- ID:
- ivo://CDS.VizieR/J/A+A/600/A22
- Title:
- Iron-peak elements in solar neighbourhood
- Short Name:
- J/A+A/600/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this paper is to characterise the abundance patterns of five iron-peak elements (Mn, Fe, Ni, Cu, and Zn) for which the stellar origin and chemical evolution are still debated. We automatically derived iron peak (Mn, Fe, Ni, Cu, and Zn) and alpha element (Mg) chemical abundances for 4666 stars. We used the bimodal distribution of [Mg/Fe] to chemically classify sample stars into different Galactic substructures: thin disc, metal-poor and high-alpha metal rich, high-alpha and low-alpha metal-poor populations. High-alpha and low-alpha metal-poor populations are fully distinct in Mg, Cu, and Zn. Thin disc trends of [Ni/Fe] and [Cu/Fe] are very similar and show a small increase at supersolar metallicities. Thin and thick disc trends of Ni and Cu are very similar and indistinguishable. Mn looks different from Ni and Cu. [Mn/Fe] trends of thin and thick discs actually have noticeable differences: the thin disc is slightly Mn richer than the thick disc. [Zn/Fe] trends look very similar to those of [alpha/Fe] trends. The dispersion of results in both discs is low (~0.05dex for [Mg, Mn, and Cu/Fe]) and is even much lower for [Ni/Fe] (~0.035dex). Zn is an alpha-like element and could be used to separate thin and thick disc stars. [Mn/Mg] ratio could also be a very good tool for tagging Galactic substructures. Some models can partially reproduce the observed Mg, Zn, and, Cu behaviours. Models mostly fail to reproduce Mn and Ni in all metallicity domains, however, models adopting yields normalised from solar chemical properties reproduce Mn and Ni better, suggesting that there is still a lack of realistic theoretical yields of some iron-peak elements. Very low scatter (~0.05dex) in thin and thick disc sequences could provide an observational constrain for Galactic evolutionary models that study the efficiency of stellar radial migration.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/757/13
- Title:
- IR SEDs of 24um z~0.3-3 galaxies
- Short Name:
- J/ApJ/757/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we characterize the infrared spectral energy distributions (SEDs) of mid-IR-selected z~0.3-3.0 and L_IR_~10^11^-10^13^L_{sun}_ galaxies, and study how their SEDs differ from those of local and high-z analogs. Infrared SEDs depend both on the power source (AGN or star formation) and the dust distribution. Therefore, differences in the SEDs of high-z and local galaxies provide clues as to differences in their physical conditions. Our mid-IR flux-limited sample of 191 sources is unique in size, and spectral coverage, including Spitzer mid-IR spectroscopy. Here, we add Herschel photometry at 250{mu}m, 350{mu}m, and 500{mu}m, which allows us, through fitting an empirical SED model, to obtain accurate total IR luminosities, as well as constrain the relative contributions of AGNs and starbursts to those luminosities. Our sample includes three broad categories of SEDs: ~23% of the sources are AGNs (i.e., where the AGN contributes >50% of L_IR_), ~30% are starbursts where an AGN contributes <20% of L_IR_, and the mid-IR spectra are starburst-like (i.e., strong polycyclic aromatic hydrocarbon features); and the largest group (~47%) are composites which show both significant AGN and starburst activity. In summary, our results show that there is strong evolution in the SEDs between local and z~2 IR-luminous galaxies, as well as that there is a wide range of SEDs among high redshift IR-luminous sources. The publicly available SED templates we derive from our sample will be particularly useful for infrared population synthesis models, as well as in the interpretation of other mid-IR high-z galaxies, in particular those detected by the recent all sky Wide-field Infrared Survey Explorer.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/85
- Title:
- IRS multi-epoch observations of HD 69830
- Short Name:
- J/ApJ/743/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The main-sequence solar-type star HD 69830 has an unusually large amount of dusty debris orbiting close to three planets found via the radial velocity technique. In order to explore the dynamical interaction between the dust and planets, we have performed multi-epoch photometry and spectroscopy of the system over several orbits of the outer dust. We find no evidence for changes in either the dust amount or its composition, with upper limits of 5%-7% (1{sigma} per spectral element) on the variability of the dust spectrum over 1 year, 3.3% (1{sigma}) on the broadband disk emission over 4 years, and 33% (1{sigma}) on the broadband disk emission over 24 years. Detailed modeling of the spectrum of the emitting dust indicates that the dust is located outside of the orbits of the three planets and has a composition similar to main-belt, C-type asteroids in our solar system. Additionally, we find no evidence for a wide variety of gas species associated with the dust. Our new higher signal-to-noise spectra do not confirm our previously claimed detection of H_2_O ice leading to a firm conclusion that the debris can be associated with the break-up of one or more C-type asteroids formed in the dry, inner regions of the protoplanetary disk of the HD 69830 system. The modeling of the spectral energy distribution and high spatial resolution observations in the mid-infrared are consistent with a ~1 AU location for the emitting material.
- ID:
- ivo://CDS.VizieR/J/ApJS/207/37
- Title:
- IR sources spectroscopy in the AKARI NEP
- Short Name:
- J/ApJS/207/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectra of 1796 sources selected in the AKARI North Ecliptic Pole Wide Survey field, obtained with MMT/Hectospec and WIYN/Hydra, for which we measure 1645 redshifts. We complemented the generic flux-limited spectroscopic surveys at 11 {mu}m and 15 {mu}m, with additional sources selected based on the MIR and optical colors. In MMT/Hectospec observations, the redshift identification rates are ~80% for objects with R < 21.5 mag. On the other hand, in WIYN/Hydra observations, the redshift identification rates are ~80% at R magnitudes brighter than 19 mag. The observed spectra were classified through the visual inspection or from the line diagnostics. We identified 1128 star-forming or absorption-line-dominated galaxies, 198 Type-1 active galactic nuclei (AGNs), 8 Type-2 AGNs, 121 Galactic stars, and 190 spectra in unknown category due to low signal-to-noise ratio. The spectra were flux-calibrated but to an accuracy of 0.1-0.18dex for most of the targets and worse for the remainder. We derive star formation rates (SFRs) from the mid-infrared fluxes or from the optical emission lines, showing that our sample spans an SFR range of 0.1 to a few hundred M_{sun}_/yr. We find that the extinction inferred from the difference between the IR and optical SFR increases as the IR luminosity increases but with a large scatter.
- ID:
- ivo://CDS.VizieR/J/ApJS/191/96
- Title:
- IR spectra and optical constants of nitrile ices
- Short Name:
- J/ApJS/191/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectra and optical constants of nitrile ices known or suspected to be in Titan's atmosphere are presented from 2.0 to 333.3um (~5000-30/cm). These results are relevant to the ongoing modeling of Cassini CIRS observations of Titan's winter pole. Ices studied are: HCN, hydrogen cyanide; C2N2, cyanogen; CH3CN, acetonitrile; C2H5CN, propionitrile; and HC3N, cyanoacetylene. For each of these molecules, we also report new cryogenic measurements of the real refractive index, n, determined in both the amorphous and crystalline phases at 670nm. These new values have been incorporated into our optical constant calculations. Spectra were measured and optical constants were calculated for each nitrile at a variety of temperatures, including, but not limited to, 20, 35, 50, 75, 95, and 110K, in both the amorphous phase and the crystalline phase. This laboratory effort used a dedicated FTIR spectrometer to record transmission spectra of thin-film ice samples. Laser interference was used to measure film thickness during condensation onto a transparent cold window attached to the tail section of a closed-cycle helium cryostat. Optical constants, real (n) and imaginary (k) refractive indices, were determined using Kramers-Kronig analysis. Our calculation reproduces the complete spectrum, including all interference effects.
- ID:
- ivo://CDS.VizieR/J/ApJS/214/23
- Title:
- IR spectra and photometry of z<0.5 quasars
- Short Name:
- J/ApJS/214/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a step toward a comprehensive overview of the infrared (IR) diagnostics of the central engines and host galaxies of quasars at low redshift, we present Spitzer Space Telescope spectroscopic (5-40{mu}m) and photometric (24, 70, and 160{mu}m) measurements of all Palomar-Green (PG) quasars at z<0.5 and Two Micron All Sky Survey (2MASS) quasars at z<0.3. We supplement these data with Herschel measurements at 160{mu}m. The sample is composed of 87 optically selected PG quasars and 52 near-IR-selected 2MASS quasars. Here we present the data, measure the prominent spectral features, and separate emission due to star formation from that emitted by the dusty circumnuclear torus. We find that the mid-IR (5-30{mu}m) spectral shape for the torus is largely independent of quasar IR luminosity with scatter in the spectral energy distribution (SED) shape of <~0.2dex. Except for the silicate features, no large difference is observed between PG (unobscured --silicate emission) and 2MASS (obscured --silicate absorption) quasars. Only mild silicate features are observed in both cases. When in emission, the peak wavelength of the silicate feature tends to be longer than 9.7{mu}m, possibly indicating effects on grain properties near the active galactic nucleus. The IR color is shown to correlate with the equivalent width of the aromatic features, indicating that the slope of the quasar mid- to far-IR SED is to first order driven by the fraction of radiation from star formation in the IR bands.
- ID:
- ivo://CDS.VizieR/J/ApJ/730/19
- Title:
- IR spectra and SEDs for starbursts and AGNs
- Short Name:
- J/ApJ/730/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic results for all galaxies observed with the Spitzer Infrared Spectrograph (IRS) that also have total infrared fluxes f_IR_ measured with the Infrared Astronomical Satellite (IRAS), also using AKARI photometry when available. Infrared luminosities and spectral energy distributions (SEDs) from 8um to 160um are compared to polycyclic aromatic hydrocarbon emission from starburst galaxies or mid-infrared dust continuum from active galactic nuclei (AGNs) at rest-frame wavelengths ~8um. A total of 301 spectra are analyzed for which IRS and IRAS include the same unresolved source, as measured by the ratio f_{nu}_(IRAS 25um)/f_{nu}_(IRS 25um). Sources have 0.004<z<0.34 and 42.5<logL_IR_<46.8(erg/s) and cover the full range of starburst galaxy and AGN classifications.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A135
- Title:
- IR spectral of 4 Ae/Be Herbig stars
- Short Name:
- J/A+A/623/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the interstellar medium, carbon (nano-)grains are a major component of interstellar dust. This solid phase is more vulnerable to processing and destruction than its silicate counterpart. It exhibits a complex, size-dependent evolution that is due to interactions within different radiative and dynamical environments. Infrared signatures of these carbon nano-grains are seen in a large number of discs around Herbig HAeBe stars. We probe the composition and evolution of carbon nano-grains at the surface of (pre-)transitional proto-planetary discs around Herbig stars. We present spatially resolved infrared emission spectra obtained with the Nasmyth Adaptive Optics System (NAOS) Near-Infrared Imager and Spectrograph (CONICA) at the Very Large Telescope (VLT) in the 3-4 microns range with a spatial resolution of 0.1-arcsec, which allowed us to trace aromatic, olefinic, and aliphatic bands that are attributed to sub-nanometer hydrocarbon grains. We applied a Gaussian fitting to analyse the observed spectral signatures. Finally, we propose an interpretation in the framework of theThe Heterogeneous dust Evolution Model of Interstellar Solids (THEMIS). We show the presence of several spatially extended spectral features that are related to aromatic and aliphatic hydrocarbon material in discs around Herbig stars, from 10 to 50-100au, and even in inner gaps that are devoid of large grains. The correlation and constant intensity ratios between aliphatic and aromatic CH stretching bands suggests a common nature of the carriers. Given their expected high destruction rates through UV photons, our observations suggest that they are continuously replenished at the disc surfaces.
- ID:
- ivo://CDS.VizieR/J/AJ/160/63
- Title:
- IR spectra of 5 brown dwarfs with Gemini North IRS
- Short Name:
- J/AJ/160/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cold brown dwarfs are excellent analogs of widely separated, gas giant exoplanets, and provide insight into the potential atmospheric chemistry and physics we may encounter in objects to be discovered by future direct imaging surveys. We present a low-resolution, R~300, M-band spectroscopic sequence of seven brown dwarfs with effective temperatures between 750 and 250K along with Jupiter. These spectra reveal disequilibrium abundances of carbon monoxide (CO) produced by atmospheric quenching. We use the eddy diffusion coefficient (Kzz) to estimate the strength of vertical mixing in each object. The Kzz values of cooler gaseous objects are close to their theoretical maximum, and warmer objects show weaker mixing, likely due to less efficient convective mixing in primarily radiative layers. The CO-derived Kzz values imply that disequilibrium phosphine (PH3) should be easily observable in all of the brown dwarfs, but none as yet show any evidence for PH3 absorption. We find that ammonia is relatively insensitive to atmospheric quenching at these effective temperatures. We are able to improve the fit to WISE 0855's M-band spectrum by including both CO and water clouds in the atmospheric model.
- ID:
- ivo://CDS.VizieR/J/ApJ/732/116
- Title:
- IR spectra of {gamma}-ray bright blazars
- Short Name:
- J/ApJ/732/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A possible source of {gamma}-ray photons observed from the jets of blazars is inverse Compton scattering by relativistic electrons of infrared seed photons from a hot, dusty torus in the nucleus. We use observations from the Spitzer Space Telescope to search for signatures of such dust in the infrared spectra of four {gamma}-ray bright blazars, the quasars 4C 21.35, CTA102, and PKS 1510-089, and the BL Lacertae object ON231. The spectral energy distribution (SED) of 4C 21.35 contains a prominent infrared excess indicative of dust emission. After subtracting a non-thermal component with a power-law spectrum, we fit a dust model to the residual SED. The model consists of a blackbody with temperature ~1200K, plus a much weaker optically thin component at ~660K. The total luminosity of the thermal dust emission is 7.9+/-0.2x10^45^erg/s. If the dust lies in an equatorial torus, the density of infrared photons from the torus is sufficient to explain the {gamma}-ray flux from 4C 21.35 as long as the scattering occurs within a few parsecs of the central engine. We also report a tentative detection of dust in the quasar CTA102, in which the luminosity of the infrared excess is 7+/-2x10^45^erg/s. However, in CTA102 the far-infrared spectra are too noisy to detect the 10um silicate feature. Upper limits to the luminosity from thermal emission from dust in PKS 1510-089, and ON231, are 2.3x10^45^, and 6.6x10^43^erg/s, respectively. These upper limits do not rule out the possibility of inverse Compton upscattering of infrared photons to {gamma}-ray energies in these two sources.
