- ID:
- ivo://CDS.VizieR/J/MNRAS/444/2456
- Title:
- Spectral galaxy pairs from SDSS DR9
- Short Name:
- J/MNRAS/444/2456
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectral galaxy pairs (hereafter as SGPs) are composite galaxy spectra that contain two independent redshift systems. These spectra are useful for studying the dust properties of the foreground galaxies. In this article, a total of 165 spectra of SGPs are mined from the Sloan Digital Sky Survey (SDSS) Data Release 9 (DR9) using the concept of 'membership degree' from fuzzy set theory, especially defined to be suitable for fuzzy identification of emission lines. The spectra and images of this sample are classified according to their membership degree and image features, respectively. Many of the second redshift systems are too small or too dim to select from SDSS images alone, making the sample a potentially unique source of information on dust effects in low-luminosity or low surface brightness galaxies, which are underrepresented in morphological pair samples. The dust extinction of those objects with high membership degree is also estimated by Balmer decrement. Additionally, analyses for a series of spectroscopic observations of one SGP from 165 systems indicate that a newly star-forming region of our Milky Way might exist.
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- ID:
- ivo://CDS.VizieR/J/A+A/423/133
- Title:
- Spectral indexes in HII galaxies
- Short Name:
- J/A+A/423/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the stellar content of a large number of HII galaxies from the continua and absorption features of their spectra using population synthesis methods, in order to gain information about the star formation histories of these objects. We find that all galaxies of our sample contain an old stellar population (>=1Gyr) that dominates the stellar mass, and in a majority of these we also found evidence for an intermediate-age population >=50Myr apart from the presently bursting, ionizing young generation <=10^7^yr.
- ID:
- ivo://CDS.VizieR/J/A+AS/82/41
- Title:
- Spectral index for B3 radio sources
- Short Name:
- J/A+AS/82/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Flux density measurements at 4730MHz are presented for a sample of 770 radio sources from the B3 catalogue with density S408>0.35Jy. For 429 of these sources flux density measurements at 1410MHz are also presented. The radio spectral indices derived are used to investigate the dependence of median spectral index on flux density
- ID:
- ivo://CDS.VizieR/J/AJ/125/2502
- Title:
- Spectral indices of Galactic halo
- Short Name:
- J/AJ/125/2502
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our calibration of spectroscopic measures of luminosity and metallicity for halo giant candidates and give metallicities and distances for our first sample of spectroscopically confirmed giants. These giants have distances ranging from 15 to 83kpc. As surveys reach farther into the Galaxy's halo with K giant samples, identification of giants becomes more difficult. This is because the numbers of foreground halo K dwarfs rise for V magnitudes of 19-20, typical for halo giants at 100kpc. Our photometric survey uses the strength of the Mgb/H feature near 5170{AA} to weed K dwarfs out of the disk and thick disk, but we need spectroscopic measures of the strength of the Ca II K, Ca I {lambda}4227, and Mgb/H features to distinguish between the very metal-poor dwarfs and halo giants. Using a full error analysis of our spectroscopic measures, we show why a signal-to-noise ratio of ~15pixel^-1^ at Ca I {lambda}4227 and ~10 at Ca II K is needed for reliable luminosity discrimination. We use the Ca II K and Mgb features to measure metallicity in our halo giants, with typical errors (random plus systematic) of 0.3dex for [Fe/H] values from -0.8 to -3.0.
- ID:
- ivo://CDS.VizieR/J/AZh/71/200
- Title:
- Spectral Investigation of NGC 7469
- Short Name:
- J/AZh/71/200
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This investigation is mainly related to hydrogen lines in the spectrum of NGC 7469 from the 1972-1990 data obtained using an image tube on the 2.6-m telescope of the Crimean Astrophysical Observatory. The decomposition of the hydrogen lines into broad and narrow components was performed. Variations in the intensities and broad-component contours were observed. One third of the spectrograms showed a broad, symmetric Ha line, while the others showed asymmetry: the blue wings fall more steeply than the red ones. The degree of asymmetry is variable, but no correlation between it and the brightness of the nucleus was found. This asymmetry becomes weaker when passing to higher members of the Balmer series. The halfwidths of the broad components increase from Ha to H{gamma}. Redshifts of broad components with respect to narrow ones might also be larger for higher members of the Balmer series. Intensities of the broad hydrogen lines follow continuum variations with a delay of about 28 days. The Balmer decrement for broad lines is much flatter than for narrow ones.
- ID:
- ivo://CDS.VizieR/J/AJ/112/241
- Title:
- Spectral irradiance calibration. VI.
- Short Name:
- J/AJ/112/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present three new absolutely calibrated continuous stellar spectra from 3 to 35um, constructed as far as possible from actual observed spectral fragments taken from the Kuiper Airborne Observatory (KAO), and the IRAS Low Resolution Spectrometer (LRS). These stars - alpha1 Cen, alpha TrA, and epsilon Car - augment our previous archive of complete absolutely calibrated spectra for northern K and M giants. All these spectra have a common calibration pedigree. The wavelength coverage is ideal for calibration of many existing and proposed ground-based, airborne, and satellite sensors. KAO and IRAS data in the 15-30 um range suggest that the spectra of cool giants are close to Rayleigh-Jeans slopes. Our observations of alpha1 Cen, absolutely calibrated via our adopted Sirius model, indicate an angular diameter in very good agreement with values in the literature, demonstrating "closure" of the set of spectra within our absolute framework. We compare our observed alpha1 Cen spectrum with a published grid of theoretical models from Kurucz, and adopt a plausible theoretical shape, that fits our spectrum, as a secondary reference spectrum in the southern sky.
- ID:
- ivo://CDS.VizieR/J/AJ/112/2274
- Title:
- Spectral irradiance calibration. VII.
- Short Name:
- J/AJ/112/2274
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present five new absolutely calibrated continuous stellar spectra constructed as far as possible from spectral fragments observed from the ground, the Kuiper Airborne Observatory (KAO), and the IRAS Low Resolution Spectrometer. These stars, alpha Boo, gamma Dra, alpha Cet, gamma Cru, and mu UMa, augment our six, published, absolutely calibrated spectra of K and early-M giants. All spectra have a common calibration pedigree. A revised composite for alpha Boo has been constructed from higher quality spectral fragments than our previously published one. The spectrum of gamma Dra was created in direct response to the needs of instruments aboard the Infrared Space Observatory (ISO); this star's location near the north ecliptic pole renders it highly visible throughout the mission. We compare all our low-resolution composite spectra with Kurucz model atmospheres and find good agreement in shape, with the obvious exception of the SiO fundamental, still lacking in current grids of model atmospheres. The CO fundamental seems slightly too deep in these models, but this could reflect our use of generic models with solar metal abundances rather than models specific to the metallicities of the individual stars. Angular diameters derived from these spectra and models are in excellent agreement with the best observed diameters. The ratio of our adopted Sirius and Vega models is vindicated by spectral observations. We compare IRAS fluxes predicted from our cool stellar spectra with those observed and conclude that, as 12 and 25um, flux densities measured by IRAS should be revised downwards by about 4.1% to 5.7%, respectively, for consistency with our absolute calibration. We have provided extrapolated continuum versions of these spectra to 300um, in direct support of ISO (PHT and LWS instruments). These spectra are consistent with IRAS flux densities at 60 and 100um.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/44
- Title:
- Spectral lags and counts of the RHESSI GRBs
- Short Name:
- J/ApJ/756/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 427 gamma-ray bursts (GRBs) from a database (2002 February-2008 April) of the RHESSI satellite is analyzed statistically. The spectral lags and peak-count rates, which have been calculated for the first time in this paper, are studied, completing an earlier analysis of durations and hardness ratios. The analysis of the RHESSI database has already inferred the existence of a third group with intermediate duration, apart from the so-called short and long groups. The first aim of this article is to discuss the properties of these intermediate-duration bursts in terms of peak-count rates and spectral lags. The second aim is to discuss the number of GRB groups using another statistical method and by also employing the peak-count rates and spectral lags. The standard parametric (model-based clustering) and non-parametric (K-means clustering) statistical tests together with the Kolmogorov-Smirnov and Anderson-Darling tests are used. Two new results are obtained. (1) The intermediate-duration group has properties similar to those of the group of short bursts. Intermediate and long groups appear to be different. (2) The intermediate-duration GRBs in the RHESSI and Swift databases seem to be represented by different phenomena.
- ID:
- ivo://CDS.VizieR/III/219
- Title:
- Spectral Library of Galaxies, Clusters and Stars
- Short Name:
- III/219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is a compilation of spectra collected along the years at ESO, OHP, CFHT and CASLEO in the near-ultraviolet, optical and near-infrared ranges, complemented by IUE observations. Aiming at population synthesis techniques, average template spectra were built from weighted sums of individual spectra of star clusters taking into account their spectral similarities, ages and metallicities. Morphological types and spectral types, beyond spectral similarities, were considered respectively for galaxy and star template building. Both template and individual spectra are included in the library, which contains spectra for 243 galaxies, 190 clusters and 72 stars, amounting 868 spectra in the various spectral ranges.
- ID:
- ivo://CDS.VizieR/J/other/AstBu/65.150
- Title:
- Spectral line identification in 3 Pup
- Short Name:
- J/other/AstBu/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical spectra taken in 1997-2008 are used to analyze the spectral peculiarities and velocity field in the atmosphere of the peculiar supergiant 3 Pup.