the Stagger-code, using realistic input physics for the equation of state (EOS) and for continuous and line opacities. Our ~220 grid models range in effective temperature, Teff, from 4000 to 7000K in steps of 500K, in surface gravity, logg, from 1.5 to 5.0 in steps of 0.5dex, and metallicity, [Fe/H], from -4.0 to +0.5 in steps of 0.5 and 1.0dex.