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- ID:
- ivo://CDS.VizieR/J/MNRAS/423/725
- Title:
- Survey of diffuse interstellar bands
- Short Name:
- J/MNRAS/423/725
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents an atlas of diffuse interstellar bands together with tables with measurements of their parameters: central wavelengths, full widths at half-maximum and equivalent widths. For this goal the spectra of ten reddened, early-type stars have been selected. The spectra are of high resolution, ~100000, and reasonable signal-to-noise ratio, S/N>300; they cover a wide spectral range 3500-10000{AA} and show a lack of evident Doppler splitting in the interstellar KI line. The measurement technique has allowed a homogeneous set of data to be achieved. As a result, the identity of 336 DIBs from previous surveys has been confirmed and 21 new bands have been found.
- ID:
- ivo://CDS.VizieR/J/ApJ/526/788
- Title:
- Survey of infall motions toward starless cores
- Short Name:
- J/ApJ/526/788
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a survey of 220 starless cores selected primarily by their optical obscuration and observed in CS (2-1), N_2_H^+^ (1-0), and C^18^O (1-0) using the Northeast Radio Observatory Corporation (NEROC) Haystack 37 m telescope. We have detected 163 out of 196 sources observed in CS, 72 out of 142 in N_2_H^+^, and 30 out of 30 in C18O. In total, 69 sources were detected in both CS and N_2_H^+^. The isolated component of the N_2_H^+^ (1-0) spectrum (F_1_F = 0,1-1,2) usually shows a weak symmetric profile that is optically thin. In contrast, a significant fraction of the CS spectra show non-Gaussian shapes, which we interpret as arising from a combination of self-absorption due to lower excitation gas in the core front and kinematics in the core. The distribution of the normalized velocity difference ({delta}V_CS_) between the CS and N_2_H^+^ peaks appears significantly skewed to the blue (V_CS_ < 0), as was found in a similar study of dense cores with embedded young stellar objects (YSOs). The incidence of sources with blue asymmetry tends to increase as the total optical depth or the integrated intensity of the N_2_H^+^ line increases.
- ID:
- ivo://CDS.VizieR/J/ApJS/253/44
- Title:
- Survey of SiO maser emission in oxygen-rich stars
- Short Name:
- J/ApJS/253/44
- Date:
- 01 Mar 2022 00:16:35
- Publisher:
- CDS
- Description:
- Circumstellar environments of oxygen-rich stars are among the strongest SiO maser emitters. Physical processes such as collisions, infrared pumping, and overlaps favor the inversion of level population and produce maser emission at different vibrational states. Despite numerous observational and theoretical efforts, we still do not have a unified picture including all of the physical processes involved in SiO maser emission. The aim of this work is to provide homogeneous data in a large sample of oxygen-rich stars. We present a survey of 67 oxygen-rich stars from 7 to 1mm, in their rotational transitions from J=1-0 to J=5-4, for vibrational numbers v from 0 to 6 in the three main SiO isotopologs. We have used one of the 34 m NASA antennas at Robledo and the IRAM 30m radio telescope. The first tentative detection of a v=6 line is reported, as well as the detection of new maser lines. The highest vibrational levels seem confined to small volumes, presumably close to the stars. The J=1-0, v=2 line flux is greater than the corresponding v=1 in almost half of the sample, which may confirm a predicted dependence on the pulsation cycle. This database is potentially useful in models which should consider most of the physical agents, time dependency, and mass-loss rates. As a by-product, we report detections of 27 thermal rotational lines from other molecules, including isotopologs of SiS, H_2_S, SO, SO_2_, and NaCl.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A52
- Title:
- SVS13-A Class I IRAM-NOEMA images
- Short Name:
- J/A+A/654/A52
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Recent results in astrochemistry have revealed that some molecules, such as interstellar complex organic species and deuterated species, can serve as valuable tools in the investigation of star-forming regions. Sulphuretted species can also be used to follow the chemical evolution of the early stages of a Sun-like star formation process. The goal is to obtain a census of S-bearing species using interferometric images towards SVS13-A, a Class I object associated with a hot corino that is rich in interstellar complex organic molecules. To this end, we used the NGC1333 SVS13-A data at 3mm and 1.4mm obtained with the IRAM-NOEMA interferometer in the framework of the SOLIS (Seeds of Life in Space) Large Program. The line emission of S-bearing species was imaged and analyzed using local thermodynamic equilibrium (LTE) and large velocity gradient (LVG) approaches. We imaged the spatial distribution on <=300au scale of the line emission of ^32^SO, ^34^SO, C^32^S, C^34^S, C^33^S, OCS, H_2_C^32^S, H_2_C^34^S, and NS. The low excitation (9K) ^32^SO line traces: (i) the low-velocity SVS13-A outflow and (ii) the fast (up to 100km/s away from the systemic velocity) collimated jet driven by the nearby SVS13-B Class 0 object. Conversely, the rest of the lines are confined in the inner SVS13-A region, where complex organics were previously imaged.More specifically, the non-LTE LVG analysis of SO, SO_2_, and H_2_CS indicates a hot corino origin (size in the 60-120au range). Temperatures between 50K and 300K, as well as volume densities larger than 10^5^cm^-3^ have been derived. The abundances of the sulphuretted are in the following ranges: 0.3-6x10^-6^ (CS), 7x10^-9^-1x10^-7^ (SO), 1-10x10^-7^ (SO_2_), a few 10^-10^ (H_2_CS and OCS), and 10^-10^-10^-9^ (NS). The N(NS)/N(NS+) ratio is larger than 10, supporting the assessment that the NS+ ion is mainly formed in the extended envelope. The [H_2_CS]/[H_2_CO] ratio, once measured at high-spatial resolutions, increases with time (from Class 0 to Class II objects) by more than one order of magnitude (from <=10^-2^ to a few 10^-1^). This suggests that [S]/[O] changes along the process of Sun-like star formation. Finally, the estimate of the [S]/[H] budget in SVS13-A is 2%-17% of the Solar System value (1.8x10^-5^), which is consistent with what was previously measured towards Class 0 objects (1%-8%). This finding supports the notion that the enrichment of the sulphuretted species with respect to dark clouds remains constant from the Class 0 to the Class I stages of lowmass star formation. The present findings stress the importance of investigating the chemistry of star-forming regions using large observational surveys as well as sampling regions on the scale of the Solar System.
846. Swan system of C2
- ID:
- ivo://CDS.VizieR/J/ApJS/169/472
- Title:
- Swan system of C2
- Short Name:
- J/ApJS/169/472
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The C2 Swan system (d ^3^{Pi}_g_-a ^3^{Pi}_u_) was observed in emission for the {Delta}v=-3 to {Delta}v=+2 sequences in the 14000-24000cm^-1^ spectral range using a Fourier transform spectrometer. We carried out a global simultaneous fit by including a wide range of vibrational states. A total of 34 bands with v'=0-10 and v"=0-9 were rotationally assigned. Numerous discrepancies were found in the assignments and in the measured transition wavenumbers between the new measurements and previous results. Most of the measured transition wavenumbers and their assignments for relatively low-v bands agreed with published data. On the contrary, for high-v bands our line positions and assignments disagreed with the tabulated literature values. In particular, the lines of six bands involving the levels with v'=4, 5, and 6 are almost completely different from the previous work. Major sources of the disagreement are thought to be line congestion and perturbations found in these bands. From the analysis, perturbations for v'=0, 1, 2, 4, 6, 8, 9, and 10 in the d ^3^{Pi}_g_ state were identified. A study of these rotational perturbations suggest that some of them are likely caused by interactions with high-v levels of the b ^3^{Sigma}^-^_g_ state.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A138
- Title:
- Taffy system CO(1-0) datacube
- Short Name:
- J/A+A/647/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Taffy system (UGC 12914/15) consists of two massive spiral galaxies which had a head-on collision about 20Myr ago. New sensitive, high-resolution CO(1-0) observations of the Taffy system with the IRAM PdBI are presented. About 25% of the total interferometric CO luminosity stems from the bridge region. Assuming a Galactic N(H2)/ICO conversion factor for the galactic disks and a third of this value for the bridge gas, about 10% of the molecular gas mass is located in the bridge region. The giant HII region close to UGC 12915 is located at the northern edge of the high-surface brightness giant molecular cloud association (GMA), which has the highest velocity dispersion among the bridge GMAs. The bridge GMAs are clearly not virialized because of their high velocity dispersion. Three dynamical models are presented and while no single model reproduces all of the observed features, they are all present in at least one of the models. Most of the bridge gas detected in CO does not form stars. We suggest that turbulent adiabatic compression is responsible for the exceptionally high velocity dispersion of the molecular ISM and the suppression of star formation in the Taffy bridge. In this scenario the turbulent velocity dispersion of the largest eddies and turbulent substructures/clouds increase such that giant molecular clouds are no longer in global virial equilibrium. The increase of the virial parameter leads to a decrease of the star formation efficiency. Most of the low-surface density, CO-emitting gas will disperse without forming stars but some of the high-density gas will probably collapse and form dense star clusters, such as the luminous HII region close to UGC 12915. We suggest that globular clusters and super star clusters formed and still form through the gravitational collapse of gas previously compressed by turbulent adiabatic compression during galaxy interactions.
- ID:
- ivo://CDS.VizieR/J/A+A/449/583
- Title:
- Temperature effects on spectra of olivine particles
- Short Name:
- J/A+A/449/583
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The absorption spectra of the olivine particles of different Mg/Fe content were measured in the infrared spectral region between 5 and 100{mu}m, while the particles were continuously cooled down to 10K. Measurements independently carried out on different samples of synthetic forsterite, natural olivine, and synthetic fayalite at laboratories in Kyoto and Jena. The positions of the olivine infrared bands were measured for these samples in detail at up to seven individual temperatures in the interval between 300K and 10K. According to the different widths of the olivine bands in different wavelength regions, spectral resolutions of 2, 1, 0.5, 0.25, 0.2, and 0.125cm^-1^ were used in order to measure the band positions with high accuracy.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A33
- Title:
- Temperature evolution in massive clumps
- Short Name:
- J/A+A/603/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observational identification of a solid evolutionary sequence for high-mass star-forming regions is still missing. Spectroscopic observations give the opportunity to test possible schemes and connect the phases identified to physical processes. We aim to use the progressive heating of the gas caused by the feedback of high-mass young stellar objects to prove the statistical validity of the most common schemes used to observationally define an evolutionary sequence for high-mass clumps, and characterise the sensitivity of different tracers to this process. From the spectroscopic follow-ups carried out towards submillimeter continuum (dust) emission-selected massive clumps (the ATLASGAL TOP100 sample) with the IRAM 30m, Mopra, and APEX telescopes between 84GHz and 365GHz, we selected several multiplets of CH_3_N, CH_3_CH, and CH_3_H emission lines to derive and compare the physical properties of the gas in the clumps along the evolutionary sequence, fitting simultaneously the large number of lines that these molecules have in the observed band. Our findings are compared with results obtained from optically thin CO isotopologues, dust, and ammonia from previous studies on the same sample. The chemical properties of each species have a major role on the measured physical properties. Low temperatures are traced by ammonia, methanol, and CO (in the early phases), the warm and dense envelope can be probed with CH_3_N, CH_3_CH, and, in evolved sources where CO is abundant in the gas phase, via its optically thin isotopologues. CH_3_H and CH_3_N are also abundant in the hot cores, and we suggest that their high-excitation transitions are good tools to study the kinematics in the hot gas associated with the inner envelope surrounding the young stellar objects that these clumps are hosting. All tracers show, to different degrees according to their properties, progressive warming with evolution. The relation between gas temperature and the luminosity-to-mass (L/M) ratio is reproduced by a simple toy model of a spherical, internally heated clump.
- ID:
- ivo://CDS.VizieR/J/ApJ/728/70
- Title:
- The abundance of boron in diffuse clouds
- Short Name:
- J/ApJ/728/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive survey of boron abundances in diffuse interstellar clouds from observations made with the Space Telescope Imaging Spectrograph (STIS) of the Hubble Space Telescope. Our sample of 56 Galactic sight lines is the result of a complete search of archival STIS data for the BII{lambda}1362 resonance line, with each detection confirmed by the presence of absorption from OI{lambda}1355, CuII{lambda}1358, and GaII{lambda}1414 (when available) at the same velocity. Five previous measurements of interstellar BII from Goddard High Resolution Spectrograph (GHRS) observations are incorporated in our analysis, yielding a combined sample that more than quadruples the number of sight lines with significant boron detections. Our survey also constitutes the first extensive analysis of interstellar gallium from STIS spectra and expands on previously published results for oxygen and copper. The observations probe both high- and low-density diffuse environments, allowing the density-dependent effects of interstellar depletion to be clearly identified in the gas-phase abundance data for each element.