- ID:
- ivo://CDS.VizieR/J/MNRAS/390/733
- Title:
- FTS reference UV wavelengths of CrIII
- Short Name:
- J/MNRAS/390/733
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report CrIII ultraviolet (UV) transition wavelengths measured using a high-resolution Fourier transform spectrometer (FTS), for the first time, available for use as wavelength standards. The doubly ionized iron group element spectra dominate the observed opacity of hot B stars in the UV, and improved, accurate, wavelengths are required for the analysis of astronomical spectra. The spectrum was excited using a chromium-neon Penning discharge lamp and measured with the Imperial College vacuum ultraviolet FTS. 140 classified 3d^3^4s-3d^3^4p CrIII transition lines, in the spectral range 38000 to 49000cm^-1^ (2632 to 2041{AA}), the strongest having wavelength uncertainties less than one part in 10^7^, are presented.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/630/A58
- Title:
- Full infrared spectrum of molecular hydrogen
- Short Name:
- J/A+A/630/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The high spectral resolution R~45000 provided by IGRINS (Immersion Grating INfrared Spectrometer) at MacDonald Observatory and R~100000 achieved by CRIRES (CRyogenic high-resolution InfraRed) Echelle Spectrograph) at VLT challenges the present knowledge of infrared spectra. We aim to predict the full infrared spectrum of molecular hydrogen at a comparable accuracy. We take advantage of the recent theoretical ab-initio studies on molecular hydrogen to compute both the electric quadrupole and magnetic dipole transitions taking place within the ground electronic molecular state of Hydrogen. We compute the full infrared spectrum of molecular hydrogen at an unprecedented accuracy and derive for the first time the emission probabilities including both electric quadrupole ({Delta}J=0, +/-2) and magnetic dipole transitions ({Delta}J=0) as well as the total radiative lifetime of each rovibrational state. Inclusion of magnetic dipole transitions increases the emission probabilities by factors of a few for highly excited rotational levels, which occur in the 3-20{mu} range.
- ID:
- ivo://CDS.VizieR/J/A+A/577/A6
- Title:
- GaIV, GaV, and GaVI oscillator strengths
- Short Name:
- J/A+A/577/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, advanced non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These atmospheres are strongly dependent on the reliability of the atomic data that are used to calculate them. Reliable Ga IV-VI oscillator strengths are used to identify Ga lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ga abundances. We newly calculated Ga IV-VI oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for analyzing of Ga lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289.
- ID:
- ivo://CDS.VizieR/J/ApJ/791/L28
- Title:
- Gas-phase detection of c-C_3_H_3_^+^
- Short Name:
- J/ApJ/791/L28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cyclopropenyl cation (c-C_3_H_3_^+^) is the smallest aromatic hydrocarbon molecule and considered to be a pivotal intermediate in ion-molecule reactions in space. An astronomical identification has been prohibited so far, because of a lack of gas-phase data. Here we report the first high resolution infrared laboratory gas-phase spectrum of the {nu}_4_(C-H asymmetric stretching) fundamental band of c-C_3_H_3_^+^. The c-C_3_H_3_^+^ cations are generated in supersonically expanding planar plasma by discharging a propyne/helium gas pulse, yielding a rotational temperature of ~35 K. The absorption spectrum is recorded in the 3.19 {mu}m region using sensitive continuous-wave cavity ring-down spectroscopy. The analysis of about 130 ro-vibrational transitions results in precise spectroscopic parameters. These constants allow for an accurate comparison with high-level theoretical predictions, and provide the relevant information needed to search for this astrochemically relevant carbo-cation in space.
- ID:
- ivo://CDS.VizieR/J/A+A/546/A55
- Title:
- Ge V and Ge VI oscillator strengths
- Short Name:
- J/A+A/546/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- State-of-the-art spectral analysis of hot stars by means of non-LTE model-atmosphere techniques has arrived at a high level of sophistication. The analysis of high-resolution and high-S/N spectra, however, is strongly restricted by the lack of reliable atomic data for highly ionized species from intermediate-mass metals to trans-iron elements. Especially data for the latter has only been sparsely calculated. Many of their lines are identified in spectra of extremely hot, hydrogen-deficient post-AGB stars. A reliable determination of their abundances establishes crucial constraints for AGB nucleosynthesis simulations and, thus, for stellar evolutionary theory. In a previous analysis of the UV spectrum of RE 0503-289, spectral lines of highly ionized Ga, Ge, As, Se, Kr, Mo, Sn, Te, I, and Xe were identified. Individual abundance determinations are hampered by the lack of reliable oscillator strengths. Most of these identified lines stem from Ge V. In addition, we identified Ge VI lines for the first time. We calculated Ge V and Ge VI oscillator strengths in order to reproduce the observed spectrum.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A140
- Title:
- g'G'Ag-CH3CH2CHOHCH2OH transition frequencies
- Short Name:
- J/A+A/619/A140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The continuously enhanced sensitivity of radioastronomical observations allows the detection of increasingly complex organic molecules. These systems often exist in a large number of isomers leading to very congested spectra. We explore the conformational space of 1,2-butanediol and provide sets of spectroscopic parameters to facilitate searches for this molecule at millimeter wavelengths. We recorded the rotational spectrum of 1,2-butanediol in the 59.6-103.6GHz frequency region (5.03-2.89mm) using a free-jet millimeter-wave absorption spectrometer, and we analyzed the properties of 24 isomers with quantum chemical calculations. Selected measured transition lines were then searched on publicly available ALMA Band 3 data on IRAS 16293-2422 B. We assigned the spectra of six conformers, namely aG'Ag, gG'Aa, g'G'Ag, aG'G'g, aG'Gg, and g'GAa, to yield the rotational constants and centrifugal distortion constants up to the fourth or sixth order. The most intense signal belong to the aG'Ag species, that is the global minimum. Search for the corresponding 30_x,30_-29_x,29_ transition lines toward IRAS 16293-2422 B was unsuccessful. Our present data will be helpful for identifying 1,2-butanediol at millimeter wavelengths with radio telescope arrays. Among all possible conformers, first searches should be focused on the aG'Ag conformers in the 400-800GHz frequency spectral range.
- ID:
- ivo://CDS.VizieR/J/A+A/636/A33
- Title:
- Glutaronitrile rotational spectroscopy
- Short Name:
- J/A+A/636/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Nitriles constitute almost 15% of the molecules observed in the interstellar medium (ISM), surprisingly only two dinitriles have been detected in the ISM so far. The lack of astronomical detections for dinitriles may be partly explained by the absence of laboratory rotational spectroscopic data. Our goal is the investigation of the rotational spectrum of glutaronitrile, NC-CH_2_-CH_2_-CH_2_-CN, in order to allow its possible detection in the ISM. The rotational spectra of glutaronitrile was measured using two different experimental setups. A Fourier transform microwave spectrometer was employed to observe the supersonic jet rotational spectrum of glutaronitrile between 6 and 20GHz. In addition the mmW spectrum was observed in the frequency range 72-116.5GHz using a broadband millimeter-wave spectrometer based on radio astronomy receivers with fast Fourier transform backends. The spectral searches were supported by high-level ab initio calculations. A total of 111 rotational transitions with maximum values of J and Ka quantum numbers 54 and 18, respectively, were measured for the gg conformer of glutaronitrile. The analysis allowed us to accurately determine the rotational, nuclear quadrupole coupling, quartic and sextic centrifugal distortion constants. These rotational parameters were employed to search for glutaronitrile in the cold and warm molecular clouds Orion KL, Sgr B2(N), B1-b and TMC-1, using the spectral surveys captured by IRAM 30m at 3mm. Glutaronitrile was not detected and the upper limits column densities are derived. Those are a factor of 1.5 and 5 lower than those obtained for the total column densities of the analogous succionitrile in Orion KL and Sgr B2, respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A135
- Title:
- Glycolamide rotational transitions
- Short Name:
- J/A+A/639/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Glycolamide is a glycine isomer and also one of the simplest derivatives of acetamide (one hydrogen atom replaced with a hydroxyl group), which is a known interstellar molecule. In this context, the aim of our work is to provide direct experimental frequencies of the ground vibrational state of glycolamide in the centimeter-, millimeter- and submillimeter wavelength regions in order to enable its identification in the interstellar medium. We employed a battery of state-of-the-art rotational spectroscopic techniques in the frequency and time domain to measure its frequencies. We used the spectral line survey named EMoCA (Exploring Molecular Complexity with ALMA) that was performed toward the star forming region Sgr B2(N) with ALMA to search for glycolamide in space. We also searched for glycolamide toward Sgr B2(N) with the Effelsberg radio telescope. The astronomical spectra were analyzed under the local thermodynamic equilibrium approximation.We used the gas-grain chemical kinetics mode MAGICKAL to interpret the results of the astronomical observations. About 1500 transitions have been newly assigned up to 460GHz to the most stable conformer, and a precise set of spectroscopic constants was determined. Spectral features of glycolamide were then searched for in the prominent hot molecular core Sgr B2(N2). We report the non-detection of glycolamide toward this source with an abundance at least six and five times lower than that of acetamide and glycolaldehyde, respectively. Our astrochemical model suggests that glycolamide may be present in this source at a level just below the upper limit derived from the EMoCA survey. We could also not detect the molecule in the region s extended molecular envelope probed with the Effelsberg telescope. We find an upper limit to its column density that is similar to the column densities obtained earlier for acetamide and glycolaldehyde with theGreen Bank Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/143
- Title:
- Ground-state contributions around s-process
- Short Name:
- J/ApJ/738/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Modern models of s-process nucleosynthesis in stars require stellar reaction rates of high precision. Most neutron-capture cross-sections in the s-process have been measured, and for an increasing number of reactions the required precision is achieved. This does not necessarily mean, however, that the stellar rates are constrained equally well, because only the capture of the ground state of a target is measured in the laboratory. Captures of excited states can contribute considerably to stellar rates that are already at typical s-process temperatures. We show that the ground-state contribution X to a stellar rate is the relevant measure to identify reactions that are or could be well constrained by experiments and apply it to (n,{gamma}) reactions in the s-process. We further show that the maximum possible reduction in uncertainty of a rate via determination of the ground-state cross-section is given directly by X. An error analysis of X is presented, and it is found that X is a robust measure with mostly small uncertainties. Several specific examples (neutron capture of ^79^Se, ^95^Zr, ^121^Sn, ^187^Os, and ^193^Pt) are discussed in detail. The ground-state contributions for a set of 412 neutron-capture reactions around the s-process path are presented in a table. This allows identification of reactions that may be better constrained by experiments and that cannot be constrained solely by measuring ground-state cross-sections (and thus require supplementary studies).
290. GSP-spec line list
- ID:
- ivo://CDS.VizieR/J/A+A/654/A130
- Title:
- GSP-spec line list
- Short Name:
- J/A+A/654/A130
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The Gaia mission is a magnitude-limited whole-sky survey that collects an impressive quantity of astrometric, spectro-photometric and spectroscopic data. Among all the on-board instruments, the Radial Velocity Spectrometer (RVS) produces millions of spectra up to a magnitude of GRVS 16. For the brightest RVS targets, stellar atmospheric parameters and individual chemical abundances are automatically estimated by the Generalized Stellar Parametriser - spectroscopy group (GSP-Spec). These data will be published with the third Gaia Data Release. Some major ingredients of the determination of these stellar parameters include the atomic and molecular line lists that are adopted to compute reference synthetic spectra, on which the parametrisation methods rely. We aim to build such a specific line list optimised for the analysis of RVS late-type star spectra. Starting from the Gaia-ESO line lists, we first compared the observed and synthetic spectra of six well-known reference late-type stars in the wavelength range covered by the RVS instrument. We then improved the quality of the atomic data for the transitions presenting the largest mismatches. The new line list is found to produce very high-quality synthetic spectra for the tested reference stars and has thus been adopted within GSP-Spec.
