We present Spitzer IRAC ( 2.1 sq .
deg . )
and MIPS ( 6.5 sq .
deg . )
observations of star formation in the Ophiuchus North molecular clouds .
This fragmentary cloud complex lies on the edge of the Sco-Cen OB association , several degrees to the north of the well-known \rho Oph star-forming region , at an approximate distance of 130 pc .
The Ophiuchus North clouds were mapped as part of the Spitzer Gould Belt project under the working name ‘ Scorpius ’ .
In the regions mapped , selected to encompass all the cloud with visual extinction A _ { V } > 3 , eleven Young Stellar Object ( YSO ) candidates are identified , eight from IRAC/MIPS colour-based selection and three from 2MASS K _ { S } /MIPS colours .
Adding to one source previously identified in L43 ( ) , this increases the number of YSOcs identified in Oph N to twelve .
During the selection process , four colour-based YSO candidates were rejected as probable AGB stars and one as a known galaxy .
The sources span the full range of YSOc classifications from Class 0/1 to Class III , and starless cores are also present .
Twelve high-extinction ( A _ { V } > 10 ) cores are identified with a total mass of \sim 100 M _ { \odot } .
These results confirm that there is little ongoing star formation in this region ( instantaneous star formation efficiency < 0.34 % ) and that the bottleneck lies in the formation of dense cores .
The influence of the nearby Upper Sco OB association , including the 09V star \zeta Oph , is seen in dynamical interactions and raised dust temperatures but has not enhanced levels of star formation in Ophiuchus North .