Context : In star-forming regions like Taurus-Auriga , it has been found that most young stars are born as multiples , which theories for star formation should definitely take into account .
The R CrA star-forming region has a small dark cloud with quite a number of protostars , T Tauri stars , and some Herbig Ae/Be stars , plus a number of weak-line T Tauri stars around the cloud found by ROSAT follow-up observations .

Aims : We would like to detect multiples among the young stars in and around the R CrA cloud in order to investigate multiplicity in this region .

Methods : We performed interferometric and imaging observations with the speckle camera SHARP I at the ESO 3.5 m NTT and adaptive optics observation with ADONIS at the ESO 3.6 m telescope , all in the near-infrared bands JHK obtained in the years 1995 , 2000 , and 2001 .

Results : We found 13 new binaries among the young stars in CrA between 0.13 arcsec ( the diffraction limit ) and 6 arcsec ( set as an upper separation limit to avoid contamination by chance alignments ) .
While most multiples in CrA are binaries , there are also one quadruple ( TY CrA ) , and one triple ( HR 7170 ) which may form a quintuple together with the binary HR 7169 .
One of the newly detected companions with a large magnitude difference found near the M3-5 type T Tauri star [ MR 81 ] H \alpha 17 could be a brown dwarf or an infrared companion with an edge-on disk .
Among seven Herbig Ae/Be stars in CrA , six are multiple .

Conclusions : The multiplicity frequency in CrA is as high as in similar star forming regions .
By comparing with the period distribution of main-sequence stars and extrapolating to separations not probed in this survey , we conclude that the companion-star frequency is ( 95 \pm 23 ) \% ; i.e .
the average number of companions per primary is 0.95 .