Analysis of the TiO isotopologues in stellar optical spectra. (arXiv:2008.02092v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Pavlenko_Y/0/1/0/all/0/1">Ya. V. Pavlenko</a> (MAO NASU), <a href="http://arxiv.org/find/astro-ph/1/au:+Yurchenko_S/0/1/0/all/0/1">Sergei N. Yurchenko</a> (UCL), <a href="http://arxiv.org/find/astro-ph/1/au:+McKemmish_L/0/1/0/all/0/1">Laura K. McKemmish</a> (UNSW), <a href="http://arxiv.org/find/astro-ph/1/au:+Tennyson_J/0/1/0/all/0/1">Jonathan Tennyson</a> (UCL)
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.
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.
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