Vibration-rotational and rotational intensities for CO isotopes

Abstract. -We report new calculations of transition matrix elements for more than thirty thousand infrared lines of the CO molecule and its isotopomers inside the X 1 Σ + ground electronic state. These lines belong to the ∆v=1, 2, 3 bands involving very high excited states such as v ≤41 and J ≤133. The transition matrix elements have been calculated from an accurate solution of the Schrödinger equation by using two different theoretical electric dipole moment functions (Werner 1981;Langhoff & Bauschlicher 1995). For low lying levels, our data compare satisfactorily with experimental ones and related works (Goorvitch & Chackerian 1994a, b;Chackerian et al. 1994, Goorvitch 1994. Moreover, we make predictions for oscillator strengths and Einstein coefficients involving high excited transitions. In addition, we report simple analytic formulae that fit our results for 12 C 16 O with an accuracy better than 10 −2 as a function of m = [J (J + 1) − J (J + 1)]/2 for each vibrational sequence and band. They offer an easy way to compute the various intensities of these rovibrational transitions whose transition energies may be introduced via the available Dunham coefficients.

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“…This is not the case when two experimental EDMFs Tipping 1983 andChackerian et al 1984) are compared as shows Goorvitch (1994) in his Table 5.…”

Section: Calculations and Discussionmentioning

confidence: 93%

Analytic representations of rovibrational dipole matrix elements for the CO molecule and its isotopomers

Huré

Roueff

1996

Astron. Astrophys. Suppl. Ser.

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“…These values are also presented in Table 6. Then, the 13 CO column density can be calculated as follows (Garden et al 1991): where B=55101.012 MHz is the rotational constant, μ D =0.11 debyes is the permanent dipole moment for 13 CO, and J is the rotational quantum number of the lower state in the observed transition (Chackerian & Tipping 1983). In this paper, we adopt a typical abundance ratio of Hawkins & Jura (1987) for the solar neighborhood and the ratio of ∼70 in the Galaxy shown by Penzias (1980).…”

Section: Results Of Pmo Molecular Linesmentioning

confidence: 99%

The Properties of Planck Galactic Cold Clumps in the L1495 Dark Cloud

Tang¹,

Liu

Qin³

et al. 2018

ApJ

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Planck Galactic Cold Clumps (PGCCs) possibly represent the early stages of star formation. To understand better the properties of PGCCs, we studied 16 PGCCs in the L1495 cloud with molecular lines and continuum data from Herschel, JCMT/SCUBA-2, and the PMO 13.7 m telescope. Thirty dense cores were identified in 16 PGCCs from 2D Gaussian fitting. The dense cores have dust temperatures of T d =11-14 K, and H 2 column densities of N H 2 =(0.36-2.5)×1022 cm −2 . We found that not all PGCCs contain prestellar objects. In general, the dense cores in PGCCs are usually at their earliest evolutionary stages. All the dense cores have non-thermal velocity dispersions larger than the thermal velocity dispersions from molecular line data, suggesting that the dense cores may be turbulence-dominated. We have calculated the virial parameter α and found that 14 of the dense cores have α <2, while 16 of the dense cores have α >2. This suggests that some of the dense cores are not bound in the absence of external pressure and magnetic fields. The column density profiles of dense cores were fitted. The sizes of the flat regions and core radii decrease with the evolution of dense cores. CO depletion was found to occur in all the dense cores, but is more significant in prestellar core candidates than in protostellar or starless cores. The protostellar cores inside the PGCCs are still at a very early evolutionary stage, sharing similar physical and chemical properties with the prestellar core candidates.

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“…5 and 7 below, where we adopted a conservative error bar of ±0.2 dex in the CNO abundances by Harris & Lambert). Goortvitch (1994) indeed reported differences up to 3% in the A-values with respect to Chackerian & Tipping (1983) and up to a factor ∼6 in the dipole moments in some of the CO isotopes. On the other hand, note that the isotopic lines used are very weak so that the choice of the specific lines might affect the results, in a systematic manner (see above the discussion on the selection of the lines) if there is a systematic difference in the continuum placement.…”

Section: Analysis Of the C And O Ratiosmentioning

confidence: 97%

“…In particular, the 16 O/ 17 O and 16 O/ 18 O ratios increase. Secondly, the gf-values of the CO lines used by Harris & Lambert (1984) were obtained from Chackerian & Tipping (1983), while here we used those by Goorvitch (1994) on the basis of a more up-to-date electric dipole moment function. As a consequence, 7 These authors give only the C abundance derived ([C/H] = −0.7 and −0.3, respectively) without any indication of the N and O abundances derived/adopted, nor error bars.…”

Section: Analysis Of the C And O Ratiosmentioning

confidence: 99%

Carbon and oxygen isotopic ratios in Arcturus and Aldebaran

Abia

Palmerini

Busso

et al. 2012

A&A

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Context. We re-analyzed the carbon and oxygen isotopic ratios in the atmospheres of the two bright K giants Arcturus (α Boo) and Aldebaran (α Tau). Aims. These stars are in the evolutionary stage following the first dredge-up (FDU). Previous determinations (dating back more than 20 years) of their 16 O/ 18 O ratios showed a rough agreement with FDU expectations; however, the estimated 16 O/ 17 O and 12 C/ 13 C ratios were lower than in the canonical predictions for red giants. Today these anomalies are interpreted as signs of the occurrence of non-convective mixing episodes. We therefore re-investigated this problem to verify whether the observed data can be reproduced in this scenario and if the fairly well determined properties of the two stars can help us in fixing the uncertain parameters that characterize non-convective mixing and in constraining its physical nature. Methods. We used high-resolution infrared spectra from the literature to derive the 12 C/ 13 C and 16 O/ 17 O/ 18 O ratios from CO molecular lines near 5 μm, using the local termodynamic equilibrium (LTE) spectral synthesis method. We made use of the recently published ACE-FTS atlas of the infrared solar spectrum for constructing an updated atomic and molecular line lists in this spectral range. We also reconsidered the determination of the stellar parameters to build the proper atmospheric and evolutionary models. Results. We found that both the C and the O isotopic ratios for the two stars considered actually disagree with pure FDU predictions. This reinforces the idea that non-convective transport episodes occurred in these stars. By reproducing the observed elemental and isotopic abundances with the help of parametric models for the coupled occurrence of nucleosynthesis and mass circulation, we derived constraints on the properties of non-convective mixing, providing information on the so far elusive physics of these phenomena. We find that very slow mixing, like that associated to diffusive processes, is incapable of explaining the observed data, which require a fast transport. Circulation mechanisms with speeds intermediate between those typical of diffusive and convective mixing are necessary. We conclude with a word of caution on the conclusions possible at this stage however, as the parameters for the mass transport are fairly sensitive to the stellar mass and initial composition. At least for α Boo, reducing the uncertainty still remaining on these data would be highly desirable.

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Vibration-rotational and rotational intensities for CO isotopes

Cited by 127 publications

References 28 publications

Analytic representations of rovibrational dipole matrix elements for the CO molecule and its isotopomers

Analytic representations of rovibrational dipole matrix elements for the CO molecule and its isotopomers

The Properties of Planck Galactic Cold Clumps in the L1495 Dark Cloud

Carbon and oxygen isotopic ratios in Arcturus and Aldebaran

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