Updated line list for the principal isotopologue of carbon monoxide

Validation of the HITRAN 2016 and GEISA 2015 line lists using ACE-FTS solar occultation observations

An accurate line list, called XABC, is computed for nitric oxide which covers its pure rotational, vibrational and rovibronic spectra. A mixture of empirical and theoretical electronic transition dipole moments are used for the final calculation of 14N16O rovibronic $\mathrm{A}\, ^2\Sigma ^+$ – $\mathrm{X}\, ^2\Pi$, $\mathrm{B}\, ^2\Pi$ – X2Π, and $\mathrm{C}\, ^2\Pi$ – $\mathrm{X}\, ^2\Pi$ which correspond to the γ, β, and δ band systems, respectively, as well as minor improvements to transitions within the $\mathrm{X}\, ^2\Pi$ ground state. The work is a major update of the ExoMol NOname line list. It provides a high-accuracy NO ultraviolet line list covering the complicated regions where the $\mathrm{B}\, ^2\Pi$-$\mathrm{C}\, ^2\Pi$ states interact. XABC provides comprehensive data for the lowest four doublet states of NO in the region of λ > 160 nm ($\tilde{\nu } \lt 63~000~\mathrm{cm}^{-1}$) for the analysis of atmospheric NO on Earth, Venus, or Mars, other astronomical observations and applications. The data are available via www.exomol.com.

DIBs are ubiquitous in stellar spectra. Traditionally, they have been studied through their extraction from hot stars, because of their smooth continuum. In an era where there are several going-on or planned massive Galactic surveys using multi-object spectrographs, cool stars constitute an appealing set of targets. From the technical point of view, the extraction of DIBs in their spectra is more challenging due to the complexity of the continuum. In this contribution we will provide the community with an improved set of stellar lines in the spectral regions associated to the strong DIBs at l6196, l6269, l6284, and l6379. These lines will allow for the creation of better stellar synthetic spectra, reproducing the background emission and a more accurate extraction of the magnitudes associated with a given DIB. The Sun and Arcturus were used as representative examples of dwarf and giant stars, respectively. A high quality spectrum for each of them was modeled using TURBOSPECTRUM and the VALD stellar line list. The oscillator strength log(gf) and/or wavelength of specific lines were modified to create synthetic spectra where the residuals in both the Sun and Arcturus were minimized. The synthetic spectra based on the improved line lists reproduce the observed spectra for the Sun and Arcturus in the mentioned spectral ranges with greater accuracy. Residuals between the synthetic and observed spectra are always <10%, much better than with previously existing options. The new line list has been tested with some characteristic spectra, from a variety of stars, including both giant and dwarf stars, and under different degrees of extinction. As it happened with the Sun and Arcturus residuals in the fits used to extract the DIB information are smaller when using synthetic spectra made with the updated line lists. Tables with the updated parameters are provided to the community.

Recently, a line list including positions and transition strengths was published for the NH X(3)Σ(-) rovibrational and rotational transitions. The calculation of the transition strengths requires a conversion of transition matrix elements from Hund's case (b) to (a). The method of this conversion has recently been improved during other work on the OH X(2)Π rovibrational transitions, by removing an approximation that was present previously. The adjusted method has been applied to the NH line list, resulting in more accurate transition strengths. An updated line list is presented that contains all possible transitions with v' and v″ up to 6, and J up to between 25 and 44, depending on the band.

GOSAT-2014 methane spectral line list

Accurate measurements of the fundamental physical properties of very‐low‐mass stars and brown dwarfs are crucial for calibrating evolutionary models. Photometry and low‐resolution spectroscopy effectively average over absorption features that sample different layers in complex cool atmospheres. By studying a large sample of objects bright enough for high‐resolution spectroscopy, we can develop methods for determining physical properties as accurately and efficiently as possible. As part of the Brown Dwarf Spectroscopic Survey (BDSS; [1, 2]), we are conducting a detailed comparison of observed and synthetic spectra for a sample of young M and L dwarfs and field M, L, and T dwarfs ( ∼50 objects in total). High‐resolution near‐infrared spectra from NIRSPEC on Keck II provide an unequaled combination of resolving power and wavelength coverage. Synthetic spectra were created from PHOENIX atmosphere models calculated exclusively for this project with updated line lists and solar abundances. Combined with spectral types from photometric studies and low‐resolution spectra and surface gravity estimates from age determination, the high‐resolution spectra enable precise measurements of effective temperature and surface gravity, as well as accurate determination of radial velocity and projected rotational velocity. Our preliminary observation‐model comparisons distinguish between wavelength regimes for which the models reproduce observed high‐resolution spectra and regimes in which model data (line lists, oscillator strengths, etc.) are lacking.

The spectrum of dicarbon (C2) is important in astrophysics and for spectroscopic studies of plasmas and flames. The C2 spectrum is characterized by many band systems with new ones still being actively identified; astronomical observations involve eight of these bands. Recently, Furtenbacher et al. presented a set of 5699 empirical energy levels for 12C2, distributed among 11 electronic states and 98 vibronic bands, derived from 42 experimental studies and obtained using the MARVEL (Measured Active Rotational-Vibrational Energy Levels) procedure. Here, we add data from 13 new sources and update data from 5 sources. Many of these data sources characterize high-lying electronic states, including the newly detected 3 3Πg state. Older studies have been included following improvements in the MARVEL procedure that allow their uncertainties to be estimated. These older works in particular determine levels in the C 1Πg state, the upper state of the insufficiently characterized Deslandres–d’Azambuja (C 1Πg–A 1Πu) band. The new compilation considers a total of 31 323 transitions and derives 7047 empirical (marvel) energy levels spanning 20 electronic and 142 vibronic states. These new empirical energy levels are used here to update the 8states C2 ExoMol line list. This updated line list is highly suitable for high-resolution cross-correlation studies in astronomical spectroscopy of, for example, exoplanets, as 99.4 per cent of the transitions with intensities over 10−18 cm molecule−1 at 1000 K have frequencies determined by empirical energy levels.

Context. Until now, heavy interstellar extinction has meant that only a few studies of chemical abundances have been possible in the inner Galactic bulge. However, it is crucial to learn more about this structure in order to better understand the formation and evolution of the centre of the Galaxy and galaxies in general. Aims. In this paper, we aim to derive high-precision α-element abundances using CRIRES high-resolution IR spectra of 72 cool M giants of the inner Galactic bulge. Methods. Silicon, magnesium, and calcium abundances were determined by fitting a synthetic spectrum for each star. We also incorporated recent theoretical data into our spectroscopic analysis (i.e. updated K-band line list, better broadening parameter estimation, non-local thermodynamic equilibrium (NLTE) corrections). We compare these inner bulge α abundance trends with those of solar neighbourhood stars observed with IGRINS using the same line list and analysis technique; we also compare our sample to APOGEE DR17 abundances for inner bulge stars. We investigate bulge membership using spectro-photometric distances and orbital simulations. We construct a chemical-evolution model that fits our metallicity distribution function (MDF) and our α-element trends. Results. Among our 72 stars, we find four that are not bulge members. [Si/Fe] and [Mg/Fe] versus [Fe/H] trends show a typical thick disc α-element behaviour, except that we do not see any plateau at supersolar metallicities as seen in other works. The NLTE analysis lowers [Mg/Fe] typically by ∼0.1 dex, resulting in a noticeably lower trend of [Mg/Fe] versus [Fe/H]. The derived [Ca/Fe] versus [Fe/H] trend has a larger scatter than those for Si and Mg, but is in excellent agreement with local thin and thick disc trends. With our updated analysis, we constructed one of the most detailed studies of the α abundance trends of cool M giants in the inner Galactic bulge. We modelled these abundances by adopting a two-infall chemical-evolution model with two distinct gas-infall episodes with timescales of 0.4 Gyr and 2 Gyr, respectively. Conclusions. Based on a very meticulous spectral analysis, we have constructed detailed and precise chemical abundances of Mg, Si, and Ca for cool M giants. The present study can be used as a benchmark for future spectroscopic surveys.

We have computed a grid of high-resolution synthetic spectra for cool stars (2500<Teff<6000 K) in the wavelength range 6000-10200 Å by employing an updated line list of atomic and molecular lines together with state-of-the-art model atmospheres. As a by-product, by fitting TiO band heads in spectra of well-known M giants, we have derived the electronic oscillator strengths of the TiO γ', δ, , and ϕ systems. The derived oscillator strengths for the γ', , and ϕ systems differ from the laboratory and ab initio values found in the literature, but they are consistent with the model atmospheres and line lists employed, resulting in a good match to the observed spectra of M giants of known parameters. The behavior of TiO bands as a function of the stellar parameters Teff, log g and [Fe/H] is presented, and the use of TiO spectral indices in stellar population studies is discussed.

New quantum assignments and analysis of high-resolution H212CO spectra in the range 3700–4450 cm-1

New acetylene line list near 3.8-µm - Part I

A new grid of high resolution synthetic stellar spectra for population synthesis is presented. The spectra were computed in the λλ6000 — 10200 A interval, employing an updated and comprehensive list of atomic and molecular lines (for details, see Schiavon and Barbuy, 1999). The behaviour of spectral indices contained in the spectral region under study, such as the NaI ‘doublet’ (~ 8190 A), the FeH Wing-Ford band (~ 9900 A) and TiO bands, as a function of stellar atmospheric parameters has been studied by Schiavon et al. (1997a), Schiavon et al. (1997b) and Schiavon and Barbuy (1999), respectively. In this contribution the first results of the study of integrated synthetic spectra of single-aged stellar populations (SSPs) are presented.

Context. The modeling of stellar spectra of flux standards observed by the Hubble and James Webb space telescopes requires a large synthetic spectral library that covers a wide atmospheric parameter range. Aims. The aim of this paper is to present and describe the calculation methods behind the updated version of the BOSZ synthetic spectral database, which was originally designed to fit the CALSPEC flux standards. These new local thermodynamic equilibrium (LTE) models incorporate both MARCS and ATLAS9 model atmospheres, updated continuous opacities, and 23 new molecular line lists. Methods. The new grid was calculated with Synspec using the LTE approximation and covers metallicities [M/H] from −2.5 to 0.75 dex, [α/M] from −0.25 to 0.5 dex, and [C/M] from −0.75 to 0.5 dex, providing spectra for 336 unique compositions. Calculations for stars between 2800 and 8000 K use MARCS model atmospheres, and ATLAS9 is used between 7500 and 16 000 K. Results. The new BOSZ grid includes 628 620 synthetic spectra from 50 nm to 32 µm with models for 495 Teff−log 𝑔 parameter pairs per composition and per microturbulent velocity. Each spectrum has eight different resolutions spanning a range from R = 500 to 50 000 as well as the original resolution of the synthesis. The microturbulent velocities are 0, 1, 2, and 4 km s−1. Conclusions. The new BOSZ grid extends the temperature range to cooler temperatures compared to the original grid because the updated molecular line lists make modeling possible for cooler stars. A publicly available and consistently calculated database of model spectra is important for many astrophysical analyses, for example spectroscopic surveys and the determination of stellar elemental compositions.

We propose a line list that may be useful for the abundance analysis of G-type stars in the wavelength range 4080 – 6780 Å. It is expected that the line list will be useful for surveys/libraries with overlapping spectral regions (e.g. ELODIE/SOPHIE libraries, UVES-580 setting of Gaia-ESO), and in particular for the analysis of F- and G-type stars in general. The atomic data are supplemented by detailed references to the sources. We estimated the Solar abundances using stellar lines and the high-resolution Kitt Peak National Observatory (KPNO) spectra of the Sun to determine the uncertainty in the log 𝑔 𝑓 values. By undertaking a systematic search that makes use of the lower excitation potential and 𝑔 𝑓 -values and using revised multiplet table as an initial guide, we identified 363 lines of 24 species that have accurate 𝑔 𝑓 -values and are free of blends in the spectra of the Sun and a Solar analogue star, HD 218209 (G6V), for which accurate and up-to-date abundances were obtained from both ELODIE and PolarBASE spectra of the star. For the common lines with the Gaia-ESO line list v.6 provided by the Gaia-ESO collaboration, we discovered significant inconsistencies in the 𝑔 𝑓 -values for certain lines of varying species.

We derived preliminary abundances from the ultraviolet spectrum of Vega by comparing high-resolution Copernicus spectra with spectra computed with the ATLAS9 code and with updated line lists. The Teff=9400 K, log g=3.90 model, which fits the visual flux and the Balmer profiles is able to fit the ultraviolet flux either with [M/H]=−l and microturbulent velocity ξ= 2 km s−1 or with [M/H]=−0.5 and ξ=0 km s−1. The line spectrum is fitted by ξ=2 ± 0.5 km s−1 and by an iron abundance log (N(Fe)/Ntot)=−5.2 ±0.1 dex. All the observed elements indicate underabundances ranging from about −0.35 dex (C ) up to about −1 dex (Ni, Zn). The origin of the underabundances is an open question.