L1521E is a pre-stellar core in Taurus which was found to be in an early evolutionary state, and to have very little or no molecular depletion.
We have obtained ~2.5x2.5 arcminute maps in transitions of key molecular species, including C17O, CH3OH, c-C3H2, CN, SO, H2CS, and CH3CCH, using the IRAM-30m telescope, to study the chemical structure of L1521E. We compared the results to those obtained toward the more evolved and better characterized L1544 core.
Based on the IRAM-30m C17O map and N(H2) derived from Herschel/SPIRE data, CO depletion toward L1521E is more significant than suggested by earlier studies, with a lower limit of 4.9+/-1.8 on the CO depletion factor toward the dust peak.
Comparing the abundances of species toward the two cores we found that sulfur-bearing molecules such as C2S, HCS+, C34S, C33S, SO, and H2CS are factors of 10 to 50 more abundant toward L1521E than toward L1544, suggesting that significant sulphur depletion is taking place during the dynamical evolution of dense cores.