- ID:
- ivo://CDS.VizieR/J/AJ/150/88
- Title:
- Abundances in the local region. I. G and K giants
- Short Name:
- J/AJ/150/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Parameters and abundances for 1133 stars of spectral types F, G, and K of luminosity class III have been derived. In terms of stellar parameters, the primary point of interest is the disagreement between gravities derived with masses determined from isochrones, and gravities determined from an ionization balance. This is not a new result per se, but the size of this sample emphasizes the severity of the problem. A variety of arguments led to the selection of the ionization-balance gravity as the working value. The derived abundances indicate that the giants in the solar region have Sun-like total abundances and abundance ratios. Stellar evolution indicators have also been investigated with the Li abundances and the [C/Fe] and C/O ratios, indicating that standard processing has been operating in these stars. The more salient result for stellar evolution is that the [C/Fe] data across the red-giant clump indicates the presence of mass-dependent mixing in accord with standard stellar evolution predictions.
« Previous |
1 - 10 of 428
|
Next »
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/143/36
- Title:
- A catalog of Galactic infrared carbon stars
- Short Name:
- J/AJ/143/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We collected almost all of the Galactic infrared carbon stars (IRCSs) from literature published up to the present to organize a catalog of 974 Galactic IRCSs in this paper. Some of their photometric properties in the near-, mid-, and far-infrared are discussed.
- ID:
- ivo://CDS.VizieR/J/ApJS/245/10
- Title:
- A catalog of galaxies in direction of Perseus
- Short Name:
- J/ApJS/245/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 5437 morphologically classified sources in the direction of the Perseus galaxy cluster core, among them 496 early-type low-mass galaxy candidates. The catalog is primarily based on V-band imaging data acquired with the William Herschel Telescope, which we used to conduct automated source detection and derive photometry. We additionally reduced archival Subaru multiband imaging data in order to measure aperture colors and perform a morphological classification, benefiting from 0.5" seeing conditions in the r-band data. Based on morphological and color properties, we extracted a sample of early-type low-mass galaxy candidates with absolute V-band magnitudes in the range of -10 to -20mag. In the color-magnitude diagram, the galaxies are located where the red sequence for early-type cluster galaxies is expected, and they lie on the literature relation between absolute magnitude and Sersic index. We classified the early-type dwarf candidates into nucleated and nonnucleated galaxies. For the faint candidates, we found a trend of increasing nucleation fraction toward brighter luminosity or higher surface brightness, similar to what is observed in other nearby galaxy clusters. We morphologically classified the remaining sources as likely background elliptical galaxies, late-type galaxies, edge-on disk galaxies, and likely merging systems and discussed the expected contamination fraction through non-early-type cluster galaxies in the magnitude-size surface brightness parameter space. Our catalog reaches its 50% completeness limit at an absolute V-band luminosity of -12mag and a V-band surface brightness of 26mag/arcsec^2^. This makes it the largest and deepest catalog with coherent coverage compared to previous imaging studies of the Perseus cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/150/17
- Title:
- A catalog of point sources toward NGC 1333
- Short Name:
- J/AJ/150/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I present a catalog of point-source objects toward NGC 1333, resolving a wide variety of confusion about source names (and occasionally positions) in the literature. I incorporate data from optical to radio wavelengths, but focus most of the effort on being complete and accurate from J (1.25{mu}m) to 24{mu}m. The catalog encompasses 52^{deg}^<R.A.<52.5{deg} and 31{deg}<decl.<31.6{deg}. Cross-identifications include those from more than 25 papers and catalogs from 1994 to 2014, primarily those in wide use as origins of nomenclature. Gaps in our knowledge are identified, with the most important being a lack of spectroscopy for spectral types or even confirmation of youth and/or cluster membership. I fit a slope to the spectral energy distribution (SED) between 2 and 24{mu}m for the members (and candidate members) to obtain an SED classification, and I compare the resulting classes to those for the same sources in the literature, and for an SED fit between 2 and 8{mu}m. While there are certainly differences, for the majority of the sources, there is good agreement.
- ID:
- ivo://CDS.VizieR/V/138
- Title:
- A catalogue of cross-matched radio/infrared/X-ray sources
- Short Name:
- V/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of cross-correlated radio, infrared and X-ray sources using a very restrictive selection criteria with an IDL-based code developed by us. The significance of the observed coincidences was evaluated through Monte Carlo simulations of synthetic sources following a well-tested protocol. We found 3320 coincident radio/X-ray sources with a high statistical significance characterized by the sum of error-weighted coordinate differences. For 997 of them, 2MASS counterparts were found. The percentage of chance coincidences is less than 1%. X-ray hardness ratios of well-known populations of objects were used to provide a crude representation of their X-ray spectrum and to make a preliminary diagnosis of the possible nature of unidentified X-ray sources. The results support the fact that the X-ray sky is largely dominated by Active Galactic Nuclei at high galactic latitudes (|b|>=10deg). At low galactic latitudes (|b|<=10deg) most of unidentified X-ray sources (~94%) lie at |b|>=2deg. This result suggests that most of the unidentified sources found toward the Milky Way plane are galactic objects. Well-known and unidentified sources were classified in different tables with their corresponding radio/infrared and X-ray properties. These tables are intended as a useful tool for researchers interested in particular identifications.
- ID:
- ivo://CDS.VizieR/J/other/Ap/62.147
- Title:
- Activity types of ROSAT/SDSS galaxies
- Short Name:
- J/other/Ap/62.14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this study we carry out detailed spectral classification of 173 AGN candidates from the Joint HRC/BHRC sample, which is a combination of HRC (Hamburg-ROSAT Catalogue) and BHRC (Byurakan-Hamburg-ROSAT Catalogue). These objects were revealed as optical counterparts for ROSAT X-ray sources, however spectra for 173 of them are given in SDSS without definite spectral classification. We studied these 173 objects using the SDSS spectra and revealed the detailed activity types for them. Three diagnostic diagrams and direct examination of the spectra were used to have more confident classification. We also made identification of these sources in other wavelength ranges and calculated some of their parameters.
- ID:
- ivo://CDS.VizieR/J/ApJ/827/46
- Title:
- A deep Chandra ACIS survey of M51
- Short Name:
- J/ApJ/827/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained a deep X-ray image of the nearby galaxy M51 using Chandra. Here we present the catalog of X-ray sources detected in these observations and provide an overview of the properties of the point-source population. We find 298 sources within the D_25_ radii of NGC 5194/5, of which 20% are variable, a dozen are classical transients, and another half dozen are transient-like sources. The typical number of active ultraluminous X-ray sources in any given observation is ~5, and only two of those sources persist in an ultraluminous state over the 12yr of observations. Given reasonable assumptions about the supernova remnant population, the luminosity function is well described by a power law with an index between 1.55 and 1.7, only slightly shallower than that found for populations dominated by high-mass X-ray binaries (HMXBs), which suggests that the binary population in NGC 5194 is also dominated by HMXBs. The luminosity function of NGC 5195 is more consistent with a low-mass X-ray binary dominated population.
- ID:
- ivo://CDS.VizieR/J/ApJS/212/21
- Title:
- A deep Chandra ACIS survey of M83
- Short Name:
- J/ApJS/212/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained a series of deep X-ray images of the nearby galaxy M83 using Chandra, with a total exposure of 729ks. Combining the new data with earlier archival observations totaling 61ks, we find 378 point sources within the D_25_ contour of the galaxy. We find 80 more sources, mostly background active galactic nuclei (AGNs), outside of the D_25_contour. Of the X-ray sources, 47 have been detected in a new radio survey of M83 obtained using the Australia Telescope Compact Array. Of the X-ray sources, at least 87 seem likely to be supernova remnants (SNRs), based on a combination of their properties in X-rays and at other wavelengths. We attempt to classify the point source population of M83 through a combination of spectral and temporal analysis. As part of this effort, we carry out an initial spectral analysis of the 29 brightest X-ray sources. The soft X-ray sources in the disk, many of which are SNRs, are associated with the spiral arms, while the harder X-ray sources, mostly X-ray binaries (XRBs), do not appear to be. After eliminating AGNs, foreground stars, and identified SNRs from the sample, we construct the cumulative luminosity function (CLF) of XRBs brighter than 8x10^35^erg/s. Despite M83's relatively high star formation rate, the CLF indicates that most of the XRBs in the disk are low mass XRBs.
- ID:
- ivo://CDS.VizieR/J/ApJ/728/38
- Title:
- AEGIS: demographics of X-ray and optical AGN
- Short Name:
- J/ApJ/728/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We develop a new diagnostic method to classify galaxies into active galactic nucleus (AGN) hosts, star-forming galaxies, and absorption-dominated galaxies by combining the [OIII]/H{beta} ratio with rest-frame U-B color. This can be used to robustly select AGNs in galaxy samples at intermediate redshifts (z<1). We compare the result of this optical AGN selection with X-ray selection using a sample of 3150 galaxies with 0.3<z<0.8 and I_AB_<22, selected from the DEEP2 Galaxy Redshift Survey and the All-wavelength Extended Groth Strip International Survey. Among the 146 X-ray sources in this sample, 58% are classified optically as emission-line AGNs, the rest as star-forming galaxies or absorption-dominated galaxies. The latter are also known as "X-ray bright, optically normal galaxies" (XBONGs).
- ID:
- ivo://CDS.VizieR/J/ApJS/180/102
- Title:
- AEGIS-X: Chandra deep survey
- Short Name:
- J/ApJS/180/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the EGIS-X survey, a series of deep Chandra ACIS-I observations of the Extended Groth Strip. The survey comprises pointings at eight separate positions, each with nominal exposure of 200ks, covering a total area of approximately 0.67deg^2^ in a strip of length 2 degrees. We describe in detail an updated version of our data reduction and point-source-detection algorithms used to analyze these data. A total of 1325 band-merged sources have been found to a Poisson probability limit of 4x10^-6^, with limiting fluxes of 5.3x10^-21^W/m2 in the soft (0.5-2keV) band and 3.8x10^-19^W/m2 in the hard (2-10keV) band. We present simulations verifying the validity of our source-detection procedure and showing a very small, <1.5%, contamination rate from spurious sources. Optical/NIR counterparts have been identified from the DEEP2, CFHTLS, and Spitzer/Infrared Array Camera (IRAC) surveys of the same region. Using a likelihood ratio method, we find optical counterparts for 76% of our sources, complete to R_AB_=24.1, and, of the 66% of the sources that have IRAC coverage, 94% have a counterpart to a limit of 0.9uJy at 3.6um (m_AB_=23.8). After accounting for (small) positional offsets in the eight Chandra fields, the astrometric accuracy of Chandra positions is found to be 0"8rms; however, this number depends both on the off-axis angle and the number of detected counts for a given source. All data products described in this paper are made available via a public Web site.
