Analysis of first overtone bands of isotopologues of CO and SiO in stellar spectra

The first overtone ($\Delta v$ = 2) bands of the monosubstituted isotopologues of CO at 2.3 $\mu$m in the spectrum of Arcturus (K2 III), and of the monosubstituted isotopologues of SiO at 4 $\mu$m in the spectrum of the red giant HD196610 (M6 III) are modelled. To investigate problems involving the computation of the first overtone bands of isotopologues of CO and SiO in spectra of late-type stars and to determine isotopic abundances. We use fits of theoretical synthetic spectra to the observed stellar molecular bands of CO and SiO to determine abundances of isotopes of C, O and Si. Fits of synthetic spectra of the \CO first overtone bands at 2.3 $\mu$m computed with three available line lists (Goorvitch, HITEMP2010 and Li et al.) to the observed spectrum of Arcturus provide the same carbon abundance [C]=$-0.6$ and isotopic ratio of carbon $^{12}$C/$^{13}$C=10 $\pm$ 2. However, the quality of fits to the observed spectrum differ for three line lists used. Furthermore, the derived oxygen isotopic ratio $^{16}$O/$^{18}$O = 2000 $\pm$ 500 is larger than that known in the solar system where $^{16}$O/$^{18}$O = 500. The silicon isotopic ratio in the atmosphere of the red giant HD196610 is revised. Using the ExoMol SiO line list with appropriate statistical weights for the SiO isotopologues the `non-solar' ratio $^{28}$Si:$^{29}$Si:$^{30}$Si = 0.86$\pm$0.03:0.12$\pm$0.02:0.02$\pm$0.01 is obtained. We found that a) the computed isotopic carbon and silicon ratios determined by the fits to the observed spectrum depend on the adopted abundance of C and Si, respectively; b) Correct treatment of the nuclear spin degeneracies parameter is of crucial importance for the use of nowadays HITRAN/ExoMol line lists in the astrophysical computations.Comment: 9 pages, 6 figures, accepted by A&

Astronomy in Ukraine

The current and prospective status of astronomical research in Ukraine is discussed. A brief history of astronomical research in Ukraine is presented and the system organizing scientific activity is described, including astronomy education, institutions and staff, awarding higher degrees/titles, government involvement, budgetary investments and international cooperation. Individuals contributing significantly to the field of astronomy and their accomplishments are mentioned. Major astronomical facilities, their capabilities, and their instrumentation are described. In terms of the number of institutions and personnel engaged in astronomy, and of past accomplishments, Ukraine ranks among major nations of Europe. Current difficulties associated with political, economic and technological changes are addressed and goals for future research activities presented.Comment: Paper to be published in ``Organizations and Strategies in Astronomy'' -- Vol. 7, Ed. A. Heck, 2006, Springer, Dordrecht; 25 pages, 2 figs, 2 table

Analysis of the TiO isotopologues in stellar optical spectra

This study is based on the use of the new ExoMol TiO rovibronic line lists to identify and model TiO isotopologue features in spectra of M-dwarfs. We aim to investigate problems involving the computation of electronic bands for different isotopologues of TiO by modelling optical spectra of late-type stars and to determine their Ti isotopic abundances, to compare the TiO isotopologues spectra computed using line lists by different authors. We fit theoretical synthetic spectra to the observed stellar molecular bands of TiO. We model spectra of two M-dwarfs: GJ 15A (M1V) and GJ 15B (M3 V) to determine Ti isotopic ratios in their atmospheres. We demonstrate the accuracy of the ExoMol {\sc Toto} line list for differentisotopologues of TiO and the possibility of determining accurate Ti isotope abundances in a numberof spectral ranges. The 7580--7594 \AA\ spectral range seems particularly useful, with two atomic linesof Fe I and molecular band heads of $^{50}Ti$O, $^{49}Ti$O, $^{48}Ti$O, $^{47}Ti$O clearly observable in our two M-dwarf spectra. We determine non-solar Ti isotopic ratios of $^{46}Ti$ : $^{47}Ti$ : $^{48}Ti$ : $^{49}Ti$ : $^{50}Ti$ = 7.9 : 5.2 : 72.8 : 7.9 :6.2 for GJ 15A and 7.4 : 4.2 : 76.6 : 5.8 : 6.0 for GJ 15B with accuracy of order $\pm$ 0.2. [Ti] = 0.040 and 0.199 within accuracy $\pm$ 0.10 were also determined for GJ 15A and GJ 15B, respectively. We find that the ExoMol {\sc Toto} TiO line list: a) describes the fine details in line position and intensities of the M-dwarf spectra better than other available TiO line lists; b) correctly reproduces the positions and intensities of the TiO isotopologue band heads observed in M-dwarf spectra; c) can be used to determine Ti isotope abundances in atmospheres of M-stars.Comment: 17 pages, 6 Figs; accepted by A&