- ID:
- ivo://CDS.VizieR/J/A+A/647/A55
- Title:
- Rotational spectrum of propiolamide
- Short Name:
- J/A+A/647/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For all the amides detected in the interstellar medium (ISM), the corresponding nitriles or isonitriles have also been detected in the ISM, some of which have relatively high abundances. Among the abundant nitriles for which the corresponding amide has not yet been detected is cyanoacetylene (HCCCN), whose amide counterpart is propiolamide (HCCC(O)NH_2_). With the aim of supporting searches for this amide in the ISM, we provide a complete rotational study of propiolamide from 6GHz to 440GHz. Time-domain Fourier transform microwave (FTMW) spectroscopy under supersonic expansion conditions between 6GHz and 18GHz was used to accurately measure and analyze ground-state rotational transitions with resolved hyperfine structure arising from nuclear quadrupole coupling interactions of the 14N nucleus. We combined this technique with the frequency-domain roomtemperature millimeter wave and submillimeter wave spectroscopies from 75GHz to 440GHz in order to record and assign the rotational spectrain the ground state and in the low-lying excited vibrational states. We used the ReMoCA spectral line survey performed with the Atacama Large Millimeter/submillimeter Array toward the star-forming region Sgr B2(N) to search for propiolamide. We identified and measured more than 5500 distinct frequency lines of propiolamide in the laboratory. These lines were fitted using an effective semi-rigid rotor Hamiltonian with nuclear quadrupole coupling interactions taken into consideration. We obtained accurate sets of spectroscopic parameters for the ground state and the three low-lying excited vibrational states. We report the nondetection of propiolamide toward the hot cores Sgr B2(N1S) and Sgr B2(N2). We find that propiolamide is at least 50 and 13 times less abundant than acetamide in Sgr B2(N1S) and Sgr B2(N2), respectively, indicating that the abundance difference between both amides is more pronounced by at least a factor of 8 and 2, respectively, than for their corresponding nitriles. Although propiolamide has yet to be included in astrochemical modeling networks, the observed upper limit to the ratio of propiolamide to acetamide seems consistent with the ratios of related species as determined from past simulations. The comprehensive spectroscopic data presented in this paper will aid future astronomical searches.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/205/9
- Title:
- Rotational transition frequencies of HCOOCH_3_
- Short Name:
- J/ApJS/205/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cis-methyl formate molecule (HCOOCH_3_) is a well known molecule found in interstellar space. Recently, rotational lines of methyl formate in the first CH_3_ torsional excited state were observed in Orion KL and W51e2. It is quite natural to observe methyl formate in even higher vibrational states considering the temperature estimated in Orion KL and W51e2. Maeda et al. (2008JMoSp.251..293M) reported results on the laboratory spectroscopy of methyl formate including the spectral analysis in its second CH_3_ torsional state. Their assignments were limited to a series of a-type R-branch lines and low K_a_ b-type R-branch transitions, and many assigned lines are excluded in the least-squares analysis. In the present study, we extended the line assignments of both the A- and E-species transitions in the second CH_3_ torsional state especially in the frequency region below the 120GHz region. By combining the present assignments and those made by Maeda et al., 1951 transitions in total for the second CH_3_ torsional state, 1096 A-species transitions up to J=39, and K_a_=15 and 855 E-species transitions up to J=35 and K_a_=13, were least-squares analyzed by using the pseudo-principal-axis-method Hamiltonian with 42 parameters consisting of rotational, centrifugal distortion, and internal rotational constants in the second CH_3_ torsional state. In addition, 1012 transitions out of 1096 A-species transitions could also be least-squares analyzed by using Watson's A-reduced Hamiltonian with 43 parameters, which can serve to calculate the energy levels of the A-species lines of molecules with the CH_3_ internal rotation conveniently.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJS/169/28
- Title:
- Rotational transitions of Methyl carbamate
- Short Name:
- J/ApJS/169/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The rotational-torsional spectrum of the syn conformer of methyl carbamate [CH_3_OC(:O)NH_2_], an isomer of the essential amino acid glycine [NH_2_CH_2_C(:O)OH], has been recorded at room temperature in the spectral region from 79 to 371GHz. Methyl carbamate possesses a methyl group internal rotor, which gives rise to A and E torsional substates, and associated splittings in the rotational spectrum. Almost 6000 new rotational transitions arising from the vibrational ground state have been assigned, about half of them belonging to the E torsional substate. The Fast Scan Submillimeter-wave Spectroscopic Technique (FASSST) spectrometer at the Ohio State University was used for the present measurements
- ID:
- ivo://CDS.VizieR/J/PASP/109/759
- Title:
- Rotational Velocities of Intermediate-mass MS Stars
- Short Name:
- J/PASP/109/759
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (from Publ. Astron. Soc. Pac. 109, 759 (1997)) We analyze these rotation rates for a dependence on both mass and age. We compare the average rotation speeds of the field stars with mean velocities for young stars in Orion, the {Alpha} Persei cluster, the Pleiades, and the Hyades. The average rotation speeds of stars more massive than ~1.6 Msol experience little or no change during the evolutionary lifetimes of these stars on the zero age main sequence (ZAMS) or within the ZAMS band. Less massive stars in the range between 1.6 Msol and 1.3 Msol also show little decline in mean rotation rate while they are on the main sequence, and at most a factor of two decrease in velocity as they evolve off the main sequence. The e-folding time for the loss of angular momentum by the latter group of stars is at least 1-2 billion years. This inferred characteristic time scale for spindown is far longer than the established rotational braking time for solar-type stars with masses below ~1.3 Msol. We conclude from a comparison of the trends in rotation with trends in chromospheric and coronal activity that the overall decline in mean rotation speed along the main sequence, from ~2 Msol down to ~1.3 Msol, is imposed during the pre-main-sequence phase of evolution, and that this pattern changes little thereafter while the star resides on the main sequence. The magnetic activity must therefore play only a minor role in determining the rotation rates of the intermediate-mass stars, either because a solar-like dynamo is weak or absent, or else the geometry of the magnetic field is appreciably less effective in removing angular momentum from these stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/284/265
- Title:
- Rotational Velocities of 373 OB stars
- Short Name:
- J/MNRAS/284/265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of homogeneous measures of the linewidth parameter, v_e_.sin(i), for 373 O-type stars and early supergiants (including the separate components of 25 binary and triple systems), produced by cross-correlating high-resolution, short-wavelength IUE spectra against a `template' spectrum of {tau} Sco. We also tabulate terminal velocities. There are no O supergiants in our sample with v_e_.sin(i)<65km/s, and only one supergiant earlier than B5 has v_e_.sin(i)<50km/s, confirming that an important line broadening mechanism in addition to rotation must be present in these objects. A calibration of the area under the cross-correlation peak against spectral type is used to obtain estimates of continuum intensity ratios of the components in 28 spectroscopically binary or multiple systems. At least seven SB2 systems show evidence for the `Struve-Sahade effect', a systematic variation in relative line strength as a function of orbital phase. The stellar wind of the most rapid rotator in our sample, the O9III:n* star HD 191423 (v_e_.sin(i)<=436km/s), show it to have a `wind-compressed disc' similar to that of HD 93521; this star and other rapid rotators are good candidates for studies of non-radial pulsation.
- ID:
- ivo://CDS.VizieR/J/AJ/114/2402
- Title:
- Rotation curves of early-type galaxies
- Short Name:
- J/AJ/114/2402
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical long-slit rotation curves have been studied for 304 northern Sb-Sc galaxies from the Courteau-Faber (CF) sample designed for Tully-Fischer (TF) applications; r-band photometry exists also for each galaxy of the sample. The procedure of rotation curve (RC) extraction and construction of optical profiles are analogous to 21cm integrated linewidths. More than 20% of the galaxies were observed twice or more, allowing for a proper determination of systematic errors. Various measures of maximum rotational velocity to be used as input in the TF relation are tested on the basis of their repeatability, minimization of TF scatter, and match with 21cm linewidths. The best measure of TF velocity, V2.2 is given at the location of peak rotational velocity of a pure exponential disk. An alternative measure to V2.2 which makes no assumption about the luminosity profile or shape of the rotation curve is Vhist, the 20% width of the velocity histogram, though the match with 21cm linewidths is not good. The paper shows that optical TF calibrations yield internal scatter comparable to, if not smaller than, the best calibrations based on single-dish 21cm radio linewidths. Tables 6 and 7 contain the values of the parameters fitting the rotation curves of two samples of galaxies: the CF (Courteau-Faber) sample (table6) and the MAT (Mathewson et al., 1992ApJS...81..413M) sample (table7). Two fitting models were used: the ArcTan function (Model 1) where the velocity varies as v(r) = v(0) + K . arctan(R) (R being (r-r_0_)/r_t_) and a multi-parameter function (Model 2) modelling the rotation curve close to a solid-body close to the rotation center, and close to a flat rotation at large distances (see section 5 of the paper).
- ID:
- ivo://CDS.VizieR/J/AJ/111/696
- Title:
- Rotation curves of Seyfert galaxies with companions
- Short Name:
- J/AJ/111/696
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents imaging and optical spectroscopy of paired Seyfert galaxies and their companions. The aim is to seek common properties of Seyfert galaxies in interacting systems, which might provide evidence of AGN triggering in a way independent of the usual two-sample statistics which have proven ambiguous on this issue. Three kinds of comparison have been made -- the kinds of interactions involving Seyfert galaxies, the relative luminosities of the Seyferts and their companions, and the level of kinematic disturbance as measured from rotation curves. (1) Dynamics and tidal features have been used to determine (or at least limit) the sense of orbital motion (direct/ retrograde/polar with respect to the Seyfert galaxy's disk) for many of these pairs. There is no obviously preferred kind of interaction -- direct, polar, and retrograde encounters are all well represented, despite the gross differences in dynamical response of a disk to these various kinds of encounter. To the extent that triggering of Seyfert nuclei occurs due to tidal encounters, the existence of a perturbation seems more important than its exact duration or detailed effects on the disk. However, the ratio of merging to paired Seyferts is higher than for disk galaxies in general, consistent with more effective triggering of AGN in this specific phase; the implied time scale for enhanced occurrence during mergers is the same as the timescape for merger remnants to appear as such, a few disk-edge crossing times (typically several times 10^8yr). (2) Seyfert nuclei occur preferentially in the brighter members of galaxy pairs, by a median of 0.93mag after making the maximal correction for contaminating nonstellar light in the nuclei. Only about 1/3 of this effect can be accounted for by the known tendency of Seyfert nuclei to occur in more luminous galaxies. Enhancement of AGN by interactions is evidently more effective for more luminous galaxies (though this will also be the case if both star formation and AGN occurrence are enhanced in the same galaxies). (3) The rotation curves of the paired Seyferts show systematically small regions of rising or solid-body rotation compared to the disk radius, as a group comparable to Sa but very different from Sb or Sc galaxies (even for Seyfert galaxies with Hubble type later than Sa). There is weak evidence that this difference is also present with respect to more isolated Seyfert galaxies. Despite the obvious utility of a dynamically disturbed disk for transport of angular momentum and "feeding the monster," Seyfert galaxies in pairs actually have smaller kinematic disturbances (measured by the maximum departure from a symmetric rotation curve, normalized to the full rotation amplitude) than found in a complete sample of non-Seyfert spirals in pairs.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/102
- Title:
- Rotation velocity & dynamical mass of gal. from HI sp.
- Short Name:
- J/ApJ/898/102
- Date:
- 21 Mar 2022 08:49:45
- Publisher:
- CDS
- Description:
- The integrated 21cm HI emission profile of a galaxy encodes valuable information on the kinematics, spatial distribution, and dynamical state of its cold interstellar medium. The line width, in particular, reflects the rotation velocity of the galaxy, which, in combination with a size scale, can be used to constrain the dynamical mass of the system. We introduce a new method based on the concept of the curve of growth to derive a set of robust parameters to characterize the line width, asymmetry, and concentration of the integrated HI spectra. We use mock spectra to evaluate the performance of our method, to estimate realistic systematic uncertainties for the proposed parameters, and to correct the line widths for the effects of instrumental resolution and turbulence broadening. Using a large sample of nearby galaxies with available spatially resolved kinematics, we demonstrate that the newly defined line widths can predict the rotational velocities of galaxies to within an accuracy of <~30km/s. We use the calibrated line widths, in conjunction with the empirical relation between the size and mass of HI disks, to formulate a prescription for estimating the dynamical mass within the HI-emitting region of gas-rich galaxies. Our formalism yields dynamical masses accurate to ~0.3dex based solely on quantities that can be derived efficiently and robustly from current and future extragalactic HI surveys. We further extend the dynamical mass calibration to the scale of the dark matter halo.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/76
- Title:
- Rot. velocities of APOGEE stars in Kepler field
- Short Name:
- J/ApJ/898/76
- Date:
- 21 Mar 2022 08:47:46
- Publisher:
- CDS
- Description:
- We use 5337 spectroscopic vsini measurements of Kepler dwarfs and subgiants from the APOGEE survey to study stellar rotation trends. We find a detection threshold of 10km/s, which allows us to explore the spindown of intermediate-mass stars leaving the main sequence, merger products, young stars, and tidally synchronized binaries. We see a clear distinction between blue stragglers and the field turnoff in {alpha}-rich stars, with a sharp rapid rotation cutoff for blue stragglers consistent with the Kraft break. We also find rapid rotation and radial velocity variability in a sample of red straggler stars, considerably cooler than the giant branch, lending credence to the hypothesis that these are active, tidally synchronized binaries. We see clear evidence for a transition between rapid and slow rotation on the subgiant branch in the domain predicted by modern angular momentum evolution models. We find substantial agreement between the spectroscopic and photometric properties of KIC targets added by Huber+ (2014, J/ApJS/211/2) based on Two Micron All Sky Survey photometry. For the unevolved lower main sequence, we see the same concentration toward rapid rotation in photometric binaries as that observed in rotation period data, but at an enhanced rate. We attribute this difference to unresolved near-equal-luminosity spectroscopic binaries with velocity displacements on the order of the APOGEE resolution. Among cool unevolved stars we find an excess rapid rotator fraction of 4% caused by pipeline issues with photometric binaries.
