We present Herschel SPIRE and PACS maps of the Cepheus Flare clouds L1157, L1172, L1228, L1241, and L1251, observed by the Herschel Gould Belt Survey (HGBS) of nearby star-forming molecular clouds. Through modified blackbody fits to the SPIRE and PACS data, we determine typical cloud column densities of 0.5-1.0 $times$ 10$^{21}$ cm$^{-2}$ and typical cloud temperatures of 14-15 K. Using the getsources identification algorithm, we extract 832 dense cores from the SPIRE and PACS data at 160-500 $mu$m. From placement in a mass vs. size diagram, we consider 303 to be candidate prestellar cores, and 178 of these to be robust prestellar cores. From an independent extraction of sources at 70 $mu$m, we consider 25 of the 832 dense cores to be protostellar. The distribution of background column densities coincident with candidate prestellar cores peaks at 2-4 $times$ 10$^{21}$ cm$^{-2}$. About half of the candidate prestellar cores in Cepheus may have formed due to the widespread fragmentation expected to occur within filaments of transcritical line mass. The lognormal robust prestellar core mass function (CMF) drawn from all five Cepheus clouds peaks at 0.56 M$_{odot}$ and has a width of $sim$0.5 dex, similar to that of Aquilas CMF. Indeed, the width of Cepheus aggregate CMF is similar to the stellar system Initial Mass Function (IMF). The similarity of CMF widths in different clouds and the system IMF suggests a common, possibly turbulent origin for seeding the fluctuations that evolve into prestellar cores and stars.
تحميل البحث