- ID:
- ivo://CDS.VizieR/J/ApJ/745/74
- Title:
- Pre-maximum spectra of type Ia SNe
- Short Name:
- J/ApJ/745/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The presence of unburned material in the ejecta of normal Type Ia supernovae (SNe Ia) is investigated using early-time spectroscopy obtained by the Carnegie Supernova Project. The tell-tale signature of pristine material from a C+O white dwarf progenitor star is the presence of carbon, as oxygen is also a product of carbon burning. The most prominent carbon lines in optical spectra of SNe Ia are expected to arise from CII. We find that at least 30% of the objects in the sample show an absorption at {approx}6300{AA} which is attributed to CII{lambda}6580. An alternative identification of this absorption as H{alpha} is considered to be unlikely. These findings imply a larger incidence of carbon in SNe Ia ejecta than previously noted.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/216/33
- Title:
- Probing the Local Bubble with DIBs. III.
- Short Name:
- J/ApJS/216/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new high signal-to-noise ratio (S/N) observations of the diffuse interstellar bands (DIBs) in the Local Bubble and its surroundings. We observed 432 sightlines and obtain the equivalent widths of the {lambda}5780 and {lambda}5797{AA} DIBs up to a distance of ~200pc. All of the observations were carried out using the Intermediate Dispersion Spectrograph on the 2.5m Isaac Newton Telescope, during three years, to reach a minimum S/N of ~2000. All of the {lambda}5780 and {lambda}5797 absorptions are presented in this paper and we tabulate the observed values of the interstellar parameters, {lambda}5780, {lambda}5797, Na ID_1_, and Na ID_2_, including the uncertainties.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/3163
- Title:
- Properties of BAL quasars
- Short Name:
- J/MNRAS/469/3163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate broad absorption line (BAL) disappearance and emergence using a 470 BAL-quasar sample over <=0.10-5.25 rest-frame years with at least three spectroscopic epochs for each quasar from the Sloan Digital Sky Survey. We identify 14 disappearing BALs over <=1.73-4.62 rest-frame years and 18 emerging BALs over <=1.46-3.66 rest-frame years associated with the CIV{lambda}{lambda}1548,1550 and/or SiIV{lambda}{lambda}1393,1402 doublets, and report on their variability behaviour. BAL quasars in our data set exhibit disappearing/emerging C IV BALs at a rate of 2.3^+0.9^_-0.7_ and 3.0^+1.0^_-0.8_ per cent, respectively, and the frequency for BAL to non-BAL quasar transitions is 1.7^+0.8^_-0.6_ per cent. We detect four re-emerging BALs over <=3.88 rest-frame years on average and three re-disappearing BALs over <=4.15 rest-frame years on average, the first reported cases of these types. We infer BAL lifetimes along the line of sight to be nominally <=100-1000yr using disappearing CIV BALs in our sample. Interpretations of (re-)emerging and (re-)disappearing BALs reveal evidence that collectively supports both transverse-motion and ionization-change scenarios to explain BAL variations. We constrain a nominal CIV/SiIV BAL-outflow location of <=100pc from the central source and a radial size of >=1x10^-7^pc (0.02au) using the ionization-change scenario, and constrain a nominal outflow location of <=0.5pc and a transverse size of ~0.01pc using the transverse-motion scenario. Our findings are consistent with previous work, and provide evidence in support of BALs tracing compact flow geometries with small filling factors.
- ID:
- ivo://CDS.VizieR/J/A+A/547/A80
- Title:
- Properties of Collinder 69 low-mass members
- Short Name:
- J/A+A/547/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most observational studies conducted so far point toward brown dwarfs sharing a similar formation mechanism as the one that is accepted for low-mass stars. However, larger databases and more systematic studies are needed before strong conclusions can be reached. In this second paper of a series devoted to studying the spectroscopic properties of the Lambda Orionis star-forming region members, we study accretion, activity and rotation for a wide set of spectroscopically confirmed members of the central star cluster Collinder 69 to assess analogies and/or differences between the brown-dwarf and stellar populations of this cluster. Moreover, we present comparisons with other star-forming regions of similar and different ages to address environmental effects on our conclusions. We studied prominent photospheric lines to derive rotational velocities and emission lines to distinguish between accretion processes and chromospheric activity. In addition, we include information about disk presence and X-ray emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/817/79
- Title:
- Properties of emission-line galaxies
- Short Name:
- J/ApJ/817/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the physical and morphological properties of z~2 Ly{alpha} emitting galaxies (LAEs) identified in the HETDEX Pilot Survey and narrow band studies with those of z~2 optical emission line selected galaxies (oELGs) identified via HST WFC3 infrared grism spectroscopy. Both sets of galaxies extend over the same range in stellar mass (7.5<logM/M_{sun}_<10.5), size (0.5<R<3.0kpc), and star formation rate (~1<SFR<100M_{sun}_/yr). Remarkably, a comparison of the most commonly used physical and morphological parameters - stellar mass, half-light radius, UV slope, SFR, ellipticity, nearest neighbor distance, star formation surface density, specific SFR, [OIII] luminosity, and [OIII] equivalent width - reveals no statistically significant differences between the populations.
- ID:
- ivo://CDS.VizieR/J/PASJ/59/335
- Title:
- Properties of 160 F-K disk dwarfs/subgiants
- Short Name:
- J/PASJ/59/335
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The properties of 160 F, G, and K disk dwarfs/subgiants (including 27 planet-host stars) mostly within -0.6<~[Fe/H]<~+0.4, the Okayama Astrophysical Observatory spectrum collection of which had been made open to the public recently, were extensively investigated with particular attention to determining (1) the mass and the age with the help of theoretical stellar evolution calculations, (2) the kinematic parameters of orbital motions in the Galaxy, and (3) the abundances of 15 elements (Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, and Zn) by analyzing the spectra in this database. The resulting characteristics are discussed in terms of several relevant topics of interest, such as a validity check for assuming LTE, the [X/Fe] vs. [Fe/H] diagram containing information on the chemical evolution of the Galactic disk, the age-metallicity-kinematics relation, and the difference/similarity between stars with and without planets.
- ID:
- ivo://CDS.VizieR/J/ApJS/122/355
- Title:
- Properties of low z QSO absorption systems
- Short Name:
- J/ApJS/122/355
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (Partial): We examine the clustering properties of low-redshift Ly{alpha} and heavy-element QSO absorption line systems seen in the spectra of 13 QSOs at the Galactic poles. This is the densest sample of ~1 degree separated QSOs observed spectroscopically with the Hubble Space Telescope to date. At the median redshift of the Ly{alpha} sample (z{=~}0.7), the QSO lines of sight are separated on transverse scales from about 15 to 200h^-1^Mpc (q_0_=0.5, H=100h.km/s/Mpc), allowing the three-dimensional clustering of the absorbers to be examined on those scales. The Galactic poles are also regions where relatively deep and wide-field galaxy redshift surveys have taken place, so the distributions of galaxies and Ly{alpha} systems can be compared within the same volume of space. There are 545 total absorption lines detected in the complete sample from 13 QSOs. We identify 307 Ly{alpha} systems, of which 18 contain heavy-element lines. We confirm the relatively slow redshift number density evolution for Ly systems at z{<=}1. There are also five likely C IV doublets in our sample, for which the Ly{alpha} line is not accessible.
- ID:
- ivo://CDS.VizieR/J/MNRAS/427/1135
- Title:
- Properties of radio-loud BAL quasars
- Short Name:
- J/MNRAS/427/1135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We recently presented radio observations of a large sample of radio-loud broad absorption line (BAL) quasars from the Sloan Digital Sky Survey (SDSS) and Faint Images of the Radio Sky at Twenty-cm surveys, as well as a well matched sample of unabsorbed quasars, primarily to measure their radio spectral indices and estimate ensemble orientations. Here, we analyse the SDSS spectra of these samples and compare the rest-frame ultraviolet properties of radio-loud BAL and non-BAL quasars. Ultraviolet properties include the continuum shape, emission-line measurements of CIV, AlIII, CIII], FeII and MgII, and BAL properties including the balnicity index, absorption index and minimum and maximum outflow velocities. We find that radio-loud BAL quasars have similar ultraviolet properties compared to radio-loud non-BAL sources, though they do appear to have redder continua and stronger FeII emission, which is consistent with what is found for radio-quiet BAL sources. No correlations exist between outflow properties and orientation (radio spectral index), suggesting that BAL winds along any line of sight are driven by the same mechanisms. There are also few correlations between spectral index and other properties. We conclude that BAL outflows occur along all lines of sight with similar strengths and velocities.
- ID:
- ivo://CDS.VizieR/J/other/Sci/345.791
- Title:
- Pseudo-3D maps of DIB at 862nm
- Short Name:
- J/other/Sci/345.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The diffuse interstellar bands (DIBs) are absorption lines observed in visual and near-infrared spectra of stars. Understanding their origin in the interstellar medium is one of the oldest problems in astronomical spectroscopy, as DIBs have been known since 1922. In a completely new approach to understanding DIBs, we combined information from nearly 500,000 stellar spectra obtained by the massive spectroscopic survey RAVE (Radial Velocity Experiment) to produce the first pseudo-three-dimensional map of the strength of the DIB at 8620 angstroms covering the nearest 3 kiloparsecs from the Sun, and show that it follows our independently constructed spatial distribution of extinction by interstellar dust along the Galactic plane. Despite having a similar distribution in the Galactic plane, the DIB 8620 carrier has a significantly larger vertical scale height than the dust. Even if one DIB may not represent the general DIB population, our observations outline the future direction of DIB research.
- ID:
- ivo://CDS.VizieR/J/ApJ/776/136
- Title:
- QPQ VI. HI absorption of z~2 quasars
- Short Name:
- J/ApJ/776/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We use a sample of 650 projected quasar pairs to study the HI Ly{alpha} absorption transverse to luminous, z~2 quasars at proper separations of 30kpc<R_{perp}_<1Mpc. In contrast to measurements along the line-of-sight, regions transverse to quasars exhibit enhanced HI Ly{alpha} absorption and a larger variance than the ambient intergalactic medium, with increasing absorption and variance toward smaller scales. Analysis of composite spectra reveals excess absorption characterized by a Ly{alpha} equivalent width profile W=2.3{AA} (R_{perp}_/100kpc)^-0.46^. We also observe a high (=~60%) covering factor of strong, optically thick HI absorbers (HI column N_HI_>10^17.3^/cm2) at separations R_{perp}_<200kpc, which decreases to ~20% at R_{perp}_=~1Mpc, but still represents a significant excess over the cosmic average. This excess of optically thick absorption can be described by a quasar-absorber cross-correlation function {xi}_QA_(r)=(r/r_0_)^{gamma}^ with a large correlation length r_0_=12.5_-1.4_^+2.7^h^-1^Mpc (comoving) and {gamma}=1.68_-0.30_^+0.14^. The HI absorption measured around quasars exceeds that of any previously studied population, consistent with quasars being hosted by massive dark matter halos M_halo_{approx}10^12.5^M_{sun}_ at z~2.5. The environments of these massive halos are highly biased toward producing optically thick gas, and may even dominate the cosmic abundance of Lyman limit systems and hence the intergalactic opacity to ionizing photons at z~2.5. The anisotropic absorption around quasars implies the transverse direction is much less likely to be illuminated by ionizing radiation than the line-of-sight.
