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1001. Distant clusters of galaxies in the 2XMM/SDSS
ID:
ivo://CDS.VizieR/J/A+A/607/A56
Title:
Distant clusters of galaxies in the 2XMM/SDSS
Short Name:
J/A+A/607/A56
Date:
21 Oct 2021
Publisher:
CDS
Description:
Galaxy clusters at high redshift are important to test cosmological models and models for the growth of structure. They are difficult to find in wide-angle optical surveys, however, leaving dedicated follow-up of X-ray selected candidates as one promising identification route. We aim to increase the number of galaxy clusters beyond the SDSS-limit, z~0.75. We compiled a list of extended X-ray sources from the 2XMMp catalogue within the footprint of the Sloan Digital Sky Survey. Fields without optical counterpart were selected for further investigation. Deep optical imaging and follow-up spectroscopy were obtained with the Large Binocular Telescope, Arizona (LBT), of those candidates not known to the literature. From initially 19 candidates, selected by visually screening X-ray images of 478 XMM-Newton observations and the corresponding SDSS images, 6 clusters were found in the literature. Imaging data through r,z filters were obtained for the remaining candidates, and 7 were chosen for multi-object (MOS) spectroscopy. Spectroscopic redshifts, optical magnitudes, and X-ray parameters (flux, temperature, and luminosity) are presented for the clusters with spectroscopic redshifts. The distant clusters studied here constitute one additional redshift bin for studies of the L-T relation, which does not seem to evolve from high to low redshifts. The selection method of distant galaxy clusters presented here was highly successful. It is based solely on archival optical (SDSS) and X-ray (XMM-Newton) data. Out of 19 selected candidates, 6 of the 7 candidates selected for spectroscopic follow-up were verified as distant clusters, a further candidate is most likely a group of galaxies at z~1.21. Out of the remaining 12 candidates, 6 were known previously as galaxy clusters, one object is a likely X-ray emission from an AGN radio jet, and for 5 we see no clear evidence for them to be high-redshift galaxy clusters.
1002. Distant galaxy clusters photometry
ID:
ivo://CDS.VizieR/J/ApJS/142/153
Title:
Distant galaxy clusters photometry
Short Name:
J/ApJS/142/153
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical and near-infrared photometry of 45 clusters of galaxies at 0.1<z<1.3. Galaxy catalogs in each cluster were defined at the longest wavelength available, generally the K band, down to approximately 2mag below M*. We include finding chart images of the band used for catalog definition. The photometry has been used in previously published papers to examine the origin and evolution of galaxies in distant clusters. Beginning in 1991, we sought to make use of the advent of relatively large format near-IR detectors to study the galaxy populations of distant clusters. We collected imaging data in both the near-IR and the optical on a large sample of clusters drawn from several samples. These data were analyzed and detailed results were presented on the evolution of early-type galaxies at moderate redshifts in Stanford, Eisenhardt, & Dickinson (1995ApJ...450..512S, 1998ApJ...492..461S), on the evolution of the K-band luminosity function in De Propris et al. (1999AJ....118..719D), on the Butcher-Oemler effect in K-selected galaxy samples in De Propris et al. (2003, ApJ, submitted), and on the evolution of early-type galaxies in high-redshift clusters in Holden et al. (2003, ApJ, in press). So far the photometry for these various studies has been published for only two clusters, Abell 370 and Abell 851 in Stanford et al. (1995ApJ...450..512S). In this paper, we present the photometry on the other 43 clusters used in our published work on distant clusters.
1003. Distant OB Stars in the Galaxy
ID:
ivo://CDS.VizieR/J/PASP/105/1465
Title:
Distant OB Stars in the Galaxy
Short Name:
J/PASP/105/1465
Date:
21 Oct 2021
Publisher:
CDS
Description:
Distances and reddenings have been computed from UBVbeta photometry for 1044 stars in the Stephenson and Sanduleak (1971) "Catalog of Luminous Stars in the Southern Milky Way".
1004. Distant RR Lyrae stars discovered with HiTS
ID:
ivo://CDS.VizieR/J/ApJ/855/43
Title:
Distant RR Lyrae stars discovered with HiTS
Short Name:
J/ApJ/855/43
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of distant RR Lyrae stars, including the most distant known in the Milky Way, using data taken in the g-band with the Dark Energy Camera as part of the High cadence Transient Survey (HiTS; 2014 campaign). We detect a total of 173 RR Lyrae stars over a ~120deg^2^ area, including both known RR Lyrae and new detections. The heliocentric distances dH of the full sample range from 9 to >200kpc, with 18 of them beyond 90kpc. We identify three sub-groups of RR Lyrae as members of known systems: the Sextans dwarf spheroidal galaxy, for which we report 46 new discoveries, and the ultra-faint dwarf galaxies Leo IV and Leo V. Following an MCMC methodology, we fit spherical and ellipsoidal profiles of the form {rho}(R)~Rn to the radial density distribution of RR Lyrae in the Galactic halo. The best fit corresponds to the spherical case, for which we obtain a simple power-law index of n=-4.17_-0.20_^+0.18^, consistent with recent studies made with samples covering shorter distances. The pulsational properties of the outermost RR Lyrae in the sample (dH>90kpc) differ from the ones in the halo population at closer distances. The distribution of the stars in a period-amplitude diagram suggest they belong to Oosterhoff-intermediate or Oosterhoff II groups, similar to what is found in the ultra-faint dwarf satellites around the Milky Way. The new distant stars discovered represent an important addition to the few existing tracers of the Milky Way potential in the outer halo.
1005. Disturbance levels of SNe host galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/444/2428
Title:
Disturbance levels of SNe host galaxies
Short Name:
J/MNRAS/444/2428
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis of the relative frequencies of different supernova (SN) types in spirals with various morphologies and in barred or unbarred galaxies. We use a well-defined and homogeneous sample of spiral host galaxies of 692 SNe from the Sloan Digital Sky Survey in different stages of galaxy-galaxy interaction and activity classes of nucleus. We propose that the underlying mechanisms shaping the number ratios of SNe types can be interpreted within the framework of interaction-induced star formation, in addition to the known relations between morphologies and stellar populations. We find a strong trend in behaviour of the N_Ia_/N_CC_ ratio depending on host morphology, such that early spirals include more Type Ia SNe. The N_Ibc_/N_II_ ratio is higher in a broad bin of early-type hosts. The N_Ia_/N_CC_ ratio is nearly constant when changing from normal, perturbed to interacting galaxies, then declines in merging galaxies, whereas it jumps to the highest value in post-merging/remnant galaxies. In contrast, the N_Ibc_/N_II_ ratio jumps to the highest value in merging galaxies and slightly declines in post-merging/remnant subsample. The interpretation is that the star formation rates and morphologies of galaxies, which are strongly affected in the final stages of interaction, have an impact on the number ratios of SNe types. The N_Ia_/N_CC_ (N_Ibc_/N_II_) ratio increases (decreases) from star-forming to active galactic nuclei (AGN) classes of galaxies. These variations are consistent with the scenario of an interaction-triggered starburst evolving into AGN during the later stages of interaction, accompanied with the change of star formation and transformation of the galaxy morphology into an earlier type.
1006. DK Cygni light curve
ID:
ivo://CDS.VizieR/J/A+A/289/137
Title:
DK Cygni light curve
Short Name:
J/A+A/289/137
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
1007. 3D kinematics in the Draco dwarf spheroidal
ID:
ivo://CDS.VizieR/J/A+A/633/A36
Title:
3D kinematics in the Draco dwarf spheroidal
Short Name:
J/A+A/633/A36
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first three-dimensional internal motions for individual stars in the Draco dwarf spheroidal galaxy. By combining first epoch Hubble Space Telescope observations and second epoch Gaia Data Release 2 positions we measured the proper motions of 149 sources in the direction of Draco. We determined the line-of-sight velocities of a sub-sample of 81 red giant branch stars using medium resolution spectra acquired with the DEIMOS spectrograph at the Keck II telescope. Altogether this resulted in a final sample of 45 members of Draco with high-precision and accurate 3D motions, which we publish as a table in this paper. With this high-quality dataset we determined the velocity dispersions at a projected distance of ~120pc from the centre of Draco to be sigma_R_=11.0^+2.1^_-1.5_km/s, sigma_T_=9.9^+2.3^_-3.1_km/s and sigma_LOS_=9.0^+1.1^_-1.1_ km/s in the projected radial, tangential and line-of-sight directions. This results in a velocity anisotropy beta=0.25^+0.47^_-1.38_ at r>120pc. Tighter constraints can be obtained using the spherical Jeans equations and assuming constant anisotropy and NFW mass profiles, as well as that the 3D velocity dispersion should be lower than ~1/3 of the escape velocity of the system. In this case, we constrain the maximum circular velocity V_max_ of Draco to be in the range of 10.2-17.0km/s. The corresponding mass range is in good agreement with previous estimates based on line-of-sight velocities only. Our Jeans modelling supports the case for a cuspy dark matter profile in this galaxy. Firmer conclusions may be drawn by applying more sophisticated models on this dataset and with upcoming data releases.
1008. DM Cyg BVIc light curves
ID:
ivo://CDS.VizieR/J/MNRAS/397/350
Title:
DM Cyg BVIc light curves
Short Name:
J/MNRAS/397/350
Date:
21 Oct 2021
Publisher:
CDS
Description:
DM Cyg, a fundamental mode RRab star, was observed in the 2007 and 2008 seasons in the framework of the Konkoly Blazhko Survey. Very small amplitude light-curve modulation was detected with 10.57d modulation period. The maximum brightness and phase variations do not exceed 0.07mag and 7min, respectively. In spite of the very small amplitude of the modulation, beside the frequency triplets characterizing the Fourier spectrum of the light curve, two quintuplet components were also identified. The accuracy and the good phase coverage of our observations made it possible to analyse the light curves at different phases of the modulation separately.
1009. DoAr 44 ugri light curves
ID:
ivo://CDS.VizieR/J/A+A/643/A99
Title:
DoAr 44 ugri light curves
Short Name:
J/A+A/643/A99
Date:
21 Oct 2021
Publisher:
CDS
Description:
Young stars interact with their accretion disk through their strong magnetosphere. We aim to investigate the magnetospheric accretion/ejection process in the young stellar system DoAr 44 (V2062 Oph). We monitored the system over several rotational cycles, combining high-resolution spectropolarimetry at both optical and near-IR wavelengths with long-baseline near-IR inteferometry and multicolor photometry. We derive a rotational period of 2.96d from the system's light curve, which is dominated by stellar spots. We fully characterize the central star's properties from the high signal-to-noise, high-resolution optical spectra we obtained during the campaign. DoAr 44 is a young 1.2M_{sun}_ star, moderately accreting from its disk (Macc=6.510^-9^M_{sun}_/yr), and seen at a low inclination (i~=30{deg}). Several optical and near-IR line profiles probing the accretion funnel flows (H{alpha}, H{beta}, HeI 1083nm, Pa{beta}) and the accretion shock (HeI 587.6nm) are modulated at the stellar rotation period. The most variable line profile is HeI 1083nm, which exhibits modulated redshifted wings that are a signature of accretion funnel flows, as well as deep blueshifted absorptions indicative of transient outflows. The Zeeman-Doppler analysis suggests the star hosts a mainly dipolar magnetic field, inclined by about 20{deg} onto the spin axis, with an intensity reaching about 800G at the photosphere, and up to 2+/-0.8kG close to the accretion shock. The magnetic field appears strong enough to disrupt the inner disk close to the corotation radius, at a distance of about 4.6R* (0.043au), which is consistent with the 5R* (0.047au) upper limit we derived for the size of the magnetosphere in our Paper I from long baseline interferometry. DoAr 44 is a pre-transitional disk system, exhibiting a 25-30au gap in its circumstellar disk, with the inner and outer disks being misaligned. On a scale of 0.1au or less, our results indicate that the system is steadily accreting from its inner disk through its tilted dipolar magnetosphere. We conclude that in spite of a highly structured disk on the large scale, perhaps the signature of ongoing planetary formation, the magnetospheric accretion process proceeds unimpeded at the star-disk interaction level.
1010. Dolidze 25 Chandra/ACIS-I X-ray sources
ID:
ivo://CDS.VizieR/J/A+A/650/A157
Title:
Dolidze 25 Chandra/ACIS-I X-ray sources
Short Name:
J/A+A/650/A157
Date:
22 Feb 2022
Publisher:
CDS
Description:
The dispersal of protoplanetary disks sets the timescale available for planets to assemble, and thus it is one of the fundamental parameters in theories of planetary formation. Disk dispersal is determined by several properties of the central star, the disk itself, and the surrounding environment. In particular, the metallicity of disks may impact their evolution, even if to date controversial results exist: in low-metallicity clusters disks seem to rapidly disperse, while in the Magellanic Clouds some evidence supports the existence of accreting disks few tens of Myrs old. In this paper we study the dispersal timescale of disks in Dolidze 25, the young cluster in proximity of the Sun with lowest metallicity, with the aim of understanding whether disk evolution is impacted by the low-metallicity of the cluster. We have analyzed Chandra/ACIS-I observations of the cluster and combined the resulting source catalog with existing optical and infrared catalogs of the region. We selected the disk-bearing population in a 1 degree circular region centered on Dolidze~25 from criteria based on infrared colors, and the disk-less population within a smaller central region among the X-ray sources with OIR counterpart. In both cases, criteria are applied to discard contaminating sources in the foreground/background. We have derived stellar parameters from isochrones fitted to color-magnitude diagrams. We derived a disk fraction of about 34% and a median age of the cluster of 1.2Myrs. To minimize the impact of incompleteness and spatial inhomogeneity of the list of members, we restricted this calculation to stars in a magnitude range where our selection of cluster members is fairly complete and by adopting different cuts in stellar masses. By comparing this estimate with existing estimates of the disk fraction of clusters younger than 10Myrs, our study suggests that the disk fraction of Dolidze 25 is lower than what is expected from its age alone. Even if our results are not conclusive given the intrinsic uncertainty on stellar ages estimated from isochrones fitting to color-magnitude diagrams, we suggest that disk evolution in Dolidze 25 may be impacted by the environment. Given the poor O star population and low stellar density of the cluster, it is more likely that disks dispersal timescale is dictated more by the low metallicity of the cluster rather than external photoevaporation or dynamical encounters.