The pure rotational spectrum of TiS (X3Δr) at submillimeter wavelengths

Pulliam, R. L.; Zack, Lindsay N.; Ziurys, L. M.

doi:10.1016/j.jms.2010.09.005

Cited by 8 publications

(4 citation statements)

References 23 publications

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“…We note that a significant body of experimental observations of the TiS molecules exists in the literature, (e.g. Jonsson & Launila 1993;Ran et al 1999;Cheung et al 2000;Pulliam et al 2010), which may make TiS amenable for detection in future cross-correlation studies.…”

Section: Ti-v Chemistry and Condensationmentioning

confidence: 96%

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b

Hoeijmakers,

Seidel,

Pino

et al. 2020

Preprint

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Context. WASP-121 b is a hot Jupiter that was recently found to possess rich emission (day side) and transmission (limb) spectra, suggestive of the presence of a multitude of chemical species in the atmosphere. Aims. We survey the transmission spectrum of WASP-121 b for line-absorption by metals and molecules at high spectral resolution, and elaborate on existing interpretations of the optical transmission spectrum observed with HST/STIS and WFC3. Methods. We apply the cross-correlation technique and direct differential spectroscopy to search for sodium and other neutral and ionised atoms, TiO, VO and SH in high-resolution transit spectra obtained with the HARPS spectrograph. We inject models assuming chemical and hydrostatic equilibrium with varying temperature and composition to enable model comparison, and employ two bootstrap methods to test the robustness of our detections. Results. We detect neutral Mg , Na , Ca , Cr , Fe , Ni and V , which we predict exists in equilibrium with a significant quantity of VO, supporting earlier observations by HST/WFC3. Non-detections of Ti and TiO support the hypothesis that Ti is depleted via a cold-trap mechanism, as has been proposed in the literature. Atomic line depths are under-predicted by hydrostatic models by a factor of 1.5 to 8, confirming recent findings that the atmosphere is extended. We predict the existence of significant concentrations of gas-phase TiO 2 , VO 2 and TiS, which could be important absorbers at optical and near-IR wavelengths in hot Jupiter atmospheres, but for which accurate line-list data is currently not available. We find no evidence for absorption by SH, and find that inflated atomic lines can plausibly explain the slope of the transmission spectrum observed in the near-UV with HST/STIS. The Na i D lines are significantly broadened (FWHM ∼ 50 km s −1 to 70 km s −1 ) and show a difference in their respective depths of ∼ 15 scale heights, which is not expected from isothermal hydrostatic theory. If this asymmetry is of astrophysical origin, it may indicate that Na i forms an optically thin envelope reminiscent of the Na i cloud surrounding Jupiter, or that it is hydrodynamically outflowing.

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Section: Ti-v Chemistry and Condensationmentioning

confidence: 96%

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b

Hoeijmakers,

Seidel,

Pino

et al. 2020

Preprint

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“…2. Accurate frequencies of rotational transitions are known for TiN, TiS, and TiF (Namiki et al 1998;Pulliam et al 2010;Sheridan et al 2003) or can be predicted, as for TiH, with the available spectroscopic constants. However, our sensitive observations did not cover strong transitions of any of these species.…”

Section: Line Listsmentioning

confidence: 99%

An observational study of dust nucleation in Mira (o Ceti)

Kamiński

Müller

Schmidt

et al. 2017

A&A

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Context. The formation of silicate dust in oxygen-rich envelopes of evolved stars is thought to be initiated by the formation of seed particles that can withstand the high temperatures close to the stellar photosphere and act as condensation cores farther away from the star. TiO and TiO 2 are among the candidate species considered as first condensates. Aims. We aim to identify and characterize the circumstellar gas-phase chemistry of titanium that leads to the formation of solid titanium compounds in the envelope of o Ceti, the prototypical Mira, and seek an observational verification of whether titanium oxides play a major role in the onset of dust formation in M-type asymptotic giant branch (AGB) stars. Methods. We present high angular resolution (145 mas) ALMA observations at submillimeter (submm) wavelengths supplemented by APEX and Herschel spectra of the rotational features of TiO and TiO 2 . In addition, circumstellar features of TiO and Ti i are identified in optical spectra, which cover multiple pulsation cycles of o Ceti. Results. The submm ALMA data reveal TiO and TiO 2 bearing gas within the extended atmosphere of Mira. While TiO is traceable up to a radius (FWHM/2) of 4.0 stellar radii (R ), TiO 2 extends as far as 5.5 R and, unlike TiO, appears to be anisotropically distributed.Optical spectra display variable emission of Ti i and TiO from inner parts of the extended atmosphere (<3 R ).Conclusions. Chemical models that include shocks are in general agreement with the observations of gas-phase, titanium-bearing molecules. It is unlikely that substantial amounts of titanium is locked up in solids because the abundance of the gaseous titanium species is very high. The formation of hot titanium-rich condensates is very improbable because we find no traces of their hot precursor species in the gas phase. It therefore appears unlikely that the formation of dust in Mira, and possibly other M-type AGB stars, is initiated by titanium oxides.

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“…1.1. Accurate frequencies of rotational transitions are known for TiN, TiS, and TiF (Namiki et al 1998;Pulliam et al 2010;Sheridan et al 2003) or can be predicted, as for TiH, with the spectroscopic constants. However, our sensitive observations did not cover strong transitions of any of these species.…”

Section: Line Listsmentioning

confidence: 99%

An observational study of dust nucleation in Mira ($o$ Ceti): II. Titanium oxides are negligible for nucleation at high temperatures

Kamiński,

Müller,

Schmidt

et al. 2016

Preprint

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Context. The formation of silicate dust in oxygen-rich envelopes of evolved stars is thought to be initiated by formation of seed particles that can withstand the high temperatures close to the stellar photosphere and act as condensation cores farther away from the star. Among the candidate species considered as first condensates are TiO and TiO 2 . Aims. We aim to identify and characterize the circumstellar gas-phase chemistry of titanium that leads to the formation of solid titanium compounds in the envelope of o Ceti, the prototypical Mira, and seek an observational verification of whether titanium oxides play a major role in the onset of dust formation in M-type asymptotic-giant-branch (AGB) stars. Methods. We present high angular-resolution (145 mas) ALMA observations at submillimeter (submm) wavelengths supplemented by APEX and Herschel spectra of the rotational features of TiO and TiO 2 . In addition, circumstellar features of TiO and Ti i are identified in optical spectra which cover multiple pulsation cycles of o Ceti.Results. The submm ALMA data reveal TiO and TiO 2 bearing gas within the extended atmosphere of Mira. While TiO is traceable up to a radius (FWHM/2) of 4.0 stellar radii (R ⋆ ), TiO 2 extends as far as 5.5 R ⋆ and unlike TiO appears to be anisotropically distributed. Optical spectra display variable emission of Ti i and TiO from inner parts of the extended atmosphere (<3 R ⋆ ). Conclusions. Chemical models which include shocks are in general agreement with the observations of gas-phase titanium-bearing molecules. It is unlikely that substantial amounts of titanium is locked up in solids because the abundance of the gaseous titanium species is very high. In particular, formation of hot titanium-rich condensates is very improbable because we find no traces of their hot precursor species in the gas phase. It therefore appears unlikely that the formation of dust in Mira, and possibly other M-type AGB stars, is initiated by titanium oxides.

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The pure rotational spectrum of TiS (X3Δr) at submillimeter wavelengths

Cited by 8 publications

References 23 publications

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b

An observational study of dust nucleation in Mira (o Ceti)

An observational study of dust nucleation in Mira ($o$ Ceti): II. Titanium oxides are negligible for nucleation at high temperatures

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