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- ID:
- ivo://CDS.VizieR/J/ApJ/717/674
- Title:
- Ionization energies of CnN(n=4-12)
- Short Name:
- J/ApJ/717/674
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results from single photon vacuum ultraviolet photoionization of astrophysically relevant C_n_N clusters, n=4-12, in the photon energy range of 8.0eV-12.8eV are presented. The experimental photoionization efficiency curves, combined with electronic structure calculations, provide improved ionization energies of the CnN species. A search through numerous nitrogen-terminated C_n_N isomers for n=4-9 indicates that the linear isomer has the lowest energy, and therefore should be the most abundant isomer in the molecular beam. Comparison with calculated results also shed light on the energetics of the linear C_n_N clusters, particularly in the trends of the even-carbon and the odd-carbon series. These results can guide the search of potential astronomical observations of these neutral molecules together with their cations in highly ionized regions or regions with a high UV/VUV photon flux (ranging from the visible to VUV with flux maxima in the Lyman-{alpha} region) in the interstellar medium.
- ID:
- ivo://CDS.VizieR/J/A+A/466/771
- Title:
- Ionization rate coefficients for elements H to Zn
- Short Name:
- J/A+A/466/771
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The interpretation of astrophysical spectra depends directly on a knowledge of the ionization state of the emitting plasma. This is determined, in part, from collisional ionization rate coefficients. The most recent assessments of these were performed by Arnaud & Rothenflug (1985A&AS...60..425A) and Arnaud & Raymond (1992ApJ...398..394A). Since their work, new laboratory measurements of ionization cross sections have become available as well as the Flexible Atomic Code (FAC) which enables theoretical calculations of these rates. Our goal is to provide a complete set of ionization rate coefficients for the elements hydrogen through zinc.
- ID:
- ivo://CDS.VizieR/J/ApJS/168/213
- Title:
- Ionization states and cooling efficiencies
- Short Name:
- J/ApJS/168/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new computations of the equilibrium and nonequilibrium cooling efficiencies and ionization states for low-density radiatively cooling gas containing the elements H, He, C, N, O, Ne, Mg, Si, S, and Fe. We present results for gas temperatures between 10^4^ and 10^8^K, assuming dust-free and optically thin conditions, and no external radiation.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A4
- Title:
- IRC+10216 as a spectroscopic laboratory
- Short Name:
- J/A+A/618/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work presents a detailed analysis of the laboratory and astrophysical spectral data available for ^28^SiC_2_, ^29^SiC_2_, ^30^SiC_2_, Si^13^CC, and Si_2_C. New data on the rotational lines of these species between 70 and 350GHz have been obtained with high spectral resolution (195kHz) with the IRAM 30m telescope in the direction of the circumstellar envelope IRC+10216. Frequency measurements can reach an accuracy of 50kHz for features observed with a good signal to noise ratio. From the observed astrophysical lines and the available laboratory data new rotational and centrifugal distortion constants have been derived for all the isotopologues of SiC_2_, allowing to predict their spectrum with high accuracy in the millimeter and submillimeter domains. Improved rotational and centrifugal distortion constants have also been obtained for disilicon carbide, Si_2_C. This work shows that observations of IRC+10216 taken with the IRAM 30m telescope, with a spectral resolution of 195kHz, can be used for any molecular species detected in this source to derive, or improve, its rotational constants. Hence, IRC+10216 in addition to be one the richest sources in molecular species in the sky, can also be used as a state-of-the-art spectroscopy laboratory in the millimeter and submillimeter domains.
- ID:
- ivo://CDS.VizieR/J/A+A/330/676
- Title:
- IRC+10216 Silicon and sulfur chemistry
- Short Name:
- J/A+A/330/676
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a dynamical and chemical model of the inner wind of the carbon-rich, AGB star IRC+10216. We include the effect of pulsation-driven shocks on the gas envelope close to the stellar photosphere and construct an extended chemical model that includes in particular the chemistry of hydrocarbon species and silicon and sulphur-bearing molecules. The derived theoretical abundances for many molecules are in excellent agreement with values obtained from observations of infrared ro-vibrational molecular lines. We confirm the ``parent'' character of certain chemical species and show that the inner wind of IRC+10216, and more generally of evolved AGB stars, is an active dynamical and chemical region where molecules are formed and processed.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/104
- Title:
- IR high-res. sp. of hot cores of AFGL2591 & AFGL2136
- Short Name:
- J/ApJ/900/104
- Date:
- 21 Mar 2022 09:36:08
- Publisher:
- CDS
- Description:
- We have performed a high-resolution 4-13{mu}m spectral survey of the hot molecular gas associated with the massive protostars AFGL 2591 and AFGL 2136, utilizing the Echelon Cross Echelle Spectrograph (EXES) on board the Stratospheric Observatory for Infrared Astronomy, and the iSHELL instrument and Texas EchelonCross Echelle Spectrograph (TEXES) on the NASA Infrared Telescope Facility (IRTF). Here we present the results of this survey with analysis of CO, HCN, C2H2, NH3, and CS, deriving the physical conditions for each species. Also from the IRTF, iSHELL data at 3{mu}m for AFGL 2591 are presented that show HCN and C2H2 in emission. In the EXES and TEXES data, all species are detected in absorption, and temperatures and abundances are found to be high (600K and 10^-6^, respectively). Differences of up to an order of magnitude in the abundances of transitions that trace the same ground-state level are measured for HCN and C2H2. The mid-infrared continuum is known to originate in a disk, hence we attribute the infrared absorption to arise in the photosphere of the disk. As absorption lines require an outwardly decreasing temperature gradient, we conclude that the disk is heated in the midplane by viscous heating due to accretion. We attribute the near-IR emission lines to scattering by molecules in the upper layers of the disk photosphere. The absorption lines trace the disk properties at 50 au where high-temperature gas-phase chemistry is taking place. Abundances are consistent with chemical models of the inner disk of Herbig disks.
- ID:
- ivo://CDS.VizieR/J/A+A/554/A132
- Title:
- Iron line list (FeI and FeII)
- Short Name:
- J/A+A/554/A132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present homogeneous and accurate iron abundances for almost four dozen (47) of Galactic Cepheids using high-spectral resolution (R~40000) high signal-to-noise ratio (S/N>=100) optical spectra collected with UVES at VLT. A significant fraction of the sample (32) is located in the inner disk (R_G_<=6.9kpc) and for half of them we provide new iron abundances.
- ID:
- ivo://CDS.VizieR/J/A+AS/103/273
- Title:
- IRON Project II. C-like ions
- Short Name:
- J/A+AS/103/273
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
360. IRON Project L
- ID:
- ivo://CDS.VizieR/J/A+A/372/1083
- Title:
- IRON Project L
- Short Name:
- J/A+A/372/1083
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Effective collision strengths for transitions between 92 fine structure states calculated in a Breit-Pauli approximation are provided in ups.dat. Results are provided for log T in the range of 5.0-7.6 in steps of 0.1. The level indices refer to the ordering given in Table 2 in the text where the energies are also given. The format is most easily described by the fortran program provided - readups.f - which may be used to interface with user programs. Oscillator strengths for all dipole allowed transitions are provided in osc.dat which are also indexed with respect to Table 2.
