- ID:
- ivo://CDS.VizieR/J/MNRAS/471/1446
- Title:
- Ground-based proper motion of 12 nearby GC
- Short Name:
- J/MNRAS/471/1446
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive relative proper motions of stars in the fields of the globular clusters M12, NGC 6362, M4, M55, M22, NGC 6752, NGC 3201, M30, M10, NGC 362, M5 and 47 Tucanae based on data collected between 1997 and 2015 with the 1-m Swope telescope of Las Campanas Observatory. We determine membership class and membership probability for over 446000 objects, and show that these are efficient methods for separating field stars from members of the cluster. In particular, membership probabilities of variable stars and blue/yellow/red stragglers are determined. Finally, we find absolute proper motions for six globular clusters from our sample: M55, NGC 3201, M10, NGC 362, M5 and 47 Tuc. An electronic catalogue of the derived proper motions is publicly available via the internet.
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- ID:
- ivo://CDS.VizieR/J/AJ/157/21
- Title:
- Ground-based spectroscopy of the exoplanet XO-2b
- Short Name:
- J/AJ/157/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanets orbiting close to their host star are expected to support a large ionosphere, which extends to larger pressures than witnessed in our solar system. These ionospheres can be investigated with ground-based transit observations of the optical signatures of alkali metals, which are the source of the ions. However, most ground-based transit spectra do not systematically resolve the wings of the features and continuum, as needed to constrain the alkali abundances. Here we present new observations and analyses of optical transit spectra that cover the Na doublet in the atmosphere of the exoplanet XO-2b. To assess the consistency of our results, observations were obtained from two separate platforms: Gemini/GMOS and Mayall/KOSMOS. To mitigate the systematic errors, we chose XO-2, because it has a binary companion of the same brightness and stellar type, which provides an ideal reference star to model Earth's atmospheric effects. We find that interpretation of the data is highly sensitive to time-varying translations along the detector, which change according to wavelength and differ between the target and reference star. It was necessary to employ a time-dependent cross-correlation to align our wavelength bins and correct for atmospheric differential refraction. This approach allows us to resolve the wings of the Na line across five wavelength bins at a resolution of ~1.6 nm and limit the abundance of Na. We obtain consistent results from each telescope with an Na amplitude of 521+/-161 and 403+/-186 ppm for GMOS and KOSMOS, respectively. The results are analyzed with a radiative transfer model that includes the effects of ionization. The data are consistent with a clear atmosphere between ~1 and 100 mbar that establishes a lower limit on Na at 0.4_-0.3_^+2^ ppm ([Na/H]=-0.64_-0.6_^+0.78^), consistent with solar. However, we cannot rule out the presence of clouds at ~10 mbar that allow for higher Na abundances, which would be consistent with the stellar metallicity measured for the host star ([Na/H]=0.485+/-0.043).
- ID:
- ivo://CDS.VizieR/J/ApJ/738/143
- Title:
- Ground-state contributions around s-process
- Short Name:
- J/ApJ/738/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Modern models of s-process nucleosynthesis in stars require stellar reaction rates of high precision. Most neutron-capture cross-sections in the s-process have been measured, and for an increasing number of reactions the required precision is achieved. This does not necessarily mean, however, that the stellar rates are constrained equally well, because only the capture of the ground state of a target is measured in the laboratory. Captures of excited states can contribute considerably to stellar rates that are already at typical s-process temperatures. We show that the ground-state contribution X to a stellar rate is the relevant measure to identify reactions that are or could be well constrained by experiments and apply it to (n,{gamma}) reactions in the s-process. We further show that the maximum possible reduction in uncertainty of a rate via determination of the ground-state cross-section is given directly by X. An error analysis of X is presented, and it is found that X is a robust measure with mostly small uncertainties. Several specific examples (neutron capture of ^79^Se, ^95^Zr, ^121^Sn, ^187^Os, and ^193^Pt) are discussed in detail. The ground-state contributions for a set of 412 neutron-capture reactions around the s-process path are presented in a table. This allows identification of reactions that may be better constrained by experiments and that cannot be constrained solely by measuring ground-state cross-sections (and thus require supplementary studies).
- ID:
- ivo://CDS.VizieR/J/ApJ/647/418
- Title:
- Ground-state OH masers in W3(OH) study
- Short Name:
- J/ApJ/647/418
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VLBA observations of the ground-state hydroxyl masers in W3(OH) at 0.02km/s spectral resolution. Over 250 masers are detected, including 56 Zeeman pairs. Line shapes are predominantly Gaussian or combinations of several Gaussians, with normalized deviations typically of the same magnitude as in masers in other species.
- ID:
- ivo://CDS.VizieR/J/A+A/596/A14
- Title:
- Group catalogues of the local universe
- Short Name:
- J/A+A/596/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Friends-of-friends algorithms are a common tool to detect galaxy groups and clusters in large survey data. In order to be as precise as possible, they have to be carefully calibrated using mock catalogues. We create an accurate and robust description of the matter distribution in the local Universe using the most up-to-date available data. This will provide the input for a specific cosmological test planned as follow-up to this work, and will be useful for general extragalactic and cosmological research. We create a set of galaxy group catalogues based on the 2MRS (Huchra et al., 2012, Cat. J/ApJS/199/26) and SDSS DR12 galaxy samples using a friends-of-friends based group finder algorithm. The algorithm is carefully calibrated and optimised on a new set of wide-angle mock catalogues from the Millennium simulation, in order to provide accurate total mass estimates of the galaxy groups taking into account the relevant observational biases in 2MRS and SDSS. We provide four different catalogues: (i) a 2MRS based group catalogue; (ii) a SDSS DR12 based group catalogue reaching out to a redshift z=0.11 with stellar mass estimates for 70% of the galaxies; (iii) a catalogue providing additional fundamental plane distances for all groups of the SDSS catalogue that host elliptical galaxies; (iv) a catalogue of the mass distribution in the local Universe based on a combination of our 2MRS and SDSS catalogues. While motivated by a specific cosmological test, three of the four catalogues that we produced are well suited to act as reference databases for a variety of extragalactic and cosmological science cases. Our catalogue of fundamental plane distances for SDSS groups provides further added value to this paper.
- ID:
- ivo://CDS.VizieR/J/A+A/573/A111
- Title:
- Group-dominant elliptical galaxies CO spectra
- Short Name:
- J/A+A/573/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present IRAM 30m telescope observations of the CO(1-0) and (2-1) lines in a sample of 11 group-dominant elliptical galaxies selected from the CLoGS nearby groups sample. Our observations confirm the presence of molecular gas in 4 of the 11 galaxies at >4{sigma} significance, and combining these with data from the literature we find a detection rate of 43+/-14%, significantly higher than for the wider population of elliptical galaxies, and comparable to the detection rate for nearby radio galaxies. Those group-dominant galaxies which are detected typically contain ~2x10^8^M_{sun}_ of molecular gas, and although most have low star formation rates (<1M_{sun}_/yr) they have short depletion times, indicating that the gas must be replenished on timescales 10^8^yr. Almost all of the galaxies contain active nuclei, and we note that while CO detections are more common in the most radio-loud galaxies, the mass of molecular gas required to power the active nuclei through accretion is small compared to the masses observed. We consider the possible origin mechanisms for the gas, through cooling of stellar ejecta within the galaxies, group-scale cooling flows, and gas-rich mergers, and find probable examples of each type within our sample, confirming that a variety of processes act to drive the build up of molecular gas in group-dominant ellipticals.
- ID:
- ivo://CDS.VizieR/J/MNRAS/494/2090
- Title:
- Group galaxies in ALFALFA survey
- Short Name:
- J/MNRAS/494/2090
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We estimate the HI mass function (HIMF) of galaxies in groups based on thousands of ALFALFA (Arecibo Legacy Fast ALFA survey) HI detections within the galaxy groups of four widely used SDSS (Sloan Digital Sky Survey) groups catalogues. Although differences between the catalogues mean that there is no one definitive group galaxy HIMF, in general we find that the low-mass slope is flat, in agreement with studies based on small samples of individual groups, and that the 'knee' mass is slightly higher than that of the global HIMF of the full ALFALFA sample. We find that the observed fraction of ALFALFA galaxies in groups is approximately 22 per cent. These group galaxies were removed from the full ALFALFA source catalogue to calculate the field HIMF using the remaining galaxies. Comparison between the field and group HIMFs reveals that group galaxies make only a small contribution to the global HIMF as most ALFALFA galaxies are in the field, but beyond the HIMF 'knee' group galaxies dominate. Finally we attempt to separate the group galaxy HIMF into bins of group halo mass, but find that too few low-mass galaxies are detected in the most massive groups to tightly constrain the slope, owing to the rarity of such groups in the nearby Universe where low-mass galaxies are detectable with existing HI surveys.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/150
- Title:
- Group galaxies in the RCS
- Short Name:
- J/ApJ/749/150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the evolution of the red-galaxy fraction (f_red_) in 905 galaxy groups with 0.15<=z<0.52. The galaxy groups are identified by the "probability friends-of-friends" algorithm from the first Red-Sequence Cluster Survey (RCS1) photometric-redshift sample. There is a high degree of uniformity in the properties of the red sequence of the group galaxies, indicating that the luminous red-sequence galaxies in the groups are already in place by z~0.5 and that they have a formation epoch of z>~2. In general, groups at lower redshifts exhibit larger f_red_ than those at higher redshifts, showing a group Butcher-Oemler effect. We investigate the evolution of f_red_ by examining its dependence on four parameters, one of which can be classified as intrinsic and three of which can be classified as environmental: galaxy stellar mass (M_*_), total group stellar mass (M_*,grp_, a proxy for group halo mass), normalized group-centric radius (r_grp_), and local galaxy density ({Sigma}_5_).
- ID:
- ivo://CDS.VizieR/J/MNRAS/407/2207
- Title:
- Group of early-type galaxies
- Short Name:
- J/MNRAS/407/2207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fundamental plane of early-type galaxies is a rather tight three-parameter correlation discovered more than 20yr ago. It has resisted both a global and precise physical interpretation despite a consequent number of works, observational, theoretical or using numerical simulations. It appears that its precise properties depend on the population of galaxies in study. Instead of selecting a priori these populations, we propose to objectively construct homologous populations from multivariate analyses. We have undertaken multivariate cluster and cladistic analyses of a sample of 56 low-redshift galaxy clusters containing 699 early-type galaxies, using four parameters: effective radius, velocity dispersion, surface brightness averaged over effective radius and Mg_2_ index.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/194
- Title:
- Group of galaxies in gravitational lens fields
- Short Name:
- J/ApJ/833/194
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With a large, unique spectroscopic survey in the fields of 28 galaxy-scale strong gravitational lenses, we identify groups of galaxies in the 26 adequately sampled fields. Using a group-finding algorithm, we find 210 groups with at least 5 member galaxies; the median number of members is 8. Our sample spans redshifts of 0.04<=z_grp_<=0.76 with a median of 0.31, including 174 groups with 0.1<z_grp_<0.6. The groups have radial velocity dispersions of 60<={sigma}_grp_<=1200km/s with a median of 350km/s. We also discover a supergroup in field B0712+472 at z=0.29 that consists of three main groups. We recover groups similar to ~85% of those previously reported in these fields within our redshift range of sensitivity and find 187 new groups with at least five members. The properties of our group catalog, specifically, (1) the distribution of {sigma}_grp_, (2) the fraction of all sample galaxies that are group members, and (3) the fraction of groups with significant substructure, are consistent with those for other catalogs. The distribution of group virial masses agrees well with theoretical expectations. Of the lens galaxies, 12 of 26 (46%) (B1422+231, B1600+434, B2114+022, FBQS J0951+2635, HE0435-1223, HST J14113+5211, MG0751+2716, MGJ1654+1346, PG 1115+080, Q ER 0047-2808, RXJ1131-1231, and WFI J2033-4723) are members of groups with at least five galaxies, and one more (B0712+472) belongs to an additional, visually identified group candidate. There are groups not associated with the lens that still are likely to affect the lens model; in six of 25 (24%) fields (excluding the supergroup), there is at least one massive ({sigma}_grp_>=500km/s) group or group candidate projected within 2' of the lens.