- ID:
- ivo://CDS.VizieR/J/A+A/596/A49
- Title:
- Synthetic GALEX photometry for IUE sources
- Short Name:
- J/A+A/596/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galaxy Evolution Explorer (GALEX) has produced the largest photometric catalogue of ultraviolet (UV) sources. As such, it has defined the new standard bands for UV photometry: the near UV band (NUV) and the far UV band (FUV). However, due to brightness limits, the GALEX mission has avoided the Galactic plane which is crucial for astrophysical research and future space missions. The International Ultraviolet Explorer (IUE) satellite obtained 63,755 spectra in the low dispersion mode ({lambda}/{delta}{lambda}~300) during its 18-year lifetime. We have derived the photometry in the GALEX bands for the stellar sources in the IUE Archive to extend the GALEX database with observations including the Galactic plane. Good quality spectra have been selected for the IUE classes of stellar sources. The GALEX FUV and NUV magnitudes have been computed using the GALEX transmission curves, as well as the conversion equations between flux and magnitudes provided by the mission (galexgi.gsfc.nasa.gov). Consistency between GALEX and IUE synthetic photometries has been tested using White Dwarfs (WD) contained in both samples. The non-linear response performance of GALEX inferred from this data agrees with the results from GALEX calibration. The photometric database is made available to the community through the services of the Centre de Donnees Stellaires at Strasbourg (CDS). The catalogue contains FUV magnitudes for 1628 sources, ranging from FUV=1.81 to FUV=18.65mag. In the NUV band, the catalogue includes observations for 999 stars ranging from NUV=3.34 to NUV=17.74mag. UV photometry for 1490 sources not included in the GALEX AIS GR5 catalogue is provided; most of them are hot (O-A spectral type) stars. The sources in the catalogue are distributed over the full sky, including the Galactic plane.
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- ID:
- ivo://CDS.VizieR/J/ApJ/841/15
- Title:
- Synthetic JWST/MIRI fluxes and magnitudes
- Short Name:
- J/ApJ/841/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Mid-Infrared Instrument (MIRI) for the James Webb Space Telescope (JWST) will revolutionize our understanding of infrared stellar populations in the Local Volume. Using the rich Spitzer-IRS spectroscopic data set and spectral classifications from the Surveying the Agents of Galaxy Evolution (SAGE)-Spectroscopic survey of more than 1000 objects in the Magellanic Clouds, the Grid of Red Supergiant and Asymptotic Giant Branch Star Model (GRAMS; Sargent+ 2011ApJ...728...93S and Srinivasan+ 2011, J/A+A/532/A54), and the grid of YSO models by Robitaille+ (2006ApJS..167..256R), we calculate the expected flux densities and colors in the MIRI broadband filters for prominent infrared stellar populations. We use these fluxes to explore the JWST/MIRI colors and magnitudes for composite stellar population studies of Local Volume galaxies. MIRI color classification schemes are presented; these diagrams provide a powerful means of identifying young stellar objects, evolved stars, and extragalactic background galaxies in Local Volume galaxies with a high degree of confidence. Finally, we examine which filter combinations are best for selecting populations of sources based on their JWST colors.
- ID:
- ivo://CDS.VizieR/J/ApJ/601/485
- Title:
- Synthetic Lick indices of alpha-enhanced stars
- Short Name:
- J/ApJ/601/485
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Synthetic Lick indices computed with solar scaled abundances and with {alpha}-element enhancement are presented and compared with predictions from both theoretical computations (Tripicco & Bell (1995AJ....110.3035T); Thomas, Maraston, & Bender (2003MNRAS.339..897T); Barbuy et al., 2003, Cat. <J/A+A/404/661>) and empirical fitting functions (de Freitas Pacheco, 1996MNRAS.278..841D). We propose selected combinations of indices capable of singling out {alpha}-enhanced stars without requiring previous knowledge of their main atmospheric parameters. By applying this approach to the 460 stars in the Worthey et al. (1994, Cat. <J/ApJS/94/687>) catalog, we detected a list of 82 candidate {alpha}-enhanced stars. The confirmation of {alpha}-enhancement was obtained by searching the literature for individual element abundance determinations from high-resolution spectroscopy for a subsample of 34 stars. Preliminary discussion of the properties of the detected {alpha}-enhanced stars with respect to their [Fe/H] values and kinematics is presented.
- ID:
- ivo://CDS.VizieR/J/ApJ/634/1319
- Title:
- Synthetic Lick indices of alpha-enhanced stars
- Short Name:
- J/ApJ/634/1319
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 119 F, G, and K solar neighborhood stars, selected under the condition [Fe/H]>0.00, is investigated in order to detect which of them, if any, present {alpha}-enhanced characteristics. According to the kinematics, the sample represents stars of the thin-disk component of the Galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/613/312
- Title:
- Synthetic Lick indices of alpha-enhanced stars
- Short Name:
- J/ApJ/613/312
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of 402 F, G, and K solar neighborhood stars, with accurate estimates of [Fe/H] in the range -1.0 to +0.5dex, aimed at the detection of {alpha}-enhanced stars and at the investigation of their kinematical properties. The analysis is based on the comparison of 571 sets of spectral indices in the Lick/IDS system, coming from four different observational data sets, with synthetic indices computed with solar-scaled abundances and with {alpha}-element enhancement. We use selected combinations of indices to single out {alpha}-enhanced stars without requiring previous knowledge of their main atmospheric parameters. By applying this approach to the total data set, we obtain a list of 60 bona fide {alpha}-enhanced stars and of 146 stars with solar-scaled abundances. The properties of the detected {alpha}-enhanced and solar-scaled abundance stars with respect to their [Fe/H] values and kinematics are presented. A clear kinematic distinction between solar-scaled and {alpha}-enhanced stars was found, although a one-to-one correspondence to "thin disk" and "thick disk" components cannot be supported with the present data.
21296. Synthetic lines in the Sun
- ID:
- ivo://CDS.VizieR/J/A+A/528/A113
- Title:
- Synthetic lines in the Sun
- Short Name:
- J/A+A/528/A113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have computed synthetic spectra from a realistic 3D numerical simulation of the solar photosphere. We provide the spatially averaged spectra for selected lines that are commonly used on solar applications. These data can be used to calibrate Doppler velocity measurements in the solar photosphere. The calculations are carried out along the solar disk from heliocentric angle mu=1.0 to mu=0.3.
- ID:
- ivo://CDS.VizieR/J/ApJ/657/1046
- Title:
- Synthetic Mid-UV spectroscopic indices of stars
- Short Name:
- J/ApJ/657/1046
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the UVBLUE library of synthetic stellar spectra we have computed a set of mid-UV line and continuum spectroscopic indices. We explore their behavior in terms of the leading stellar parameters (Teff, logg). The overall result is that synthetic indices follow the general trends depicted by those computed from empirical databases. Separately we also examine the index sensitivity to changes in chemical composition, an analysis only feasible under a theoretical approach. In this respect, lines indices FeI 3000, BL 3096, and MgI 2852 and the continuum index 2828/2921 are the least sensitive features, an important characteristic to be taken into account for the analyses of integrated spectra of stellar systems.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A9
- Title:
- Synthetic photometry as a function of redshift
- Short Name:
- J/A+A/633/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the spectral properties of proto-GCs that would host a supermassive star (SMS). Our main goal is to quantify how such a star would affect the integrated light of the cluster, and to study the detectability of such objects. We computed nonlocal thermal equilibrium atmosphere models for SMS with various combinations of stellar parameters (luminosity, effective temperature, and mass) and metallicities appropriate for GCs, and we predict their emergent spectra. Using these spectra, we calculated the total emission of young proto-GCs with SMS as predicted in a previously reported scenario, and we computed synthetic photometry in UV, optical, and near-IR bands, in particular for the James Webb Space Telescope (JWST). At an effective temperature of 10000K, the spectrum of SMSs shows a Balmer break in emission. This feature is due to strong nonlocal thermal equilibrium effects (implied by the high luminosity) and is not observed in "normal" stars. The hydrogen lines also show a peculiar behavior, with Balmer lines in emission while higher series lines are in absorption. At 7000 K, the Balmer break shows a strong absorption. At high effective temperatures, the Lyman break is found in emission. Cool and luminous SMSs are found to dominate the integrated spectrum of the cluster, except for the UV range. The predicted magnitudes of these proto-GCs are mag_AB_~28-30 between 0.7 and 8um and for redshifts z~4-10, which is detectable with the JWST. The peculiar observational features of cool SMSs imply that they might in principle be detected in color-color diagrams that probe the spectral energy distribution below and above the Balmer break.
- ID:
- ivo://CDS.VizieR/J/MNRAS/371/1503
- Title:
- Synthetic photometry of RR Lyr
- Short Name:
- J/MNRAS/371/1503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The luminosities and effective temperatures, as well as the whole bolometric light curves of non-linear convective RR Lyrae models with 0.0001<=Z<=0.006, are transformed into the Sloan Digital Sky Survey (SDSS) photometric system. The obtained ugriz light curves, mean magnitudes and colours, pulsation amplitudes and colour-colour loops are shown and analytical relations connecting pulsational to intrinsic stellar parameters, similar to the ones currently used in the JohnsonCousins filters, are derived. Finally, the behaviour in the colour-colour planes is compared with available observations in the literature and possible systematic uncertainties affecting this comparison are discussed.
- ID:
- ivo://CDS.VizieR/J/MNRAS/504/3730
- Title:
- Synthetic RGB photometry of bright stars
- Short Name:
- J/MNRAS/504/3730
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although the use of RGB photometry has exploded in the last decades due to the advent of high-quality and inexpensive digital cameras equipped with Bayer-like colour filter systems, there is surprisingly no catalogue of bright stars that can be used for calibration purposes. Since due to their excessive brightness, accurate enough spectrophotometric measurements of bright stars typically cannot be performed with modern large telescopes, we have employed historical 13-colour medium-narrow-band photometric data, gathered with quite reliable photomultipliers, to fit the spectrum of 1346 bright stars using stellar atmosphere models. This not only constitutes a useful compilation of bright spectrophotometric standards well spread in the celestial sphere, the UCM library of spectrophotometric spectra, but allows the generation of a catalogue of reference RGB magnitudes, with typical random uncertainties ~0.01 mag. For that purpose, we have defined a new set of spectral sensitivity curves, computed as the median of 28 sets of empirical sensitivity curves from the literature, that can be used to establish a standard RGB photometric system. Conversions between RGB magnitudes computed with any of these sets of empirical RGB curves and those determined with the new standard photometric system are provided. Even though particular RGB measurements from single cameras are not expected to provide extremely accurate photometric data, the repeatability and multiplicity of observations will allow access to a large amount of exploitable data in many astronomical fields, such as the detailed monitoring of light pollution and its impact on the night sky brightness, or the study of meteors, Solar system bodies, variable stars, and transient objects. In addition, the RGB magnitudes presented here make the sky an accessible and free laboratory for the calibration of the cameras themselves.