Empirical Line Lists and Absorption Cross Sections for Methane at High Temperatures

Hot methane is found in many cool sub-stellar astronomical sources including brown dwarfs and exoplanets, as well as in combustion environments on Earth. We report on the first high-resolution laboratory absorption spectra of hot methane at temperatures up to 1200 K. Our observations are compared to the latest theoretical spectral predictions and recent brown dwarf spectra. The expectation that millions of weak absorption lines combine to form a continuum, not seen at room temperature, is confirmed. Our high-resolution transmittance spectra account for both the emission and absorption of methane at elevated temperatures. From these spectra, we obtain an empirical line list and continuum that is able to account for the absorption of methane in high temperature environments at both high and low resolution. Great advances have recently been made in the theoretical prediction of hot methane, and our experimental measurements highlight the progress made and the problems that still remain. © 2015. The American Astronomical Society

Spectroscopic Constants, Abundances, and Opacities of the TiH Molecule

Using previous measurements and quantum chemical calculations to derive the molecular properties of the TiH molecule, we obtain new values for its ro-vibrational constants, thermochemical data, spectral line lists, line strengths, and absorption opacities. Furthermore, we calculate the abundance of TiH in M and L dwarf atmospheres and conclude that it is much higher than previously thought. We find that the TiH/TiO ratio increases strongly with decreasing metallicity, and at high temperatures can exceed unity. We suggest that, particularly for subdwarf L and M dwarfs, spectral features of TiH near $\sim$0.52 \mic, 0.94 \mic, and in the $H$ band may be more easily measureable than heretofore thought. The recent possible identification in the L subdwarf 2MASS J0532 of the 0.94 \mic feature of TiH is in keeping with this expectation. We speculate that looking for TiH in other dwarfs and subdwarfs will shed light on the distinctive titanium chemistry of the atmospheres of substellar-mass objects and the dimmest stars.Comment: 37 pages, including 4 figures and 13 tables, accepted to the Astrophysical Journa

Line Intensities and Molecular Opacities of the FeH F4Δi−X4ΔiF^4\Delta_i-X^4\Delta_i Transition

We calculate new line lists and opacities for the $F^4\Delta_i-X^4\Delta_i$ transition of FeH. The 0-0 band of this transition is responsible for the Wing-Ford band seen in M-type stars, sunspots and brown dwarfs. The new Einstein A values for each line are based on a high level ab initio calculation of the electronic transition dipole moment. The necessary rotational line strength factors (H\"onl-London factors) are derived for both the Hund's case (a) and (b) coupling limits. A new set of spectroscopic constants were derived from the existing FeH term values for v=0, 1 and 2 levels of the $X$ and $F$ states. Using these constants extrapolated term values were generated for v=3 and 4 and for $J$ values up to 50.5. The line lists (including Einstein A values) for the 25 vibrational bands with v$\leq$4 were generated using a merged list of experimental and extrapolated term values. The FeH line lists were use to compute the molecular opacities for a range of temperatures and pressures encountered in L and M dwarf atmospheres. Good agreement was found between the computed and observed spectral energy distribution of the L5 dwarf 2MASS-1507.Comment: 52 pages, 3 figures, many tables, accepted for publication in the Astrophysical Journal Supplement

High resolution infrared emission spectra of AlH andAlD

High resolution infrared emission spectra of aluminum monohydride and monodeuteride have been recorded. Gaseous AlH and AID were generated by reacting molten aluminum metal with hydrogen and deuterium gas. Approximately 265 AlH lines with v = 1 -to to v= 5 + 4 and 470 AID lines with v= 1 +O to u= 7 -) 6 are reported. Dunham Yii constants were obtained by fitting the data of each isotopomer separately to the Dunham energy level expression while massreduced Dunham Uij constants were obtained from a combined fit of all isotopomer data. A second set of Dunham lJij constants was obtained from a fit where Uij's with j < 2 were treated as adjustable parameters and all remaining Uij'S fixed to values that satisfy the constraints imposed by the Dunham model. Finally, an effective Born-Oppenheimer potential was determined by fitting all the data directly to the eigenvalues of the radial Schriidinger equation -containing a parametrized potential function

Air-Broadening of H2O as a Function of Temperature: 696 - 2163 cm(exp -1)

The temperature dependence of air-broadened halfwidths are reported for some 500 transitions in the (000)-(000) and (010)-(000) bands of H2(16)O using gas sample temperatures ranging from 241 to 388 K. These observations were obtained from infrared laboratory spectra recorded at 0.006 to 0.011 cm(exp-1) resolution with the McMath-Pierce Fourier transform spectrometer located at Kitt Peak. The experimental values of the temperature dependence exponents, eta, were grouped into eight subsets and fitted to empirical functions in a semi-global procedure. Overall, the values of eta were found to decrease with increasing rotational quantum number J. The number of measurements (over 2200) and transitions (586) involved exceeds by a large margin that of any other comparable reported study

CRIRES-POP: A library of high resolution spectra in the near-infrared

New instrumental capabilities and the wealth of astrophysical information extractable from the near-infrared wavelength region have led to a growing interest in the field of high resolution spectroscopy at 1-5 mu. We aim to provide a library of observed high-resolution and high signal-to-noise-ratio near-infrared spectra of stars of various types throughout the Hertzsprung-Russell diagram. This is needed for the exploration of spectral features in this wavelength range and for comparison of reference targets with observations and models. High quality spectra were obtained using the CRIRES near-infrared spectrograph at ESO's VLT covering the range from 0.97 to 5.3 mu at high spectral resolution. Accurate wavelength calibration and correction for of telluric lines were performed by fitting synthetic transmission spectra for the Earth's atmosphere to each spectrum individually. We describe the observational strategy and the current status and content of the library which includes 13 objects. The first examples of finally reduced spectra are presented. This publication will serve as a reference paper to introduce the library to the community and explore the extensive amount of material.Comment: accepted for publication in A&A; see also the project webpage http://www.univie.ac.at/crirespo

The properties of V838 Mon in 2002 November

We present the results of modelling the 0.45--1 micron spectral energy distribution of V838 Mon for 2002 November. Synthetic spectra were calculated using the NextGen model atmospheres of Hauschildt et al. (1999), which incorporate line lists for H2O, TiO, CrH, FeH, CO, and MgH, as well as the VALD atomic line list. Fits to the observed spectra show that, in 2002 November, the effective temperature of V838 Mon was approximately 2000 +/-100 K. Our theoretical spectra show a comparatively weak dependence on log g. Preliminary analysis of the hot star observed together with V838 Mon shows it to be a normal B3V dwarf.Comment: 7 pages, 4 figs, accepted by A&

SPECTROSCOPY FOR HOT SUPER-EARTH EXOPLANETS

Author Institution: Department of Chemistry \& Biochemistry, Old Dominion University, 4541 Hampton Boulevard, Norfolk, VA, 23529-0126, USASpectroscopic observations of exoplanets are now possible by transit methods and direct emission. Spectroscopic requirements for exoplanet atmospheres will be reviewed based on existing measurements and model predictions for hot Jupiters and super-Earths. Super-Earths are exoplanets with masses in the range of about 2 to 10 Earth masses (i.e., between the size of Earth and Neptune). Many of them have very short orbital periods like hot Jupiters and are also hot because of proximity to their parent star. For example, Kepler-10b has a mass of 4.54 times that of Earth, a density of 8.74 g cm$^{-3}$ and a surface temperature of 1833 K. More than thirty super-Earths have been discovered and the most interesting objects are rocky planets such as Kepler-10b and CoRoT-7b. Schaefer \textit{et al.} have calculated the chemical equilibrium composition of super-Earths with temperatures in the range 500-4000 K based on the vaporization of silicate rocks similar to those of the Earth's continental crust and bulk silicate Earth. In addition to H$_2$O, CO$_2$, CH$_4$, CO and H$_2$ found in hot Jupiters, additional species such as SO$_2$, O$_2$, HCl, HF, NaCl, KCl, KF, KOH and NaOH are expected to be present. Similar to our previous work on hot ammonia \textbf{735}, 111.} and hot methane 2012, Hot Methane Line Lists for Exoplanet and Brown Dwarf Atmospheres, \textit{Astrophys. J.} \textbf{757}, 46.}, emission spectra of hot SO$_2$ will be presented. Continuing work on NaCl and KCl emission spectra will also be covered

THE ELECTRONIC STRUCTURE OF PrO

$^{1}$E.A. Shenyavskaya, J. Mol. Spectrosc. 47, 355 (1973).Author Institution:As is typical of the rare earth oxides, PrO has many low-lying electronic states and many incompletely analyzed electronic transitions are $know.^{1}$ By high precision ($0.001 cm^{-1}$), Doppler-limited, selective-fluorescence-detected, cw dye laser excitation spectroscopy, we have analyzed the rotational and $^{141}$Pr(I = 5/2) hyperfine structure of several electronic transitions. Spectra of narrow-bandwith laser excited resolved fluorescence $(\sim 0.5$ $cm^{-1}$ precision) sample numerous low-lying electronic states and provide energy-linkages between several of the transitions tabulated by $Shenyavskaya.^{1}$ For example, the lower levels of the XXI and XVII systems are, respectively, $\Omega^{\prime\prime} = 4.5$ and 3.5 with the 4.5 level at $217 cm^{-1}$ higher energy. The energy level diagram of PrO and the configurational parentage of several electronic states will be discussed