- ID:
- ivo://CDS.VizieR/J/AJ/149/32
- Title:
- Integrated radio continuum spectra of galaxies
- Short Name:
- J/AJ/149/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the spectral shape of the total continuum radiation, between 74MHz and 5GHz (400-6cm in wavelength), for a large sample of bright galaxies. We take advantage of the overlapping survey coverage of the VLA Low-Frequency Sky Survey, the Westerbork Northern Sky Survey, the NRAO VLA Sky Survey, and the Green Bank 6cm Survey to achieve significantly better resolution, sensitivity, and sample size compared to prior efforts of this nature. For our sample of 250 bright galaxies we measure a mean spectral index, {alpha}, of -0.69 between 1.4 and 4.85GHz, -0.55 between 325MHz and 1.4GHz, and -0.45 between 74 and 325MHz, which amounts to a detection of curvature in the mean spectrum. The magnitude of this curvature is approximately {Delta}{alpha}=-0.2 per logarithmic frequency decade when fit with a generalized function having constant curvature. No trend in low-frequency spectral flattening versus galaxy inclination is evident in our data, suggesting that free-free absorption is not a satisfying explanation for the observed curvature. The ratio of thermal to non-thermal emission is estimated through two independent methods: (1) using the IRAS far-IR fluxes and (2) with the value of the total spectral index. Method (1) results in a distribution of 1.4GHz thermal fractions of 9%+/-3%, which is consistent with previous studies, while method (2) produces a mean 1.4GHz thermal fraction of 51% with dispersion 26%. The highly implausible values produced by method (2) indicate that the sum of typical power-law thermal and non-thermal components is not a viable model for the total spectral index between 325 and 1.4GHz. An investigation into relationships between spectral index, infrared-derived quantities, and additional source properties reveals that galaxies with high radio luminosity in our sample are found to have, on average, a flatter radio spectral index, and early types tend to have excess radio emission when compared to the radio-infrared ratio of later types. Early types also have radio emission that is more compact than later type galaxies, as compared to the optical size of the galaxy. Despite these differences, no relation between spectral index and galaxy type is detected.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/550/A114
- Title:
- Integrated spectroscopy of HRS galaxies
- Short Name:
- J/A+A/550/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present long-slit integrated spectroscopy of 238 late-type galaxies belonging to the Herschel Reference Survey, a volume-limited sample representative of the nearby universe. This sample has a unique legacy value since it was ideally defined for any statistical study of the multifrequency properties of galaxies spanning a wide range in morphological type and luminosity. The spectroscopic observations cover the spectral range 3600-6900{AA} at a resolution R~=1000 and are thus suitable for separating both the underlying absorption from the emission of the H{beta} line and the two [NII] lines from the H{alpha} emission. We measured the fluxes and the equivalent widths of the strongest emission lines ([OII]{lambda}3727, H{beta}, [OIII]{lambda}4959 and [OIII]{lambda}5007, [NII]{lambda}6548, H{alpha}, [NII]{lambda}6584, [SII]{lambda}6717, and [SII]{lambda}6731). We used the data to study the distribution of the equivalent width of all the emission lines, of the Balmer decrement C(H{beta}), and of the observed underlying Balmer absorption under H{beta} (EWH{beta}_abs_) in this sample. Combining these new spectroscopic data with those available at other frequencies, we also study the dependence of C(H{beta}) and EWH{beta}_abs_ on morphological type, stellar mass, stellar surface density, star formation rate, birthrate parameter, and metallicity in galaxies belonging to different environments (fields vs. Virgo cluster). The distribution of the equivalent width of all the emission lines, of C(H{beta}) (or equivalently of A(H{alpha}), and of EWH{beta}_abs_ are systematically different in cluster and field galaxies. The Balmer decrement increases with the stellar mass, stellar surface density, metallicity, and star formation rate of the observed galaxies, while it is unexpectedly almost independent of the column density of the atomic and molecular gas. The dependence of C(H{beta}) on stellar mass is steeper than previously found in other works. The underlying Balmer absorption does not significantly change with any of these physical parameters.
- ID:
- ivo://CDS.VizieR/VII/236
- Title:
- Interacting galaxies catalogue
- Short Name:
- VII/236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present edition unifies two parts of Catalogue of interacting galaxies by B.A. Vorontsov-Velyaminov (1959VV....C......0V, 1970, 1977A&AS...28....1V). It contains 852 known interacting VV-systems and 1162 new objects taken from the comments on the galaxies in Morphological catalogues of galaxies by Vorotsov-Velyaminov et al. (1962, 1963, 1964, 1968, 1974, Cats. <VII/62>, <VII/100>) with numbers from VV853 to VV2014. The classification of interacting galaxies is given in accord with the suggestion s of Vorotsov-Velyaminov. The catalogue contains new information for the galaxies included taken from the NEDA-NASA/IPAC extragalactic data base.
- ID:
- ivo://CDS.VizieR/I/323
- Title:
- International Celestial Reference Frame 2, ICRF2
- Short Name:
- I/323
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This Technical Note describes the generation by an international team of the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of Very Long Baseline Interferometry (VLBI) observations. ICRF2 contains precise positions of 3414 compact radio astronomical sources, more than five times the number as in the first ICRF, hereafter ICRF1. Further, the ICRF2 is found to have a noise floor of only 40{mu}as, some 5-6 times better than ICRF1, and an axis stability of 10{mu}as, nearly twice as stable as ICRF1. Alignment of ICRF2 with the International Celestial Reference System (ICRS) was made using 138 stable sources common to both ICRF2 and ICRF1-Ext2. Future maintenance of ICRF2 will be made using a set of 295 new "defining" sources selected on the basis of positional stability and the lack of extensive intrinsic source structure. The stability of these 295 defining sources, and their more uniform sky distribution eliminates the two largest weaknesses of ICRF1.
- ID:
- ivo://CDS.VizieR/J/A+A/594/A63
- Title:
- International Deep Planet Survey results
- Short Name:
- J/A+A/594/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity and transit methods are effective for the study of short orbital period exoplanets but they hardly probe objects at large separations for which direct imaging can be used. We carried out the international deep planet survey of 292 young nearby stars to search for giant exoplanets and determine their frequency. We developed a pipeline for a uniform processing of all the data that we have recorded with NIRC2/KeckII, NIRI/Gemini North, NICI/Gemini South, NACO/VLT for 14 years. The pipeline first applies cosmetic corrections and then reduces the speckle intensity to enhance the contrast in the images. The main result of the international deep planet survey is the discovery of the HR 8799 exoplanets. We also detected 59 visual multiple systems including 16 new binary stars and 2 new triple stellar systems, as well as 2279 point-like sources. We used Monte-Carlo simulations and the Bayesian' theorem to determine that 1.05% (+2.80% and -0.70%) of stars harbor at least one giant planet between 0.5 and 14M_{Jup}_, and between 20 and 300AU. This result is obtained assuming uniform distributions of planet masses and semi-major axes. If we consider power law distributions as measured for close-in planets instead, the derived frequency is 2.30% (+5.95% and -1.55%), reminding the strong impact of assumptions on Monte-Carlo output distributions. We also find no evidence that the derived frequency depends on the mass of the hosting star whereas it does for close-in planets. The international deep planet survey provides a database of confirmed background sources that may be useful for other exoplanet direct imaging surveys. It also puts new constraints on the number of stars with at least one giant planet reducing by a factor of two the frequencies derived by almost all previous works.
- ID:
- ivo://CDS.VizieR/J/AJ/105/427
- Title:
- IRAS fluxes of UCM galaxies
- Short Name:
- J/AJ/105/427
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of IRAS observations of the UCM (Universidad Complutense de Madrid) sample of emission-line galaxies, which have been selected from wide-dispersion H{alpha} objective-prism plates. These data are intended to provide a convenient summary of the relevant far-infrared (FIR) properties of these galaxies. Color-color diagrams, as interpreted by theoretical models, suggest that emission from UCM galaxies is mainly due to dust heated directly by photons emitted in active star-forming regions. Statistical analysis of some samples, including the IRAS minisurvey and blue selected objective-prism samples, have been performed. Comparisons, based on FIR luminosity distributions, with the IRAS minisurvey make evident the lower metallicity of the UCM galaxies which cannot be considered as a parent population of IRAS-detected galaxies. The FIR luminosity distributions of different samples have been compared using nonparametric methods and the best correlation has been found for the UCM and Wasilewski samples. Finally, a more detailed analysis of a UCM subsample has been performed from a three component model in order to get information concerning the fractional contribution of disk, star formation activity, and nonthermal mechanisms operating in the UCM galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A110
- Title:
- Isolated galaxies, pairs and triplets
- Short Name:
- J/A+A/578/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The construction of catalogues of galaxies and the posterior study of galaxy properties in relation to their environment, have been hampered by the scarce redshift information. The new 3-dimensional (3D) surveys permit to distinguish small, faint, physically bound satellites from a background projected galaxy population, giving a more comprehensive 3D picture of the surroundings. We aim to provide representative samples of isolated galaxies, isolated pairs, and isolated triplets for testing galaxy evolution and secular processes in low density regions of the local Universe, as well as to characterise their local and large-scale environments. We use spectroscopic data from the tenth data release of the Sloan Digital Sky Survey (SDSS-DR10) to automatically and homogeneously compile catalogues of 3,702 isolated galaxies, 1,240 isolated pairs, and 315 isolated triplets in the local Universe (z<=0.080). To quantify the effects of their local and large-scale environments, we compute the projected density and the tidal strength for the brightest galaxy in each sample. We find evidence of isolated pairs and isolated triplets physically bound at projected separation up to d<=450kpc with radial velocity difference {Delta}v<=160km/s, where the effect of the companion typically accounts for more than 98% of the total tidal strength affecting the central galaxy. For galaxies in the catalogues, we provide their positions, redshifts, and degrees of relation with their physical and large-scale environments. The catalogues are publicly available to the scientific community. For isolated galaxies, isolated pairs, and isolated triplets there is no difference in their degree of interaction with the large-scale structure (up to 5Mpc), which may suggest that they have a common origin in their formation and evolution. We find that most of them belong to the outer parts of filaments, walls, and clusters, and generally differ from the void population of galaxies.
- ID:
- ivo://CDS.VizieR/J/other/AstBu/73.310
- Title:
- Isolated galaxy pair limited to M<=-18.5
- Short Name:
- J/other/AstBu/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present paper is devoted to the construction of a catalog of isolated galaxy pairs extracted from the HyperLEDA extragalactic database. The radial velocities of the galaxies in the pairs are in the range [3000, 16000]km/s. In order to get an unbiased pair catalog as complete as possible, we have limited the absolute magnitude of the galaxies to M<=-18.5). The criteria used to define the isolated galaxy pairs are the following: 1) Velocity criterion: radial velocity difference between the pair members {Delta}V<500km/s; 2) Interdistance criterion: projected distance between the members r_p_<1Mpc; 3) Reciprocity criterion: each member is the closest galaxy to the other one, which excludes multiplets; 4) Isolation criterion: we define a pair as isolated if the ratio {rho}=r_3_/r_p_ of the projected distance of the pair to its closest galaxy (this one having a velocity difference lower than 500km/s with respect to the pair) and the members projected interdistance r_p is larger than 2.5. We have searched for these closest galaxies first in HyperLEDA M-limited source catalog, then in the full one. We have managed not to suppress the small number of pairs having close-by but faint dwarf galaxy companions. The galaxy pair catalog lists the value of {rho} for each isolated pair. This method allows the user of the catalog to select any isolation level (beyond the chosen limit {rho}>2.5). Our final catalog contains 13114 galaxy pairs, of which 57% are fairly isolated with {rho}>5, and 30% are highly isolated with {rho}>=10.
- ID:
- ivo://CDS.VizieR/VII/77
- Title:
- Isolated Pairs of Galaxies in Northern Hemisphere
- Short Name:
- VII/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is a compilation of observational data for 603 isolated pairs of galaxies with component magnitudes brighter than 15.7 and north of declination -3 degrees. The catalog includes pair numbers and component letters, coordinates, apparent magnitudes, radial velocities, major axes and eccentricities, Hubble classifications, spectral types, and distances between components.
- ID:
- ivo://CDS.VizieR/VII/83
- Title:
- Isolated Triplets of galaxies
- Short Name:
- VII/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The complete data for radial velocities of components of triple galaxies are presented. The main part of observations was accomplished with the 6-meter telescope.
