Results from the Herschel Gould Belt Survey in the Ophiuchus Main Cloud
The Ophiuchus Molecular Cloud is a well documented star-forming cloud located ~140 pc from the Sun. It is therefore an excellent laboratory for dense core search and classification. Harbouring low-mass star formation, its protostellar population have been studied for about three decades from the near infrared to the millimeter and radio range.
As part of the Herschel Gould Belt Survey (http://www.herschel.fr/cea/gouldbelt/
), extensive submillimeter images of the Ophiuchus Main Cloud (L1688) were produced and a deep census of both prestellar cores and young protostars was obtained using the multi-scale, multi-wavelength source extraction algorithm, getsources (Mensh'chikov et al. 2012).
About 300 starless cores were extracted, including ~100 candidates gravitationally bound prestellar cores. The prestellar cores are primarily found in high column density filamentary structures above AV
~7. Based on these data we discuss, the properties of the prestellar core mass function (CMF) as well as its variations in the various clumps of the cloud. The peak of the prestellar CMF appears to be close to 0.3 Solar masses in L1688.
Conceptually, the low-mass end of the prestellar CMF is populated by pre-brown dwarf cores, the prototype of which is Oph-B11, a 20 Jovian masses object identified with SCUBA and IRAM (Greaves et al. 2003, André et al. 2012). Our Herschel census of dense cores in L1688 contains a few other candidate ultra low-mass cores under the hydrogen-burning limit (0.08 M⊙) which will be discussed.