An upper limit on the sulphur abundance in HE?1327-2326

摘要

Context. Star HE?1327-2326 is a unique object, with the lowest measured iron abundance ([Fe/H] ?~??6) and a peculiar chemical composition that includes large overabundances of C, N, and O with respect to iron. One important question is whether the chemical abundances in this star reflect the chemical composition of the gas cloud from which it was formed or if they have been severely affected by other processes, such as dust-gas winnowing. Aims. We measure or provide an upper limit to the abundance of the volatile element sulphur, which can help to discriminate between the two scenarios. Methods. We observed HE?1327-2326 with the high resolution infra-red spectrograph CRIRES at the VLT to observe the S?i lines of Multiplet 3 at 1045?nm. Results. We do not detect the S?i line. A 3σ upper limit on the equivalent width (EW) of any line in our spectrum is EW?