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2971. Ultraviolet P Cygni profiles
ID:
ivo://CDS.VizieR/J/ApJS/95/163
Title:
Ultraviolet P Cygni profiles
Short Name:
J/ApJS/95/163
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have selected spectra of 232 stars from the IUE archives for inclusion in an atlas intended for various uses but tailored especially for the study of stellar winds. The atlas covers the range in spectral types from O3 to F8. The full atlas covers the reduced and normalized high resolution spectra from the IUE long- and short-wavelength spectrographs. Here we discuss the selection of the stars and the data reduction, and we present in velocity units the profiles of lines formed in the stellar winds. The selected lines cover a wide range of ionizations, allowing a comparison of the profiles from different ions in the wind of each star and a comparison of the different wind lines as a function of spectral type and luminosity. We also present the basic data on the program stars to facilitate study of the dependence of wind features on stellar parameters such as luminosity, temperature, escape velocity, and v sin i. We provide an overview of the characteristic behavior of the wind lines in the H-R diagram. The complete spectra are available in digital form through the NASA Astrophysics Data System (ADS). We offer a description of the electronic database that is available through the ADS and guidelines for obtaining access to that database.
2972. Ultraviolet Spectral Atlas of VV Cephei
ID:
ivo://CDS.VizieR/J/ApJS/171/249
Title:
Ultraviolet Spectral Atlas of VV Cephei
Short Name:
J/ApJS/171/249
Date:
21 Oct 2021
Publisher:
CDS
Description:
The first observations of the ultraviolet spectrum of the binary system VV Cep (M2Iab + B?) during total eclipse have been made with the HST. A rich emission-line spectrum is seen, with over two thousand emission features present. Shortward of 1600{AA}, a weak continuum presumably due to Rayleigh scattering of the hot component is present, strengthening markedly shortward of 1500{AA}. The continuum of the M supergiant becomes apparent longward of 2650{AA}. Numerous circumstellar and interstellar absorption features are also seen. We present an atlas of the spectrum from 1300-3160{AA} as observed near midtotality and at two epochs closer to egress, when gas surrounding the hot component has begun to emerge from eclipse and the flux on the short-wavelength edges of many emission lines has increased. This atlas has been annotated with line identifications. Circumstellar and interstellar absorption features seen out of eclipse remain in absorption during totality and are also annotated on the atlas. Well over 90% of the emission features have plausible identifications, but there are many blends. Only a few hundred features appear to be free enough from blending for useful measurement of the peak flux in the line. We present a list of these unblended features.
2973. Ultraviolet Spectrum of the Sun
ID:
ivo://CDS.VizieR/J/A+AS/113/237
Title:
Ultraviolet Spectrum of the Sun
Short Name:
J/A+AS/113/237
Date:
21 Oct 2021
Publisher:
CDS
Description:
An ultraviolet atlas of the solar spectrum with a spectral resolution of 15mA in the region 1948-2000A is presented. It is the first part of the spectra recorded on the quiet Sun between 1900 and 2130A. Measurements were performed from a balloon-borne instrumentation flown at an altitude of 39km. The wavelength atlas with a list of about 550 lines has been synthesized from data at center of the Sun ({mu}=1) and at {mu}=0.89, smoothed out over an area of 30 arcsec. The wavelength scale is given with respect to the average solar spectrum. Tracings are presented at {mu}=0.89, with an intensity scale adjusted in absolute values on the level of the continuum near 2000A.
2974. UMa Group
ID:
ivo://CDS.VizieR/J/AJ/105/226
Title:
UMa Group
Short Name:
J/AJ/105/226
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Ursa Major Group (UMaG) is studied as a test case for the authenticity of Stellar Kinematic Groups, using Coravel radial velocities, recent compilations of astrometric data and new spectroscopic observations. Spectroscopic age indicators, particularly indices of the strength of chromospheric emission, are applied to solar-type candidate members of UMaG, and it is shown that stars that meet the spectroscopic criteria also have kinematics that agree better with the space motions of the nucleus of UMaG than does the starting sample as a whole. The primary limitation on the precision of kinematics is now parallaxes instead of radial velocities. These more restrictive kinematic criteria are then applied to other UMaG candidates and a list summarizing membership is presented. UMaG is also examined as a cluster, confirming its traditional age of 0.3 Gyr and a mean [Fe/H] of -0.08 +/- 0.09 for those stars most likely to be bona fide members.
2975. 24um flux-limited sample of galaxies
ID:
ivo://CDS.VizieR/J/ApJ/693/370
Title:
24um flux-limited sample of galaxies
Short Name:
J/ApJ/693/370
Date:
21 Oct 2021
Publisher:
CDS
Description:
The mid-infrared spectroscopic analysis of a flux-limited sample of galaxies with f_{nu}_(24um)>10mJy is presented. Sources observed are taken from the Spitzer First Look Survey (FLS) catalog and from the NOAO Deep Wide-Field Survey region in Bootes (NDWFS). The spectroscopic sample includes 60 of the 100 sources in these combined catalogs having f_{nu}_(24um)>10 mJy. New spectra from the Spitzer Infrared Spectrograph are presented for 25 FLS sources and for 11 Bootes active galactic nuclei (AGNs); these are combined with 24 Bootes starburst galaxies previously published to determine the distribution of mid-infrared spectral characteristics for the total 10mJy sample. Sources have 0.01<z<2.4 and 41.8<log{nu}L_{nu}_(15um)<46.2(ergs/s).
2976. 8.1um SiO spectra of cool evolved stars
ID:
ivo://CDS.VizieR/J/A+A/561/A47
Title:
8.1um SiO spectra of cool evolved stars
Short Name:
J/A+A/561/A47
Date:
21 Oct 2021
Publisher:
CDS
Description:
The mass-loss mechanism in red giants and red supergiants is not yet understood well. The SiO fundamental lines near 8 m are potentially useful for probing the outer atmosphere, which is essential for clarifying the mass-loss mechanism. However, these lines have been little explored until now. We present high spectral resolution spectroscopic observations of the SiO fundamental lines near 8.1um in 16 bright red giants and red supergiants. Our sample consists of seven normal (i.e., non-Mira) K-M giants (from K1.5 to M6.5), three Mira stars, three optically bright red supergiants, two dusty red supergiants, and the enigmatic object GCIRS3 near the Galactic center.
2977. 0.8-2.5um spectra of 2 red quasars
ID:
ivo://CDS.VizieR/J/A+A/610/A31
Title:
0.8-2.5um spectra of 2 red quasars
Short Name:
J/A+A/610/A31
Date:
21 Oct 2021
Publisher:
CDS
Description:
Red quasars are very red in the optical through near-infrared (NIR) wavelengths, which is possibly due to dust extinction in their host galaxies as expected in a scenario in which red quasars are an intermediate population between merger-driven star-forming galaxies and unobscured type 1 quasars. However, alternative mechanisms also exist to explain their red colors: (i) an intrinsically red continuum; (ii) an unusual high covering factor of the hot dust component, that is, CF_HD_=L_HD_/L_bol_, where the L_HD_ is the luminosity from the hot dust component and the L_bol_ is the bolometric luminosity; and (iii) a moderate viewing angle. In order to investigate why red quasars are red, we studied optical and NIR spectra of 20 red quasars at z~0.3 and 0.7, where the usage of the NIR spectra allowed us to look into red quasar properties in ways that are little affected by dust extinction. The Paschen to Balmer line ratios were derived for 13 red quasars and the values were found to be ~10 times higher than unobscured type 1 quasars, suggesting a heavy dust extinction with A_V_>2.5mag. Furthermore, the Paschen to Balmer line ratios of red quasars are difficult to explain with plausible physical conditions without adopting the concept of the dust extinction. The CF_HD_ of red quasars are similar to, or marginally higher than, those of unobscured type 1 quasars. The Eddington ratios, computed for 19 out of 20 red quasars, are higher than those of unobscured type 1 quasars (by factors of 3-5), and hence the moderate viewing angle scenario is disfavored. Consequently, these results strongly suggest the dust extinction that is connected to an enhanced nuclear activity as the origin of the red color of red quasars, which is consistent with the merger-driven quasar evolution scenario.
2978. 1.1-2.4um spectra of 7 young M and L dwarfs
ID:
ivo://CDS.VizieR/J/A+A/564/A55
Title:
1.1-2.4um spectra of 7 young M and L dwarfs
Short Name:
J/A+A/564/A55
Date:
21 Oct 2021
Publisher:
CDS
Description:
Gravity modifies the spectral features of young brown dwarfs (BDs). A proper characterization of these objects is crucial for the identification of the least massive and latest-type objects in star-forming regions, and to explain the origin(s) of the peculiar spectrophotometric properties of young directly imaged extrasolar planets and BD companions. We obtained medium-resolution (R~1500-1700) near-infrared (1.1-2.5um) spectra of seven young M9.5-L3 dwarfs classified at optical wavelengths. We aim to empirically confirm the low surface gravity of the objects in the near-infrared. We also test whether self-consistent atmospheric models correctly represent the formation and the settling of dust clouds in the atmosphere of young late-M and L dwarfs. We used the Infrared Spectrometer And Array Camera (ISAAC) at the Very Large Telescope (VLT) to obtain the spectra of the targets. We compared the spectra to those of mature and young BDs, and to young late-type companions to nearby stars with known ages, to identify and study gravity-sensitive features. We computed spectral indices weakly sensitive to the surface gravity to derive near-infrared spectral types. Finally, we found the best fit between each spectrum and synthetic spectra from the BT-Settl 2010 and 2013 atmospheric models. Using the best fit, we derived the atmospheric parameters of the objects and identified which spectral characteristics the models do not reproduce.
2979. Unidentified cometary emission lines
ID:
ivo://CDS.VizieR/J/PAZh/30/946
Title:
Unidentified cometary emission lines
Short Name:
J/PAZh/30/946
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss the possible nature of unidentified cometary emission lines. We propose a model of the ice particles in cometary halos as a mixture of frozen polycyclic aromatic hydrocarbons (PAHs) and acyclic hydrocarbons. We describe the general properties of frozen hydrocarbon particles (FHPs) and suggest interpreting some of the unidentified cometary emission lines as the photoluminescence of FHPs. We compare the position of quasi-lines in the spectrum of Comet 122P/de Vico with the position of quasi-lines in the photoluminescence spectrum of PAHs that were dissolved in acyclic hydrocarbons at a temperature of 77K and that constituted a polycrystalline solution. We estimated the detectability of FHP photoluminescence in cometary spectra.
2980. Updated O3N2 and N2 abundance indicators
ID:
ivo://CDS.VizieR/J/A+A/559/A114
Title:
Updated O3N2 and N2 abundance indicators
Short Name:
J/A+A/559/A114
Date:
21 Oct 2021
Publisher:
CDS
Description:
The use of integral field spectroscopy is since recently allowing to measure the emission line fluxes of an increasingly large number of star-forming galaxies both locally and at high redshift. Many studies have used these fluxes to derive gas-phase metallicity of the galaxies by applying the so-called strong-line methods. However, the metallicity indicators that these datasets use were empirically calibrated using few direct abundance data points (Te-based measurements). Furthermore, a precise determination of the prediction intervals of these indicators is commonly lacking in these calibrations. Such limitations might lead to systematic errors in determining the gas-phase metallicity, especially at high redshift, which might have a strong impact on our understanding of the chemical evolution of the Universe. The main goal of this study is to review the most widely used empirical oxygen calibrations, O3N2 and N2, by using new direct abundance measurements. We pay special attention to (1) the expected uncertainty of these calibrations as a function of the index value or abundance derived and (2) the presence of possible systematic offsets. This is possible thanks to the analysis of the most ambitious compilation of Te-based Hii regions to date. This new dataset compiles the Te-based abundances of 603 Hii regions extracted from the literature but also includes new measurements from the CALIFA survey.

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