- ID:
- ivo://CDS.VizieR/J/A+A/617/A83
- Title:
- MIDI atlas of low- and intermediate-mass YSOs
- Short Name:
- J/A+A/617/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Protoplanetary disks show large diversity regarding their morphology and dust composition. With mid-infrared interferometry the thermal emission of disks can be spatially resolved, and the distribution and properties of the dust within can be studied. Our aim is to perform a statistical analysis on a large sample of 82 disks around low- and intermediate-mass young stars, based on mid-infrared interferometric observations. We intend to study the distribution of disk sizes, variability, and the silicate dust mineralogy. Archival mid-infrared interferometric data from the MIDI instrument on the Very Large Telescope Interferometer are homogeneously reduced and calibrated. Geometric disk models are used to fit the observations to get spatial information about the disks. An automatic spectral decomposition pipeline is applied to analyze the shape of the silicate feature. We present the resulting data products in the form of an atlas, containing N band correlated and total spectra, visibilities, and differential phases. The majority of our data can be well fitted with a continuous disk model, except for a few objects, where a gapped model gives a better match. From the mid-infrared size-luminosity relation we find that disks around T Tauri stars are generally colder and more extended with respect to the stellar luminosity than disks around Herbig Ae stars. We find that in the innermost part of the disks (r<~1au) the silicate feature is generally weaker than in the outer parts, suggesting that in the inner parts the dust is substantially more processed. We analyze stellar multiplicity and find that in two systems (AB Aur and HD 72106) data suggest a new companion or asymmetric inner disk structure. We make predictions for the observability of our objects with the upcoming Multi-AperTure mid- Infrared SpectroScopic Experiment (MATISSE) instrument, supporting the practical preparations of future MATISSE observations of T Tauri stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/201/11
- Title:
- Mid-infrared spectral variability atlas of YSOs
- Short Name:
- J/ApJS/201/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The atlas presents medium-resolution mid-infrared spectra of low- and intermediate mass pre-main sequence objects obtained by the ISOPHOT-S spectrophotometer of the Infrared Space Observatory (ISO) and the Infrared Spectrograph (IRS) of the Spitzer Space Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJS/190/147
- Title:
- Mid-IR galaxy morphology from S^4^G
- Short Name:
- J/ApJS/190/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spitzer Space Telescope Infrared Array Camera imaging provides an opportunity to study all known morphological types of galaxies in the mid-IR at a depth significantly better than ground-based near-infrared and optical images. The goal of this study is to examine the imprint of the de Vaucouleurs classification volume in the 3.6um band, which is the best Spitzer waveband for galactic stellar mass morphology owing to its depth and its reddening-free sensitivity mainly to older stars. For this purpose, we have prepared classification images for 207 galaxies from the Spitzer archive, most of which are formally part of the Spitzer Survey of Stellar Structure in Galaxies (S^4^G), a Spitzer post-cryogenic ("warm") mission Exploration Science Legacy Program survey of 2331 galaxies closer than 40Mpc. For the purposes of morphology, the galaxies are interpreted as if the images are blue light, the historical waveband for classical galaxy classification studies. We find that 3.6um classifications are well correlated with blue-light classifications, to the point where the essential features of many galaxies look very similar in the two very different wavelength regimes. We present an atlas of all of the 207 galaxies analyzed here and bring attention to special features or galaxy types, such as nuclear rings, pseudobulges, flocculent spiral galaxies, I0 galaxies, double-stage and double-variety galaxies, and outer rings, that are particularly distinctive in the mid-IR.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A165
- Title:
- MILES atmospheric parameters
- Short Name:
- J/A+A/531/A165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Empirical libraries of stellar spectra are used to classify stars and synthetize stellar populations. MILES is a medium spectral-resolution library in the optical domain covering a wide range of temperatures, surface gravities and metallicities. We redetermine the atmospheric parameters of these stars in order to improve the homogeneity and accuracy. We build an interpolating function that returns a spectrum as a function of the three atmospheric parameters, and finally we characterize the precision of the wavelength calibration and stability of the spectral resolution. We used the ULySS program with the ELODIE library as a reference and compared the results with those in the literature. Results. We obtain precisions of 60K, 0.13, and 0.05dex, respectively, for Teff, logg, and [Fe/H] for the FGK stars. For the M stars, the mean errors are 38K, 0.26, and 0.12dex and 3.5%, 0.17, and 0.13dex for the OBA. We construct an interpolator that we test against the MILES stars themselves. We test it also by measuring the atmospheric parameters of the CFLIB stars with MILES as reference and find it to be more reliable than the ELODIE interpolator for the evolved hot stars, like those of the blue horizontal branch in particular.
- ID:
- ivo://CDS.VizieR/J/MNRAS/371/703
- Title:
- MILES library of empirical spectra
- Short Name:
- J/MNRAS/371/703
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new stellar library developed for stellar population synthesis modelling is presented. The library consists of 985 stars spanning a large range in atmospheric parameters. The spectra were obtained at the 2.5-m Isaac Newton Telescope and cover the range 3525-7500{AA} at 2.3{AA} (full width at half-maximum) spectral resolution. The spectral resolution, spectral-type coverage, flux-calibration accuracy and number of stars represent a substantial improvement over previous libraries used in population-synthesis models.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A103
- Title:
- Model 1D (LHD) and 3D (CO5BOLD) spectra
- Short Name:
- J/A+A/550/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To derive space velocities of stars along the line of sight from wavelength shifts in stellar spectra requires accounting for a number of second-order effects. For most stars, gravitational redshifts, convective blueshifts, and transverse stellar motion are the dominant contributors. We provide theoretical corrections for the net velocity shifts due to convection expected for the measurements from the Gaia Radial Velocity Spectrometer (RVS). We used a set of three-dimensional time-dependent simulations of stellar surface convection computed with CO5BOLD to calculate spectra of late-type stars in the Gaia RVS range and to infer the net velocity offset that convective motions will induce in radial velocities derived by cross-correlation. The net velocity shifts derived by cross-correlation depend both on the wavelength range and spectral resolution of the observations. Convective shifts for Gaia RVS observations are less than 0.1km/s for late-K-type stars, and they increase with stellar mass, reaching about 0.3km/s or more for early F-type dwarfs. This tendency is the result of an increase with effective temperature in both temperature and velocity fluctuations in the line-forming region. Our simulations also indicate that the net RVS convective shifts can be positive (i.e. redshifts) in some cases. Overall, the blueshifts weaken slightly with increasing surface gravity, and are enhanced at low metallicity. Gravitational redshifts amount up to 0.7km/s and dominate convective blueshifts for dwarfs, but become much weaker for giants.
- ID:
- ivo://CDS.VizieR/J/ApJS/125/349
- Title:
- Morphology of 12micron Seyfert Galaxies
- Short Name:
- J/ApJS/125/349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 263 optical and near-infrared (NIR) images for 42 1s and 48 Seyfert 2s, selected from the Extended 12{mu}m Galaxy Sample. Elliptically averaged profiles are derived from the images, and isophotal radii and magnitudes are calculated from these. We also report virtual aperture photometry that, judging from comparison with previous work, is accurate to roughly 0.05 mag in the optical, and 0.07 mag in the NIR. Our B-band isophotal magnitude and radii, obtained from ellipse fitting, are in good agreement with those of Third Reference Catalogue of Bright Galaxies. When compared with the B band, V, I, J, and K isophotal diameters show that the colors in the outer regions of Seyfert galaxies are consistent with the colors of normal spirals. Differences in the integrated isophotal colors and comparison with a simple model show that the active nucleus+bulge are stronger and redder in the NIR than in the optical. Finally, roughly estimated Seyfert disk surface brightnesses are significantly brighter in B and K than those in normal spirals of similar morphological type.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A100
- Title:
- MUSE library of stellar spectra
- Short Name:
- J/A+A/629/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Empirical stellar spectral libraries have applications in both extragalactic and stellar studies, and they confer an advantage over theoretical libraries because they naturally include all relevant chemical species and physical processes. In recent years we have seen a stream of new sets of high-quality spectra, but increasing the spectral resolution and widening the wavelength coverage means resorting to multi-order echelle spectrographs. Assembling the spectra from many pieces results in lower fidelity of their shapes. We aim to offer the community a library of high-signal-to-noise spectra with reliable continuum shapes. Furthermore, the use of an integral field unit (IFU) alleviates the issue of slit losses. Our library was built with the MUSE (Multi-Unit Spectroscopic Explorer) IFU instrument. We obtained spectra over nearly the entire visual band ({lambda}~4800-9300{AA}). We assembled a library of 35 high-quality MUSE spectra for a subset of the stars from the X-shooter Spectral Library. We verified the continuum shape of these spectra with synthetic broadband colors derived from the spectra. We also report some spectral indices from the Lick system, derived from the new observations. We offer a high-fidelity set of stellar spectra covering the Hertzsprung-Russell diagram. These can be used for both extragalactic and stellar studies and demonstrate that the IFUs are excellent tools for building reliable spectral libraries.
- ID:
- ivo://CDS.VizieR/III/181
- Title:
- Near Infrared Spectra of Normal Stars
- Short Name:
- III/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The authors present digital spectra of O to M stars, luminosity classes V, III, and Ib in the wavelength range 5750-8950{AA}, at 15.5{AA} resolution. The stars follow well defined morphological sequences in both temperature and luminosity. This wavelength region and resolution, combined with the high sensitivity of silicon-based detectors, are very useful for spectral classification. Details of the observations, identifications of the main spectral features, and spectral lines most sensitive to temperature and luminosity are given in the paper.
- ID:
- ivo://CDS.VizieR/J/ApJS/161/154
- Title:
- Near-IR spectral atlas of OB stars
- Short Name:
- J/ApJS/161/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present intermediate-resolution (R~8000-12000) high signal-to-noise (S/N) H- and K-band spectroscopy of a sample of 37 optically visible stars, ranging in spectral type from O3 to B3 and representing most luminosity classes. Spectra of this quality can be used to constrain the temperature, luminosity, and general wind properties of OB stars, when used in conjunction with sophisticated atmospheric model codes. Most important is the need for moderately high resolutions (R>=5000) and very high signal-to-noise (S/N>=150) spectra for a meaningful profile analysis. When using near-infrared spectra for a classification system, moderately high signal-to-noise (S/N~100) is still required, though the resolution can be relaxed to just a thousand or two. In the Appendix we provide a set of very high-quality near-infrared spectra of Brackett lines in six early-A dwarfs. These can be used to aid in the modeling and removal of such lines when early-A dwarfs are used for telluric spectroscopic standards.
