CCS and NH3Emission Associated with Low‐Mass Young Stellar Objects

In this work we present a sensitive and systematic single-dish survey of CCSemission (complemented with ammonia observations) at 1 cm, toward a sample oflow- and intermediate-mass young star forming regions known to harbor watermaser emission, made with NASA's 70 m antenna at Robledo de Chavela, Spain. Out of the 40 star forming regions surveyed in the CCS(2_{1}-1_{0}) line,only 6 low-mass sources show CCS emission: one transitional object betweenpre-stellar and protostellar Class 0 phase (GF9-2), three Class 0 protostars(L1448-IRS3, L1448C, and B1-IRS), a Class I source (L1251A), and a young TTauri star (NGC2071-North). Since CCS is considered an ``early-time'' (<10E+5yr) molecule, we explain these results by either proposing a revision of theclassification of the age of NGC2071-North and L1251A, or suggesting thepossibility that the particular physical conditions and processes of eachsource affect the destruction/production of the CCS. No statisticallysignificant relationship was found between the presence of CCS and parametersof the molecular outflows and their driving sources. Nevertheless, we found asignificant relationship between the detectability of CCS and the ammonia peakintensity (higher in regions with CCS), but not with its integrated intensity.This tendency found may suggest that the narrower ammonia line widths in theless turbulent medium associated with younger cores may compensate for thedifferences in ammonia peak intensity, rendering differences in integratedintensity negligible. From the CCS detection rate we derive a lifetime of thismolecule of ~(0.7-3) x 10E+4 yr in low-mass star forming regions.Comment: 28 pages, 1 figure, 3 tables, to appear in the 2006 May 1 issue of the Astrophysical Journa