- ID:
- ivo://CDS.VizieR/J/AJ/131/1559
- Title:
- Diameters of Galactic open star clusters
- Short Name:
- J/AJ/131/1559
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present paper presents a tabulation of data on all 600 Galactic open clusters for which it is currently possible to calculate linear diameters. As expected, the youngest "clusters", with ages <15Myr, contain a significant (>=20%) admixture of associations. Among intermediate-age clusters, with ages in the range 15Myr to 1.5Gyr, the median cluster diameter is found to increase with age. Small, compact clusters are rare among objects with ages >1.5Gyr. Open clusters with ages >1Gyr appear to form what might be termed a "cluster thick disk", part of which consists of objects that were probably captured gravitationally by the main body of the Galaxy.
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- ID:
- ivo://CDS.VizieR/J/A+A/596/A25
- Title:
- Disc breaks across masses and wavelengths
- Short Name:
- J/A+A/596/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Breaks in the surface brightness profiles in the outer regions of galactic discs are thought to have formed by various internal (e.g. bar resonances) and external (e.g. galaxy merging) processes. By studying the disc breaks we aim to better understand what processes are responsible for the evolution of the outer discs of galaxies, and galaxies in general. We use a large well-defined sample to study how common the disc breaks are, and whether their properties depend on galaxy mass. By using both optical and infrared data we study whether the observed wavelength affects the break features as a function of galaxy mass and Hubble type. We studied the properties of galaxy discs using radial surface brightness profiles of 753 galaxies, obtained from the 3.6um images of the Spitzer Survey of Stellar Structure in Galaxies (S4G), and the Ks-band data from the Near InfraRed S0-Sa galaxy Survey (NIRS0S), covering a wide range of galaxy morphologies (-2<=T<=9) and stellar masses (8.5<~log10 (M*/M_{sun}_)<~11). In addition, optical Sloan Digital Sky Survey (SDSS) or Liverpool telescope data was used for 480 of these galaxies. We find that in low-mass galaxies the single exponential profiles (Type I) are most common, and that their fraction decreases with increasing galaxy stellar mass. The fraction of down-bending (Type II) profiles increases with stellar mass, possibly due to more common occurrence of bar resonance structures. The up-bending (Type III) profiles are also more common in massive galaxies. The observed wavelength affects the scalelength of the disc of every profile type. Especially the scalelength of the inner disc (h_i_) of Type II profiles increases from infrared to u-band on average by a factor of ~2.2. Consistent with the previous studies, but with a higher statistical significance, we find that Type II outer disc scalelengths (h_o_) in late-type and low mass galaxies (T>4, log10(M*/M_{sun}_)<~10.5) are shorter in bluer wavelengths, possibly due to stellar radial migration populating the outer discs with older stars. In Type III profiles h_o are larger in the u band, hinting to the presence of young stellar population in the outer disc. While the observed wavelength affects the disc parameters, it does not significantly affect the profile type classification in our sample. Our results indicate that the observed wavelength is a significant factor when determining the profile types in very low mass dwarf galaxies, for which more Type II profiles have been previously found using optical data.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A76
- Title:
- Disc galaxies baryonic specific ang. mom.
- Short Name:
- J/A+A/647/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Specific angular momentum (the angular momentum per unit mass, j=J/M) is one of the key parameters that control the evolution of galaxies, and it is closely related with the coupling between dark and visible matter. In this work, we aim to derive the baryonic (stars plus atomic gas) specific angular momentum of disc galaxies and study its relation with the dark matter specific angular momentum. Using a combination of high-quality HI rotation curves, HI surface densities, and near-infrared surface brightness profiles, we homogeneously measure the stellar (j*) and gas (jgas) specific angular momenta for a large sample of nearby disc galaxies. This allows us to determine the baryonic specific angular momentum (jbar) with high accuracy and across a very wide range of masses. We confirm that the j*-M* relation is an unbroken power-law from 7<~log(M*/M_{sun}_)<~11.5, with a slope 0.54+/-0.02, setting a stronger constraint at dwarf galaxy scales than previous determinations. Concerning the gas component, we find that the jgas-Mgas relation is also an unbroken power-law from 6<~log(Mgas/M_{sun}_)<~11, with a steeper slope of 1.01+/-0.04. Regarding the baryonic relation, our data support a correlation characterized by a single power-law with a slope 0.58+/-0.02. Our analysis shows that our most massive spirals and smallest dwarfs lie along the same jbar-Mbar sequence. While the relations are tight and unbroken, we find internal correlations inside them: At fixed M, galaxies with larger j have larger disc scale lengths, and at fixed Mbar, gas-poor galaxies have lower jbar than expected. We estimate the retained fraction of baryonic specific angular momentum, f_jbar_, finding it constant across our entire mass range with a value of 0.7, indicating that the baryonic specific angular momentum of present-day disc galaxies is comparable to the initial specific angular momentum of their dark matter haloes. In general, these results set important constraints for hydrodynamical simulations and semi-analytical models that aim to reproduce galaxies with realistic specific angular momenta.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2085
- Title:
- Disk brightness profiles in galaxies
- Short Name:
- J/AJ/127/2085
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the disk brightness profiles of 218 spiral and lenticular galaxies. At least 28% of disk galaxies exhibit inner truncations in these profiles. There are no significant trends of truncation incidence with Hubble type, but the incidence among barred systems is 49%, more than 4 times that for non-barred galaxies. However, not all barred systems have inner truncations, and not all inner-truncated systems are currently barred. Truncations represent a real dearth of disk stars in the inner regions and are not an artifact of our selection or fitting procedures nor the result of obscuration by dust.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/727
- Title:
- Distance and mass of Infrared Dark Clouds
- Short Name:
- J/ApJ/706/727
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared Dark Clouds (IRDCs) are dark clouds seen in silhouette in mid-infrared surveys. They are thought to be the birthplace of massive stars, yet remarkably little information exists on the properties of the population as a whole (e.g., mass spectrum, spatial distribution). Genetic forward modeling is used along with the Two Micron All Sky Survey and the Besancon Galactic model to deduce the three-dimensional distribution of interstellar extinction toward previously identified IRDC candidates. This derived dust distribution can then be used to determine the distance and mass of IRDCs, independently of kinematic models of the Milky Way. Along a line of sight that crosses an IRDC, the extinction is seen to rise sharply at the distance of the cloud. Assuming a dust-to-gas ratio, the total mass of the cloud can be estimated. The method has been successfully applied to 1259 IRDCs, including over 1000 for which no distance or mass estimate currently exists. The IRDCs are seen to lie preferentially along the spiral arms and in the molecular ring of the Milky Way, reinforcing the idea that they are the birthplace of massive stars. Also, their mass spectrum is seen to follow a power law with an index of -1.75+/-0.06, steeper than giant molecular clouds (GMCs) in the inner Galaxy but comparable to clumps in GMCs. This slope suggests that the IRDCs detected using the present method are not gravitationally bound, but are rather the result of density fluctuations induced by turbulence.
- ID:
- ivo://CDS.VizieR/J/MNRAS/361/109
- Title:
- Distant cluster galaxies Tully-Fisher relation
- Short Name:
- J/MNRAS/361/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured maximum rotation velocities (Vrot) for a sample of 111 emission-line galaxies with 0.1~<z~<1, observed in the fields of six clusters. From these data we construct 'matched' samples of 58 field and 22 cluster galaxies, covering similar ranges in redshift (0.25<=z<=1.0) and luminosity (M_B_<=-19.5mag), and selected in a homogeneous manner.
- ID:
- ivo://CDS.VizieR/J/MNRAS/394/2197
- Title:
- Distant radio galaxies in southern hemisphere
- Short Name:
- J/MNRAS/394/2197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have compiled a sample of 234 ultra-steep-spectrum (USS) selected radio sources in order to find high-redshift radio galaxies. The sample covers the declination range -40{deg}<{delta}<-30{deg} in the overlap region between the 1400-MHz National Radio Astronomy Observatory (NRAO) Very Large Array (VLA) Sky Survey (NVSS), 408-MHz Revised Molonglo Reference Catalogue and the 843-MHz Sydney University Molonglo Sky Survey (the MRCR-SUMSS sample). This is the second in a series of papers on the MRCR-SUMSS sample, and here we present the K-band (2.2{mu}m) imaging of 173 of the sources primarily from the Magellan and the Anglo-Australian Telescopes. We detect a counterpart to the radio source in 93 per cent of the new K-band images which, along with previously published data, makes this the largest published sample of K-band counterparts to USS-selected radio galaxies. The location of the K-band identification has been compared to the features of the radio emission for the double sources. We find that the identification is most likely to lie near the mid-point of the radio lobes rather than closer to the brighter lobe, making the centroid a less likely place to find the optical counterpart. 79 per cent of the identifications are less than 1arcsec from the radio lobe axis. These results differ from studies of low-redshift radio samples where the environments are typically not nearly so dense and disturbed as those at high redshift. In contrast to some literature samples, we find that the majority of our sample shows no alignment between the near-infrared and radio axes. Several different morphologies of aligned structures are found and those that are aligned within 10{deg} are consistent with jet-induced star formation. The distribution and median value of the K-band magnitudes for the MRCR-SUMSS sample are found to be similar to several other USS-selected samples even though each sample has a very different median 1400MHz flux density. USS selection from a lower radio-frequency sample has not netted fainter K-band magnitudes, which may imply that the k-correction is not responsible for the effectiveness of USS selection.
- ID:
- ivo://CDS.VizieR/J/ApJ/680/70
- Title:
- Distant spheroids in the GOODS fields
- Short Name:
- J/ApJ/680/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the first results of a new study aimed at understanding the diversity and evolutionary history of distant galactic bulges in the context of now well-established trends for pure spheroidal galaxies. To this end, bulges have been isolated for a sample of 137 spiral galaxies within the redshift range 0.1<z<1.2 in the GOODS fields. Using proven photometric techniques, we determine the characteristic parameters (size, surface brightness, profile shape) of both the disk and bulge components in our sample. In agreement with earlier work that utilized aperture colors, distant bulges show a broader range of optical colors than would be the case for passively evolving populations. To quantify the amount of recent star formation necessary to explain this result, we used DEIMOS to secure stellar velocity dispersions for a sizeable fraction of our sample. This has enabled us to compare the fundamental plane of our distant bulges with that for spheroidal galaxies in a similar redshift range.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/115
- Title:
- Double-component model fitting of elliptical gal.
- Short Name:
- J/ApJ/836/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate two-dimensional image decomposition of nearby, morphologically selected early-type galaxies (ETGs). We are motivated by recent observational evidence of significant size growth of quiescent galaxies and theoretical development advocating a two-phase formation scenario for ETGs. We find that a significant fraction of nearby ETGs show changes in isophotal shape that require multi-component models. The characteristic sizes of the inner and outer component are ~3 and ~15kpc. The inner component lies on the mass-size relation of ETGs at z~0.25-0.75, while the outer component tends to be more elliptical and hints at a stochastic buildup process. We find real physical differences between single- and double-component ETGs, with double-component galaxies being younger and more metal-rich. The fraction of double-component ETGs increases with increasing {sigma} and decreases in denser environments. We hypothesize that double-component systems were able to accrete gas and small galaxies until later times, boosting their central densities, building up their outer parts, and lowering their typical central ages. In contrast, the oldest galaxies, perhaps due to residing in richer environments, have no remaining hints of their last accretion episode.
- ID:
- ivo://CDS.VizieR/J/A+A/539/A106
- Title:
- DPOSS II compact group survey. EMMI-NTT sample
- Short Name:
- J/A+A/539/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a redshift survey of 138 candidate compact groups from the DPOSS II catalogue, which extends the available redshift range of spectroscopically confirmed compact groups of galaxies to redshift z~0.2. In this survey, we aim to confirm group membership via spectroscopic redshift information, to measure the characteristic properties of the confirmed groups, namely their mass, radius, luminosity, velocity dispersion, and crossing time, and to compare them with those of nearby compact groups. Using information available from the literature, we also studied the surrounding group environment and searched for additional, previously unknown, group members, or larger scale structures to whom the group might be associated.
