Draco 119: A Remarkable Heavy‐Element–deficient Giant

We report the abundance analysis of new high S/N spectra of the mostmetal-poor ([Fe/H] $= -2.95$) star presently known to be a member of a dwarfgalaxy, the Draco dSph red giant, D119. No absorption lines for elementsheavier than Ni are detected in two Keck HIRES spectra covering the$\lambda\lambda$ 3850--6655 \AA{} wavelength range, phenomenon not previouslynoted in any other metal-poor star. We present upper limits for several heavyelement abundances. The most stringent limits, based on the non-detection of\ion{Sr}{2} and \ion{Ba}{2} lines, indicate that the total s- and r-processenrichment of D119 is at least 100 times smaller than Galactic stars of similarmetallicity. The light element abundances are consistent with the star havingformed out of material enciched primarily by massive Type II supernovae (M $>20$--25 M$_{\odot}$). If this is the case, we are forced to conclude thatmassive, metal-poor Type II supernovae did not contribute to the r-process inthe proto-Draco environment. We compare the abundance pattern observed in D119to current predictions of prompt enrichement and pair-instability supernovaeand find that the model predictions fail by an order or maginitude or more formany elements.Comment: Published in the September 1, 2004 edition of Ap