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Start Over Subject infrared astronomy Content Level Research
251. EPOCH Project. EROS-2 LMC periodic variables
ID:
ivo://CDS.VizieR/J/A+A/566/A43
Title:
EPOCH Project. EROS-2 LMC periodic variables
Short Name:
J/A+A/566/A43
Date:
21 Oct 2021
Publisher:
CDS
Description:
The EPOCH (EROS-2 periodic variable star classification using machine learning) project aims to detect periodic variable stars in the EROS-2 light curve database. In order to classify these variables, we first build a training set by compiling known variables in the Large Magellanic Could area from the OGLE and MACHO surveys. We crossmatch these variables with the EROS-2 sources and extract 22 variability features from 28,392 light curves of the corresponding EROS-2 sources. We then use Random Forests to classify the EROS-2 sources in the training set. We design the model to separate not only Delta Scuti stars, RR Lyraes, Cepheids, eclipsing binaries and long-period variables, the "superclasses", but also their subclasses, such as RRab, RRc, RRd and RRe for RR Lyraes, and similarly for the other variable types. We apply the trained model to the entire EROS-2 LMC database containing about 29 million sources and find 117,234 periodic variable candidates. Out of these 117,234 periodic variables, 55,285 have not been discovered by either OGLE or MACHO variability studies. This set comprises 1906 Delta Scuti stars, 6,607 RR Lyraes, 638 Cepheids, 178 Type II Cepheids, 34,562 eclipsing binaries and 11,394 long-period variables.
252. Epsilon Indi Ba and Bb IR spectra
ID:
ivo://CDS.VizieR/J/A+A/510/A99
Title:
Epsilon Indi Ba and Bb IR spectra
Short Name:
J/A+A/510/A99
Date:
21 Oct 2021
Publisher:
CDS
Description:
The discovery of epsilon Indi Ba, Bb, a binary brown dwarf system very close to the Sun, makes possible a concerted campaign to characterise the physical parameters of two T dwarfs. Recent observations suggest substellar atmospheric and evolutionary models may be inconsistent with observations, but there have been few conclusive tests to date. We therefore aim to characterise these benchmark brown dwarfs to place constraints on such models. We have obtained high angular resolution optical, near-infrared, and thermal-infrared imaging and medium-resolution (up to R~5000) spectroscopy of epsilon Indi Ba, Bb with the ESO VLT and present VRIzJHKL'M' broad-band photometry and 0.63-5.1 micron spectroscopy of the individual components. The photometry and spectroscopy of the two partially blended sources were extracted with a custom algorithm. Furthermore, we use deep AO-imaging to place upper limits on the (model-dependent) mass of any further system members. We derive luminosities of log L/L_{sun}=-4.699+/-0.017 and -5.232+/-0.020 for epsilon Indi Ba, Bb, respectively, and using the dynamical system mass and COND03 evolutionary models predict a system age of 3.7-4.3Gyr, in excess of previous estimates and recent predictions from observations of these brown dwarfs. Moreover, the effective temperatures of 1352-1385K and 976-1011K predicted from the COND03 evolutionary models, for epsilon Indi Ba and Bb respectively, are in disagreement with those derived from the comparison of our data with the BT-Settl atmospheric models where we find effective temperatures of 1300-1340K and 880-940K, for epsilon Indi Ba and Bb respectively, with surface gravities of logg=5.25 and 5.50. Finally, we show that spectroscopically determined effective temperatures and surface gravities for ultra-cool dwarfs can lead to underestimated masses even where precise luminosity constraints are available.
253. Equivalent widths of cool stars
ID:
ivo://CDS.VizieR/J/A+A/549/A129
Title:
Equivalent widths of cool stars
Short Name:
J/A+A/549/A129
Date:
21 Oct 2021
Publisher:
CDS
Description:
The near-infrared (NIR) wavelength range offers some unique spectral features, and it is less prone to the extinction than the optical one. Recently, the first flux calibrated NIR library of cool stars from the NASA Infrared Telescope Facility (IRTF) have become available, and it has not been fully exploited yet. We want to develop spectroscopic diagnostics for stellar physical parameters based on features in the wavelength range 1-5um. In this work we test the technique in the I and K bands. The study of the Y, J, H, and L bands will be presented in the following paper. An objective method for semi-empirical definition of spectral features sensitive to various physical parameters is applied to the spectra. It is based on sensitivity map - i.e., derivative of the flux in the spectra with respect to the stellar parameters at a fixed wavelength. New optimized indices are defined and their equivalent widths (EWs) are measured.
254. Equivalent widths of two post-AGB stars
ID:
ivo://CDS.VizieR/J/A+A/417/269
Title:
Equivalent widths of two post-AGB stars
Short Name:
J/A+A/417/269
Date:
21 Oct 2021
Publisher:
CDS
Description:
In an effort to extend the still limited sample of s-process enriched post-AGB stars, high-resolution, high signal-to-noise VLT+UVES spectra of the optical counterparts of the infrared sources IRAS 06530-0213 and IRAS 08143-4406 were analysed.
255. 51 Eri b near-infrared spectrum
ID:
ivo://CDS.VizieR/J/other/Sci/350.64
Title:
51 Eri b near-infrared spectrum
Short Name:
J/other/Sci/350.
Date:
21 Oct 2021
Publisher:
CDS
Description:
Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric composition and luminosity, which is influenced by their formation mechanism. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20Myr-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water vapor absorption. Modeling of the spectra and photometry yields a luminosity of L/LS=1.6-4.0x10^-6^ and an effective temperature of 600-750K. For this age and luminosity, "hot-start" formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the "cold- start" core accretion process that may have formed Jupiter.
256. 51 Eri b SPHERE/IFS spectra & atmosphere models
ID:
ivo://CDS.VizieR/J/A+A/603/A57
Title:
51 Eri b SPHERE/IFS spectra & atmosphere models
Short Name:
J/A+A/603/A57
Date:
21 Oct 2021
Publisher:
CDS
Description:
51 Eridani b is an exoplanet around a young (20Myr) nearby (29.4pc) F0-type star, which was recently discovered by direct imaging. It is one of the closest direct imaging planets in angular and physical separation (~0.5", ~13AU) and is well suited for spectroscopic analysis using integral field spectrographs. We aim to refine the atmospheric properties of the known giant planet and to constrain the architecture of the system further by searching for additional companions. We used the extreme adaptive optics instrument SPHERE at the Very Large Telescope (VLT) to obtain simultaneous dual-band imaging with IRDIS and integral field spectra with IFS, extending the spectral coverage of the planet to the complete Y- to H-band range and providing additional photometry in the K12-bands (2.11, 2.25 micron). We present the first spectrophotometric measurements in the Y and K bands for the planet and revise its J-band flux to values 40% fainter than previous measurements. Cloudy models with uniform cloud coverage provide a good match to the data. We derive the temperature, radius, surface gravity, metallicity, and cloud sedimentation parameter fsed. We find that the atmosphere is highly super-solar ([Fe/H]~1.0), and the low fsed~1.26 value is indicative of a vertically extended, optically thick cloud cover with small sized particles. The model radius and surface gravity estimates suggest higher planetary masses of M_gravity_=9.1^+4.9^_-3.3_. The evolutionary model only provides a lower mass limit of >2M_jupiter_ (for pure hot-start). The cold-start model cannot explain the luminosity of the planet. The SPHERE and NACO/SAM detection limits probe the 51 Eri system at solar system scales and exclude brown-dwarf companions more massive than 20M_jupiter_ beyond separations of ~2.5AU and giant planets more massive than 2M_jupiter_ beyond 9 au.
257. EROs in Groth Strip
ID:
ivo://CDS.VizieR/J/MNRAS/414/2246
Title:
EROs in Groth Strip
Short Name:
J/MNRAS/414/2246
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new catalogue of EROs from the Groth Strip and study the relation between their morphology and mass. With a selection criterion F814W-Ks>=4 and Ks<=21.0 we find 102 EROs, over a survey area of 155 arcmin2, leading to a surface density of 0.66arcmin^-2^. The photometric data include U, B, F606W, F814W, J, Ks bands. Morphologies are based on a by eye classification and we distinguish between three basic classes: compact objects, targets with a disc and/or a bulge component and irregular or merger candidates. An additional group consists of the few objects which could not be classified.
258. ESO 1D reduced spectra
ID:
ivo://eso.org/ssap
Title:
ESO 1D reduced spectra
Short Name:
ESO SSAP
Date:
29 Mar 2022 09:14:37
Publisher:
European Southern Observatory
Description:
The ESO Simple Spectral Access service provides access to the 1D reduced spectra generated either by the principal investigators of ESO observations, or by an unattended ESO processing-pipeline that makes use of certified master calibrations. The spectra are FITS files adhering to the ESO Science Data Product standard, based on the Virtual Observatory Spectral Data Model standard (v1.0 for some spectra, and v2.0 for some others, use the VOCLASS FITS keyword to discern the two).
259. Euclid preparation. XIV. C3R2 survey DR3
ID:
ivo://CDS.VizieR/J/ApJS/256/9
Title:
Euclid preparation. XIV. C3R2 survey DR3
Short Name:
J/ApJS/256/9
Date:
18 Jan 2022 14:01:22
Publisher:
CDS
Description:
The Complete Calibration of the Color-Redshift Relation (C3R2) survey is obtaining spectroscopic redshifts in order to map the relation between galaxy color and redshift to a depth of i~24.5 (AB). The primary goal is to enable sufficiently accurate photometric redshifts for Stage IV dark energy projects, particularly Euclid and the Nancy Grace Roman Space Telescope (Roman), which are designed to constrain cosmological parameters through weak lensing. We present 676 new high-confidence spectroscopic redshifts obtained by the C3R2 survey in the 2017B-2019B semesters using the DEIMOS, LRIS, and MOSFIRE multiobject spectrographs on the Keck telescopes. Combined with the 4454 redshifts previously published by this project, the C3R2 survey has now obtained and published 5130 high-quality galaxy spectra and redshifts. If we restrict consideration to only the 0.2<z_p_<2.6 range of interest for the Euclid cosmological goals, then with the current data release, C3R2 has increased the spectroscopic redshift coverage of the Euclid color space from 51% (as reported by Masters+ 2017, J/ApJ/841/111) to the current 91%. Once completed and combined with extensive data collected by other spectroscopic surveys, C3R2 should provide the spectroscopic calibration set needed to enable photometric redshifts to meet the cosmology requirements for Euclid, and make significant headway toward solving the problem for Roman.
260. EX Lup SPHERE and SINFONI images
ID:
ivo://CDS.VizieR/J/A+A/641/A33
Title:
EX Lup SPHERE and SINFONI images
Short Name:
J/A+A/641/A33
Date:
21 Oct 2021
Publisher:
CDS
Description:
EX Lup is a well-studied T Tauri star that represents the prototype of young eruptive stars EXors. These are characterized by repetitive outbursts due to enhanced accretion from the circumstellar disk onto the star. In this paper we analyze new adaptive optics imaging and spectroscopic observations to study EX Lup and its circumstellar environment in near-infrared in its quiescent phase. We aim at providing a comprehensive understanding of the circumstellar environment around EX Lup in quiescence that builds upon the vast literature data. We observed EX Lup in quiescence with the high contrast imager SPHERE/IRDIS in the dual-beam polarimetric imaging mode to resolve the circumstellar environment in near-infrared scattered light. We complemented these data with earlier SINFONI spectroscopy, also taken in quiescence. Results.We resolve for the first time in scattered light a compact feature around EX Lup azimuthally extending from ~280{deg} to ~360{deg}, and radially extending from 0.3" to 0.55" in the plane of the disk. We explore two different scenarios for the detected emission. The first one accounts for the emission as coming from the brightened walls of the cavity excavated by the outflow whose presence was suggested by ALMA observations in the J=3-2 line of ^12^CO. The second one accounts for the emission as coming from an inclined disk. In this latter case we detect for the first time a more extended circumstellar disk in scattered light, which shows that a region between 10 and 30au is depleted of um-size grains. We compare the J-, H- and K- band spectra obtained with SINFONI in quiescence with the spectra taken during the outburst, showing that all the emission lines were due to the episodic accretion event. Based on the morphology analysis we favour the scenario in which the scattered light is coming from a circumstellar disk rather than the outflow around EX Lup. We analyze the origin of the observed feature either as coming from a continuous circumstellar disk with a cavity, or from the illuminated wall of the outer disk or from a shadowed disk. Moreover, we discuss what is the origin of the m-size grains depleted region, exploring the possibility that a sub-stellar companion may be the cause of it.