- ID:
- ivo://CDS.VizieR/J/AJ/151/82
- Title:
- The 4 brightest red giants in the UFD galaxy Ret 2
- Short Name:
- J/AJ/151/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ultra-faint dwarf (UFD) galaxy Reticulum 2 (Ret 2) was recently discovered in images obtained by the Dark Energy Survey (Diehl et al. 2014SPIE.9149E..0VD). We have observed the four brightest red giants in Ret 2 at high spectral resolution using the Michigan/Magellan Fiber System. We present detailed abundances for as many as 20 elements per star, including 12 elements heavier than the Fe group. We confirm previous detection of high levels of r-process material in Ret 2 (mean [Eu/Fe]=+1.69+/-0.05) found in three of these stars (mean [Fe/H]=-2.88+/-0.10). The abundances closely match the r-process pattern found in the well-studied metal-poor halo star CS 22892-052. Such r-process-enhanced stars have not been found in any other UFD galaxy, though their existence has been predicted by at least one model. The fourth star in Ret 2 ([Fe/H]=-3.42+/-0.20) contains only trace amounts of Sr ([Sr/Fe]=-1.73+/-0.43) and no detectable heavier elements. One r-process enhanced star is also enhanced in C (natal [C/Fe]~+1.1). This is only the third such star known, which suggests that the nucleosynthesis sites leading to C and r-process enhancements are decoupled. The r-process-deficient star is enhanced in Mg ([Mg/Fe]=+0.81+/-0.14), and the other three stars show normal levels of {alpha}-enhancement (mean [Mg/Fe]=+0.34+/-0.03). The abundances of other {alpha} and Fe-group elements closely resemble those in UFD galaxies and metal-poor halo stars, suggesting that the nucleosynthesis that led to the large r-process enhancements either produced no light elements or produced light-element abundance signatures indistinguishable from normal supernovae.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/830/126
- Title:
- The Carina project. X. Radial velocities
- Short Name:
- J/ApJ/830/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocity (RV) measurements of old (horizontal branch) and intermediate-age (red clump) stellar tracers in the Carina dwarf spheroidal. They are based on more than 2200 low-resolution spectra collected with VIMOS at Very Large Telescope (VLT). The targets are faint (20<~V<~21.5mag), but the accuracy at the faintest limit is <=9km/s. These data were complemented with RV measurements either based on spectra collected with FORS2 and FLAMES/GIRAFFE at VLT or available in the literature. We ended up with a sample of 2748 stars and among them, 1389 are candidate Carina stars. We found that the intermediate-age stellar component shows a well-defined rotational pattern around the minor axis. The western and the eastern side of the galaxy differ by +5 and -4km/s when compared with the main RV peak. The old stellar component is characterized by a larger RV dispersion and does not show evidence of the RV pattern. We compared the observed RV distribution with N-body simulations for a former disky dwarf galaxy orbiting a giant Milky Way-like galaxy. We rotated the simulated galaxy by 60{deg} with respect to the major axis, we kept the observer on the orbital plane of the dwarf and extracted a sample of stars similar to the observed one. Observed and predicted V_rot_/{sigma} ratios across the central regions are in remarkable agreement. This evidence indicates that Carina was a disky dwarf galaxy that experienced several strong tidal interactions with the Milky Way. Owing to these interactions, Carina transformed from a disky to a prolate spheroid and the rotational velocity transformed into random motions.
- ID:
- ivo://CDS.VizieR/J/ApJS/197/21
- Title:
- The Carnegie-Irvine Galaxy Survey (CGS). I.
- Short Name:
- J/ApJS/197/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Carnegie-Irvine Galaxy Survey (CGS) is a long-term program to investigate the photometric and spectroscopic properties of a statistically complete sample of 605 bright (B_T_<12.9mag), southern ({delta}<0{deg}) galaxies using the facilities at Las Campanas Observatory. This paper, the first in a series, outlines the scientific motivation of CGS, defines the sample, and describes the technical aspects of the optical broadband (BVRI) imaging component of the survey, including details of the observing program, data reduction procedures, and calibration strategy. The overall quality of the images is quite high, in terms of resolution (median seeing ~1"), field of view (8.9'x8.9'), and depth (median limiting surface brightness ~27.5, 26.9, 26.4, and 25.3mag/arcsec^2^ in the B, V, R, and I bands, respectively). We prepare a digital image atlas showing several different renditions of the data, including three-color composites, star-cleaned images, stacked images to enhance faint features, structure maps to highlight small-scale features, and color index maps suitable for studying the spatial variation of stellar content and dust. In anticipation of upcoming science analyses, we tabulate an extensive set of global properties for the galaxy sample. These include optical isophotal and photometric parameters derived from CGS itself, as well as published information on multiwavelength (ultraviolet, U-band, near-infrared, far-infrared) photometry, internal kinematics (central stellar velocity dispersions, disk rotational velocities), environment (distance to nearest neighbor, tidal parameter, group, or cluster membership), and HI content.
- ID:
- ivo://CDS.VizieR/II/365
- Title:
- The CatWISE2020 catalog (updated version 28-Jan-2021)
- Short Name:
- II/365
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CatWISE2020 Catalog consists of 1,890,715,640 sources over the entire sky selected from WISE and NEOWISE survey data at 3.4 and 4.6um (W1 and W2) collected from 2010 Jan 7 to 2018 Dec 13. This dataset adds two years to that used for the CatWISE Preliminary Catalog (Eisenhardt+ 2020ApJS..247...69E), bringing the total to six times as many exposures spanning over sixteen times as large a time baseline as the AllWISE catalog. The other major change from the CatWISE Preliminary Catalog is that the detection list for CatWISE2020 was generated using "crowdsource" software (Schlafly+ 2019ApJS..240...30S), while the Preliminary Catalog used the detection software used for AllWISE (II/328). These two factors result in roughly twice as many sources in CatWISE2020. The scatter with respect to Spitzer photometry at faint magnitudes in the COSMOS field, which is out of the Galactic plane and at low ecliptic latitude (corresponding to lower WISE coverage depth) is similar to that for the CatWISE Preliminary Catalog. The 90% completeness depth for CatWISE2020 is at roughly W1=17.7 and W2=17.5, about 1.7 mag deeper than in the Preliminary Catalog. From comparison to Gaia, CatWISE2020 motions are over a dozen times more accurate than those from AllWISE.
- ID:
- ivo://CDS.VizieR/J/ApJS/185/198
- Title:
- The Cepheus flare observed with IRAC and MIPS
- Short Name:
- J/ApJS/185/198
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer Infrared Array Camera (IRAC; ~2deg^2^) and Multiband Imaging Photometer for Spitzer (MIPS; ~8deg^2^) observations of the Cepheus Flare, which is associated with the Gould Belt, at an approximate distance of ~300pc. Around 6500 sources are detected in all four IRAC bands, of which ~900 have MIPS 24um detections. We identify 133 young stellar object (YSO) candidates using color-magnitude diagram techniques, and a large number of the YSO candidates are associated with the NGC 7023 reflection nebula. Cross-identifications were made with the Guide Star Catalog II and the IRAS Faint Source Catalog, and spectral energy distributions (SEDs) were constructed. SED modeling was conducted to estimate the degree of infrared excess. It was found that a large majority of disks were optically thick accreting disks, suggesting that there has been little disk evolution in these sources. Nearest-neighbor clustering analysis identified four small protostellar groups (L1228, L1228N, L1251A, and L1251B) with 5-15 members each and the larger NGC 7023 association with 32 YSO members. The star-formation efficiency for cores with clusters of protostars and for those without clusters was found to be ~8% and ~1%, respectively. The cores L1155, L1241, and L1247 are confirmed to be starless down to our luminosity limit of L_bol_=0.06L_{sun}_.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/30
- Title:
- The Chandra COSMOS survey. III.
- Short Name:
- J/ApJS/201/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8Ms, Chandra program that has imaged the central 0.9deg^2^ of the COSMOS field down to limiting depths of 1.9x10^-16^erg/cm^2^/s in the soft (0.5-2keV) band, 7.3x10^-16^erg/cm^2^/s in the hard (2-10keV) band, and 5.7x10^-16^erg/cm^2^/s in the full (0.5-10keV) band. In this paper we report the i, K, and 3.6um identifications of the 1761 X-ray point sources. We use the likelihood ratio technique to derive the association of optical/infrared counterparts for 97% of the X-ray sources. For most of the remaining 3%, the presence of multiple counterparts or the faintness of the possible counterpart prevented a unique association. For only 10 X-ray sources we were not able to associate a counterpart, mostly due to the presence of a very bright field source close by. Only two sources are truly empty fields. The full catalog, including spectroscopic and photometric redshifts and classification described here in detail, is available online.
- ID:
- ivo://CDS.VizieR/J/AJ/157/85
- Title:
- The CIDA Variability Survey of Orion OB1. II.
- Short Name:
- J/AJ/157/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of our large-scale, optical, multi-epoch photometric survey across ~180 square degrees in the Orion OB1 association, complemented with extensive follow-up spectroscopy. Our focus is mapping and characterizing the off-cloud, low-mass, pre-main-sequence (PMS) populations. We report 2062 K- and M-type confirmed T Tauri members; 59% are located in the OB1a subassociation, 27% in the OB1b subassociation, and the remaining 14% in the A and B molecular clouds. We characterize two new clusterings of T Tauri stars, the HD 35762 and HR 1833 groups, both located in OB1a not far from the 25 Ori cluster. We also identify two stellar overdensities in OB1b, containing 231 PMS stars, and find that the OB1b region is composed of two populations at different distances, possibly due to the OB1a subassociation overlapping with the front of OB1b. A ~2 deg wide halo of young stars surrounds the Orion Nebula Cluster, corresponding in part to the low-mass populations of NGC 1977 and NGC 1980. We use the strength of H{alpha} in emission, combined with the IR excess and optical variability, to define a new type of T Tauri star, the C/W class, stars we propose may be nearing the end of their accretion phase, in an evolutionary state between classical and weak-lined T Tauri stars. The evolution of the ensemble-wide equivalent width of Li I{lambda}6707 indicates a Li depletion timescale of ~8.5 Myr. Disk accretion declines with an e-folding timescale of ~2 Myr, consistent with previous studies.
2938. The CNOC2 survey. I.
- ID:
- ivo://CDS.VizieR/J/ApJS/129/475
- Title:
- The CNOC2 survey. I.
- Short Name:
- J/ApJS/129/475
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Canadian Network for Observational Cosmology Field Galaxy Redshift Survey (CNOC2) obtained spectroscopic redshifts for about 6200 galaxies to a nominal limit of R=21.5. The survey area of about 1.5 square degrees was spread over four patches on the sky. This catalog presents photometry and redshifts for all galaxies in the CNOC2 0223+00 Patch (area of 1409 square arcminutes). A future paper will provide catalogs for the other three patches.
2939. The COSMOS2015 catalog
- ID:
- ivo://CDS.VizieR/J/ApJS/224/24
- Title:
- The COSMOS2015 catalog
- Short Name:
- J/ApJS/224/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the COSMOS2015 catalog, which contains precise photometric redshifts and stellar masses for more than half a million objects over the 2deg^2^ COSMOS field. Including new YJHKs images from the UltraVISTA-DR2 survey, Y-band images from Subaru/Hyper-Suprime-Cam, and infrared data from the Spitzer Large Area Survey with the Hyper-Suprime-Cam (SPLASH) Spitzer legacy program, this near-infrared-selected catalog is highly optimized for the study of galaxy evolution and environments in the early universe. To maximize catalog completeness for bluer objects and at higher redshifts, objects have been detected on a {chi}^2^ sum of the YJHKs and z^++^ images. The catalog contains ~6x10^5^ objects in the 1.5deg^2^ UltraVISTA-DR2 region and ~1.5x10^5^ objects are detected in the "ultra-deep stripes" (0.62deg^2^) at Ks<=24.7 (3{sigma}, 3", AB (AB) magnitude). Through a comparison with the zCOSMOS-bright spectroscopic redshifts, we measure a photometric redshift precision of {sigma}_{Delta}z/(1+zs)_=0.007 and a catastrophic failure fraction of {eta}=0.5%. At 3<z<6 , using the unique database of spectroscopic redshifts in COSMOS, we find {sigma}_{Delta}z/(1+zs)_=0.021 and {eta}=13.2% . The deepest regions reach a 90% completeness limit of 10^10^M_{sun}_ to z=4. Detailed comparisons of the color distributions, number counts, and clustering show excellent agreement with the literature in the same mass ranges. COSMOS2015 represents a unique, publicly available, valuable resource with which to investigate the evolution of galaxies within their environment back to the earliest stages of the history of the universe.
- ID:
- ivo://CDS.VizieR/J/ApJ/877/81
- Title:
- The C3R2 survey: DR2 new spectroscopic redshifts
- Short Name:
- J/ApJ/877/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Complete Calibration of the Color-Redshift Relation (C3R2) survey is a multi-institution, multi-instrument survey that aims to map the empirical relation of galaxy color to redshift to i~24.5 (AB), thereby providing a firm foundation for weak lensing cosmology with the Stage IV dark energy missions Euclid and WFIRST. Here we present 3171 new spectroscopic redshifts obtained in the 2016B and 2017A semesters with a combination of DEIMOS, LRIS, and MOSFIRE on the Keck telescopes. The observations come from all of the Keck partners: Caltech, NASA, the University of Hawaii, and the University of California. Combined with the 1283 redshifts published in DR1, the C3R2 survey has now obtained and published 4454 high-quality galaxy redshifts. We discuss updates to the survey design and provide a catalog of photometric and spectroscopic data. Initial tests of the calibration method performance are given, indicating that the sample, once completed and combined with extensive data collected by other spectroscopic surveys, should allow us to meet the cosmology requirements for Euclid, and make significant headway toward solving the problem for WFIRST. We use the full spectroscopic sample to demonstrate that galaxy brightness is weakly correlated with redshift once a galaxy is localized in the Euclid or WFIRST color space, with potentially important implications for the spectroscopy needed to calibrate redshifts for faint WFIRST and LSST sources.
