Improved HCN/HNC linelist, model atmospheres and synthetic spectra for WZ Cas

Harris, G. J.; Tennyson, Jonathan; Kaminsky, B.; Pavlenko, Ya. V.; Jones, H. R. A.

doi:10.1111/j.1365-2966.2005.09960.x

Cited by 170 publications

(136 citation statements)

References 30 publications

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“…We found that among the complete set of 105 molecules contained in the chemical model, these are the most abundant ones in all cases and will therefore dominate the spectral modulation. The wavelength-dependent cross sections for these absorbing molecules were computed using line lists from ExoMol (Barber et al 2006(Barber et al , 2014Harris et al 2006;Yurchenko et al 2011Yurchenko et al , 2013Tennyson & Yurchenko 2012), HITRAN (Rothman et al 2013), and HITEMP (Rothman et al 2010). Note that the mean molecular weight of each atmospheric layer is coupled to the mixing ratio of all 105 molecules.…”

Section: Synthetic High-resolution Transmission Spectramentioning

confidence: 99%

Exploring Biases of Atmospheric Retrievals in Simulated JWST Transmission Spectra of Hot Jupiters

Rocchetto

Waldmann

Venot

et al. 2016

ApJ

107

115

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With a scheduled launch in 2018 October, the James Webb Space Telescope ( JWST) is expected to revolutionize the field of atmospheric characterization of exoplanets. The broad wavelength coverage and high sensitivity of its instruments will allow us to extract far more information from exoplanet spectra than what has been possible with current observations. In this paper, we investigate whether current retrieval methods will still be valid in the era of JWST, exploring common approximations used when retrieving transmission spectra of hot Jupiters. To assess biases, we use 1D photochemical models to simulate typical hot Jupiter cloud-free atmospheres and generate synthetic observations for a range of carbon-to-oxygen ratios. Then, we retrieve these spectra using TauREx, a Bayesian retrieval tool, using two methodologies: one assuming an isothermal atmosphere, and one assuming a parameterized temperature profile. Both methods assume constant-with-altitude abundances. We found that the isothermal approximation biases the retrieved parameters considerably, overestimating the abundances by about one order of magnitude. The retrieved abundances using the parameterized profile are usually within 1σ of the true state, and we found the retrieved uncertainties to be generally larger compared to the isothermal approximation. Interestingly, we found that by using the parameterized temperature profile we could place tight constraints on the temperature structure. This opens the possibility of characterizing the temperature profile of the terminator region of hot Jupiters. Lastly, we found that assuming a constant-with-altitude mixing ratio profile is a good approximation for most of the atmospheres under study.

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Section: Synthetic High-resolution Transmission Spectramentioning

confidence: 99%

Exploring Biases of Atmospheric Retrievals in Simulated JWST Transmission Spectra of Hot Jupiters

Rocchetto

Waldmann

Venot

et al. 2016

ApJ

107

115

View full text Add to dashboard Cite

show abstract

“…The eigenenergies published in Ref. 25 have been used for this analysis. When the assignment work was started there was no reason to try to construct a better PES and to recalculate the rovibrational eigenenergies.…”

Section: Approximate Twofold Rotational Degeneracy Of the Hcn Anmentioning

confidence: 99%

“…In fact all 45 000 eigenvalues up to the isomerisation barrier have already been calculated. 24,25 molecular system only parity and total angular momentum are exact quantum numbers and the eigenenergies have to be labeled with vibrational quantum numbers in an assignment procedure. This work presents the results from the rotational assignment of all rovibrational eigenenergies up to the isomerisation barrier.…”

Section: Approximate Twofold Rotational Degeneracy Of the Hcn Anmentioning

confidence: 99%

Rovibrational eigenenergy structure of the [H,C,N] molecular system

Mellau¹

2011

The Journal of Chemical Physics

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The vibrational-rotational eigenenergy structure of the [H,N,C] molecular system is one of the key features needed for a quantum mechanical understanding of the HCN HNC model reaction. The rotationless vibrational structure corresponding to the multidimensional double well potential energy surface is well established. The rotational structure of the bending vibrational states up to the isomerisation barrier is still unknown. In this work the structure of the rotational states for low and high vibrational angular momentum is described from the ground state up to the isomerisation barrier using hot gas molecular high resolution spectroscopy and rotationally assigned ab initio rovibronic states. For low vibrational angular momentum the rotational structure of the bending excitations splits in three regions. For J < 40 the structure corresponds to that of a typical linear molecule, for 40 < J < 60 has an approximate double degenerate structure and for J > 60 the splitting of the e and f components begins to decrease and the rotational constant increases. For states with high angular momentum, the rotational structure evolves into a limiting structure for v 2 > 7 -the molecule is locked to the molecular axis. For states with v 2 > 11 the rotational structure already begins to accommodate to the lower rotational constants of the isomerisation states. The vibrational energy begins to accommodate to the levels above the barrier only at high vibrational excitations of v 2 > 22 just above the barrier whereas this work shows that the rotational structure is much more sensitive to the double well structure of the potential energy surface. The rotational structure already experiences the influence of the barrier at much lower energies than the vibrational one.

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“…To get precise estimates of T eff , additional model atmospheres were produced that resulted in a grid spacing of ΔT = 10 K. All the main molecular opacities typical of C-stars were included: CO (Goorvitch & Chackerian 1994), C 2 (Querci et al 1974), HCN (Harris et al 2006), CN (Jørgensen 1997) in the form of line lists, and C 2 H 2 and C 3 (Jorgensen et al 1989) as OS data. CS is not included due to the lack of line lists and OS data.…”

Section: Hydrostatic Modelsmentioning

confidence: 99%

Catching the fish – Constraining stellar parameters for TX Piscium using spectro-interferometric observations

Klotz

Paladini

Hron

et al. 2013

A&A

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Context. Stellar parameter determination is a challenging task when dealing with galactic giant stars. The combination of different investigation techniques has proven to be a promising approach. Aims. We analyse archive spectra obtained with the Short Wavelength Spectrometer (SWS) onboard ISO, and new interferometric observations from the Very Large Telescope MID-infrared Interferometric instrument (VLTI/MIDI) of a very well studied carbon-rich giant: TX Psc. The aim of this work is to determine stellar parameters using spectroscopy and interferometry. Methods. The observations are used to constrain the model atmosphere, and eventually the stellar evolutionary model in the region where the tracks map the beginning of the carbon star sequence. Two different approaches are used to determine stellar parameters: (i) the "classic" interferometric approach where the effective temperature is fixed by using the angular diameter in the N-band (from interferometry) and the apparent bolometric magnitude; (ii) parameters are obtained by fitting a grid of state-of-the-art hydrostatic models to spectroscopic and interferometric observations. Results. We find good agreement between the parameters of the two methods. The effective temperature and luminosity clearly place TX Psc in the carbon-rich AGB star domain in the H-R-diagram. Current evolutionary tracks suggest that TX Psc became a C-star just recently, which means that the star is still in a "quiet" phase compared to the subsequent strong-wind regime. This agrees with the C/O ratio being only slightly greater than one.

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Improved HCN/HNC linelist, model atmospheres and synthetic spectra for WZ Cas

Cited by 170 publications

References 30 publications

Exploring Biases of Atmospheric Retrievals in Simulated JWST Transmission Spectra of Hot Jupiters

Exploring Biases of Atmospheric Retrievals in Simulated JWST Transmission Spectra of Hot Jupiters

Rovibrational eigenenergy structure of the [H,C,N] molecular system

Catching the fish – Constraining stellar parameters for TX Piscium using spectro-interferometric observations

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