- ID:
- ivo://CDS.VizieR/J/ApJ/855/21
- Title:
- Improved A^3^{Pi}-X^3^{Sigma}^-^ transitions of OH+
- Short Name:
- J/ApJ/855/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Molecular ions are key reaction intermediates in the interstellar medium. OH+ plays a central role in the formation of more complex chemical species and for estimating the cosmic ray ionization rate in astrophysical environments. Here, we use a recent analysis of a laboratory spectrum in conjunction with ab initio methods to calculate infrared and ultraviolet oscillator strengths. These new oscillator strengths include branch dependent intensity corrections, arising from the Herman-Wallis effect, that have not been included before. We estimate 10% total uncertainty in the UV and 6% total uncertainty in the IR for the oscillator strengths.
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- ID:
- ivo://CDS.VizieR/J/ApJ/849/139
- Title:
- Interstellar acetone (CH_3_COCH_3_) in 3 regions
- Short Name:
- J/ApJ/849/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of interstellar acetone (CH_3_COCH_3_) detected in broadband line surveys in the 1.3mm band from the Caltech Submillimeter Observatory (CSO). The observations were conducted toward three massive star-forming regions: GAL31.41+0.31, GAL034.3+00.2, and GAL10.47+00.03. Numerous acetone lines were detected in these three sources. The results were analyzed using the assumption of local thermodynamic equilibrium. These results rigorously confirm the previous reports of acetone detections in GAL31.41+0.31 and GAL10.47+00.03, and add a new acetone detection in GAL034.3+00.2. Source-averaged column densities for acetone were determined to be 1.1(6)x10^16^cm^-2^ for GAL31.41+0.31, 6.4(3)x10^16^cm^-2^ for GAL10.47+00.03, and 1.3(3)x10^15^cm^-2^ for GAL034.3+00.2. The rotational temperatures of acetone in these three sources range from 49 to 132K, which suggests a complicated formation mechanism for interstellar acetone.
- ID:
- ivo://CDS.VizieR/J/ApJS/234/6
- Title:
- IR absorbance spectra of CH4, C2H6, C3H8 & C4H10
- Short Name:
- J/ApJS/234/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The only known phosphorus-containing organic compounds of extraterrestrial origin, alkylphosphonic acids, were discovered in the Murchison meteorite and have accelerated the hypothesis that reduced oxidation states of phosphorus were delivered to early Earth and served as a prebiotic source of phosphorus. While previous studies looking into the formation of these alkylphosphonic acids have focused on the iron-nickel phosphide mineral schreibersite and phosphorous acid as a source of phosphorus, this work utilizes phosphine (PH3), which has been discovered in the circumstellar envelope of IRC +10216, in the atmosphere of Jupiter and Saturn, and believed to be the phosphorus carrier in comet 67P/Churyumov-Gerasimenko. Phosphine ices prepared with interstellar molecules such as carbon dioxide, water, and methane were subjected to electron irradiation, which simulates the secondary electrons produced from galactic cosmic rays penetrating the ice, and probed using infrared spectroscopy to understand the possible formation of alkylphosphonic acids and their precursors on interstellar icy grains that could become incorporated into meteorites such as Murchison. We present the first study and results on the possible synthesis of alkylphosphonic acids produced from phosphine-mixed ices under interstellar conditions. All functional groups of alkylphosphonic acids were detected through infrared spectroscopically, suggesting that this class of molecules can be formed in interstellar ices.
- ID:
- ivo://CDS.VizieR/J/A+A/642/L7
- Title:
- IRAS 04302+2247 CO, CS, CN, H2CO, CH3OH maps
- Short Name:
- J/A+A/642/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemical composition of planets is inherited from that of the natal protoplanetary disk at the time of planet formation. Increasing observational evidence suggests that planet formation occurs in less than 1-2Myr. This motivates the need for spatially resolved spectral observations of young Class I disks, as carried out by the ALMA chemical survey of Disk-Outflow sources in Taurus (ALMA-DOT). In the context of ALMA-DOT, we observe the edge-on disk around the Class I source IRAS 04302+2247 (the butterfly star) in the 1.3mm continuum and five molecular lines. We report the first tentative detection of methanol (CH_3_OH) in a Class I disk and resolve, for the first time, the vertical structure of a disk with multiple molecular tracers. The bulk of the emission in the CO 2-1, CS 5-4, and o-H_2_CO 3_1,2_-2_1,1_ lines originates from the warm molecular layer, with the line intensity peaking at increasing disk heights, z, for increasing radial distances, r. Molecular emission is vertically stratified, with CO observed at larger disk heights (aperture z/r~0.41-0.45) compared to both CS and H2CO, which are nearly cospatial (z/r~0.21-0.28). In the outer midplane, the line emission decreases due to molecular freeze-out onto dust grains (freeze-out layer) by a factor of >100 (CO) and 15 (CS). The H_2_CO emission decreases by a factor of only about 2, which is possibly due to H2CO formation on icy grains, followed by a nonthermal release into the gas phase. The inferred [CH_3_OH]/[H_2_CO] abundance ratio is 0.5-0.6, which is 1-2 orders of magnitude lower than for Class 0 hot corinos, and a factor ~2.5 lower than the only other value inferred for a protoplanetary disk (in TW Hya, 1.3-1.7). Additionally, it is at the lower edge but still consistent with the values in comets. This may indicate that some chemical reprocessing occurs in disks before the formation of planets and comets.
- ID:
- ivo://CDS.VizieR/J/ApJS/233/24
- Title:
- Iso-propyl cyanide rotational study
- Short Name:
- J/ApJS/233/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A detailed analysis of the rotational spectra of the interstellar iso-propyl cyanide has been carried out up to 480GHz using three different high-resolution spectroscopic techniques. Jet-cooled broadband chirped pulse Fourier transform microwave spectroscopy from 6 to 18GHz allowed us to measure and analyze the ground-state rotational transitions of all singly substituted ^13^C and ^15^N isotopic species in their natural abundances. The monohydrate of iso-propyl cyanide, in which the water molecule bounds through a stronger O-H...N and weaker bifurcated (C-H)_2_...O hydrogen bonds in a C_s_ configuration, has also been detected in the supersonic expansion. Stark-modulation spectroscopy in the microwave and millimeter wave range from 18 to 75GHz allowed us to analyze the vibrational satellite pattern arising from pure rotational transitions in the low-lying vibrational excited states. Finally, assignments and measurements were extended through the millimeter and submillimeter wave region. The room temperature rotational spectra made possible the assignment and analysis of pure rotational transitions in 19 vibrationally excited states. Significant perturbations were found above 100GHz in most of the observed excited states. Due to the complexity of the interactions and importance of this astrophysical region for future radioastronomical detection, both a graphical plot approach and a coupled fit have been used to assign and measure almost 10000 new lines.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A179
- Title:
- Laboratory spectroscopy of isotopic c-H2C3O
- Short Name:
- J/A+A/647/A179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cyclopropenone was first detected in the cold and less dense envelope of the giant molecular cloud Sagittarius B2(N). It was found later in several cold dark clouds and it may be possible to detect its minor isotopic species in these environments. In addition, the main species may well be identified in warmer environments. We aim to extend existing line lists of isotopologs of c-H_2_C_3_O from the microwave to the millimeter region and create one for the singly deuterated isotopolog to facilitate their detections in space. Furthermore, we aim to extend the line list of the main isotopic species to the submillimeter region and to evaluate an equilibrium structure of the molecule.
- ID:
- ivo://CDS.VizieR/J/MNRAS/497/1972
- Title:
- LEGO II. 3mm molecular line study
- Short Name:
- J/MNRAS/497/1972
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The current generation of (sub)mm-telescopes have allowed molecular line emission to become a major tool for studying the physical, kinematic, and chemical properties of extra-galactic systems, yet exploiting these observations requires a detailed understanding of where emission lines originate within the Milky Way. In this paper, we present 60" (~3pc) resolution observations of many 3mm-band molecular lines across a large map of the W49 massive star-forming region (~100pcx100pc at 11kpc), which were taken as part of the "LEGO" IRAM-30m large project. We find that the spatial extent or brightness of the molecular line transitions are not well correlated with their critical densities, highlighting abundance and optical depth must be considered when estimating line emission characteristics. We explore how the total emission and emission efficiency (i.e. line brightness per H_2_ column density) of the line emission vary as a function of molecular hydrogen column density and dust temperature. We find that there is not a single region of this parameter space responsible for the brightest and most efficiently emitting gas for all species. For example, we find that the HCN transition shows high emission efficiency at high column density (10^22^cm^-2^) and moderate temperatures (35K), whilst e.g. N_2_H^+^ emits most efficiently towards lower temperatures (10^22^cm^-2^; <20K). We determine X_CO(1-0)_~0.3x10^20^cm^-2^/(K.km/s), and {alpha}_HCN(1-0)_~30M_{sun}_/(K.(km/s)pc^2^), which both differ significantly from the commonly adopted values. In all, these results suggest caution in interpreting molecular line emission.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/8
- Title:
- Line lists for X^1^{Sigma}^+^ AlF and AlCl
- Short Name:
- J/ApJS/237/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Vibration-rotation line lists for AlF, Al^35^Cl, and Al^37^Cl have been prepared in their ground electronic states (X^1^{Sigma}^+^). Experimental rotational and ro-vibrational lines were employed to calculate a potential energy surface (PES) by direct potential fitting. The PES was used to calculate ro-vibrational energy levels. Born-Oppenheimer Breakdown corrections were included in the energy level calculations for AlCl. Ro-vibrational energy levels were calculated for the v=0 to v=11 vibrational levels and up to Jmax=200 for the rotational levels. Dipole moment functions covering the range of the PES turning points were calculated for AlCl and AlF by ab initio methods and used to determine line intensities. Partition functions for temperatures up to 3000K were calculated. AlF and AlCl have been detected in circumstellar envelopes and are predicted to occur in cool stellar and sub- stellar atmospheres.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/8
- Title:
- Line lists for X^1^{Sigma}^+^ LiF and LiCl
- Short Name:
- J/ApJS/235/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Vibration-rotation line lists for ^6^LiF, ^7^LiF, ^6^Li^35^Cl, ^6^Li^37^Cl, ^7^Li^35^Cl, and ^7^Li^37^Cl in the X^1^{Sigma}^+^ ground states have been prepared. The rovibrational energy levels have been calculated using potential energy surfaces determined by direct potential-fitting employing the rotational and rovibrational transition frequencies of all isotopologues, and required the inclusion of Born-Oppenheimer breakdown terms. Dipole moment functions calculated ab initio at the MRCI/aug-cc-pwCV5Z level have been used for line strength calculations. Partition functions for temperatures up to 5000K have been calculated. LiF and LiCl are predicted to be present in the atmospheres of hot rocky exoplanets, brown dwarfs, and cool stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/236/46
- Title:
- Line positions for TiO singlet states
- Short Name:
- J/ApJS/236/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A consistent set of spectroscopic constants for the a^1^{Delta}, d^1^{Sigma}^+^, b^1^{Pi}, c^1^{Phi}, and f^1^{Delta} states of ^48^Ti^16^O has been determined from analysis of the b^1^{Pi}-a^1^{Delta}, b^1^{Pi}-d^1^{Sigma}^+^, c^1^{Phi}-a^1^{Delta}, and f^1^{Delta}-a^1^{Delta} systems. Three Fourier transform emission spectra have been used for the analysis. New bands of the b^1^{Pi}-a^1^{Delta} and c^1^{Phi}-a^1^{Delta} systems have been fitted. The first analysis of the c^1^{Phi}-a^1^{Delta} system using Fourier transform spectra is also provided. Extensive and improved line positions are measured. TiO is prominent in the spectra of oxygen-rich cool stellar objects and may be present in hot-Jupiter exoplanet atmospheres.
