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2241. CDIPS. I. LCs from TESS sectors 6 and 7
ID:
ivo://CDS.VizieR/J/ApJS/245/13
Title:
CDIPS. I. LCs from TESS sectors 6 and 7
Short Name:
J/ApJS/245/13
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Transiting Exoplanet Survey Satellite (TESS) is providing precise time-series photometry for most star clusters in the solar neighborhood. Using the TESS images, we have begun a Cluster Difference Imaging Photometric Survey, in which we are focusing both on stars that are candidate cluster members and on stars that show indications of youth. Our aims are to discover giant transiting planets with known ages, and to provide light curves suitable for studies in stellar astrophysics. For this work, we made 159343 light curves of candidate young stars, across 596 distinct clusters. Each light curve represents between 20 and 25 days of observations of a star brighter than G_Rp_=16, with 30-minute sampling. We describe the image-subtraction and time-series analysis techniques we used to create the light curves, which have noise properties that agree with theoretical expectations. We also comment on the possible utility of the light-curve sample for studies of stellar rotation evolution and binary eccentricity damping.
2242. c2d Spitzer final data release (DR4)
ID:
ivo://CDS.VizieR/II/332
Title:
c2d Spitzer final data release (DR4)
Short Name:
II/332
Date:
21 Oct 2021
Publisher:
CDS
Description:
Crucial steps in the formation of stars and planets can be studied only at mid- to far-infrared wavelengths, where the Space Infrared Telescope (SIRTF) provides an unprecedented improvement in sensitivity. We will use all three SIRTF instruments (Infrared Array Camera [IRAC], Multiband Imaging Photometer for SIRTF [MIPS], and Infrared Spectrograph [IRS]) to observe sources that span the evolutionary sequence from molecular cores to protoplanetary disks, encompassing a wide range of cloud masses, stellar masses, and star-forming environments. In addition to targeting about 150 known compact cores, we will survey with IRAC and MIPS (3.6-70{mu}m) the entire areas of five of the nearest large molecular clouds for new candidate protostars and substellar objects as faint as 0.001 solar luminosities. We will also observe with IRAC and MIPS about 190 systems likely to be in the early stages of planetary system formation (ages up to about 10Myr), probing the evolution of the circumstellar dust, the raw material for planetary cores. Candidate planet-forming disks as small as 0.1 lunar masses will be detectable. Spectroscopy with IRS of new objects found in the surveys and of a select group of known objects will add vital information on the changing chemical and physical conditions in the disks and envelopes. The resulting data products will include catalogs of thousands of previously unknown sources, multiwavelength maps of about 20deg^2^ of molecular clouds, photometry of about 190 known young stars, spectra of at least 170 sources, ancillary data from ground-based telescopes, and new tools for analysis and modeling. These products will constitute the foundations for many follow-up studies with ground-based telescopes, as well as with SIRTF itself and other space missions such as SIM, JWST, Herschel, and TPF/Darwin.
2243. c2d Spitzer survey of interstellar ices. I.
ID:
ivo://CDS.VizieR/J/ApJ/678/985
Title:
c2d Spitzer survey of interstellar ices. I.
Short Name:
J/ApJ/678/985
Date:
21 Oct 2021
Publisher:
CDS
Description:
To study the physical and chemical evolution of ices in solar-mass systems, a spectral survey is conducted of a sample of 41 low-luminosity YSOs (L~0.1-10L_{sun}_) using 3-38um Spitzer and ground-based spectra. The sample is complemented with previously published Spitzer spectra of background stars and with ISO spectra of well-studied massive YSOs (L~10^5^L_{sun}_). The long-known 6.0 and 6.85um bands are detected toward all sources, with the Class 0-type YSOs showing the deepest bands ever observed. The 6.0um band is often deeper than expected from the bending mode of pure solid H_2_O. The additional 5-7um absorption consists of five independent components, which, by comparison to laboratory studies, must be from at least eight different carriers. Much of this absorption is due to simple species likely formed by grain surface chemistry, at abundances of 1%-30% for CH_3_OH, 3%-8% for NH_3_, 1%-5% for HCOOH, ~6% for H_2_CO, and ~0.3% for HCOO- relative to solid H_2_O. The 6.85um band has one or two carriers, of which one may be less volatile than H_2_O. Its carrier(s) formed early in the molecular cloud evolution and do not survive in the diffuse ISM. If an NH_4_^+^ -containing salt is the carrier, its abundance relative to solid H_2_O is ~7%, demonstrating the efficiency of low-temperature acid-base chemistry or cosmic-ray-induced reactions. Possible origins are discussed for enigmatic, very broad absorption between 5 and 8um. Finally, the same ices are observed toward massive and low-mass YSOs, indicating that processing by internal UV radiation fields is a minor factor in their early chemical evolution.
2244. CDWFS: Chandra survey in Bootes. I. X-ray cat.
ID:
ivo://CDS.VizieR/J/ApJS/251/2
Title:
CDWFS: Chandra survey in Bootes. I. X-ray cat.
Short Name:
J/ApJS/251/2
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new, ambitious survey performed with the Chandra X-ray Observatory of the 9.3deg^2^ Bootes field of the NOAO Deep Wide-Field Survey. The wide field probes a statistically representative volume of the universe at high redshift. The Chandra Deep Wide-field Survey exploits the excellent sensitivity and angular resolution of Chandra over a wide area, combining 281 observations spanning 15yr, for a total exposure time of 3.4Ms, and detects 6891 X-ray point sources down to limiting fluxes of 4.7x10^-16^, 1.5x10^-16^, and 9x10^-16^erg/cm^2^/s in the 0.5-7, 0.5-2, and 2-7keV bands, respectively. The robustness and reliability of the detection strategy are validated through extensive, state-of-the-art simulations of the whole field. Accurate number counts, in good agreement with previous X-ray surveys, are derived thanks to the uniquely large number of point sources detected, which resolve 65.0%+/-12.8% of the cosmic X-ray background between 0.5 and 2keV and 81.0%+/-11.5% between 2 and 7keV. Exploiting the wealth of multiwavelength data available on the field, we assign redshifts to ~94% of the X-ray sources, estimate their obscuration, and derive absorption-corrected luminosities.
2245. CEDAG Catalogue of Clusters of Galaxies
ID:
ivo://CDS.VizieR/VII/88
Title:
CEDAG Catalogue of Clusters of Galaxies
Short Name:
VII/88
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalog contains for 10411 objects, the Abell, Zwicky, and Kalinkov numbers of groups of galaxies. In addition, it contains: Abell or Zwicky coordinates, the Abell or Zwicky numbers of the supercluster which contains each group, the diameter (Zwicky), the magnitude (Abell), the compactness (Zwicky), the distance of the group (both Abell and Zwicky), the richness (Abell) and the population (Zwicky).
2246. Celescope Catalogue of UV magnitudes
ID:
ivo://CDS.VizieR/II/6
Title:
Celescope Catalogue of UV magnitudes
Short Name:
II/6
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalog contains the observational results obtained by the Celescope Experiment during the first 16 months of operation of NASA's Orbiting Astronomical Observatory (OAO-2). Magnitudes were obtained from more than 8000 television images in UV.
2247. Celestial Reference Frame at 24 and 43 GHz
ID:
ivo://CDS.VizieR/J/AJ/139/1695
Title:
Celestial Reference Frame at 24 and 43 GHz
Short Name:
J/AJ/139/1695
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present astrometric results for compact extragalactic objects observed with the Very Long Baseline Array at radio frequencies of 24 and 43GHz. Data were obtained from ten 24-hr observing sessions made over a five-year period. These observations were motivated by the need to extend the International Celestial Reference Frame (ICRF) to higher radio frequencies to enable improved deep space navigation after 2016 and to improve state-of-the-art astrometry. Source coordinates for 268 sources were estimated at 24GHz and for 131 sources at 43GHz.
2248. Celestial Reference Frame at 24 and 43GHz. II
ID:
ivo://CDS.VizieR/J/AJ/139/1713
Title:
Celestial Reference Frame at 24 and 43GHz. II
Short Name:
J/AJ/139/1713
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have measured the submilliarcsecond structure of 274 extragalactic sources at 24 and 43 GHz in order to assess their astrometric suitability for use in a high-frequency celestial reference frame (CRF). Ten sessions of observations with the Very Long Baseline Array have been conducted over the course of ~5 years, with a total of 1339 images produced for the 274 sources. There are several quantities that can be used to characterize the impact of intrinsic source structure on astrometric observations including the source flux density, the flux density variability, the source structure index, the source compactness, and the compactness variability.
2249. 67 CEMP-s stars model analysis
ID:
ivo://CDS.VizieR/J/A+A/581/A22
Title:
67 CEMP-s stars model analysis
Short Name:
J/A+A/581/A22
Date:
21 Oct 2021
Publisher:
CDS
Description:
Many of the carbon-enhanced metal-poor (CEMP) stars that we observe in the Galactic halo are found in binary systems and show enhanced abundances of elements produced by the slow neutron-capture process (s-elements). The origin of the peculiar chemical abundances of these CEMP-s stars is believed to be accretion in the past of enriched material from a primary star in the asymptotic giant branch (AGB) phase of its evolution. We investigate the mechanism of mass transfer and the process of nucleosynthesis in low-metallicity AGB stars by modelling the binary systems in which the observed CEMP-s stars were formed. For this purpose we compare a sample of 67 CEMP-s stars with a grid of binary stars generated by our binary evolution and nucleosynthesis model. We classify our sample CEMP-s stars in three groups based on the observed abundance of europium. In CEMP-s/r stars the europium-to-iron ratio is more than ten times higher than in the Sun, whereas it is lower than this threshold in CEMP-s/nr stars. No measurement of europium is currently available for CEMP-s/ur stars. On average our models reproduce the abundances observed in CEMP-s/nr stars well, whereas in CEMP-s/r stars and CEMP-s/ur stars the abundances of the light-s elements (strontium, yttrium, zirconium) are systematically overpredicted by our models, and in CEMP-s/r stars the abundances of the heavy-s elements (barium, lanthanum) are underestimated. In all stars our modelled abundances of sodium overestimate the observations. This discrepancy is reduced only in models that underestimate the abundances of most of the s-elements. Furthermore, the abundance of lead is underpredicted in most of our model stars, independent of the metallicity. These results point to the limitations of our AGB nucleosynthesis model, particularly in the predictions of the element-to-element ratios. In our models CEMP-s stars are typically formed in wide systems with periods above 10000-days, while most of the observed CEMP-s stars are found in relatively close orbits with periods below 5000-days. This evidence suggests that either the sample of CEMP-s binary stars with known orbital parameters is biased towards short periods or that our wind mass-transfer model requires more efficient accretion in close orbits.
2250. Cen A 118MHz MWA image
ID:
ivo://CDS.VizieR/J/MNRAS/436/1286
Title:
Cen A 118MHz MWA image
Short Name:
J/MNRAS/436/1286
Date:
07 Feb 2022 14:36:33
Publisher:
CDS
Description:
We present new wide-field observations of Centaurus A (Cen A) and the surrounding region at 118MHz with the Murchison Widefield Array (MWA) 32-tile prototype, with which we investigate the spectral-index distribution of Cen A's giant radio lobes. We compare our images to 1.4GHz maps of Cen A and compute spectral indices using temperature-temperature plots and spectral tomography. We find that the morphologies at 118MHz and 1.4GHz match very closely apart from an extra peak in the southern lobe at 118MHz, which provides tentative evidence for the existence of a southern counterpart to the northern middle lobe of Cen A. Our spatially averaged spectral indices for both the northern and southern lobes are consistent with previous analyses, however we find significant spatial variation of the spectra across the extent of each lobe. Both the spectral-index distribution and the morphology at low radio frequencies support a scenario of multiple outbursts of activity from the central engine. Our results are consistent with inverse-Compton modelling of radio and gamma-ray data that support a value for the lobe age of between 10 and 80Myr.