We report radio continuum and molecular line observations of the Galactic super star cluster RCW 38 , obtained from the Atacama Large Millimeter/Submillimeter Array with a minimum angular resolution of 0 ^ { \prime \prime } 17 \times 0 ^ { \prime \prime } 15 ( \simeq 289 { AU } \times 255 { AU } ) .
The C ^ { 18 } O image reveal many massive condensations embedded within filamentary structures extending along the northwest-southeast direction in the center of cluster .
The condensations have sizes of 0.01–0.02 pc , H _ { 2 } column densities of 10 ^ { 23 } – 10 ^ { 24 } cm ^ { -2 } , and H _ { 2 } masses of 10–130 M _ { \odot } .
In addition , the 233-GHz continuum image discovered that two dense , small millimeter-sources with radii of 460 and 200 AU ( Source A and Source B ) .
Source A is embedded within the most massive C ^ { 18 } O condensation , whereas no counterpart is seen for Source B .
The masses of Source A and Source B are estimated as 13 and 3 M _ { \odot } at the optically-thin limit , respectively .
The C ^ { 18 } O emission shows a velocity gradient of 2 km s ^ { -1 } at the central 2000 AU of Source A , which could be interpreted as a Keplerian rotation with a central mass of a few M _ { \odot } or infall motion of gas .
Further , the ALMA ^ { 12 } CO data reveal that Source A and Source B are associated with molecular outflows exhibiting maximum velocities of \sim 30–70 km s ^ { -1 } .
The outflows have short dynamical timescales of < 1000 yr and high mass outflow rates of \sim 10 ^ { -4 } – 10 ^ { -3 } M _ { \odot } yr ^ { -1 } .
These observational signatures suggest an early evolutionary phase of the massive star formation in Source A and Source B , although further investigation based on the high-resolution observations are needed to reach a firm conclusion .