- ID:
- ivo://CDS.VizieR/J/ApJS/228/19
- Title:
- Exploring the SDSS data set. I. EMP & CV stars
- Short Name:
- J/ApJS/228/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for extremely metal-poor (EMP), carbon-enhanced metal-poor (CEMP), and cataclysmic variable (CV) stars using a new exploration tool based on linked scatter plots (LSPs). Our approach is especially designed to work with very large spectrum data sets such as the SDSS, LAMOST, RAVE, and Gaia data sets, and it can be applied to stellar, galaxy, and quasar spectra. As a demonstration, we conduct our search using the SDSS DR10 data set. We first created a 3326-dimensional phase space containing nearly 2 billion measures of the strengths of over 1600 spectral features in 569738 SDSS stars. These measures capture essentially all the stellar atomic and molecular species visible at the resolution of SDSS spectra. We show how LSPs can be used to quickly isolate and examine interesting portions of this phase space. To illustrate, we use LSPs coupled with cuts in selected portions of phase space to extract EMP stars, CEMP stars, and CV stars. We present identifications for 59 previously unrecognized candidate EMP stars and 11 previously unrecognized candidate CEMP stars. We also call attention to 2 candidate He II emission CV stars found by the LSP approach that have not yet been discussed in the literature.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/244/32
- Title:
- Extended Aperture Photometry of K2 RR Lyrae stars
- Short Name:
- J/ApJS/244/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler Space Telescope observed thousands of RR Lyrae stars in the K2 mission. In this paper, we present our photometric solutions using extended apertures in order to conserve the flux of the stars to the highest possible extent. With this method, we are able to avoid most of the problems that RR Lyrae light curves produced by other pipelines suffer from. For post-processing, we apply the K2SC pipeline to our light curves. We provide the EAP (Extended Aperture Photometry) of 432 RR Lyrae stars observed in campaigns 3, 4, 5, and 6. We also provide subclass classifications based on Fourier parameters. We investigated in particular the presence of the Blazhko effect in the stars and found it to be 44.7% among the RRab stars, in agreement with results from independent samples. We found that the amplitude and phase modulation in the Blazhko stars may behave rather differently, at least over the length of a K2 Campaign. We also identified four anomalous Cepheid candidates in the sample, one of which is potentially the first Blazhko-modulated member of its class.
- ID:
- ivo://CDS.VizieR/J/other/OEJV/87
- Title:
- Extended catalog of NSVS red AGB variable stars
- Short Name:
- J/other/OEJV/87
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In this paper we present the catalog of new Mira-type and SR+L variable stars in the Northern Sky Variability Survey (NSVS) database, found after complementing the original NSVS object tables with a number of additional parameters. By extending the amount of criteria search queries can take advantage of and filtering known objects out, it became convenient to apply better constrained filters to search new variable star candidates. As an example of presented approach, the quest for red variables has resulted in 78 Mira-type and 717 SR+L stars found that have no identification in General Catalogue of Variable Stars, SIMBAD and VSX databases. Most likely the stars presented are new discoveries. The classification of these stars is based on the near-infrared colors from Two Micron All Sky Survey (2MASS) photometry, amplitude and period with the accuracy of the classification given ~90%, estimated basing on the current GCVS classification scheme.
- ID:
- ivo://CDS.VizieR/V/137D
- Title:
- Extended Hipparcos Compilation (XHIP)
- Short Name:
- V/137D
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Extended Hipparcos Compilation (XHIP) cross-references the New Hipparcos Reduction (HIP2, Cat. I/311) with relatable data from a broad survey of presently available sources. The resulting collection uniquely assigns 116,096 spectral classifications, 46,392 radial velocities, and 19,097 iron abundances [Fe/H] to Hipparcos stars. Stellar classifications from SIMBAD and indications of multiplicity from either CCDM (Cat. I/274) or WDS (Cat. B/wds) are provided. Parameters for solar encounters and Galactic orbits are calculated for a subset of stars that can be made kinematically complete. Memberships in open clusters and stellar associations are assigned. We also provide stellar ages from The Geneva-Copenhagen survey of the Solar neighbourhood III (Cat. V/130), identifications of exoplanet host stars, and supplemental photometry from 2MASS (Cat. II/246) and SIMBAD.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A74
- Title:
- Extended main-sequence turn-offs isochrones
- Short Name:
- J/A+A/632/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extended main-sequence turn-offs (eMSTO) are a commonly observed property of young clusters. A global theoretical interpretation for the eMSTOs is still lacking, but stellar rotation is considered a necessary ingredient to explain the eMSTO. We aim to assess the importance of core-boundary and envelope mixing in stellar interiors for the interpretation of eMSTOs in terms of one coeval population. We construct isochrone-clouds based on interior mixing profiles of stars with a convective core calibrated from asteroseismology of isolated galactic field stars. We fit these isochrone-clouds to the measured eMSTO to estimate the age and core mass of the stars in the two young clusters NGC 1850 and NGC 884, assuming one coeval population and fixing the metallicity to the one measured from spectroscopy. We assess the correlations between the interior mixing properties of the cluster members and their rotational and pulsational properties. We find that stellar models based on asteroseismically-calibrated interior mixing profiles lead to enhanced core masses of eMSTO stars and can explain a good fraction of the observed eMSTOs of the two considered clusters in terms of one coeval population of stars, with similar ages to those in the literature, given the large uncertainties. The rotational and pulsational properties of the stars in NGC 884 are not sufficiently well known to perform asteroseismic modelling, as it is achieved for field stars from space photometry. The stars in NGC 884 for which we have vsini and a few pulsation frequencies show no correlation between these properties and the core masses of the stars that set the cluster age. Future cluster space asteroseismology may allow to interpret the values of the core masses in terms of the physical processes that cause them, based on the modelling of the interior mixing profiles for the individual member stars with suitable identified modes.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A23
- Title:
- Extended photometric survey of near-Earth objects
- Short Name:
- J/A+A/644/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The near-Earth objects (NEOs), whose proximity makes them the most accessible bodies in the Solar System, allow us to sample asteroids from tens of kilometers down to objects of a few meters in size. However, while the physical properties for the largest bodies are mostly known, we have very little physical information regarding the small NEOs. These objects today represent the overall majority among the ~2500 new discoveries each year, but they are usually only bright enough to be observable during their close approaches. Our aim was to extend our survey that started in 2015 on the NEO population, using ground-based observations to characterize the fainter (and typically smaller) NEOs observable each night. We performed BVRIz photometry of NEOs, making use of the DOLORES instrument at the Telescopio Nazionale Galileo (TNG, La Palma, Spain) and the Asiago Schmidt telescope (Italy), in order to derive visible color indexes and the taxonomic classification for each target in our sample. We taxonomically classified 51 new NEOs for the first time. Together with data obtained in our previous work and collected by other surveys available online, we analyzed an extended sample of 1081 individual NEOs. While the overall majority of them belong to the S-complex, our analysis of the taxonomic distribution found a larger contribution for dark bodies going toward larger H, suggesting that they could be more abundant among the fainter NEOs. Moreover, we find an interesting correlation between semi-major axis and diameter, which could be in part related to the Yarkovsky effect. Rapid characterization of the fainter NEO population shortly after their discovery will be crucial in the future, before those bodies become too faint to be observed, or lost forever.
- ID:
- ivo://CDS.VizieR/J/MNRAS/434/2877
- Title:
- Extended radio sources in ATLBS
- Short Name:
- J/MNRAS/434/2877
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the environments of extended radio sources in the Australia Telescope Low-Brightness Survey (ATLBS). The radio sources were selected from the ATLBS Extended Source Sample, which is a well defined sample containing the most extended of radio sources in the ATLBS sky survey regions. The environments were analysed using 4-m Cerro-Tololo Inter-American Observatory Blanco telescope observations carried out for ATLBS fields in the Sloan Digital Sky Survey r' band. We have estimated the properties of the environments using smoothed density maps derived from galaxy catalogues constructed using these optical imaging data. The angular distribution of galaxy density relative to the axes of the radio sources has been quantified by defining anisotropy parameters that are estimated using a new method presented here. Examining the anisotropy parameters for a subsample of extended double radio sources that includes all sources with pronounced asymmetry in lobe extents, we find good evidence for environmental anisotropy being the dominant cause for lobe asymmetry in that higher galaxy density occurs almost always on the side of the shorter lobe, and this validates the usefulness of the method proposed and adopted here. The environmental anisotropy parameters have been used to examine and compare the environments of Fanaroff-Riley Class I (FRI) and Fanaroff-Riley Class II (FRII) radio sources in two redshift regimes (z<0.5 and z>0.5). Wide-angle tail sources and head-tail sources lie in the most overdense environments. The head-tail source environments (for the HT sources in our sample) display dipolar anisotropy in that higher galaxy density appears to lie in the direction of the tails. Excluding the head-tail and wide-angle tail sources, subsamples of FRI and FRII sources from the ATLBS appear to lie in similar moderately overdense environments, with no evidence for redshift evolution in the regimes studied herein.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/4933
- Title:
- Extended red emission in IC59 and IC63
- Short Name:
- J/MNRAS/469/4933
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analysed new wide-field, wide- and narrow-band optical images of IC 59 and IC 63, two nebulae that are externally illuminated by the early B-star {gamma} Cas, with the objective of mapping the extended red emission (ERE), a dust-related photoluminescence process that is still poorly understood, in these two clouds. The spatial distribution of the ERE relative to the direction of the incident radiation and relative to other emission processes, whose carriers and excitation requirements are known, provides important constraints on the excitation of the ERE. In both nebulae, we find the ERE intensity to peak spatially well before the more extended distribution of mid-infrared emission in the unidentified infrared bands, supporting earlier findings that point towards far-ultraviolet (11<E_photon_<13.6eV) photons as the source of ERE excitation. The band-integrated absolute intensities of the ERE in IC 59 and IC 63 measured relative to the number density of photons available for ERE excitation are lower by about two orders of magnitude compared to ERE intensities observed in the high-latitude diffuse interstellar medium. This suggests that the lifetime of the ERE carriers is significantly reduced in the more intense radiation field prevailing in IC 59 and IC 63, pointing towards potential carriers that are only marginally stable against photoprocessing under interstellar conditions. A model involving isolated molecules or molecular ions, capable of inverse internal conversion and recurrent fluorescence, appears to provide the most likely explanation for our observational results.
- ID:
- ivo://CDS.VizieR/J/A+A/409/361
- Title:
- Extension of ICRF for selected areas down to V=16
- Short Name:
- J/A+A/409/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of accurate positions and proper motions for 678,828 objects is provided. Objects are within areas of special astronomical interest, containing extragalactic radio sources, mostly from ICRF (see Cat. <I/251>), and pre-main-sequence (PMS) stars in Southern star-forming regions (Chamaeleon, Lupus and Upper Scorpius-Ophiuchus). This work represents a major upgrade of that presented in Camargo et al., 2001, Cat. <J/A+A/375/308>, aiming at the extension of the ICRF at optical wavelengths in regions of special astronomical interest, using observations from the Bordeaux and Valinhos meridian circles. Along with the new fields, the main differences, when compared to the first release, are: a much larger sky coverage, the replacement of the AC2000 by its upgraded version AC2000.2 (<I/275>) as one of the first epoch astrometrical sources, inclusion of Tycho-2 (<I/259>) and 2MASS (2nd Incremental Data Release, See Cat <II/246>) photometry when available, and the correction for a magnitude equation on the Valinhos right ascension system as well. Positional external precisions, on both coordinates, range from 50-60mas (V<=13.5) to 70-140mas (13.5<V<=16.0). For the proper motions, precisions range from 3mas/year to about 15mas/year, depending on magnitude and declination. The strips scanned by the meridian circles are described in Table 1
- ID:
- ivo://CDS.VizieR/J/BaltA/11/441
- Title:
- Extinction along Cam and Per border
- Short Name:
- J/BaltA/11/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interstellar extinction in a ~100 sq. degree area at the Camelopardalis and Perseus border is investigated. The study is based on the results of photoelectric photometry of 455 stars in the seven-color Vilnius photometric system published earlier. The nearest 100 stars with Hipparcos parallaxes show that the extinction starts to grow at a distance of 110-150pc. At a distance of 1 kpc the extinction A_v_ is within 1.2 and 2.4mag. At larger distances the extinction determination is affected by the limiting magnitude effect. At distances >1.5kpc a number of O-B stars with the extinctions between 2 and 4mag are found.
