- ID:
- ivo://CDS.VizieR/J/A+A/644/A3
- Title:
- rotational transitions of cyanoacetamide
- Short Name:
- J/A+A/644/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cyanoacetamide is a branched chain -CN bearing molecule which is also an amide derivative target molecule in the interstellar medium. The aim of our investigation is to analyze the feasibility of a plausible formation process of protonated cyanoacetamide under interstellar conditions and to provide direct experimental frequencies of the ground vibrational state of the neutral form in the microwave region in order to enable its eventual identification in the interstellar medium. We used high-level theoretical computations to study the formation process of protonated cyanoacetamide. Furthermore, we employed a high resolution laser ablation molecular beam Fourier transform (LA-MB-FTMW) spectroscopic technique to measure the frequencies of the neutral form. We report the first rotational characterization of cyanoacetamide and a precise set of the relevant rotational spectroscopic constants have been determined as a first step to identify the molecule in the interstellar medium. We performed full exploration of the Potential Energy Surface (PES) to study a gas-phase reaction on the formation process of protonated cyanoacetamide. We found an exothermic process with no net activation barrier initiated by the high-energy isomer of protonated hydroxylamine, which leads to protonated cyanoacetamide.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/897/122
- Title:
- Rotational velocities for PHANGS sample of galaxies
- Short Name:
- J/ApJ/897/122
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We present kinematic orientations and high-resolution (150pc) rotation curves for 67 main-sequence star-forming galaxies surveyed in CO (2-1) emission by PHANGS-ALMA. Our measurements are based on the application of a new fitting method tailored to CO velocity fields. Our approach identifies an optimal global orientation as a way to reduce the impact of nonaxisymmetric (bar and spiral) features and the uneven spatial sampling characteristic of CO emission in the inner regions of nearby galaxies. The method performs especially well when applied to the large number of independent lines of sight contained in the PHANGS CO velocity fields mapped at 1" resolution. The high-resolution rotation curves fitted to these data are sensitive probes of mass distribution in the inner regions of these galaxies. We use the inner slope as well as the amplitude of our fitted rotation curves to demonstrate that CO is a reliable global dynamical mass tracer. From the consistency between photometric orientations from the literature and kinematic orientations determined with our method, we infer that the shapes of stellar disks in the mass range of log(M*(M{odot}))=9.0-10.9 probed by our sample are very close to circular and have uniform thickness.
- ID:
- ivo://CDS.VizieR/J/ApJ/642/868
- Title:
- Rotation measures for 223 pulsars
- Short Name:
- J/ApJ/642/868
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The large-scale magnetic field of our Galaxy can be probed in three dimensions using Faraday rotation of pulsar signals. We report on the determination of 223 rotation measures from polarization observations of relatively distant southern pulsars made using the Parkes radio telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/513/A65
- Title:
- Rotation measures in the fourth Galactic quadrant
- Short Name:
- J/A+A/513/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have re-examined the published rotation measures (RMs) of extragalactic point sources and pulsars with |b|<3{deg} to study the magnetic field in the fourth Galactic quadrant. We reduced the influence of structure in electron density as much as possible by excluding objects for which H{alpha}-data indicate large fluctuations in n_e_ somewhere along the line of sight. We also excluded objects for which the RM may have been significantly "corrupted" by an intervening supernova remnant. We modelled RM(l), the longitude dependence of RM of the unaffected extragalactic sources and pulsars. We assumed several geometries for the large-scale field. All but one of those are based on logarithmic spiral arms (with various pitch angles and widths), while one has circular symmetry. We also made different assumptions about the large-scale n_e_-distribution.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A56
- Title:
- Rotation Measure synthesis of WSRT obs.
- Short Name:
- J/A+A/549/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotation Measure synthesis (RM synthesis) of the Westerbork Synthesis Radio Telescope (WSRT) observations at 2m wavelength of the FAN region at l=137deg, b=+7deg shows the morphology of structures in the ionized interstellar medium.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A123
- Title:
- SABOCA imaging of G304.74+01.32
- Short Name:
- J/A+A/609/A123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to determine the occurrence of fragmentation into cores in the clumps of the filamentary IRDC G304.74+01.32. We also aim to determine the basic physical characteristics of the clumps and cores in G304.74. We mapped the G304.74 filament at 350 micron using the SABOCA bolometer. The new SABOCA data have a factor of 2.2 times higher resolution than our previous LABOCA 870 micron map of the cloud (9" versus 19.86"). We also employed the Herschel far-IR and submillimetre, and WISE IR imaging data available for G304.74. The WISE data allowed us to trace the IR emission of the YSOs associated with the cloud. The SABOCA 350 micron data show that G304.74 is composed of a dense filamentary structure with a mean width of only 0.18+/-0.05pc. The percentage of LABOCA clumps that are found to be fragmented into SABOCA cores is 36%+/-16%, but the irregular morphology of some of the cores suggests that this multiplicity fraction could be higher. The WISE data suggest that 65%+/-18% of the SABOCA cores host YSOs. The mean dust temperature of the clumps, derived by comparing the Herschel 250, 350, and 500 micron flux densities, was found to be 15.0+/-0.8K. The mean mass, beam-averaged H_2_ column density, and H_2_ number density of the LABOCA clumps are estimated to be 55+/-10M_{sun}_, (2.0+/-0.2)x10^22^cm^-2^, and (3.1+/-0.2)x10^4^cm^-3^. The corresponding values for the SABOCA cores are 29+/-3M_{sun}_, (2.9+/-0.3)x10^22^cm^-2^, and (7.9+/-1.2)x10^4^cm^-3^. The G304.74 filament is estimated to be thermally supercritical by a factor of >~3.5 on the scale probed by LABOCA, and by a factor of >~1.5 for the SABOCA filament. Our data strongly suggest that the IRDC G304.74 has undergone hierarchical fragmentation. On the scale where the clumps have fragmented into cores, the process can be explained in terms of gravitational Jeans instability. Besides the filament being fragmented, the finding of embedded YSOs in G304.74 indicates its thermally supercritical state, although the potential non-thermal (turbulent) motions can render the cloud a virial equilibrium system on scale traced by LABOCA. The IRDC G304.74 has a seahorse-like morphology in the Herschel images, and the filament appears to be attached by elongated, perpendicular striations. This is potentially evidence that G304.74 is still accreting mass from the surrounding medium, and the accretion process can contribute to the dynamical evolution of the main filament. One of the clumps in G304.74, IRAS 13039-6108, is already known to be associated with high-mass star formation, but the remaining clumps and cores in this filament might preferentially form low and intermediate-mass stars owing to their mass reservoirs and sizes. Besides the presence of perpendicularly oriented, dusty striations and potential embedded intermediate-mass YSOs, G304.74 is a relatively nearby (d~2.5kpc) IRDC, which makes it a useful target for future star formation studies. Owing to its observed morphology, we propose that G304.74 could be nicknamed the Seahorse Nebula. Description: The SABOCA 350 micron and LABOCA 870 micron dust continuum maps of G304.74+01.32. The data were reduced using the CRUSH-2 software
- ID:
- ivo://CDS.VizieR/J/PASP/122/683
- Title:
- SAGE-Spec Spitzer legacy program
- Short Name:
- J/PASP/122/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SAGE-Spec Spitzer Legacy program is a spectroscopic follow-up to the SAGE-LMC photometric survey of the Large Magellanic Cloud carried out with the Spitzer Space Telescope. We present an overview of SAGE-Spec and some of its first results. The SAGE-Spec program aims to study the life cycle of gas and dust in the Large Magellanic Cloud and to provide information essential to the classification of the point sources observed in the earlier SAGE-LMC photometric survey. We acquired 224.6h of observations using the infrared spectrograph and the spectral energy distribution (SED) mode of the Multiband Imaging Photometer for Spitzer. The SAGE-Spec data, along with archival Spitzer spectroscopy of objects in the Large Magellanic Cloud, are reduced and delivered to the community. We discuss the observing strategy, the specific data-reduction pipelines applied, and the dissemination of data products to the scientific community. Initial science results include the first detection of an extragalactic 21um feature toward an evolved star and elucidation of the nature of disks around RV Tauri stars in the Large Magellanic Cloud. Toward some young stars, ice features are observed in absorption. We also serendipitously observed a background quasar, at a redshift of z~~0.14, which appears to be hostless.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A168
- Title:
- Sample of 31 dwarf and 18 Lyman-Break galaxies
- Short Name:
- J/A+A/641/A168
- Date:
- 10 Mar 2022 07:07:07
- Publisher:
- CDS
- Description:
- The chemical enrichment in the interstellar medium (ISM) of galaxies is regulated by several physical processes: star birth and death, grain formation and destruction, and galactic inflows and outflows. Understanding such processes and their relative importance is essential to following galaxy evolution and the chemical enrichment through the cosmic epochs, and to interpreting current and future observations. Despite the importance of such topics, the contribution of different stellar sources to the chemical enrichment of galaxies, for example massive stars exploding as Type II supernovae (SNe) and low-mass stars, as well as the mechanisms driving the evolution of dust grains, such as for example grain growth in the ISM and destruction by SN shocks, remain controversial from both observational and theoretical viewpoints. In this work, we revise the current description of metal and dust evolution in the ISM of local low-metallicity dwarf galaxies and develop a new description of Lyman-break galaxies (LBGs) which are considered to be their high-redshift counterparts in terms of star formation, stellar mass, and metallicity. Our goal is to reproduce the observed properties of such galaxies, in particular (i) the peak in dust mass over total stellar mass (sMdust) observed within a few hundred million years; and (ii) the decrease in sMdust at a later time. We fitted spectral energy distribution (SED) of dwarf galaxies and LBGs with the 'Code Investigating GALaxies Emission' (CIGALE), through which the total stellar mass, dust mass, and star formation rate are estimated. For some of the dwarf galaxies considered, the metal and gas content are available from the literature. We computed different prescriptions for metal and dust evolution in these systems (e.g. different initial mass functions for stars, dust condensation fractions, SN destruction, dust accretion in the ISM, and inflow and outflow efficiency), and we fitted the properties of the observed galaxies through the predictions of the models. Only some combinations of models are able to reproduce the observed trend and simultaneously fit the observed properties of the galaxies considered. In particular, we show that (i) a top-heavy initial mass function that favours the formation of massive stars and a dust condensation fraction for Type II SNe of around 50% or more help to reproduce the peak of sMdust observed after ~100Myr from the beginning of the baryon cycle for both dwarf galaxies and LBGs; (ii) galactic outflows play a crucial role in reproducing the observed decline in sMdust with age and are more efficient than grain destruction from Type II SNe both in local galaxies and at high-redshift; (iii) a star formation efficiency (mass of gas converted into stars) of a few percent is required to explain the observed metallicity of local dwarf galaxies; and (iv) dust growth in the ISM is not necessary in order to reproduce the values of sMdust derived for the galaxies under study, and, if present, the effect of this process would be erased by galactic outflows.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/29
- Title:
- Scintillation of AGNs observed with the VLA
- Short Name:
- J/ApJ/756/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fraction of compact active galactic nuclei (AGNs) that exhibit interstellar scintillation (ISS) at radio wavelengths, as well as their scintillation amplitudes, have been found to decrease significantly for sources at redshifts z>~2. This can be attributed to an increase in the angular sizes of the {mu}as-scale cores or a decrease in the flux densities of the compact {mu}as cores relative to that of the mas-scale components with increasing redshift, possibly arising from (1) the space-time curvature of an expanding universe, (2) AGN evolution, (3) source selection biases, (4) scatter broadening in the ionized intergalactic medium (IGM) and intervening galaxies, or (5) gravitational lensing. We examine the frequency scaling of this redshift dependence of ISS to determine its origin, using data from a dual-frequency survey of ISS of 128 sources at 0<~z<~4. We present a novel method of analysis which accounts for selection effects in the source sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/234/22
- Title:
- SCUBA-2 Galactic Center compact source catalog
- Short Name:
- J/ApJS/234/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new JCMT SCUBA-2 observations of the Galactic Center region from 355{deg}<l<5{deg} and b<+/-1{deg}, covering 10x2 square degrees along the Galactic Plane to a depth of 43mJy/beam at 850{mu}m and 360mJy/beam at 450{mu}m. We describe the mapping strategy and reduction method used. We present ^12^CO(3-2) observations of selected regions in the field. We derive the molecular-line conversion factors (mJy/beam per K.km/s) at 850 and 450{mu}m, which are then used to obtain the amount of contamination in the continuum maps due to ^12^CO(3-2) emission in the 850{mu}m band. Toward the fields where the CO contamination has been accounted for, we present an 850{mu}m CO-corrected compact source catalog. Finally, we look for possible physical trends in the CO contamination with respect to column density, mass, and concentration. No trends were seen in the data despite the recognition of three contributors to CO contamination: opacity, shocks, and temperature, which would be expected to relate to physical conditions. These SCUBA-2 Galactic Center data are available via http://doi.org/10.11570/17.0009.
