Rotational Spectroscopy of Isotopologues of Silicon Monoxide, SiO, and Spectroscopic Parameters from a Combined Fit of Rotational and Rovibrational Data

Müller, H. S. P.; Spezzano, S.; Bizzocchi, L.; Gottlieb, C. A.; Esposti, C. Degli; McCarthy, Michael

doi:10.1021/jp408391f

Cited by 39 publications

(31 citation statements)

References 86 publications

(241 reference statements)

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“…There are a total (Barton et al 2013). These values are similar to those in the Cologne Database for Molecular Spectroscopy (CDMS 12 ; version Jan. 2014; Müller et al 2001Müller et al , 2005Müller et al , 2013.…”

Section: Sio Molecular Datasupporting

confidence: 60%

Resolving the extended atmosphere and the inner wind of Mira (oCeti) with long ALMA baselines

Wong

Kamiński

Menten

et al. 2016

A&A

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Context. High angular resolution (sub)millimetre observations of asymptotic giant branch (AGB) stars, now possible with the Atacama Large Millimeter/submillimeter Array (ALMA), allow direct imaging of these objects' photospheres. The physical properties of the molecular material around these regions, which until now has only been studied by imaging of maser emission and spatially unresolved absorption spectroscopy, can be probed with radiative transfer modelling and compared to hydrodynamical model predictions. The prototypical Mira variable, o Cet (Mira), was observed as a Science Verification target in the 2014 ALMA Long Baseline Campaign, offering the first opportunity to study these physical conditions in detail. Aims. With the longest baseline of 15 km, ALMA produces clearly resolved images of the continuum and molecular line emission/absorption at an angular resolution of ∼30 mas at 220 GHz. Models are constructed for Mira's extended atmosphere to investigate the physics and molecular abundances therein. Methods. We imaged the data of 28 SiO = 0, 2 J = 5−4 and H 2 O v 2 = 1 J Ka,Kc = 5 5,0 −6 4,3 transitions and extracted spectra from various lines of sight towards Mira's extended atmosphere. In the course of imaging the emission/absorption, we encountered ambiguities in the resulting images and spectra that appear to be related to the performance of the CLEAN algorithm when applied to a combination of extended emission, and compact emission and absorption. We addressed these issues by a series of tests and simulations. We derived the gas density, kinetic temperature, molecular abundance, and outflow/infall velocities in Mira's extended atmosphere by modelling the SiO and H 2 O lines. Results. We resolve Mira's millimetre continuum emission and our data are consistent with a radio photosphere with a brightness temperature of 2611 ± 51 K. In agreement with recent results obtained with the Very Large Array, we do not confirm the existence of a compact region (<5 mas) of enhanced brightness. Our modelling shows that SiO gas starts to deplete beyond 4 R and at a kinetic temperature of 600 K. The inner dust shells are probably composed of grain types other than pure silicates. During this ALMA observation, Mira's atmosphere generally exhibited infall motion with a shock front of velocity 12 km s −1 outside the radio photosphere. Despite the chaotic nature of Mira's atmosphere, the structures predicted by the hydrodynamical model, codex, can reproduce the observed spectra in astonishing detail, while some other models fail when confronted with the new data. Conclusions. For the first time, millimetre-wavelength molecular absorption against the stellar continuum has been clearly imaged. Combined with radiative transfer modelling, the ALMA data successfully demonstrates the ability to reveal the physical conditions of the extended atmospheres and inner winds of AGB stars in unprecedented detail. Long-term monitoring of oxygen-rich evolved stars will be the key to understanding the unsolved problem of dust ...

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Section: Sio Molecular Datasupporting

confidence: 60%

Resolving the extended atmosphere and the inner wind of Mira (oCeti) with long ALMA baselines

Wong

Kamiński

Menten

et al. 2016

A&A

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“…Precise rest frequencies have also been reported for a number of the more abundant isotopic species at millimeter-wave and submillimeter-wave wavelengths 19. For SiO18,22 and to a lesser extent CS,23,24 the same is true, however, the laboratory measurements for SiC are significantly more limited, although the pure rotational transitions from the 3 Π ground state and v = 1 have been observed in the millimeter-wave band, as has lines of ground state 29 SiC and Si 13 C 25. Those up to v = 5 for normal SiC were derived at somewhat lower resolution by Butenhoff and Rohlfing26 by laser-induced fluorescence excitation spectroscopy, but very little high-resolution spectroscopy of this radical has been reported since the early 1990s.…”

Section: Interferometric Spectral Line Surveys: Evidence For a Rich Imentioning

confidence: 89%

Building Blocks of Dust and Large Organic Molecules: A Coordinated Laboratory and Astronomical Study of Agb Stars

McCarthy¹,

Gottlieb²,

Cernicharo³

2017

Proceedings of the 72nd International Symposium on Molecular Spectroscopy

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This article provides an overview of recent astronomical studies and a closely coordinated laboratory program devoted to the study of the physics and chemistry of carbon rich Asymptotic Giant Branch (AGB) stars. The increased sensitivity and angular resolution of high altitude ground-based millimeter-wave interferometers in the past few years has enabled molecular astronomers to determine the excitation and spatial distribution of molecules within a few stellar radii of the central star where the molecular seeds of dust are formed, and to critically assess the physicochemical mechanisms of dust formation and growth. However the astronomical studies are crucially dependent on precise laboratory measurements of the rotational spectra — both in the ground and vibrationally excited states of the normal and rare isotopic species — of the principal molecules in the inner region which appear to contain only two or three heavy atoms Much remains to be done by laboratory spectroscopists as evidenced by the large number of unassigned millimeters-wave rotational lines that are observed in the inner envelope of carbon rich AGB stars. As an illustration we refer to the example of an initial laboratory approach for establishing whether vibrationally excited SiC2 and HCN are the carriers of some of the unassigned features observed in the prototypical carbon rich AGB star IRC+10216 with ALMA. Also highlighted are ongoing laboratory studies of the silicon carbides SiC2 and SiCSi in their ground and excited vibrational states, and SiC3 in the ground vibrational state. Following the initial detection of SiC3 and SiCSi in the outer molecular envelope of IRC+10216, the laboratory spectroscopy was extended to higher frequency in support of the recent interferometric measurements. Thirty-two new millimeter-wave rotational transitions of SiCSi with J ≤ 48, Ka ≤ 3 and upper level energies Eu ≤ 484 K in the range from 178 – 391 GHz, and 35 new transitions of SiC3 with J ≤ 38, Ka ≤ 20 and Eu ≤ 875 K between 315 and 440 GHz were measured in the laboratory. In addition five to six rotational transitions in one quanta of each of the three fundamental vibrational modes of SiCSi, and the two lowest rotational transitions in the previously unexplored C–C stretching mode (ν1) of SiCC were measured in the normal and doubly substituted 13C isotopic species.

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“…The final spectroscopic parameters are given in Tables 5 and 6, de- rived parameters are in Table 7, in both cases presented alongside data from the previous study (Müller et al 2015). The reported uncertainties are only those from the respective fits; uncertainties of the atomic masses (Wang et al 2012) (for the ∆s and for r e ), the mass of the electron in atomic mass units (for the ∆s), or of the conversion factor from B e to the moment of inertia, derived from Mohr et al (2012) (see also Müller et al (2013) for the conversion factor), are negligible here. The line, parameter and fit files = 4 − 0 , are probably the most straightforward way to improve the NO spectroscopic parameters and predictions of rovibrational spectra, especially those of minor isotopic species.…”

Section: Spfit: Determination Of No Spectroscopic Parametersmentioning

confidence: 95%

ExoMol line list – XXI. Nitric Oxide (NO)

Wong

Yurchenko

Bernath

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Line lists for the X 2 Π electronic ground state for the parent isotopologue of nitric oxide ( 14 N 16 O) and five other major isotopologues ( 14 N 17 O, 14 N 18 O, 15 N 16 O, 15 N 17 O and 15 N 18 O) are presented. The line lists are constructed using empirical energy levels (and line positions) and high-level ab inito intensities. The energy levels were obtained using a combination of two approaches, from an effective Hamiltonian and from solving the rovibronic Schrödinger equation variationally. The effective hamiltonian model was obtained through a fit to the experimental line positions of NO available in the literature for all six isotopologues using the programs SPFIT and SPCAT. The variational model was built through a least squares fit of the ab inito potential and spin-orbit curves to the experimentally derived energies and experimental line positions of the main isotopologue only using the Duo program. The ab inito potential energy, spin-orbit and dipole moment curves (PEC, SOC and DMC) are computed using high-level ab inito methods and the MARVEL method is used to obtain energies of NO from experimental transition frequencies. The line lists are constructed for each isotopologue based on the use of the most accurate energy levels and the ab inito DMC. Each line list covers a wavenumber range from 0 -40,000 cm −1 with approximately 22,000 rovibronic states and 2.3 -2.6 million transitions extending to J max = 184.5 and max = 51. Partition functions are also calculated up to a temperature of 5000 K. The calculated absorption line intensities at 296 K using these line lists show excellent agreement with those included in the HITRAN and HITEMP databases. The computed NO line lists are the most comprehensive to date, covering a wider wavenumber and temperature range compared to both the HITRAN and HITEMP databases. These line lists are also more accurate than those used in HITEMP. The full line lists are available from the CDS http://cdsarc.u-strasbg.fr and ExoMol www.exomol.com databases; data will also be available from CDMS www.cdms.de.

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Rotational Spectroscopy of Isotopologues of Silicon Monoxide, SiO, and Spectroscopic Parameters from a Combined Fit of Rotational and Rovibrational Data

Cited by 39 publications

References 86 publications

Resolving the extended atmosphere and the inner wind of Mira (oCeti) with long ALMA baselines

Resolving the extended atmosphere and the inner wind of Mira (oCeti) with long ALMA baselines

Building Blocks of Dust and Large Organic Molecules: A Coordinated Laboratory and Astronomical Study of Agb Stars

ExoMol line list – XXI. Nitric Oxide (NO)

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