On producers of cosmic organic compounds: exploring the boron abundance in lithium-rich K giant stars. (arXiv:1911.12856v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Drake_N/0/1/0/all/0/1">N.A. Drake</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reza_R/0/1/0/all/0/1">R. de la Reza</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smith_V/0/1/0/all/0/1">V.V. Smith</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cunha_K/0/1/0/all/0/1">K. Cunha</a>
The element boron belongs, together with lithium and beryllium, to a known
trio of important elements for the study of evolutionary processes in low mass
stars. Because B is the least fragile of this trio to be destroyed in the
stellar interiors, it can be used to test if the Li enrichment is of planetary
origin. Here, for the first time, boron lines are examined in the UV for four
giants with different degrees of large Li enrichment by means of observations
with the Hubble telescope. Two main results are found in our study. One is that
to first approximation B abundances appear not to be in excess, invalidating
the planet engulfment mechanism. The second one is that the two stars with very
large Li abundances present emission lines indicating that quite strong active
chromospheres are acting in these very Li-rich giants. These new results
obtained from the UV complement our recent studies in the mid-IR (de la Reza et
al. 2015) where strong emission-line features of organic material were found in
the spectra of some Li-rich stars.
The element boron belongs, together with lithium and beryllium, to a known
trio of important elements for the study of evolutionary processes in low mass
stars. Because B is the least fragile of this trio to be destroyed in the
stellar interiors, it can be used to test if the Li enrichment is of planetary
origin. Here, for the first time, boron lines are examined in the UV for four
giants with different degrees of large Li enrichment by means of observations
with the Hubble telescope. Two main results are found in our study. One is that
to first approximation B abundances appear not to be in excess, invalidating
the planet engulfment mechanism. The second one is that the two stars with very
large Li abundances present emission lines indicating that quite strong active
chromospheres are acting in these very Li-rich giants. These new results
obtained from the UV complement our recent studies in the mid-IR (de la Reza et
al. 2015) where strong emission-line features of organic material were found in
the spectra of some Li-rich stars.
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