- ID:
- ivo://CEFCA/j-plus/J-PLUS-DR3
- Title:
- J-PLUS DR3 Catalogue (July, 2022)
- Short Name:
- J-PLUS-DR3
- Date:
- 20 Sep 2023 06:30:00
- Publisher:
- Centro de Estudios de Física del Cosmos de Aragón (CEFCA)
- Description:
- J-PLUS DR3 Catalogue (July, 2022) is based on scientific images in 12 filters collected from November 2015 to February 2022 covering a total area of ~3000 square degrees. The Javalambre Photometric Local Universe Survey (J-PLUS) is an ongoing 12-band photometric optical survey, observing thousands of square degrees of the Northern Hemisphere from the dedicated JAST80 telescope at the Observatorio Astrofísico de Javalambre (OAJ, Teruel, Spain) . Please include the following in any published material that makes use of this data: "Based on observations made with the JAST80 telescope for the J-PLUS project at the Observatorio Astrofísico de Javalambre, in Teruel, owned, managed and operated by the Centro de Estudios de Física del Cosmos de Aragón."
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- ID:
- ivo://CEFCA/j-plus/J-PLUS-DR2
- Title:
- J-PLUS DR2 Catalogue (July, 2020)
- Short Name:
- J-PLUS-DR2
- Date:
- 20 Sep 2023 06:30:00
- Publisher:
- Centro de Estudios de Física del Cosmos de Aragón (CEFCA)
- Description:
- J-PLUS DR2 Catalogue (July, 2020) is based on scientific images in 12 filters collected from November 2015 to February 2020 covering a total area of ~2000 square degrees. The Javalambre Photometric Local Universe Survey (J-PLUS) is an ongoing 12-band photometric optical survey, observing thousands of square degrees of the Northern Hemisphere from the dedicated JAST80 telescope at the Observatorio Astrofísico de Javalambre (OAJ, Teruel, Spain) . Please include the following in any published material that makes use of this data: "Based on observations made with the JAST80 telescope for the J-PLUS project at the Observatorio Astrofísico de Javalambre, in Teruel, owned, managed and operated by the Centro de Estudios de Física del Cosmos de Aragón."
- ID:
- ivo://CEFCA/j-plus/J-PLUS-DR1
- Title:
- J-PLUS DR1 Catalogue (July, 2018)
- Short Name:
- J-PLUS-DR1
- Date:
- 20 Sep 2023 06:30:00
- Publisher:
- Centro de Estudios de Física del Cosmos de Aragón (CEFCA)
- Description:
- J-PLUS DR1 Catalogue (July, 2018) is based on scientific images in 12 filters collected from November 2015 to January 2018 covering a total area of ~1020 square degrees. The Javalambre Photometric Local Universe Survey (J-PLUS) is an ongoing 12-band photometric optical survey, observing thousands of square degrees of the Northern Hemisphere from the dedicated JAST80 telescope at the Observatorio Astrofísico de Javalambre (OAJ, Teruel, Spain) . Please include the following in any published material that makes use of this data: "Based on observations made with the JAST80 telescope for the J-PLUS project at the Observatorio Astrofísico de Javalambre, in Teruel, owned, managed and operated by the Centro de Estudios de Física del Cosmos de Aragón."
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A149
- Title:
- J-PLUS Ly{alpha}-emitting candidates
- Short Name:
- J/A+A/643/A149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the photometric determination of the bright-end of the Ly{alpha} luminosity function (at L_Ly{alpha}_>~10^43.5^erg/s) within four redshifts windows ({Delta}z<0.16) in the interval 2.2<~z<~3.3. Our work is based on the Javalambre Photometric Local Universe Survey (J-PLUS) first data-release, which provides multiple narrow-band measurements over ~1000deg^2^, with limiting magnitude ~22. Theanalysis of high-z Ly{alpha}-emitting sources over such a wide area is unprecedented, and allows to select a total of ~14500 hyper-bright(L_Ly{alpha}_>10^43.3^erg/s) Ly{alpha}-emitting candidates. We test our selection with two spectroscopic follow-up programs at the GTC telescope,which confirm as line-emitting sources ~89% of the targets, with ~64% being genuine z~2.2 QSOs. We extend the 2.2<~z<~3.3 Ly{alpha} luminosity function for the first time above L_Ly{alpha}_~10^44^erg/s and down to densities of ~10^-8^Mpc^-3^. Our results unveil with high detail the Schechter exponential-decay of the brightest-end of the Ly{alpha} LF, complementing the power-law component of previous LF determinations at 43.3<~Log10(L_Ly{alpha}_/(erg/s))<~44. We measure {PHI}*=(3.33+/-0.19)x10^-6^, Log(L*)=44.65+/-0.65 and {alpha}=-1.35+/-0.84 as an average over the redshifts we probe. These values are significantly different than the typical Schechter parameters measured for the Ly{alpha} LF of high-z star-forming LAEs. This suggests that z>2 AGN/QSOs (likely dominant in our samples) are described by a structurally different LF than z>2 star-forming LAEs, namely with L*_QSOs_~100 L*_LAEs_ and {PHI}*_QSOs_~10^-3^{PHI}*_LAEs_. Finally, our method identifies very efficiently as high-z line-emitters sources without previous spectroscopic confirmation, currently classified as stars (~2000 objects in each redshift bin, on average). Assuming a large predominance of Ly{alpha}-emitting AGN/QSOs in our samples, this supports the scenario by which these are the most abundant class of z>~2 Ly{alpha} emitters at L_Ly{alpha}_>~10^43.3^erg/s.
- 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/A+A/658/A79
- Title:
- J-PLUS white dwarf atmospheric parameters
- Short Name:
- J/A+A/658/A79
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We estimated the spectral evolution of white dwarfs with effective temperature using the Javalambre Photometric Local Universe Survey (J-PLUS) second data release (DR2), which provides 12 photometric optical passbands over 2176deg^2^. We analyzed 5926 white dwarfs with r<19.5mag in common between a white dwarf catalog defined from Gaia EDR3 and J-PLUS DR2. We performed a Bayesian analysis by comparing the observed J-PLUS photometry with theoretical models of hydrogen- and helium-dominated atmospheres. We estimated the probability distribution functions for effective temperature (Teff), surface gravity, parallax, and composition; and the probability of having a H-dominated atmosphere (p_H_) for each source. We applied a prior in parallax, using Gaia EDR3 measurements as a reference, and derived a self-consistent prior for the atmospheric composition as a function of Teff. We described the fraction of white dwarfs with a He-dominated atmosphere (f_He_) with a linear function of the effective temperature at 5000<Teff<30000K. We find f_He_=0.24+/-0.01 at Teff=10000K, a change rate along the cooling sequence of 0.14+/-0.02 per 10kK, and a minimum He-dominated fraction of 0.08+/-0.02 at the high-temperature end. We tested the obtained p_H_ by comparison with spectroscopic classifications, finding that it is reliable. We estimated the mass distribution for the 351 sources with distance d<100pc, mass M>0.45M_{sun}_, and Teff>6000K. The result for H-dominated white dwarfs agrees with previous studies, with a dominant M=0.59M_{sun}_ peak and the presence of an excess at M~0.8M_{sun}_. This high-mass excess is absent in the He-dominated distribution, which presents a single peak. The J-PLUS optical data provide a reliable statistical classification of white dwarfs into H- and He-dominated atmospheres. We find a 21+/-3% increase in the fraction of He-dominated white dwarfs from Teff=20000K to Teff=5000K.
- ID:
- ivo://CDS.VizieR/J/MNRAS/341/534
- Title:
- J-type carbon stars in LMC
- Short Name:
- J/MNRAS/341/534
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 1497 carbon stars in the Large Magellanic Cloud (LMC) has been observed in the red part of the spectrum with the 2dF facility on the Anglo-Australian Telescope. Of these, 156 have been identified as J-type (i.e. ^13^C-rich) carbon stars using a technique which provides a clear distinction between J stars and the normal N-type carbon stars that comprise the bulk of the sample, and yields few borderline cases. A simple two-dimensional classification of the spectra, based on their spectral slopes in different wavelength regions, has been constructed and found to be related to the more conventional c and j indices, modified to suit the spectral regions observed. Most of the J stars form a photometric sequence in the K-(J-K) colour-magnitude diagram, parallel to and 0.6mag fainter than the N-star sequence. A subset of the J stars (about 13 per cent) are brighter than this J-star sequence; most of these are spectroscopically different from the other J stars. The bright J stars have stronger CN bands than the other J stars and are found strongly concentrated in the central regions of the LMC. Most of the rather few stars in common with Hartwick and Cowley's sample (1988ApJ...334..135H) of suspected CH stars are J stars. Overall, the proportion of carbon stars identified as J stars is somewhat lower than has been found in the Galaxy. The Na D lines are weaker in the LMC J stars than in either the Galactic J stars or the LMC N stars, and do not seem to depend on temperature.
7439. Jurassic structure
- ID:
- ivo://CDS.VizieR/J/A+A/644/A83
- Title:
- Jurassic structure
- Short Name:
- J/A+A/644/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detailed elemental-abundance patterns of giant stars in the Galactic halo measured by the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) have revealed the existence of a unique and significant stellar subpopulation of silicon-enhanced ([Si/Fe]>+0.5) metal-poor stars, spanning a wide range of metallicities (-1.5<[Fe/H]<-0.8). Stars with over-abundances in [Si/Fe] are of great interest because these have very strong silicon (^28^Si) spectral features for stars of their metallicity and evolutionary stage, offering clues about rare nucleosynthetic pathways in globular clusters (GCs). Si-rich field stars have been conjectured to have been evaporated from GCs, however, the origin of their abundances remains unclear, and several scenarios have been offered to explain the anomalous abundance ratios. These include the hypothesis that some of them were born from a cloud of gas previously polluted by a progenitor that underwent a specific and peculiar nucleosynthesis event or, alternatively, that they were due to mass transfer from a previous evolved companion. However, those scenarios do not simultaneously explain the wide gamut of chemical species that are found in Si-rich stars. Instead, we show that the present inventory of such unusual stars, as well as their relation to known halo substructures (including the in situ halo, Gaia-Enceladus, the Helmi Stream(s), and Sequoia, among others), is still incomplete. We report the chemical abundances of the iron-peak (Fe), the light- (C and N), the alpha- (O and Mg), the odd-Z (Na and Al), and the s-process (Ce and Nd) elements of 55 newly identified Si-rich field stars (among more than ~600000 APOGEE-2 targets), which exhibit over-abundances of [Si/Fe] as extreme as those observed in some Galactic GCs, and they are relatively well distinguished from other stars in the [Si/Fe]-[Fe/H] plane. This new census confirms the presence of a statistically significant and chemically-anomalous structure in the inner halo: Jurassic. The chemo-dynamical properties of the Jurassic structure is consistent with it being the tidally disrupted remains of GCs, which are easily distinguished by an over-abundance of [Si/Fe] among Milky Way (MW) populations or satellites.
7440. JVLA images of W51A
- ID:
- ivo://CDS.VizieR/J/A+A/595/A27
- Title:
- JVLA images of W51A
- Short Name:
- J/A+A/595/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new JVLA observations of the high-mass cluster-forming region W51A from 2 to 16GHz with resolution {theta}_fwhm_~~0.3-0.5". The data reveal a wealth of observational results: (1) Currently-forming, very massive (proto-O) stars are traced by o-H_2_CO 2_1,1_-2_1,2_ emission, suggesting that this line can be used efficiently as a massive protostar tracer. (2) There is a spatially distributed population of <~mJy continuum sources, including hypercompact HII regions and candidate colliding wind binaries, in and around the W51 proto-clusters. (3) There are two clearly detected protoclusters, W51e and W51 IRS2, that are gas-rich but may have most of their mass in stars within their inner <~0.05pc. The majority of the bolometric luminosity in W51 most likely comes from a third population of OB stars between these clusters. The presence of a substantial population of exposed O-stars coincident with a population of still-forming massive stars, along with a direct measurement of the low mass loss rate via ionized gas outflow from W51 IRS2, together imply that feedback is ineffective at halting star formation in massive protoclusters. Instead, feedback may shut off the large-scale accretion of diffuse gas onto the W51 protoclusters, implying that they are evolving towards a state of gas exhaustion rather than gas expulsion. Recent theoretical models predict gas exhaustion to be a necessary step in the formation of gravitationally bound stellar clusters, and our results provide an observational validation of this process.