612 research outputs found
Line lists for the A2PI-X2Sigma+ (red) and {B2Sigma+-X2Sigma} (violet) Systems of CN, 13C14N, and 12C15N, and Application to Astronomical Spectra
New red and violet system line lists for the CN isotopologues 13C14N and
12C15N have been generated. These new transition data are combined with those
previously derived for 12C14N, and applied to the determination of CNO
abundances in the solar photosphere and in four red giant stars: Arcturus, the
bright very low-metallicity star HD 122563, and carbon-enhanced metal-poor
stars HD 196944 and HD 201626. When lines of both red and violet system lines
are detectable in a star, their derived N abundances are in good agreement. The
mean N abundances determined in this work generally are also in accord with
published values.Comment: ApJS, in press, 37 pages, 7 figures, 3 table
Fourier Transform Emission Spectroscopy of YH and YD: Observation of New A¹Δ and B¹ΠElectronic States
The emission spectra of YH and YD molecules have been investigated in the 3600–12 000 cm−1 region using a Fourier transform spectrometer. Molecules were formed in an yttrium hollow cathode lamp operated with a continuous flow of a mixture of Ne and Ar gases, and YH and YD were observed together in the same spectra. A group of bands observed near 1 μm have been identified as 0-0 and 1-1 bands of the A1Δ-X1Σ+ and B1Π-X1Σ+ transitions of YH and the 0-0 bands of the same two transitions for YD. The A1Δ and B1Πstates of YH are separated by only about 12 cm−1 and are involved in strong interactions. A perturbation analysis has been performed using the PGOPHER program to fit the two interacting electronic states and spectroscopic parameters for the A1Δ and B1Πstates, including the interaction matrix elements, have been obtained for the first time
The Magnesium Isotopologues of MgH in the A2Π-X 2Σ+ System
Using laboratory hollow cathode spectra we have identified lines of the less common magnesium isotopologues of MgH, 25MgH and 26MgH, in the A2Π-X2Σ+ system. Based on the previous analysis of 24MgH, molecular lines have been measured and molecular constants derived for 25MgH and 26MgH. Term values and linelists, in both wavenumber and wavelength units, are presented. The A2Π-X2Σ+ system of MgH is important for measuring the magnesium isotope ratios in stars. Examples of analysis using the new linelists to derive the Mg isotope ratio in a metal poor dwarf and giant are shown. © 2013. The American Astronomical Society
Line Strengths of Rovibrational and Rotational Transitions in the X Ground State of OH
A new line list including positions and absolute intensities (in the form of
Einstein values and oscillator strengths) has been produced for the OH
ground X\DP\ state rovibrational (Meinel system) and pure rotational
transitions. All possible transitions are included with v\primed and
v\Dprimed up to 13, and up to between 9.5 and 59.5, depending on the
band. An updated fit to determine molecular constants has been performed, which
includes some new rotational data and a simultaneous fitting of all molecular
constants. The absolute line intensities are based on a new dipole moment
function, which is a combination of two high level ab initio calculations. The
calculations show good agreement with an experimental v=1 lifetime,
experimental values, and v=2 line intensity ratios
from an observed spectrum. To achieve this good agreement, an alteration in the
method of converting matrix elements from Hund's case (b) to (a) was made.
Partitions sums have been calculated using the new energy levels, for the
temperature range 5-6000 K, which extends the previously available (in HITRAN)
70-3000 K range. The resulting absolute intensities have been used to calculate
O abundances in the Sun, Arcturus, and two red giants in the Galactic open and
globular clusters M67 and M71. Literature data based mainly on [O I] lines are
available for the Sun and Arcturus, and excellent agreement is found.Comment: 17 pages, 8 figues. 7 supplementary files: dipole moment functions
(OH-X-DMFs.txt), equilibrium constants (OH-X-Equilibrium_Constants.txt),
partition function (OH-X-Q_5-6000K.dat), PGOPHER file with molecular
constants and transition matric elements (OH-XX.pgo), vibrational Einstein A
and f values (OH-XX-Avv_fvv.txt), line list (OH-XX-Line_list.txt), and
OH-Transformation_Equation_Extra.doc
Organic molecules in the spectral line survey of Orion KL with the Odin Satellite from 486492 GHz and 541577 GHz
Proceedings of the International Astronomical Union, 2008, v. 4 n. S251, p. 29-30A spectral line survey of Orion KL has been performed over the frequency range of 486492 GHz and 541577 GHz using the Odin satellite. Over 1000 lines have been identified from 40 different molecular species, including several organic compounds such as methyl cyanide (CH3CN), methanol (CH3OH, 13CH3OH), and dimethyl ether (CH3OCH3). © 2008 International Astronomical Union.published_or_final_versio
Note: Improved line strengths of rovibrational and rotational transitions within the X3Σ− ground state of NH
Recently, a line list including positions and transition strengths was published for the NH X3Σ− 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 X2Πrovibrational 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
CH in stellar atmospheres: an extensive linelist
The advent of high-resolution spectrographs and detailed stellar atmosphere
modelling has strengthened the need for accurate molecular data.
Carbon-enhanced metal-poor (CEMP) stars spectra are interesting objects with
which to study transitions from the CH molecule. We combine programs for
spectral analysis of molecules and stellar-radiative transfer codes to build an
extensive CH linelist, including predissociation broadening as well as newly
identified levels. We show examples of strong predissociation CH lines in CEMP
stars, and we stress the important role played by the CH features in the
Bond-Neff feature depressing the spectra of barium stars by as much as 0.2
magnitudes in the 3000 -- 5500 \AA\ range. Because of the extreme
thermodynamic conditions prevailing in stellar atmospheres (compared to the
laboratory), molecular transitions with high energy levels can be observed.
Stellar spectra can thus be used to constrain and improve molecular data.Comment: 33pages, 15 figures, accepted in A&A external data available at
http://www.astro.ulb.ac.be/~spectrotools
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