- ID:
- ivo://CDS.VizieR/J/A+A/657/A24
- Title:
- HCCCHCN laboratory observations
- Short Name:
- J/A+A/657/A24
- Date:
- 21 Mar 2022 09:22:16
- Publisher:
- CDS
- Description:
- The reaction between carbon atoms and vinyl cyanide, CH_2_CHCN, is a possible formation route for interstellar 3-cyano propargyl radical, CH_2_C_3_N. 1-Cyano propargyl radical (HC_3_HCN), an isomer of CH_2_C_3_N, is predicted to be produced in the same reaction at least twice more efficiently than CH_2_C_3_N. Hence, HC_3_HCN is a plausible candidate to be observed in space as well. We aim to generate HC_3_HCN radical in the gas phase in order to investigate its rotational spectrum. The derived spectroscopic parameters for this species will be use to obtain reliable frequency predictions to support its detection in the space. Rotational spectrum of HC_3_HCN radical was produce by electric discharges and characterized using a Balle-Flygare narrowband type Fourier-transform microwave (FTMW) spectrometer operating in the frequency region of 4-40GHz. The spectral analysis was supported by high-level ab initio calculations. A total of 193 hyperfine components originated from twelve rotational transitions, a- and b-type, were measured for HC_3_HCN radical. The analysis allowed us to accurately determine twenty-two molecular constants, including rotational and centrifugal distortion constants as well as the fine and hyperfine constants. Transition frequency predictions were used to search for HC_3_HCN radical in TMC-1 using the QUIJOTE survey between 30.1-50.4GHz. We can not confirm the presence of HC_3_HCN in TMC-1 and obtain an upper limit to the column density of HC_3_HCN in TMC-1 of 6.0*10^11^cm^-2^.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/821/113
- Title:
- HCG and RSCG compact group galaxies with WISE
- Short Name:
- J/ApJ/821/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Compact groups provide an environment to study the growth of galaxies amid multiple prolonged interactions. With their dense galaxy concentrations and relatively low velocity dispersions, compact groups mimic the conditions of hierarchical galaxy assembly. Compact group galaxies are known to show a bimodality in Spitzer IRAC infrared color space: galaxies are preferentially either quiescent with low specific star formation rates (SSFRs) or prolifically forming stars-galaxies with moderate levels of specific star formation are rare. Previous Spitzer IRAC studies identifying this "canyon" have been limited by small number statistics. We utilize whole-sky Wide-field Infrared Survey Explorer (WISE) data to study 163 compact groups, thereby tripling our previous sample and including more galaxies with intermediate mid-IR colors indicative of moderate SSFRs. We define a distinct WISE mid-IR color space (log[f_12_/f_4.6_]) versus (log[f_22_/f_3.4_]) that we use to identify canyon galaxies from the larger sample. We confirm that compact group galaxies show a bimodal distribution in the mid-infrared and identify 37 canyon galaxies with reliable photometry and intermediate mid-IR colors. Morphologically, we find that the canyon harbors a large population of both Sa-Sbc and E/S0 type galaxies, and that they fall on the optical red sequence rather than the green valley. Finally, we provide a catalog of WISE photometry for 567 of 652 galaxies selected from the sample of 163 compact groups.
7943. HCG HI-deficiency
- ID:
- ivo://CDS.VizieR/J/A+A/325/473
- Title:
- HCG HI-deficiency
- Short Name:
- J/A+A/325/473
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present HI observations of 54 Hickson Compact Groups (HCG) of which 41 have been detected in the 21-cm line of neutral hydrogen. For 13 objects upper limits have been obtained. The integrated M_HI_/L_B_ values of the observed HCGs scatter over a large range of values showing strong HI-deficiencies for a great number of objects.
- ID:
- ivo://CDS.VizieR/J/A+A/656/A146
- Title:
- HCN and CN emission in Serpens Main region
- Short Name:
- J/A+A/656/A146
- Date:
- 21 Mar 2022 09:00:12
- Publisher:
- CDS
- Description:
- Ultraviolet radiation (UV) influences the physics and chemistry of star-forming regions, but its properties and significance in the immediate surroundings of low-mass protostars are still poorly understood. We aim to extend the use of the CN/HCN ratio, already established for high-mass protostars, to the low-mass regime to trace and characterize the UV field around low-mass protostars on ~0.6x0.6pc scales. The spatial distribution of HCN and CS are well-correlated with CO 6-5 emission that traces outflows. The CN emission is extended from the central protostars to their immediate surroundings also tracing outflows, likely as a product of HCN photodissociation. The ratio of CN to HCN total column densities ranges from ~1 to 12 corresponding to G_0_~10^1^-10^3^ for gas densities and temperatures typical for outflows of low-mass protostars. UV radiation associated with protostars and their outflows is indirectly identified in a significant part of the Serpens Main low-mass star-forming region. Its strength is consistent with the values obtained from the OH and H_2_O ratios observed with Herschel and compared with models of UV-illuminated shocks. From a chemical viewpoint, the CN to HCN ratio is an excellent tracer of UV fields around low- and intermediate-mass star-forming regions.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A118
- Title:
- HCN(1-0) cube for the nucleus of M51
- Short Name:
- J/A+A/593/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AGN feedback is invoked as one of the most relevant mechanisms that shape the evolution of galaxies. Our goal is to understand the interplay between AGN feedback and the interstellar medium in M51, a nearby spiral galaxy with a modest AGN and a kpc-scale radio jet expanding through the disc of the galaxy. For that, we combine molecular gas observations in the CO(1-0) and HCN(1-0) lines from the Plateau de Bure interferometer with archival radio, X-ray, and optical data. We show that there is a significant scarcity of CO emission in the ionisation cone, while molecular gas emission tends to accumulate towards the edges of the cone. The distribution and kinematics of CO and HCN line emission reveal AGN feedback effects out to r~500pc, covering the whole extent of the radio jet, with complex kinematics in the molecular gas which displays strong local variations. We propose that this is the result of the almost coplanar jet pushing on molecular gas in different directions as it expands; the effects are more pronounced in HCN than in CO emission, probably as the result of radiative shocks. Following previous interpretation of the redshifted molecular line in the central 5" as caused by a molecular outflow, we estimate the outflow rates to be Mdot_H2~0.9M_{sun}_/yr and dM/dt_dense_~0.6M_{sun}_/yr, which are comparable to the molecular inflow rates (~1M_{sun}_/yr); gas inflow and AGN feedback could be mutually regulated processes. The agreement with findings in other nearby radio galaxies suggests that this is not an isolated case, and probably the paradigm of AGN feedback through radio jets, at least for galaxies hosting low-luminosity active nuclei.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A129
- Title:
- HCN, HNC and DNC spectra of 27 sources
- Short Name:
- J/A+A/609/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ratio between the two stable isotopes of nitrogen, ^14^N and ^15^N, is well measured in the terrestrial atmosphere (~272), and for the pre-solar nebula (~441, deduced from the solar wind). Interestingly, some pristine solar system materials show enrichments in 15N with respect to the pre-solar nebula value. However, it is not yet clear if and how these enrichments are linked to the past chemical history because we have only a limited number of measurements in dense star-forming regions. In this respect, dense cores, which are believed to be the precursors of clusters and also contain intermediate- and high-mass stars, are important targets because the solar system was probably born within a rich stellar cluster, and such clusters are formed in high-mass star-forming regions. The number of observations in such high-mass dense cores has remained limited so far. In this work, we show the results of IRAM-30m observations of the J=1-0 rotational transition of the molecules HCN and HNC and their 15N-bearing counterparts towards 27 intermediate- and high-mass dense cores that are divided almost equally into three evolutionary categories: high-mass starless cores, high-mass protostellar objects, and ultra-compact Hii regions. We have also observed the DNC(2-1) rotational transition in order to search for a relation between the isotopic ratios D/H and ^14^N/^15^N. We derive average ^14^N/^15^N ratios of 359+/-16 in HCN and of 438+/-21 in HNC, with a dispersion of about 150-200. We find no trend of the ^14^ N/^15^ N ratio with evolutionary stage. This result agrees with what has been found for N_2_H^+^ and its isotopologues in the same sources, although the ^14^N/^15^N ratios from N2H+ show a higher dispersion than in HCN/HNC, and on average, their uncertainties are larger as well. Moreover, we have found no correlation between D/H and ^14^N/^15^N in HNC. These findings indicate that (1) the chemical evolution does not seem to play a role in the fractionation of nitrogen, and that (2) the fractionation of hydrogen and nitrogen in these objects is not related.
- ID:
- ivo://CDS.VizieR/J/ApJ/903/111
- Title:
- HCN, HNC, H13CN & HC3N of Galactic Center map. II.
- Short Name:
- J/ApJ/903/111
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- We report a statistical analysis exploring the origin of the overall low star formation efficiency (SFE) of the Galactic central molecular zone (CMZ) and the SFE diversity among the CMZ clouds using a wide-field HCN J=4-3 map, whose optically thin critical density (~10^7^/cm^3^) is the highest among the tracers ever used in CMZ surveys. Logistic regression is performed to empirically formulate star formation probability of 195 HCN clumps, 13 of which contain star formation signatures. The explanatory parameters in the best-fit model are reduced into the virial parameter {alpha}_vir_ without significant contribution from other parameters, whereas the performance of the model without {alpha}_vir_ is no better than that using randomly generated data. The threshold {alpha}_vir_ is 6, which translates into a volume density (n_H_2__) of 10^4.6^/cm^3^ with the n_H_2__-{alpha}_vir_ correlation. The scarcity of the low-{alpha}_vir_ clumps, whose fraction to all HCN clumps is 0.1, can be considered as one of the immediate causes of the suppressed SFE. No correlation between the clump size or mass and star formation probability is found, implying that HCN J= 4-3 does not immediately trace the mass of star-forming gas above a threshold density. Meanwhile, star-forming and non-star-forming clouds are degenerate in the physical parameters of the CS J=1-0 clouds, highlighting the efficacy of the HCN J=4-3 line to probe star-forming regions in the CMZ. The timescale of the high-{alpha}_vir_ to low-{alpha}_vir_ transition is <~2Myr, which is consistent with the tidal compression and X1/X2 orbit transition models but possibly does not fit the cloud-cloud collision picture.
7948. H13CN/HN13C linelist
- ID:
- ivo://CDS.VizieR/VI/131
- Title:
- H13CN/HN13C linelist
- Short Name:
- VI/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A linelist of vibration-rotation transitions for ^13^C substituted HCN is presented. The line list is constructed using known experimental levels where available, calculated levels and ab initio line intensities originally calculated for the major isotopologue. Synthetic spectra are generated and compared with observations for cool carbon star WZ Cas. It is suggested that high resolution HCN spectra recorded near 14um should be particularly sensitive to the ^13^C-^12^C ratio.
7949. HC_3_N in Orion KL
- ID:
- ivo://CDS.VizieR/J/A+A/559/A51
- Title:
- HC_3_N in Orion KL
- Short Name:
- J/A+A/559/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of cyanoacetylene (HC_3_N) and cyanodiacetylene (HC_5_N) in Orion KL, using observations from two line surveys performed with the IRAM 30-m telescope and the HIFI instrument onboard the Herschel telescope. The frequency ranges covered are 80-280GHz and 480-1906GHz. This study (divided by families of molecules) is part of a global analysis of the physical conditions of Orion KL and the molecular abundances in the different components of this cloud. We modeled the observed lines of HC_3_N, HC_5_N, their isotopologues (including DC_3_N), and vibrational modes using a non-local thermodynamic equilibrium (non-LTE) radiative transfer code. In addition, to investigate the chemical origin of HC_3_N and DC_3_N in Orion KL, we used a time-dependent chemical model.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A4
- Title:
- HCN-to-HNC intensity ratio
- Short Name:
- J/A+A/635/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The gas kinetic temperature (TK) determines the physical and chemical evolution of the interstellar medium (ISM). However, obtaining reliable TK estimates usually requires expensive observations including the combination of multi-line analysis and dedicated radiative transfer calculations. This work explores the use of HCN and HNC observations, and particularly the I(HCN)-to-I(HNC) intensity ratio (I(HCN)/I(HNC)) of their J=1-0 lines, as direct probe of the gas kinetic temperature in the molecular ISM. We obtained a new set of large-scale observations of the HCN and HNC (1-0) lines throughout the Integral Shape Filament (ISF) in Orion. In combination with ancillary gas and dust temperature measurements, we find a systematic temperature dependence of the observed I(HCN)-to-I(HNC) intensity ratio throughout our maps. Additional comparisons with chemical models demonstrate that these observed I(HCN)/I(HNC) variations are driven by the effective destruction and isomerization mechanisms of HNC under low-energy barriers. The observed variations of I(HCN)/I(HNC) with TK can be described with a two-part linear function. This empirical calibration is then used to create a temperature map of the entire ISF. Comparisons with similar dust temperature measurements in this cloud, as well as in other regions and galactic surveys, validate this simple technique for obtaining direct estimates of the gas kinetic temperature in a wide range of physical conditions and scales with an optimal working range between 15K<TK<=40K. Both observations and models demonstrate the strong sensitivity of the I(HCN)/I(HNC) ratio to the gas kinetic temperature. Since these lines are easily obtained in observations of local and extragalactic sources, our results highlight the potential use of this observable as new chemical thermometer for the ISM.