- ID:
- ivo://CDS.VizieR/J/AJ/137/4795
- Title:
- Dynamical state of brightest cluster galaxies
- Short Name:
- J/AJ/137/4795
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A large sample of Abell clusters of galaxies, selected for the likely presence of a dominant galaxy, is used to study the dynamical properties of the brightest cluster members (BCMs). From visual inspection of Digitized Sky Survey images combined with redshift information we identify 1426 candidate BCMs located in 1221 different redshift components associated with 1169 different Abell clusters. This is the largest sample published so far of such galaxies. From our own morphological classification we find that ~92% of the BCMs in our sample are early-type galaxies and 48% are of cD type. We confirm what was previously observed based on much smaller samples, namely, that a large fraction of BCMs have significant peculiar velocities. From a subsample of 452 clusters having at least 10 measured radial velocities, we estimate a median BCM peculiar velocity of 32% of their host clusters' radial velocity dispersion. This suggests that most BCMs are not at rest in the potential well of their clusters. This phenomenon is common to galaxy clusters in our sample, and not a special trait of clusters hosting cD galaxies. We show that the peculiar velocity of the BCM is independent of cluster richness and only slightly dependent on the Bautz-Morgan type. We also find a weak trend for the peculiar velocity to rise with the cluster velocity dispersion. The strongest dependence is with the morphological type of the BCM: cD galaxies tend to have lower relative peculiar velocities than elliptical galaxies. This result points to a connection between the formation of the BCMs and that of their clusters. Our data are qualitatively consistent with the merging-groups scenario, where BCMs in clusters formed first in smaller subsystems comparable to compact groups of galaxies. In this scenario, clusters would have formed recently from the mergers of many such groups and would still be in a dynamically unrelaxed state.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AZh/88/530
- Title:
- Dynamical study of ADS 12815
- Short Name:
- J/AZh/88/530
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A homogeneous series of photographic position measurements of the visual binary ADS 12815 obtained on the 26-inch refractor of the Pulkovo Observatory (1960-2007) is analyzed. The Pulkovo observations allow for the existence of the planet around component B discovered by Cochran et al. (1997ApJ...483..457C) based on radial-velocity measurements. The orbit of the planet must be steeply inclined to the plane of the sky (i>=70{deg}). Uniform series of position measurements obtained at the Dearborn Observatory, US Naval Observatory, and Pulkovo Observatory, the HIPPARCOS parallax, and the relative radial velocities obtained by Hauser andMarcy at the Lick Observatory are used to calculate the elements of possible orbits for the ADS 12815 stars using the apparent motion parameters method. The corresponding periods are more than 20000yr, the semi-major axes more than 900AU, and the eccentricities more than 0.65. All possible orbits are steeply inclined to the Galactic plane. The obtained family of orbits is in better agreement with observations than the family calculated by Hauser and Marcy.
- ID:
- ivo://CDS.VizieR/J/PAZh/34/446
- Title:
- Dynamical study of wide pairs of stars from WDS
- Short Name:
- J/PAZh/34/446
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the method of apparent motion parameters, we have studied the relative motion of the components in 561 pairs of wide (rho>2") and relatively nearby (Hipparcos parallaxes >0.01") visual double stars based on data from the WDS catalog. The minimum masses of the double stars have been calculated at given parallaxes. We have identified 358 optical pairs. For 11 stellar pairs, we have found the minimum mass to exceed the estimate corresponding to their spectral types and luminosities. This excess is 5-7M_{sun}_ for two stars, ADS7446 and 9701.
- ID:
- ivo://CDS.VizieR/J/A+A/591/A130
- Title:
- Dynamic SEDs of southern blazars - DSSB
- Short Name:
- J/A+A/591/A130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Simultaneous broadband spectral and temporal studies of blazars are an important tool for investigating active galactic nuclei (AGN) jet physics. We study the spectral evolution between quiescent and flaring periods of 22 radio-loud AGN through multiepoch, quasi-simultaneous broadband spectra. For many of these sources these are the first broadband studies. We use a Bayesian block analysis of Fermi/LAT light curves to determine time ranges of constant flux for constructing quasi-simultaneous spectral energy distributions (SEDs). The shapes of the resulting 81 SEDs are described by two logarithmic parabolas and a blackbody spectrum where needed.
- ID:
- ivo://CDS.VizieR/J/A+A/297/28
- Title:
- Dynamics in E+E pairs of galaxies
- Short Name:
- J/A+A/297/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematic study of three E+E galaxy pairs, NGC 741/742, 1587/1588 (CPG 99) and 2672/2673 (CPG 175). All three pairs show a similar morphological distortion (i.e. the off-centering of inner versus outer isophotes; Davoust & Prugniel 1988) which is ascribed to the ongoing interaction. The data was obtained at the CFHT equipped with the Herzberg Spectrograph at a resolution of 0.88 Apx^-1^. NGC 741 and 2673 show significant rotation along the apparent minor axis. Both components of CPG 99 rotate very fast (with no evidence for rotation along the minor axis of either component). None of the galaxies show abnormally high central velocity dispersion. We report some of the first clear detections of well defined velocity dispersion curves for interacting pairs. They show a systematic decrease with distance from the center, as expected for normal ellipticals. They do not show obvious heating in the outer parts as was previously reported. NGC 741 and 2672 show, respectively, possible U and inverse U-shaped structure in their velocity profiles.
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/2645
- Title:
- Dynamics of A3266. I. An Optical View.
- Short Name:
- J/MNRAS/468/2645
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopy of 880 galaxies within a 2-degree field around the massive, merging cluster Abell 3266. This sample, which includes 704 new measurements, was combined with the existing redshifts measurements to generate a sample of over 1300 spectroscopic redshifts; the largest spectroscopic sample in the vicinity of A3266 to date. We define a cluster sub-sample of 790 redshifts which lie within a velocity range of 14000 to 22000km/s and within 1 degree of the cluster centre. A detailed structural analysis finds A3266 to have a complex dynamical structure containing six groups and filaments to the north of the cluster as well as a cluster core which can be decomposed into two components split along a northeast-southwest axis, consistent with previous X-ray observations. The mean redshift of the cluster core is found to be 0.0594+/-0.0005 and the core velocity dispersion is given as 1462+/-99km/s. The overall velocity dispersion and redshift of the entire cluster and related structures are 1337+/-67 km/s and 0.0596+/-0.0002, respectively, though the high velocity dispersion does not represent virialised motions but rather is due to relative motions of the cluster components. We posit A3266 is seen following a merger along the northeast southwest axis, however, the rich substructure in the rest of the cluster suggests that the dynamical history is more complex than just a simple merger with a range of continuous dynamical interactions taking place. It is thus likely that turbulence in A3266 is very high, even for a merging cluster.
- ID:
- ivo://CDS.VizieR/J/A+AS/137/419
- Title:
- Dynamics of blue compact galaxies I. The data
- Short Name:
- J/A+AS/137/419
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of six luminous blue compact galaxies (BCGs) and two star forming companion galaxies were carried out with the CIGALE scanning Fabry-Perot interferometer attached to the ESO 3.6m telescope on La Silla. The observations were made in the H-alpha emission line which is prominent in BCGs. A velocity sampling of 5km/s and a pixel size of 0.9arcseconds were used. In this paper we present the observations and the data together with the velocity fields and the derived rotation curves. In addition we provide rough estimates of the total dynamical mass and of the ionised gas mass for each galaxy. All galaxies display rotation, but while the companion galaxies have regular velocity fields, those of the BCGs are complex and appear perturbed. This is the most extensive study to date of the optical velocity fields of BCGs. The interpretation of these results will be presented in a forthcoming paper (Paper II).
- ID:
- ivo://CDS.VizieR/J/ApJ/347/251
- Title:
- Dynamics of Globular Cluster M15
- Short Name:
- J/ApJ/347/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The velocity dispersion as a function of radius in the globular cluster M15 is derived from measurements of 120 individual stars between 0.1' and 4.6' of the cluster center, and from the integrated light of the central cusp. The stellar measurements, with an individual accuracy of 1 km/s, indicate a mean cluster velocity of -107.1+/-0.9 km/s, and a mean velocity dispersion of 9.0+/-0.6 km/s. The velocity dispersion inside 1' varies with radius. The dispersion of the 27 stars within 20" is 14.2+/-1.9 km/s, while that of the 30 stars between 0.5' and 1.2' is 8.4+/-1.4 km/s. The cusp itself appears to have a dispersion of at least 25 km/s. Except for its greater velocity broadening, the spectrum of the integrated light of the cusp is indistinguishable from that formed by superposition of the individual M15 giant spectra, demonstrating that the excess light at the center is due primarily to the normal M15 population. The increase of the dispersion toward the center is not consistent with truncated isothermal (King-Michie) models, for which the velocity dispersion is nearly constant within a few core radii and then falls steeply beyond. The observed behaviour is difficult to reconcile as well with current post-core collapse models, which are also isothermal and whose central energy sources are modest. It is indicative of a nonthermal energy distribution with substantial heating in the central regions; this is consistent with a central black hole of about 1000 M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/106/1508
- Title:
- Dynamics of globular cluster NGC 362
- Short Name:
- J/AJ/106/1508
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we have examined the internal dynamics of the globular cluster NGC 362 using a combination of V-band CCD images and echelle spectra of the member red giants. A V-band surface brightness profile (SBP) was constructed from the CCD images, and, after it was determined that the cluster is not post core-collapse, fit with single- and multi-pass King-Michie (KM) models. We found that for small values of the mass function slope, x, anisotropic models were favored while for steeper mass functions isotropic orbits provided superior fits. The total cluster luminosity is 1.70 +/- 0.1 x 10^5 L(Vsun) [assumes (m-M)0 = 14.77]. A total of 285 stellar spectra were obtained of 215 stars for radial velocity determinations. Three stars were obvious nonmembers and four showed strong evidence for radial velocity variations; these latter stars are probably members of binary systems with periods less than a few years. The true cluster binary fraction was determined from simulations to be 0.15 for circular orbits or 0.27 for orbits with a distribution function f(e) = e (e is eccentricity). This relatively high binary detection frequency may indicate that NGC 362 is overabundant in binaries compared to other clusters. The 208 remaining stellar velocities showed no sign of rotation and had kinematics which were incompatible with KM models having isotropic orbits and luminosity profiles consistent with the SBP. Therefore, the best agreement with both the kinematic data and the SBP were for shallow mass functions x = 0.0-0.5 and intermediate amounts of anisotropy in the velocity dispersion tensor. In this best-fit range, the derived cluster mass is M = 2.5-3.5x10^5 Msun for a global mass-to-light ratio of M/L(V) = 1.5-2.0 Msun/L(Vsun). This low value for x is in disagreement with the correlation between x and the height above the Galactic disk seen for a sample of other clusters. The results are also different from the sharp turnup in the low mass end of mass functions derived from the deep luminosity functions of three other globular clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/604/A135
- Title:
- Dynamics of ionized and neutral gas in M8
- Short Name:
- J/A+A/604/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic study of the dynamics of the ionized and neutral gas throughout the Lagoon nebula (M8), using VLT/FLAMES data from the Gaia-ESO Survey. We explore the connections between the nebular gas and the stellar population of the associated star cluster NGC6530. We characterize through spectral fitting emission lines of H{alpha}, [NII] and [SII] doublets, [OIII], and absorption lines of sodium D doublet, using data from the FLAMES/Giraffe and UVES spectrographs, on more than 1000 sightlines towards the entire face of the Lagoon nebula. Gas temperatures are derived from line-width comparisons, densities from the [SII] doublet ratio, and ionization parameter from H{alpha}/[NII] ratio. Although doubly-peaked emission profiles are rarely found, line asymmetries often imply multiple velocity components along the same line of sight. This is especially true for the sodium absorption, and for the [OIII] lines. Spatial maps for density and ionization are derived, and compared to other known properties of the nebula and of its massive stars 9 Sgr, Herschel 36 and HD 165052 which are confirmed to provide most of the ionizing flux. The detailed velocity fields across the nebula show several expanding shells, related to the cluster NGC6530, the O stars 9 Sgr and Herschel 36, and the massive protostar M8East-IR. The origins of kinematical expansion and ionization of the NGC6530 shell appear to be different. We are able to put constrains on the line-of-sight (relative or absolute) distances between some of these objects and the molecular cloud. The large obscuring band running through the middle of the nebula is being compressed by both sides, which might explain its enhanced density. We also find an unexplained large-scale velocity gradient across the entire nebula. At larger distances, the transition from ionized to neutral gas is studied using the sodium lines.