BPM 3066 line list

The observed ratio ^7^Li/^9^Be is 7.9, which is close to that expected from a synthesis by spallation processes. Overabundances of Si, Al, and of the neutron capture elements Sr,Y, Zr, and Ba are also measured. Kinematically, BPM 3066 has an eccentric, strongly retrograde orbit, confined to a height lower than 1 kpc from the galactic plane, and it is a candidate member of the Sequoia/Thamnos accreted galaxy.

The processes leading to the ^7^Li and ^9^Be synthesis could have occurred in the environment of a hypernova. This is supported by some abundance anomalies like the high value of Si, [Si/Fe]=1.2 and [Si/O]=1.1. However, the simultaneous high values of N, Na, Al, Sc, Ti, and Cu are at odds with the expectations from a hypernova.

Alternatively, the abundances of BPM 3066 could result from the engulfing of rocky planets that were rich in spallated Li and Be. In both cases, it is remarkable that such an extreme abundance pattern has been found in a star belonging to the Sequoia/Thamnos accreted galaxy.