- ID:
- ivo://CDS.VizieR/J/A+A/560/A8
- Title:
- STAGGER-grid of 3D stellar models. II.
- Short Name:
- J/A+A/560/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the implications of averaging methods with different reference depth scales for 3D hydrodynamical model atmospheres computed with the Stagger-code. The temporally and spatially averaged (hereafter denoted as <3D>) models are explored in the light of local thermodynamic equilibrium (LTE) spectral line formation by comparing spectrum calculations using full 3D atmosphere structures with those from <3D> averages. We explored methods for computing mean <3D> stratifications from the Stagger-grid time-dependent 3D radiative hydrodynamical atmosphere models by considering four different reference depth scales (geometrical depth, column-mass density, and two optical depth scales). Furthermore, we investigated the influence of alternative averages (logarithmic, enforced hydrostatic equilibrium, flux-weighted temperatures). For the line formation we computed curves of growth for FeI and FeII lines in LTE.
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- ID:
- ivo://CDS.VizieR/J/A+A/573/A89
- Title:
- STAGGER-grid of 3D stellar models. III.
- Short Name:
- J/A+A/573/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the relation between 1D atmosphere models that rely on the mixing length theory and models based on full 3D radiative hydrodynamic (RHD) calculations to describe convection in the envelopes of late-type stars. The adiabatic entropy value of the deep convection zone, s_bot_, and the entropy jump, {Delta}s, determined from the 3D RHD models, are matched with the mixing length parameter, {alpha}_MLT_, from 1D hydrostatic atmosphere models with identical microphysics (opacities and equation-of-state). We also derive the mass mixing length, {alpha}_m_, and the vertical correlation length of the vertical velocity, C[V_z_,V_z_], directly from the 3D hydrodynamical simulations of stellar subsurface convection.
- ID:
- ivo://CDS.VizieR/J/A+A/573/A90
- Title:
- STAGGER-grid of 3D stellar models. IV.
- Short Name:
- J/A+A/573/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compute the emergent stellar spectra from the UV to far infrared for different viewing angles using realistic 3D model atmospheres for a large range in stellar parameters to predict the stellar limb darkening. We have computed full 3D LTE synthetic spectra based on 3D radiative hydrodynamic atmosphere models from the Stagger-grid in the ranges: Teff from 4000 to 7000K, logg from 1.5 to 5.0, and [Fe/H], from -4.0 to +0.5. From the resulting intensities at different wavelength, we derived coefficients for the standard limb darkening laws considering a number of often-used photometric filters. Furthermore, we calculated theoretical transit light curves, in order to quantify the differences between predictions by the widely used 1D model atmosphere and our 3D models.
- ID:
- ivo://CDS.VizieR/J/A+A/611/A11
- Title:
- STAGGER-grid of 3D stellar models. V.
- Short Name:
- J/A+A/611/A11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have calculated spectra from 1000 to 200000{AA} with a constant resolving power of {lambda}/{Delta}{lambda}=20000 and from 8470 and 8710{AA} (Gaia Radial Velocity Spectrometer - RVS - spectral range) with a constant resolving power of {lambda}/{Delta}{lambda}=300000. This for the Stagger-grid 3D stellar atmosphere models in the ranges: Teff from 4000 to 7000K, logg from 1.5 to 5.0, and [Fe/H], from -4.0 to +0.5. We used synthetic spectra to compute theoretical colours in the Johnson-Cousins UBV(RI)C, SDSS, 2MASS, Gaia, SkyMap- per, Stroemgren systems, and HST-WFC3.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A153
- Title:
- Staked SEDs and templates of LBGs at z~3
- Short Name:
- J/A+A/630/A153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore, from a statistical point of view, the rest-frame far-ultraviolet (FUV) to far-infrared (FIR) emission of a population of Lyman-break galaxies (LBGs) at z~3 that cannot be individually detected from current FIR observations. We performed a stacking analysis over a sample of ~17000 LBGs at redshift 2.5<z<3.5 in the COSMOS field. The sample is binned as a function of UV luminosity (L_FUV_), UV continuum slope (beta_UV_), and stellar mass (M*), and then stacked at optical (BVriz bands), near-infrared (YJHKs bands), IRAC (3.6, 4.5, 5.6 and 8.0um), MIPS (24um), PACS (100 and 160 um), SPIRE (250, 350, and 500um), and AzTEC (1.1mm) observations. We obtained 30 rest-frame FUV-to-FIR spectral energy distributions (SEDs) of LBGs at z~3, and analyzed these with the CIGALE SED-fitting analysis code. We were able to derive fully consistent physical parameters, that is, M*, beta_UV_, L_FUV_, L_IR_, A_FUV_, star formation rate, and the slope of the dust attenuation law; we built a semiempirical library of 30 rest-frame FUV-to-FIR stacked LBG SEDs as functions of L_FUV_, beta_UV_, and M*. Additionally, We used the so-called IR-excess (IRX) to investigate the dust attenuation and the shape of the dust attenuation curve as a function of L_UV_, beta_UV_ and M*.
- ID:
- ivo://CDS.VizieR/J/AJ/132/1445
- Title:
- Standard calibration stars infrared spectra
- Short Name:
- J/AJ/132/1445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared spectra with increased spectral resolution and accuracy of the absolute infrared spectral flux have been created for a subset of stellar standards created by Cohen and his collaborators in previous papers in this series. Moderate-resolution ({lambda}/{Delta}{lambda}~400) spectroscopy obtained on infrared standard stars by the Short Wavelength Spectrometer on the Infrared Space Observatory was combined with high-quality photometry tied to our recent absolute calibration from the Midcourse Space Experiment. Thus, 1-35 micron spectra were created for 33 stars, 9 of which are Cohen et al. secondary standards and another 20 of which are tertiary standards for which Cohen adopted spectral templates. The wavelength spacing is given by (0.0001/1 micron)*lambda^2, which provides for 10,000 samples over the 1-35 micron spectral range
- ID:
- ivo://CDS.VizieR/J/other/RoAJ/10.51
- Title:
- Standard errors for PPM and Tycho stars
- Short Name:
- J/other/RoAJ/10.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The connection between the optical reference frame and the radio one constitutes one of the main purposes of the astrometry. The paper is pointing out the contribution of the Bucharest Observatory in this direction. The statistic analysis of the standard errors for the astrometric PPM and TYCHO stars is presented.
- ID:
- ivo://CDS.VizieR/J/AJ/153/96
- Title:
- Standard Galactic field RR Lyrae. I. Photometry
- Short Name:
- J/AJ/153/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength compilation of new and previously published photometry for 55 Galactic field RR Lyrae variables. Individual studies, spanning a time baseline of up to 30 years, are self-consistently phased to produce light curves in 10 photometric bands covering the wavelength range from 0.4 to 4.5 microns. Data smoothing via the GLOESS technique is described and applied to generate high-fidelity light curves, from which mean magnitudes, amplitudes, rise times, and times of minimum and maximum light are derived. 60000 observations were acquired using the new robotic Three-hundred MilliMeter Telescope (TMMT), which was first deployed at the Carnegie Observatories in Pasadena, CA, and is now permanently installed and operating at Las Campanas Observatory in Chile. We provide a full description of the TMMT hardware, software, and data reduction pipeline. Archival photometry contributed approximately 31000 observations. Photometric data are given in the standard Johnson UBV, Kron-Cousins R_C_I_C_, 2MASS JHK, and Spitzer [3.6] and [4.5] bandpasses.
- ID:
- ivo://CDS.VizieR/II/222
- Title:
- Standard magnitudes in the E regions
- Short Name:
- II/222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A single table combines the revised and extended results of 24 series of photometric observations made in South Africa between 1947 and 1960 on the nine Harvard E regions at declination -45{deg}. For each of about 90 stars in each region are tabulated V and B-V on the standard U,B,V system, an ultraviolet-free blue magnitude S'Pg, a photovisual magnitude SPv and, in most cases, an ultraviolet minus blue colour (U-B)_C_. The internal standard error of an entry is +/-0.01mag or less.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/9
- Title:
- Stand2015 Atmospheric Chemical Network for HCNO
- Short Name:
- J/ApJS/224/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There are many open questions about prebiotic chemistry in both planetary and exoplanetary environments. The increasing number of known exoplanets and other ultra-cool, substellar objects has propelled the desire to detect life and prebiotic chemistry outside the solar system. We present an ion-neutral chemical network constructed from scratch, Stand2015, that treats hydrogen, nitrogen, carbon, and oxygen chemistry accurately within a temperature range between 100 and 30000K. Formation pathways for glycine and other organic molecules are included. The network is complete up to H6C2N2O3. Stand2015 is successfully tested against atmospheric chemistry models for HD 209458b, Jupiter, and the present-day Earth using a simple one-dimensional photochemistry/diffusion code. Our results for the early Earth agree with those of Kasting for CO_2_, H_2_, CO, and O_2_, but do not agree for water and atomic oxygen. We use the network to simulate an experiment where varied chemical initial conditions are irradiated by UV light. The result from our simulation is that more glycine is produced when more ammonia and methane is present. Very little glycine is produced in the absence of any molecular nitrogen and oxygen. This suggests that the production of glycine is inhibited if a gas is too strongly reducing. Possible applications and limitations of the chemical kinetics network are also discussed.