- ID:
- ivo://CDS.VizieR/J/A+A/659/A181
- Title:
- J-PLUS DR1 stellar param, and abundances
- Short Name:
- J/A+A/659/A181
- Date:
- 25 Mar 2022 09:03:05
- Publisher:
- CDS
- Description:
- The Javalambre Photometric Local Universe Survey (J-PLUS) has obtained precise photometry in twelve specially designed filters for large numbers of Galactic stars. Deriving their precise stellar atmospheric parameters and individual elemental abundances is crucial for studies of Galactic structure, and the assembly history and chemical evolution of our Galaxy. Our goal is to estimate not only stellar parameters (effective temperature, Teff, surface gravity, logg, and metallicity, [Fe/H]), but also [{alpha}/Fe] and four elemental abundances ([C/Fe], [N/Fe], [Mg/Fe], and [Ca/Fe]) using data from J-PLUS DR1. By combining recalibrated photometric data from J-PLUS DR1, Gaia DR2, and spectroscopic labels from LAMOST, we design and train a set of cost-sensitive neural networks, the CSNet, to learn the non-linear mapping from stellar colors to their labels. We have achieved precisions of {delta}Teff~55K, {delta}logg~0.15dex, and {delta}[Fe/H]~0.07dex, respectively, over a wide range of temperature, surface gravity, and metallicity. The uncertainties of the abundance estimates for [{alpha}/Fe] and the four individual elements are in the range 0.04-0.08 dex. We compare our parameter and abundance estimates with those from other spectroscopic catalogs such as APOGEE and GALAH, and find an overall good agreement. Conclusions. Our results demonstrate the potential of well-designed, high-quality photometric data for determinations of stellar parameters as well as individual elemental abundances. Applying the method to J-PLUS DR1, we have obtained the aforementioned parameters for about two million stars, providing an outstanding data set for chemo-dynamic analyses of the Milky Way.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/659/A144
- Title:
- J-PLUS. STAR-GALAXY-QSO Classification
- Short Name:
- J/A+A/659/A144
- Date:
- 18 Mar 2022 08:13:24
- Publisher:
- CDS
- Description:
- In modern astronomy, machine learning has proved to be efficient and effective in mining big data from the newest telescopes. In this study, we construct a supervised machine-learning algorithm to classify the objects in the Javalambre Photometric Local Universe Survey first data release (J-PLUS DR1). The sample set is featured with 12-waveband photometry and labeled with spectrum-based catalogs, including Sloan Digital Sky Survey (SDSS) spectroscopic data, the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), and VERON- CAT - the Veron Catalog of Quasars & AGN (VV13. Cat. VII/258). The performance of the classifier is presented with the applications of blind test validations based on RAdial Velocity Extension (RAVE), the Kepler Input Catalog (KIC), the 2 MASS (the Two Micron All Sky Survey) Redshift Survey (2MRS), and the UV-bright Quasar Survey (UVQS). A new algorithm was applied to constrain the potential extrapolation that could decrease the performance of the machine-learning classifier. The accuracies of the classifier are 96.5% in the blind test and 97.0% in training cross-validation. The F1-scores for each class are presented to show the balance between the precision and the recall of the classifier. We also discuss different methods to constrain the potential extrapolation.
- ID:
- ivo://CDS.VizieR/J/ApJ/560/566
- Title:
- K-band galaxy luminosity function from 2MASS
- Short Name:
- J/ApJ/560/566
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measured the K-band luminosity function using a complete sample of 4192 morphologically typed 2MASS galaxies with {mu}_Ks_=20mag/arcsec^2^ isophotal magnitudes 7<K_20_<11.25mag spread over 2.12sr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/312/557
- Title:
- K-band Luminosity Function of Field Galaxies
- Short Name:
- J/MNRAS/312/557
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a measurement of the K-band luminosity function (LF) of field galaxies obtained from near-infrared imaging of a sample of 345 galaxies selected from the Stromlo-APM Redshift Survey. The LF is reasonably well fitted over the 10-mag range -26 < M(K-band) < -16 by a Schechter function with the parameters {alpha}=-1.16+/-0.19, M*=-23.58+/-0.42 and {phi*}=0.012+/-0.008 Mpc-3, assuming a Hubble constant of 100 km.s-1.Mpc-1. We have also estimated the LF for two subsets of galaxies subdivided by the equivalent width of the H{alpha} emission line at EW(H{alpha})=1nm. There is no significant difference in LF shape between the two samples, although there is a hint (~1{sigma} significance) that emission-line galaxies (ELGs) have M* roughly 1 mag fainter than non-ELGs. Contrary to the optical LF, there is no difference in the faint end slope {alpha} between the two samples.
- ID:
- ivo://CDS.VizieR/II/211
- Title:
- K-band survey in high galactic latitude
- Short Name:
- II/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The survey is a high galactic latitude, large area (552 square arcmin) blank-field sample to a 5{sigma} limit of K=17.3mag. Star-galaxy discrimination is performed. The infrared observations were made over the period 1987-1988, using the infrared camera IRCAM at the 3.8m UKIRTelescope at Mauna Kea, Hawai. The pixel size is 1.2arcsec. The redshift survey (spectro.dat) concerns 124 galaxies of the survey, and was carried out on the Anglo-Australian telescope and the William Herschel telescope at La Palma over the period 1990-1992, with a multi-fibre spectrograph for the brighter objects (R<19), long and multi-slit spectrographs for fainter objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/748/56
- Title:
- K2-detected clusters in the CFHTLS-W1 field
- Short Name:
- J/ApJ/748/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first weak gravitational lensing analysis of the completed Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). We study the 64 deg^2^ W1 field, the largest of the CFHTLS-Wide survey fields, and present the largest contiguous weak lensing convergence "mass map" yet made. 2.66 million galaxy shapes are measured, using the Kaiser Squires and Broadhurst Method (KSB) pipeline verified against high-resolution Hubble Space Telescope imaging that covers part of the CFHTLS. Our i'-band measurements are also consistent with an analysis of independent r'-band imaging. The reconstructed lensing convergence map contains 301 peaks with signal-to-noise ratio {nu}>3.5, consistent with predictions of a {Lambda}CDM model. Of these peaks, 126 lie within 3.0' of a brightest central galaxy identified from multicolor optical imaging in an independent, red sequence survey. We also identify seven counterparts for massive clusters previously seen in X-ray emission within 6 deg^2^ XMM-LSS survey. With photometric redshift estimates for the source galaxies, we use a tomographic lensing method to fit the redshift and mass of each convergence peak. Matching these to the optical observations, we confirm 85 groups/clusters with {chi}^2^_reduced_<3.0, at a mean redshift <z_c_>=0.36 and velocity dispersion <{sigma}_c_>=658.8km/s. Future surveys, such as DES, LSST, KDUST, and EUCLID, will be able to apply these techniques to map clusters in much larger volumes and thus tightly constrain cosmological models.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/123
- Title:
- Keck Lyman continuum spectroscopic survey (KLCS)
- Short Name:
- J/ApJ/869/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a deep spectroscopic survey quantifying the statistics of the escape of ionizing radiation from star-forming galaxies at z~3. We measure the ratio of ionizing to non-ionizing UV flux density <f_900_/f_1500_>_obs_, where f_900_ is the mean flux density evaluated over the range [880,910]{AA}. We quantify the emergent ratio of ionizing to non-ionizing UV flux density by analyzing high signal-to-noise ratio composite spectra formed from subsamples with common observed properties and numbers sufficient to reduce the statistical uncertainty in the modeled IGM+CGM correction to obtain precise values of <f_900_/f_1500_>_out_, including a full-sample average <f_900_/f_1500>_out_=0.057{+/-}0.006. We show that <f_900_/f_1500_>_out_ increases monotonically with W_{lambda}_(Ly{alpha}), inducing an inverse correlation with UV luminosity as a by-product. We fit the composite spectra using stellar spectral synthesis together with models of the ISM in which a fraction f_c_ of the stellar continuum is covered by gas with column density N_HI_. We show that the composite spectra simultaneously constrain the intrinsic properties of the stars (L_900_/L_1500_)_int_ along with f_c_, N_HI_, E(B-V), and f_esc,abs_, the absolute escape fraction of ionizing photons. We find a sample-averaged f_esc,abs_=0.09{+/-}0.01, with subsamples falling along a linear relation <f_esc,abs_>~0.75[W_{lambda}_(Ly{alpha})/110{AA}]. Using the far-UV luminosity function, the distribution function n(W(Ly{alpha})), and the relationship between W_{lambda}_(Ly{alpha}) and <f_900_/f_1500_>_out_, we estimate the total ionizing emissivity of z~3 star-forming galaxies with M_uv_<=-19.5, which exceeds the contribution of quasi-stellar objects by a factor of ~3, and accounts for ~50% of the total {epsilon}LyC at z~3 estimated using indirect methods.
- ID:
- ivo://CDS.VizieR/J/ApJS/221/2
- Title:
- Keck+Magellan survey for LLSs. III.
- Short Name:
- J/ApJS/221/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an absorption-line survey of optically thick gas clouds --Lyman Limit Systems (LLSs)-- observed at high dispersion with spectrometers on the Keck and Magellan telescopes. We measure column densities of neutral hydrogen N_H1_ and associated metal-line transitions for 157 LLSs at z_LLS_=1.76-4.39 restricted to 10^17.3^cm^-2^<=N_HI_<10^20.3^cm^-2^. An empirical analysis of ionic ratios indicates an increasing ionization state of the gas with decreasing N_H1_ and that the majority of LLSs are highly ionized, confirming previous expectations. The Si^+^/H^0^ ratio spans nearly four orders of magnitude, implying a large dispersion in the gas metallicity. Fewer than 5% of these LLSs have no positive detection of a metal transition; by z~3 nearly all gas that is dense enough to exhibit a very high Lyman limit opacity has previously been polluted by heavy elements. We add new measurements to the small subset of LLS (~5%-10%) that may have super-solar abundances. High Si^+^/Fe^+^ ratios suggest an {alpha}-enhanced medium, whereas the Si^+^/C^+^ ratios do not exhibit the super-solar enhancement inferred previously for the Ly{alpha} forest.
- ID:
- ivo://CDS.VizieR/IV/34
- Title:
- K2 Ecliptic Plane Input Catalog (EPIC)
- Short Name:
- IV/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The K2 Mission (Howell+, 2014PASP..126..398H) uses the Kepler spacecraft to obtain high-precision photometry over ~80 day campaigns in the ecliptic plane. The Ecliptic Plane Input Catalog (EPIC) provides coordinates, photometry, and kinematics based on a federation of all-sky catalogs to support target selection and target management for the K2 mission.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/2
- Title:
- K2 EPIC stellar properties for 138600 targets
- Short Name:
- J/ApJS/224/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The K2 Mission uses the Kepler spacecraft to obtain high-precision photometry over ~80 day campaigns in the ecliptic plane. The Ecliptic Plane Input Catalog (EPIC) provides coordinates, photometry, and kinematics based on a federation of all-sky catalogs to support target selection and target management for the K2 mission. We describe the construction of the EPIC, as well as modifications and shortcomings of the catalog. Kepler magnitudes (Kp) are shown to be accurate to ~0.1mag for the Kepler field, and the EPIC is typically complete to Kp~17 (Kp~19 for campaigns covered by Sloan Digital Sky Survey). We furthermore classify 138600 targets in Campaigns 1-8 (~88% of the full target sample) using colors, proper motions, spectroscopy, parallaxes, and galactic population synthesis models, with typical uncertainties for G-type stars of ~3% in Teff, ~0.3dex in logg~40% in radius, ~10% in mass, and ~40% in distance. Our results show that stars targeted by K2 are dominated by K-M dwarfs (~41% of all selected targets), F-G dwarfs (~36%), and K giants (~21%), consistent with key K2 science programs to search for transiting exoplanets and galactic archeology studies using oscillating red giants. However, we find significant variation of the fraction of cool dwarfs with galactic latitude, indicating a target selection bias due to interstellar reddening and increased contamination by giant stars near the galactic plane. We discuss possible systematic errors in the derived stellar properties, and differences with published classifications for K2 exoplanet host stars.
