The Li overabundance of J37: Diffusion or Accretion?
Johanna Fleur Ashwell (Astrophysics Group, School of Chemistry & Physics, Keele University, Staffordshire, ST5 5BG, UK)
R.D. Jeffries, Barry Smalley (Astrophysics Group, Keele University, UK)
et al. ()
In September 2002 the discovery of a super Li-rich F-dwarf (J37) in NGC
6633, an iron poor analogue of the better studied Hyades and Praecepe open
clusters, was announced. This, at the time, unique star was thought to be
the smoking gun for the action of diffusion models which predict a narrow
"Li-peak" at roughly the right temperature. However, with the recent
discovery of similar stars in a number of open clusters of different ages,
J37 may represent the first of a new class of star providing firm evidence
of the accretion of planetesimals or other material from the circumstellar
environment of new born stars.
Thanks to the specific predictions made about the behavior of Be
abundances, (the most striking of which being we should see no Be in
super-Li-rich dwarfs) the opposing diffusion/accretion predictions can be
tested.
Using the UVES/UT2 combination we are measuring detailed abundances for
many chemical elements Fe, Mn, Ti etc but most critically Beryllium.