Astronomy and Astrophysics – Astronomy
Scientific paper
Sep 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011ess.....2.3501c&link_type=abstract
American Astronomical Society, ESS meeting #2, #35.01
Astronomy and Astrophysics
Astronomy
Scientific paper
We have identified twelve red giant stars as candidates for having accreted a former planetary companion in a previous study aimed at understanding the role of planet accretion in creating the unusual red giant rapid rotators. Their planet accretion candidacy is based on the apparent replenishment of lithium in their atmospheres and (in some cases) enhanced rotation speeds, coupled with the difficulty of alternative Li-enhancement mechanisms working at these stars' evolutionary stages. The stellar mass estimates, however, are not precise enough to unambiguously describe the mass-dependent chemical processing (e.g., the degree of light element dilution) expected in these stars. In this study, we explore additional chemical signatures expected to be unique to planet accretion. For example, one hallmark of a planetary composition is a trend of increased abundance with condensation temperature, i.e., relative enhancement of refractory elements over volatiles. In main sequence stars, a relative enhancement of refractory elements in stellar atmospheres has been explored as a signature of the accretion of planetary material (e.g., Smith et al. 2001) while the opposite trend (depleted refractories in the Sun) has been suggested as a possible indicator that a star hosts terrestrial planets (Melendez et al. 2009). Here we explore whether condensation temperature dependent abundance patterns exist in our red giant planet-accretion candidates and the implications of the presence or absence of such a trend. Finally, we briefly highlight future experiments to further test our hypothesis that these stars have accreted planets, such as looking for changes in specific abundance ratios and the feasibility of radial velocity monitoring to look for unaccreted planets.
Carlberg Joleen K.
Cunha Katia
Majewski Steven R.
Smith Verne V.
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