- ID:
- ivo://CDS.VizieR/J/MNRAS/463/1332
- Title:
- Anomalous RRd stars in Magellanic Clouds
- Short Name:
- J/MNRAS/463/1332
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a new subclass of double-mode RR Lyrae stars in the Large and Small Magellanic Clouds. The sample of 22 pulsating stars has been extracted from the latest edition of the Optical Gravitational Lensing Experiment collection of RR Lyrae variables in the Magellanic System. The stars pulsating simultaneously in the fundamental (F) and first-overtone (1O) modes have distinctly different properties than regular double-mode RR Lyrae variables (RRd stars). The P_1O_/P_F_ period ratios of our anomalous RRd stars are within a range of 0.725-0.738, while 'classical' double-mode RR Lyrae variables have period ratios in the range of 0.742-0.748. In contrast to the typical RRd stars, in the majority of the anomalous pulsators, the F-mode amplitudes are higher than the 1O-mode amplitudes. The light curves associated with the F-mode in the anomalous RRd stars show different morphology than the light curves of, both, regular RRd stars and single-mode RRab stars. Most of the anomalous double-mode stars show long-term modulations of the amplitudes (Blazhko-like effect). Translating the period ratios into the abundance parameter, Z, we find for our stars Z{in}(0.002, 0.005) - an order of magnitude higher values than typical for RR Lyrae stars. The mass range of the RRd stars inferred from the W_I_ versus P_F_ diagram is (0.55-0.75)M_{sun}_. These parameters cannot be accounted for with single star evolution assuming a Reimers-like mass-loss. Much greater mass-loss caused by interaction with other stars is postulated. We blame the peculiar pulsation properties of our stars to the parametric resonance instability of the 1O-mode to excitation of the F- and 2O-modes as with the inferred parameters of the stars 2{omega}_1O_~={omega}_F_+{omega}_2O_.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/3883
- Title:
- A non-parametric method for galaxy morphology
- Short Name:
- J/MNRAS/437/3883
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a non-parametric cell-based method of selecting highly pure and largely complete samples of spiral galaxies using photometric and structural parameters as provided by standard photometric pipelines and simple shape fitting algorithms. The performance of the method is quantified for different parameter combinations, using purely human-based classifications as a benchmark. The discretization of the parameter space allows a markedly superior selection than commonly used proxies relying on a fixed curve or surface of separation. Moreover, we find structural parameters derived using passbands longwards of the g band and linked to older stellar populations, especially the stellar mass surface density mu_*_ and the r band effective radius r_e_, to perform at least equally well as parameters more traditionally linked to the identification of spirals by means of their young stellar populations, e.g. UV/optical colours. In particular the distinct bimodality in the parameter mu_*_, consistent with expectations of different evolutionary paths for spirals and ellipticals, represents an often overlooked yet powerful parameter in differentiating between spiral and non-spiral/elliptical galaxies. We use the cell-based method for the optical parameter set including r_e_ in combination with the Sersic index n and the i-band magnitude to investigate the intrinsic specific star-formation rate - stellar mass relation ({psi}_*_-M_*_) for a morphologically defined volume limited sample of local universe spiral galaxies. The relation is found to be well described by {psi}_*_{propto}M_*_^-0.5^ over the range of 10^9.5^M_{sun}_<=M_*_<=10^11^M_{sun}_ with a mean interquartile range of 0.4dex. This is somewhat steeper than previous determinations based on colour-selected samples of star-forming galaxies, primarily due to the inclusion in the sample of red quiescent disks.
- ID:
- ivo://CDS.VizieR/VIII/3
- Title:
- An Optical Catalogue of Radio Galaxies
- Short Name:
- VIII/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains basic optical information on all known radio galaxies (with L[radio] greater than about 10**[41] ergs/s) that had been identified as of 1979 and for which measured redshifts were available. The data include the right ascension and declination (1950); galaxy (optical) type; visual magnitude; photoelectric colors; redshift (z) and the spectral lines on which the redshift measurements were based; coordinate designations; radio flux and frequency; radio spectral index; other names; and the references for the galaxy identification, photometric data, redshift, radio flux, radio spectral index, and radio map number. Note that the ADC version of this catalog differs somewhat from the original printed catalog in that some fields were added or modified and other fields reordered. In addition to the catalog data file itself, two additional files containing the list of references for the catalog are also available. The first reference list is in alphabetical order, and the second is in numerical order.
- ID:
- ivo://CDS.VizieR/J/AJ/161/196
- Title:
- An optical overview of blazars with LAMOST. I.
- Short Name:
- J/AJ/161/196
- Date:
- 16 Mar 2022 11:51:00
- Publisher:
- CDS
- Description:
- The extragalactic {gamma}-rays sky observed by the Fermi Large Area Telescope (LAT) is dominated by blazars. In the fourth release of the Fermi LAT Point Source Catalog (4FGL) are sources showing a multifrequency behavior similar to that of blazars but lacking an optical spectroscopic confirmation of their nature, known as blazar candidates of uncertain type (BCUs). We aim at confirming the blazar nature of BCUs and test if new optical spectroscopic observations can reveal spectral features, allowing us to get a redshift estimate for known BL Lac objects. We also aim to search for and discover changing-look blazars (i.e., blazars that show a different classification at different epochs). We carry out an extensive search for optical spectra available in the Large Sky Area Multi-object Fibre Spectroscopic Telescope (LAMOST) Data Release 5 (DR5) archive. We select sources out of the 4FGL catalog, the list of targets from our follow-up spectroscopic campaign of unidentified or unassociated {gamma}-ray sources, and the multifrequency catalog of blazars: the Roma-BZCAT. We select a total of 392 spectra. We also compare some of the LAMOST spectra with those available in the literature. We classify 20 BCUs confirming their blazar-like nature. Then we obtain 15 new redshift estimates for known blazars. We discover 26 transitional (i.e., changing-look) blazars that changed their classification. Finally, we are able to confirm the blazar-like nature of six BL Lac candidates. All remaining sources analyzed agree with previous classifications. BL Lac objects are certainly the most elusive type of blazars in the {gamma}-ray extragalactic sky.
- ID:
- ivo://CDS.VizieR/II/97
- Title:
- ANS UV Catalogue of Point Sources
- Short Name:
- II/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog is a result of the observations made with the Astronomical Netherlands Satellite (ANS) which operated between October 1974 and April 1976. The ANS satellite observed in five UV channels centered around 150, 180, 220, 250 and 330nm. The photometric bands are: -------------------------------------------------------------------------- Band designation 15N 15W 18 22 25 33 -------------------------------------------------------------------------- Central wavelength (nm) 154.5 154.9 179.9 220.0 249.3 329.4 Bandwidth (nm) 5.0 14.9 14.9 20.0 15.0 10.1 -------------------------------------------------------------------------- The reported magnitudes were obtained from mean count rates converted to fluxes using the ANS absolute calibration of Wesselius et al. (1980A&A....85..221W). In addition to the ultraviolet magnitudes, the catalog contains positions taken from the satellite pointing, spectral types, and UBV data from other sources as well as comments on duplicity, variability, and miscellaneous notes concerning individual objects.
- ID:
- ivo://CDS.VizieR/J/AZh/84/695
- Title:
- An SX Phoenicis Variable light curve
- Short Name:
- J/AZh/84/695
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present investigation of V=17mag star, which appears to be SX Phe type variable. Observations at 1.8 and 1.0 meter telescopes of Boyhunsan and Mount Lemon observatories permit us to improve the light elements and to investigate the power spectrum. We applied a Fourier decomposition to the data in order to determine the component frequencies of the synthetic light curve, and five components including a pair of closely separated components of f_1_=24.6539 and f_2_=24.8173 c/d were identified. We proposed that one of these two components corresponds to a non-radial oscillation mode. Other observed frequencies are the combinations of the first two. Metallicity of the star was estimated to be [Fe/H]<-2. We also found that one of the faint variable stars, No. 14, in the field is RRc type pulsator.
- ID:
- ivo://CDS.VizieR/J/AJ/140/75
- Title:
- Antennae galaxies (NGC 4038/4039) revisited
- Short Name:
- J/AJ/140/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Advanced Camera for Surveys and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) have been used to obtain new Hubble Space Telescope images of NGC 4038/4039 ("The Antennae"). These new observations allow us to better differentiate compact star clusters from individual stars, based on both size and color.
- ID:
- ivo://CDS.VizieR/J/other/PhRvD/103.H3016
- Title:
- Antimatter sources E flux sensitivity
- Short Name:
- J/other/PhRvD/10
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- It is generally taken for granted that our Universe is free of antimatter objects and domains. This certitude has recently been challenged by the possible detection of anti-helium nuclei by AMS-02. Should the observation be confirmed, the existence of nearby antistars would make a plausible hypothesis to explain the origin of the antinuclei. In this paper we use the 10-years F Large Area Telescope (LAT) gamma-ray source catalog to set constraints on the abundance of antistars around the Sun. We identify in the catalog 14 antistar candidates not associated with any objects belonging to established gamma-ray source classes and with a spectrum compatible with baryon-antibaryon annihilation. We use them along with an estimate of the LAT sensitivity to antistars to set upper limits on the local antistar fraction f_bar*_ with respect to normal stars. We provide parametric limits as a function of the closest antistar mass, velocity, and surrounding matter density. We also employ a novel Monte~Carlo method to set limits for a few hypotheses about the antistar population. For a population with properties equivalent to those of regular stars concentrated in the Galactic disk we obtain f_bar*_<2.5x10^-6^ at 95% confidence level, which is 20 times more constraining than limits previously available. For a primordial population of antistars distributed in the Galactic halo we obtain new local upper limits which decrease as a function of antistar mass M from f_bar*_<0.2 at 95% confidence level for M=1M_{sun}_ to f_bar*_<1.6x10^-4^ at 95% confidence level for M=10M_{sun}_. By combining these limits with existing microlensing constraints for lighter objects in the Magellanic clouds, we infer that a primordial population of halo antistars must have a density lower than O (10^-5^pc^-3^) to O (10^-2^pc^-3^) depending on their masses. Our limits can constrain models for the origin and propagation of antinuclei in cosmic rays.
- ID:
- ivo://CDS.VizieR/J/MNRAS/477/1760
- Title:
- Antlia galaxies geometric parameters
- Short Name:
- J/MNRAS/477/1760
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a statistical isophotal analysis of 138 early-type galaxies in the Antlia cluster, located at a distance of ~35Mpc. The observational material consists of CCD images of four 36x36arcmin^2^ fields obtained with the MOSAIC II camera at the Blanco 4-m telescope at Cerro Tololo Interamerican Observatory. Our present work supersedes previous Antlia studies in the sense that the covered area is four times larger, the limiting magnitude is M_B_~-9.6mag, and the surface photometry parameters of each galaxy are derived from Sersic model fits extrapolated to infinity. In a companion previous study we focused on the scaling relations obtained by means of surface photometry, and now we present the data, on which the previous paper is based, the parameters of the isophotal fits as well as an isophotal analysis. For each galaxy, we derive isophotal shape parameters along the semimajor axis and search for correlations within different radial bins. Through extensive statistical tests, we also analyse the behaviour of these values against photometric and global parameters of the galaxies themselves. While some galaxies do display radial gradients in their ellipticity ({epsilon}) and/or their Fourier coefficients, differences in mean values between adjacent regions are not statistically significant. Regarding Fourier coefficients, dwarf galaxies usually display gradients between all adjacent regions, while non-dwarfs tend to show this behaviour just between the two outermost regions. Globally, there is no obvious correlation between Fourier coefficients and luminosity for the whole magnitude range (-12>=M_V_>=-22); however, dwarfs display much higher dispersions at all radii.
- ID:
- ivo://CDS.VizieR/III/157
- Title:
- An Ultraviolet Atlas of Quasar and Blazar Spectra
- Short Name:
- III/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This atlas contains the ultraviolet spectra of 70 quasars, blazars, and Seyfert 1 galaxies that were produced by combining over 100 low resolution spectra from the International Ultraviolet Explorer (IUE) data archive. The spectra have been extracted with an optimal algorithm (see Kinney et al. 1991) and co-added to produce spectra with the best possible signal-to-noise ratio.
