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1351. B-band photometry of ellipticals in Virgo
ID:
ivo://CDS.VizieR/J/A+A/430/411
Title:
B-band photometry of ellipticals in Virgo
Short Name:
J/A+A/430/411
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on a complete CCD imaging survey of 226 elliptical galaxies in the North-East quadrant of the Virgo cluster, representative of the properties of giant and dwarf elliptical galaxies in this cluster. We fit their radial light profiles with the Sersic r^1/n^ model of light distribution. We confirm the result of Graham & Guzman (2003AJ....125.2936G) that the apparent dichotomy between E and dE galaxies in the luminosity-<{mu}>_e_ plane no longer appears when other structural parameters are considered and can be entirely attributed to the onset of "core" galaxies at B_T_~-20.5mag. When "core" galaxies are not considered, E and dE form a unique family with n linearly increasing with the luminosity. For 90 galaxies we analyze the B-I color indices, both in the nuclear and in the outer regions. Both indices are bluer toward fainter luminosities. We find also that the outer color gradients do not show any significant correlation with the luminosity. The scatter in all color indicators increases significantly toward lower luminosities, e.g. galaxies fainter than B_T_~-15 have a B-I spread>0.5mag.
1352. B6-B9.5 stars abundance analysis
ID:
ivo://CDS.VizieR/J/A+A/506/213
Title:
B6-B9.5 stars abundance analysis
Short Name:
J/A+A/506/213
Date:
21 Oct 2021
Publisher:
CDS
Description:
The CoRoT satellite is collecting precise time-resolved photometry for tens of asteroseismology targets. To ensure a correct interpretation of the CoRoT data, the atmospheric parameters, chemical compositions, and rotational velocities of the stars must be determined. The main goal of the ground-based seismology support program for the CoRoT mission was to obtain photometric and spectroscopic data for stars in the fields monitored by the satellite. These ground-based observations were collected in the GAUDI archive. High-resolution spectra of more than 200 B-type stars are available in this database, and about 45% of them is analysed here. To derive the effective temperature of the stars, we used photometric indices. Surface gravities were obtained by comparing observed and theoretical Balmer line profiles. To determine the chemical abundances and rotational velocities, we used a spectrum synthesis method, which consisted of comparing the observed spectrum with theoretical ones based on the assumption of LTE. Atmospheric parameters, chemical abundances, and rotational velocities were determined for 89 late-B stars. The dominant species in their spectra are iron-peak elements. The average Fe abundance is 7.24+/-0.45dex. The average rotational velocity is 126km/s, but there are 13 and 20 stars with low and moderate Vsini values, respectively. The analysis of this sample of 89 late B-type stars reveals many chemically peculiar (CP) stars. Some of them were previously known, but at least 9 new CP candidates, among which at least two HgMn stars, are identified in our study. These CP stars as a group exhibit Vsini values lower than the stars with normal surface chemical composition.
1353. BBXRT Archive
ID:
ivo://nasa.heasarc/bbxrt
Title:
BBXRT Archive
Short Name:
BBXRT
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
The BBXRT database table contains information about each observation made by the Broad Band X-Ray Telescope. It includes a catalog of observations and spectral and lightcurve products for each of the 10 pixels per observation. This is a service provided by NASA HEASARC .
1354. BCG C4 cluster catalog
ID:
ivo://CDS.VizieR/J/MNRAS/379/867
Title:
BCG C4 cluster catalog
Short Name:
J/MNRAS/379/867
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the Sloan Digital Sky Survey (SDSS) to construct a sample of 625 brightest group and cluster galaxies (BCGs) together with control samples of non-BCGs matched in stellar mass, redshift and colour. We investigate how the systematic properties of BCGs depend on stellar mass and on their privileged location near the cluster centre. The groups and clusters that we study are drawn from the C4 catalogue of Miller et al. (2005, Cat. <J/AJ/130/968>) but we have developed improved algorithms for identifying the BCG and for measuring the cluster velocity dispersion. Since the SDSS photometric pipeline tends to underestimate the luminosities of large galaxies in dense environments, we have developed a correction for this effect which can be readily applied to the published catalogue data.
1355. BCG high radio-frequency properties
ID:
ivo://CDS.VizieR/J/MNRAS/453/1223
Title:
BCG high radio-frequency properties
Short Name:
J/MNRAS/453/1223
Date:
21 Oct 2021
Publisher:
CDS
Description:
We consider the high radio-frequency (15-353GHz) properties and variability of 35 brightest cluster galaxies (BCGs). These are the most core-dominated sources drawn from a parent sample of more than 700 X-ray selected clusters, thus allowing us to relate our results to the general population. We find that >=6.0 percent of our parent sample (>=15.1 percent if only cool-core clusters are considered) contain a radio source at 150GHz of at least 3mJy (~1x10^23^W/Hz at our median redshift of z~0.13). Furthermore, >=3.4 percent of the BCGs in our parent sample contain a peaked component (Gigahertz Peaked Spectrum, GPS) in their spectra that peaks above 2GHz, increasing to >=8.5 percent if only cool-core clusters are considered. We see little evidence for strong variability at 15GHz on short (week-month) time-scales although we see variations greater than 20 percent at 150GHz over six-month time frames for 4 of the 23 sources with multi-epoch observations. Much more prevalent is long-term (year-decade time-scale) variability, with average annual amplitude variations greater than 1 percent at 15GHz being commonplace. There is a weak trend towards higher variability as the peak of the GPS-like component occurs at higher frequency. We demonstrate the complexity that is seen in the radio spectra of BCGs and discuss the potentially significant implications of these high-peaking components for Sunyaev-Zel'dovich cluster searches.
1356. BCGs with radio AGN
ID:
ivo://CDS.VizieR/J/ApJ/704/1586
Title:
BCGs with radio AGN
Short Name:
J/ApJ/704/1586
Date:
21 Oct 2021
Publisher:
CDS
Description:
The radio active galactic nucleus (AGN) feedback in X-ray cool cores has been proposed as a crucial ingredient in the evolution of baryonic structures. However, it has long been known that strong radio AGNs also exist in "noncool core" clusters, which brings up the question whether an X-ray cool core is always required for the radio feedback. In this work, we present a systematic analysis of brightest cluster galaxies (BCGs) and strong radio AGNs in 152 groups and clusters from the Chandra archive. All 69 BCGs with radio AGN more luminous than 2x10^23^W/Hz at 1.4GHz are found to have X-ray cool cores. BCG cool cores can be divided into two classes: the large cool core (LCC) class and the corona class. As examples of the corona class, we also present detailed analyses of a BCG corona associated with a strong radio AGN (ESO 137-006 in A3627) and one of the faintest coronae known (NGC 4709 in the Centaurus cluster).
1357. BCG up to z=1.80 physical properties
ID:
ivo://CDS.VizieR/J/A+A/649/A42
Title:
BCG up to z=1.80 physical properties
Short Name:
J/A+A/649/A42
Date:
22 Feb 2022
Publisher:
CDS
Description:
Brightest cluster galaxies (BCGs) have grown by accreting numerous smaller galaxies and can be used as tracers of cluster formation and evolution in the cosmic web. However, there is still a controversy on the main epoch of formation of BCGs, since some authors believe they have already formed before redshift z=2, while others still find them to evolve at more recent epochs. We aim to analyse the physical properties of a large sample of BCGs covering a wide redshift range up to z=1.8 and analysed in a homogeneous way, to see if their characteristics vary with redshift. As a first step, we also present a new tool to define for each cluster which galaxy is the BCG. For a sample of 137 clusters with HST images in the optical and/or infrared, we analyse the BCG properties by applying GALFIT with one or two Sersic components. For each BCG, we compute the Sersic index, effective radius, major axis position angle, surface brightness. We then search for correlations of these quantities with redshift. We find that BCGs follow the Kormendy relation (between the effective radius and the mean surface brightness), with a slope that remains constant with redshift, but with a variation with redshift of the ordinate at the origin. Although the trends are faint, we find that both the absolute magnitudes and effective radii tend to become respectively brighter and bigger with decreasing redshift. On the other hand, we find no significant correlation of the mean surface brightnesses or Sersic indices with redshift. The major axes of the cluster elongations and of the BCGs agree within 30 degrees for 73% of our clusters at redshift z<=0.9. Our results agree with the BCGs being mainly formed before redshift z=2. The alignment of the major axes of BCGs with their clusters agree with the general idea that BCGs form at the same time as clusters by accreting matter along the filaments of the cosmic web.
1358. BCool survey of solar-type stars
ID:
ivo://CDS.VizieR/J/MNRAS/444/3517
Title:
BCool survey of solar-type stars
Short Name:
J/MNRAS/444/3517
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a major high-resolution spectropolarimetric BCool project magnetic survey of 170 solar-type stars. Surface magnetic fields were detected on 67 stars, with 21 classified as mature solar-type stars, a result that increases by a factor of 4 the number of mature solar-type stars on which magnetic fields have been observed. In addition, a magnetic field was detected for 3 out of 18 of the subgiant stars surveyed. For the population of K-dwarfs, the mean value of |Bl| (|Bl|_mean_) was also found to be higher (5.7G) than |Bl|_mean_ measured for the G-dwarfs (3.2G) and the F-dwarfs (3.3G). For the sample as a whole, |Bl|_mean_ increases with rotation rate and decreases with age, and the upper envelope for |Bl| correlates well with the observed chromospheric emission. Stars with a chromospheric S-index greater than about 0.2 show a high magnetic field detection rate and so offer optimal targets for future studies. This survey constitutes the most extensive spectropolarimetric survey of cool stars undertaken to date, and suggests that it is feasible to pursue magnetic mapping of a wide range of moderately active solar-type stars to improve our understanding of their surface fields and dynamos.
1359. BDKP. III. Parallaxes for 70 ultracool dwarfs
ID:
ivo://CDS.VizieR/J/ApJ/752/56
Title:
BDKP. III. Parallaxes for 70 ultracool dwarfs
Short Name:
J/ApJ/752/56
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report parallax measurements for 70 ultracool dwarfs (UCDs) including 11 late-M, 32 L, and 27 T dwarfs. In this sample, 14 M and L dwarfs exhibit low surface gravity features, 6 are close binary systems, and 2 are metal-poor subdwarfs. We combined our new measurements with 114 previously published UCD parallaxes and optical-mid-IR photometry to examine trends in spectral-type/absolute magnitude, and color-color diagrams. We report new polynomial relations between spectral type and M_JHK_. Including resolved L/T transition binaries in the relations, we find no reason to differentiate between a "bright" (unresolved binary) and a "faint" (single source) sample across the L/T boundary. Isolating early T dwarfs, we find that the brightening of T0-T4 sources is prominent in M_J_ where there is a [1.2-1.4] mag difference. A similar yet dampened brightening of [0.3-0.5] mag happens at M_H_ and a plateau or dimming of [-0.2 to -0.3] mag is seen in M_K_. Comparison with evolutionary models that vary gravity, metallicity, and cloud thickness verifies that for L into T dwarfs, decreasing cloud thickness reproduces brown dwarf near-IR color-magnitude diagrams. However we find that a near constant temperature of 1200 +/-100 K along a narrow spectral subtype of T0-T4 is required to account for the brightening and color-magnitude diagram of the L-dwarf/T-dwarf transition. There is a significant population of both L and T dwarfs which are red or potentially "ultra-cloudy" compared to the models, many of which are known to be young indicating a correlation between enhanced photospheric dust and youth. For the low surface gravity or young companion L dwarfs we find that 8 out of 10 are at least [0.2-1.0] mag underluminous in M_JH_and/or M_K_compared to equivalent spectral type objects. We speculate that this is a consequence of increased dust opacity and conclude that low surface gravity L dwarfs require a completely new spectral-type/absolute magnitude polynomial for analysis.
1360. BDKP IV. RVs of late-M and L dwarfs with MagE
ID:
ivo://CDS.VizieR/J/ApJS/220/18
Title:
BDKP IV. RVs of late-M and L dwarfs with MagE
Short Name:
J/ApJS/220/18
Date:
21 Oct 2021
Publisher:
CDS
Description:
Radial velocity measurements are presented for 85 late M- and L-type very low-mass stars and brown dwarfs obtained with the Magellan Echellette spectrograph. Targets primarily have distances within 20pc of the Sun, with more distant sources selected for their unusual spectral energy distributions. We achieved precisions of 2-3km/s, and combined these with astrometric and spectrophotometric data to calculate UVW velocities. Most are members of the thin disk of the Galaxy, and velocity dispersions indicate a mean age of 5.2+/-0.2Gyr for sources within 20pc. We find significantly different kinematic ages between late-M dwarfs (4.0+/-0.2Gyr) and L dwarfs (6.5+/-0.4Gyr) in our sample that are contrary to predictions from prior simulations. This difference appears to be driven by a dispersed population of unusually blue L dwarfs which may be more prevalent in our local volume-limited sample than in deeper magnitude-limited surveys. The L dwarfs exhibit an asymmetric U velocity distribution with a net inward flow, similar to gradients recently detected in local stellar samples. Simulations incorporating brown dwarf evolution and Galactic orbital dynamics are unable to reproduce the velocity asymmetry, suggesting non-axisymmetric perturbations or two distinct L dwarf populations. We also find the L dwarfs to have a kinematic age-activity correlation similar to more massive stars. We identify several sources with low surface gravities, and two new substellar candidate members of nearby young moving groups: the astrometric binary DENIS J08230313-4912012AB, a low-probability member of the {beta} Pictoris Moving Group; and 2MASS J15104786-2818174, a moderate-probability member of the 30-50Myr Argus Association.

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