- ID:
- ivo://CDS.VizieR/J/MNRAS/373/1483
- Title:
- W UMa type and CAB stars dynamical evolution
- Short Name:
- J/MNRAS/373/1483
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orbital angular momentum (OAM, Jo), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of and logJo-logP, logM-logP and logJo-logM were formed from 119 CAB and 102 W UMa stars. The log Jo-logM diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A slightly curved borderline (contact border) separating the detached and the contact systems was discovered on the logJo-logM diagram. Since the orbital size (a) and period (P) of binaries are determined by their current Jo, M and mass ratio, q, the rates of OAM loss (dlogJo/dt) and mass loss (dlogM/dt) are primary parameters to determine the direction and the speed of the dynamical evolution. A detached system becomes a contact system if its own dynamical evolution enables it to pass the contact border on the logJo-logM diagram. The evolution of q for a mass-losing detached system is unknown unless the mass-loss rate for each component is known. Assuming q is constant in the first approximation and using the mean decreasing rates of Jo and M from the kinematical ages of CAB stars, it has been predicted that 11, 23 and 39 per cent of current CAB stars would transform to W UMa systems if their nuclear evolution permits them to live 2, 4 and 6Gyr, respectively.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/185
- Title:
- W UMa-type contact binaries ages and masses
- Short Name:
- J/MNRAS/437/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recently, our understanding of the origin of W UMa-type contact binaries has become clearer. Initial masses of their components were successfully estimated by Yildiz and Dogan using a new method mainly based on observational properties of overluminous secondary components. In this paper, we continue to discuss the results and make computations for age and orbital evolution of these binaries. It is shown that the secondary mass, according to its luminosity, also successfully predicts the observed radius. While the current mass of the primary component is determined by initial masses, the current secondary mass is also a function of initial angular momentum. We develop methods to compute the age of A- and W-subtype W UMa-type contact binaries in terms of initial masses and mass according to the luminosity of the secondaries. Comparisons of our results with the mean ages from kinematic properties of these binaries and data pertaining to contact binaries in open and globular clusters have increased our confidence on this method. The mean ages of both A- and W-subtype contact binaries are found as 4.4 and 4.6Gyr, respectively. From kinematic studies, these ages are given as 4.5 and 4.4Gyr, respectively. We also compute orbital properties of A-subtype contact binaries at the time of the first overflow. Initial angular momentum of these binaries is computed by comparing them with the well-known detached binaries. The angular momentum loss rate derived in the present study for the detached phase is in very good agreement with the semi-empirical rates available in the literature. In addition to the limitations on the initial masses of W UMa-type contact binaries, it is shown that the initial period of these binaries is less than about 4.45d.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/43
- Title:
- WWFI g'-band obs. of bright cluster galaxies
- Short Name:
- J/ApJS/247/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of 170 local (z<~0.08) galaxy clusters in the northern hemisphere have been obtained with the Wendelstein Telescope Wide Field Imager (WWFI). We correct for systematic effects such as point-spread function broadening, foreground star contamination, relative bias offsets, and charge persistence. Background inhomogeneities induced by scattered light are reduced down to {Delta}SB>31 g' mag/arcsec^2^ by large dithering and subtraction of night-sky flats. Residual background inhomogeneities brighter than SB_{sigma}_<27.6 g' mag/arcsec^2^ caused by galactic cirrus are detected in front of 23% of the clusters. However, the large field of view allows discrimination between accretion signatures and galactic cirrus. We detect accretion signatures in the form of tidal streams in 22%, shells in 9.4%, and multiple nuclei in 47% of the brightest cluster galaxies (BCGs) and find two BCGs in 7% of the clusters. We measure semimajor-axis surface brightness profiles of the BCGs and their surrounding intracluster light (ICL) down to a limiting surface brightness of SB=30 g' mag/arcsec^2^. The spatial resolution in the inner regions is increased by combining the WWFI light profiles with those that we measured from archival Hubble Space Telescope images or deconvolved WWFI images. We find that 71% of the BCG+ICL systems have surface brightness (SB) profiles that are well described by a single Sersic function, whereas 29% require a double Sersic function to obtain a good fit. We find that BCGs have scaling relations that differ markedly from those of normal ellipticals, likely due to their indistinguishable embedding in the ICL.
- ID:
- ivo://CDS.VizieR/J/ApJS/252/27
- Title:
- WWFI g'-band obs. of bright galaxy clusters
- Short Name:
- J/ApJS/252/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore several ways to dissect brightest cluster galaxies (BCGs) and their surrounding intracluster light (ICL) using a surface brightness (SB) cut, a luminosity cut, excess light above a de Vaucouleurs profile, or a double Sersic decomposition. Assuming that all light above M{<}-21.85g'mag is attributable to the ICL, we find that an average fraction of f_ICL_^MT^=71+/-22% of all diffuse light centered on the BCG belongs to the ICL. Likewise, if we assume that all light fainter than SB>27g'mag/arcsec^2^ belongs to the ICL, the average ICL fraction is f_ICL_^SB27^=34+/-19% . After fitting a de Vaucouleurs profile to the inner parts of the SB profile, we detect excess light at large radii, corresponding to an average ICL fraction of f_ICL_^DV^=48+/-20% . Finally, by decomposing the SB profile into two Sersic functions, we find an average ICL fraction of f_ICL_^Sx^=52+/-21% associated with the outer Sersic component. Our measured ICL and BCG+ICL luminosities agree well with predictions from high-resolution simulations where the outer Sersic component traces the unrelaxed, accreted stellar material. BCG and ICL properties defined in this way are correlated with cluster parameters to study the coevolution of BCGs, ICL, and their host clusters. We find positive correlations between BCG+ICL brightness and cluster mass, cluster velocity dispersion, cluster radius, and integrated satellite brightness, confirming that BCG/ICL growth is indeed coupled with cluster growth. On average, the ICL is better aligned than the BCG with the host cluster in terms of position angle, ellipticity, and centering. That makes it a potential dark-matter tracer.
- ID:
- ivo://CDS.VizieR/J/A+A/436/799
- Title:
- X- and gamma-ray fluxes of {gamma}-ray-loud blazars
- Short Name:
- J/A+A/436/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determined the basic parameters, such as the central black hole mass (M), the boosting factor (or Doppler factor) ({delta}) the propagation angle ({Phi}) and the distance along the axis to the site of {gamma}-ray production (d) for 23 {gamma}-ray-loud blazars using their available variability timescales.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/125
- Title:
- X and {gamma} spectral indexes of Fermi blazars
- Short Name:
- J/ApJ/761/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, a sample of 451 blazars (193 flat spectrum radio quasars (FSRQs), 258 BL Lacertae objects) with corresponding X-ray and Fermi {gamma}-ray data is compiled to investigate the correlation both between the X-ray spectral index and the {gamma}-ray spectral index and between the spectral index and the luminosity, and to compare the spectral indexes {alpha}_X_, {alpha}_{gamma}_, {alpha}_X{gamma}_, and {alpha}_{gamma}X{gamma}_ for different subclasses. We also investigated the correlation between the X-ray and the {gamma}-ray luminosity.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A39
- Title:
- X-ATLAS X-ray sources photometric redshifts
- Short Name:
- J/A+A/608/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric redshifts for 1,031 X-ray sources in the X-ATLAS field using the machine-learning technique TPZ. X-ATLAS covers 7.1 deg2 observed with XMM-Newton within the Science Demonstration Phase (SDP) of the H-ATLAS field, making it one of the largest contiguous areas of the sky with both XMM-Newton and Herschel coverage. All of the sources have available SDSS photometry, while 810 additionally have mid-IR and/or near-IR photometry. A spectroscopic sample of 5,157 sources primarily in the XMM/XXL field, but also from several X-ray surveys and the SDSS DR13 redshift catalogue, was used to train the algorithm. Our analysis reveals that the algorithm performs best when the sources are split, based on their optical morphology, into point-like and extended sources. Optical photometry alone is not enough to estimate accurate photometric redshifts, but the results greatly improve when at least mid-IR photometry is added in the training process. In particular, our measurements show that the estimated photometric redshifts for the X-ray sources of the training sample have a normalized absolute median deviation, nmadh0.06, and a percentage of outliers, {eta}=10-14%, depending upon whether the sources are extended or point like. Our final catalogue contains photometric redshifts for 933 out of the 1,031 X-ray sources with a median redshift of 0.9.
15838. XBACs, the sample
- ID:
- ivo://CDS.VizieR/J/MNRAS/281/799
- Title:
- XBACs, the sample
- Short Name:
- J/MNRAS/281/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an essentially complete, all-sky, X-ray flux-limited sample of 242 Abell clusters of galaxies (six of which are double) compiled from ROSAT All-Sky Survey data. Our sample is uncontaminated in the sense that systems featuring prominent X-ray point sources such as AGN or foreground stars have been removed. The sample is limited to high Galactic latitudes (|b|>=20{deg}), the nominal redshift range of the ACO catalogue of z<=0.2, and X-ray fluxes above 5.0x10^-12^erg/cm^2^/s in the 0.1-2.4keV band. Owing to the X-ray flux limit, our sample consists, at intermediate and high redshifts, exclusively of very X-ray-luminous clusters. Since the latter tend to be also optically rich, the sample is not affected by the optical selection effects and, in particular, not by the volume incompleteness known to be present in the Abell and ACO catalogues for richness class 0 and 1 clusters. Our sample is the largest X-ray flux-limited sample of galaxy clusters compiled to date and will allow investigations of unprecedented statistical quality into the properties and distribution of rich clusters in the local Universe.
- ID:
- ivo://CDS.VizieR/I/302
- Title:
- XC1 catalogue of positions and proper motions
- Short Name:
- I/302
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the astrometric catalogue of faint reference stars in 255deg^2^ sized fields with ICRF objects of northern hemisphere. The XC1 is based on our results of measurements and astrometric reduction of digitized images of Schmidt plates POSS-I and POSS-II sky surveys obtained from USNOFS PMM Image Archive. The Tycho-2 (Cat. <I/259>) catalogue was used as a reference catalogue for astrometric reductions. The mean positions and proper motions of stars were derived from their individual positions at the different epochs. For some stars the 2MASS (Cat. <II/246>) positions were used also. The limiting magnitude is about V=19mag. The estimated external errors are 50-150mas in positions at mean epoch, and 2-5mas/yr in proper motions, depending on magnitude. The catalog is present as a set of individual fields in separate files. The name of each file is the ERS designation of corresponding ICRF radio source.
15840. X-CLASS/GROND catalogue
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/662
- Title:
- X-CLASS/GROND catalogue
- Short Name:
- J/MNRAS/468/662
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The XMM Cluster Archive Super Survey (X-CLASS) is a serendipitously detected X-ray-selected sample of 845 galaxy clusters based on 2774 XMM archival observations and covering an approximately 90deg^2^ spread across the high-Galactic latitude (|b|>20{deg}) sky. The primary goal of this survey is to produce a well-selected sample of galaxy clusters on which cosmological analyses can be performed. This paper presents the photometric redshift follow-up of a high signal-to-noise ratio subset of 265 of these clusters with declination {delta}<+20{deg} with Gamma-Ray Burst Optical and Near-Infrared Detector (GROND), a 7-channel (grizJHK) simultaneous imager on the MPG 2.2-m telescope at the ESO La Silla Observatory. We use a newly developed technique based on the red sequence colour-redshift relation, enhanced with information coming from the X-ray detection to provide photometric redshifts for this sample. We determine photometric redshifts for 232 clusters, finding a median redshift of z=0.39 with an accuracy of {Delta}z=0.02(1+z) when compared to a sample of 76 spectroscopically confirmed clusters. We also compute X-ray luminosities for the entire sample and find a median bolometric luminosity of 7.2x10^43^erg/s and a median temperature of 2.9 keV. We compare our results to those of the XMM-XCS and XMM-XXL surveys, finding good agreement in both samples. The X-CLASS catalogue is available online at http://xmm-lss.in2p3.fr:8080/l4sdb/.
