Probing lambda Böotis formation models using multiple systems

D. CALVO; M.E. VERAMENDI; A. COLLADO; P. MIQUELARENA; M. FLORES; R. ANGELONI; C. SAFFE; J. ALACORIA; G. MARTÍN GIRARDI; M. JAQUE ARANCIBIA; F. GUNELLA

Tucumán

Congreso; IV JAE Jornadas de Astrofísica Estelar; 2022

The lambda Boötis stars are a group of chemically peculiar objects on the upper main-sequence, showing under-abundances (1?2 dex) of iron-peak elements and near-solar abundances of C, N, O, and S. The class was named following the bright prototype lambda Boötis, which is one extreme member of theclass. This group of refractory-poor objects comprises about 2% of early B through early F stars. However, among the pre-main-sequence Herbig Ae/Be stars, that is to say, the progenitors of A-type stars, the lambda Boötis-like fraction is about 33% (see e.g. the recent review of Murphy & Paunzen 2017, and references therein).