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Hot line lists for Diatomics and Astronomical Applications
E. J. Barton, J. Tennyson and S. N. Yurchenko Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT Introduction
One aim of ExoMol is to provide spectroscopic data for hot diatomics of importance in the atmospheres of planets. Although intended for use in the characterisation of planets the ExoMol line lists can also be used to interpret the spectra of other astronomical objects. Diatomics studied so far by ExoMol include BeH, MgH, CaH, SiO, KCl and NaCl. BeH, MgH and CaH are all present in stellar and/or sunspot spectra. The latter is also present in molecular clouds and galactic disks. SiO appears to be ubiquitous in our galaxy and is frequently found in the interstellar medium, sunspots, dwarf, giant and supergiant stars. KCl and NaCl have both been detected in a carbon star and the latter has also been observed in oxygen stars.

Hot Diatomic Line Lists
The following table summarises hot diatomic line lists produced so far. Molecule Number of Maximum Number of Isotopes Temperature lines per list CaH MgH BeH SiO *KCl *NaCl *New result. 1 3 1 5 4 2 3000 3000 3000 9000 3000 3000 K K K K K K 26,000 6700 3900 1.8 million 7.2 million 4.7 million

Comparison with Astronomical Spectra

NaCl and KCl

Comparison of synthesised SiO spectra with M dwarf HD225212 spectra from Lebzelter et al. (2012). Line positions and intensities predicted by the line lists are well correlated with observed features.

Astronomical Application
Ohnaka (2013) employed the SiO line lists in his analysis of VISIR spectra of K-M giants.

Adapted from Figures 5 and 6 of Barton et al. 2014 (submitted). The line lists reproduce experimental frequencies to within 0.01cm-1. Considering the experimental issues the intensity comparison must be regarded as satisfactory.

Adapted from Figures 1 and 8 of Ohnaka (2013). The observed and synthetic spectra (as predicted by the MARCS model) are shown by the black and red solid lines, respectively. The relatively isolated 28SiO, 29SiO, and 30SiO lines are marked by the black, red, and green arrows, respectively.

In Progress
The following diatomics are currently being studied by ExoMol: AlO, MgO, ScH, TiH, CrH, SuH, SH and PN

References
1. 2. 3. 4. 5. 6. 7. Yadin et al, "ExoMol line lists I: BeH, MgH and CaH", MNRAS 425, 34-43 (2012). Barton, Yurchenko and Tennyson, "ExoMol line lists II: SiO", MNRAS 434, 1469-1475 (2013). Barber et al, "ExoMol line lists III: HCN and HNC", MNRAS 437, 1828-1835 (2014). Yurchenko and Tennyson, "ExoMol line lists IV: CH4", MNRAS (accepted) (2014). Barton et al, "ExoMol molecular line lists V: NaCl and KCl", MNRAS (submitted) (2014). Ohnaka, "High spectral resolution spectroscopy of the SiO fundamental lines in red giants and red supergiants with VLT/VISIR", A&A (accepted) (2013). Lebzelter et al, "CRIRES-POP: A library of high resolution spectra in the near-infrared" A&A 539, A190 (2012).

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