Line Intensities and Molecular Opacities of the FeHF4Δi–X4ΔiTransition

Dulick, M.; Bauschlicher, Charles W.; Burrows, Adam; Sharp, Catherine; Ram, R. S.; Bernath, Peter F.

doi:10.1086/376791

Cited by 162 publications

(191 citation statements)

References 43 publications

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“…for Ce +3 and Tb +3 ). The partition function for FeH is given from Dulick et al (2003) over a temperature range from 1000 to 3500 K in steps of 100 K. Then, for all the revised species, we have obtained the fitting coefficients of Eq. (18) by the method of least-squares fitting.…”

Section: Thermodynamic Datamentioning

confidence: 99%

Low-temperature gas opacity

Marigo¹,

Aringer

2009

A&A

206

215

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We introduce a new tool -AESOPUS: Accurate Equation of State and OPacity Utility Software -for computing the equation of state and the Rosseland mean (RM) opacities of matter in the ideal gas phase. Results are given as a function of one pair of state variables, (i.e. temperature T in the range 3.2 ≤ log(T ) ≤ 4.5, and parameter R = ρ/(T/10 6 K) 3 in the range −8 ≤ log(R) ≤ 1), and arbitrary chemical mixture. The chemistry is presently solved for about 800 species, consisting of almost 300 atomic and 500 molecular species. The gas opacities account for many continuum and discrete sources, including atomic opacities, molecular absorption bands, and collision-induced absorption. Several tests made on AESOPUS have proved that the new opacity tool is accurate in the results, flexible in the management of the input prescriptions, and agile in terms of computational time requirement. Purpose of this work is to greatly expand the public availability of Rosseland mean opacity data in the low-temperature regime. We set up a web-interface (http://stev.oapd.inaf.it/aesopus) which enables the user to compute and shortly retrieve RM opacity tables according to his/her specific needs, allowing a full degree of freedom in specifying the chemical composition of the gas. As discussed in the paper, useful applications may regard, for instance, RM opacities of gas mixtures with i) scaled-solar abundances of metals, choosing among various solar mixture compilations available in the literature; ii) varying CNO abundances, suitable for evolutionary models of red and asymptotic giant branch stars and massive stars in the Wolf-Rayet stages; iii) various degrees of enhancement in α-elements, and C-N, O-Na, and Mg-Al abundance anti-correlations, necessary to properly describe the properties of stars in early-type galaxies and Galactic globular clusters; iv) zero-metal abundances appropriate for studies of gas opacity in primordial conditions.

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Section: Thermodynamic Datamentioning

confidence: 99%

Low-temperature gas opacity

Marigo¹,

Aringer

2009

A&A

206

215

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“…We compared our FeH line list with that of Dulick et al (2003) by calculating spectra with both lists for the two stars GJ 436 and GJ 628. An overall comparison showed that the FeH lines calculated with the Dulick et al (2003) list were somewhat weaker than when using the BP list. Line-depth ratios between a number of selected FeH lines appearing in both lists and in the observations were calculated.…”

Section: Spectral Line Datamentioning

confidence: 99%

M-dwarf metallicities. A high-resolution spectroscopic study in the near infrared

Önehag

Heiter

Gustafsson

et al. 2012

A&A

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Context. The relatively wide spread in the derived metallicities ([Fe/H]) of M dwarfs shows that various approacheshave not yet converged to consistency. The presence of strong molecular features and incomplete line lists for the corresponding molecules have made determining the metallicity of M dwarfs difficult. Furthermore, the faint M dwarfs require long exposure times for the signalto-noise ratio needed for a detailed spectroscopic abundance analysis. Aims. We present a high-resolution (R ∼ 50 000) spectroscopic study of a sample of eight single M dwarfs and three wide-binary systems observed in the infrared J band. Methods. The absence of large molecular contributions allows for a precise continuum placement. We derived metallicities based on the best fit of synthetic spectra to the observed spectra. To verify the accuracy of the applied atmospheric models and test our synthetic spectrum approach, three binary systems with a K-dwarf primary and an M-dwarf companion were observed and analysed along with the single M dwarfs. Results. We obtain good agreement between the metallicities derived for the primaries and secondaries of our test binaries, thereby confirming the reliability of our method of analysing M dwarfs. Our metallicities agree well with some earlier determinations, and deviate from others. Conclusions. We conclude that spectroscopic abundance analysis in the J band is a reliable method for establishing the metallicity scale for M dwarfs. We recommend its application to a larger sample covering lower, as well as higher, metallicities. Further prospects for the method include abundance determinations for individual elements.

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“…The AMES-COND v2.2 models use the H 2 O line list of Barber et al (2006), the FeH list of Dulick et al (2003), and the damping constants used for the K i lines are published in Allard et al (2003). Figure 2 illustrates the identification of some near-infrared features over a synthetic spectrum with v rot sin i = 0, T eff = 1000 K and log g = 4.5.…”

Section: Description Of Atmosphere Modelsmentioning

confidence: 99%

Physical parameters of T dwarfs derived from high-resolution near-infrared spectra

Burgo

Martín

Osorio

et al. 2009

A&A

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Aims. We determine the effective temperature, surface gravity and projected rotational velocity of nine T dwarfs from the comparison of high-resolution near-infrared spectra and synthetic models, and estimate the mass and age of the objects from state-of-the-art models. Methods. We use the AMES-COND cloudless solar metallicity models provided by the PHOENIX code to match the spectra of nine T-type field dwarfs observed with the near-infrared high-resolution spectrograph NIRSPEC using ten echelle orders to cover part of the J band from 1.147 to 1.347 μm with a resolving power R ∼ 20 000. The projected rotational velocity, effective temperature and surface gravity of the objects are determined based on the minimum root mean square of the differences between the modelled and observed relative fluxes. Estimates of the mass and age of the objects are obtained from effective temperature-surface gravity diagrams, where our results are compared with existing solar metallicity models. Results. The modelled spectra reproduce quite well the observed features for most of the T dwarfs, with effective temperatures in the range of 922-1009 K, and surface gravities between 10 4.1 and 10 4.9 cm s −2 . Our results support the assumption of a dust free atmosphere for T dwarfs later than T5, where dust grains form and then gravitationally sediment into the low atmosphere. The modelled spectra do not accurately mimic some individual very strong lines like the K i doublet at 1.2436 and 1.2525 μm. Our modelled spectra does not match well the observed spectra of the two T dwarfs with earlier spectral types, namely SDSSp J125453.90-012247.4 (T2) and 2MASS J05591914-1404488 (T4.5), which is likely due to the presence of condensate clouds that are not incorporated in the models used here. By comparing our results and their uncertainties to evolutionary models, we estimate masses in the interval ≈5−75 M J for T dwarfs later than T5, which are in good agreement with those found in the literature. We found apparent young ages that are typically between 0.1 and a few Gyr for the same T dwarfs, which is consistent with recent kinematical studies.

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Line Intensities and Molecular Opacities of the FeHF⁴Δ_i–X⁴Δ_iTransition

Cited by 162 publications

References 43 publications

Low-temperature gas opacity

Low-temperature gas opacity

M-dwarf metallicities. A high-resolution spectroscopic study in the near infrared

Physical parameters of T dwarfs derived from high-resolution near-infrared spectra

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