We present the results of ALMA observations of dust continuum emission and molecular rotational lines toward a dense core MC27 ( aka L1521F ) in Taurus , which is considered to be at a very early stage of star formation .
The detailed column density distribution on size scales from a few tens AU to \sim 10,000 AU scale are revealed by combining the ALMA ( 12 m array + 7 m array ) data with the published/unpublished single-dish data .
The high angular resolution observations at 0.87 mm with a synthesized beam size of \sim 0 \farcs 74 \times 0 \farcs 32 reveal that a protostellar source , MMS-1 , is not spatially resolved and lacks associated gas emission , while a starless high-density core , MMS-2 , has substructures both in dust and molecular emission .
The averaged radial column density distribution of the inner part of MC27/L1521F ( r \lesssim 3000 AU ) is N _ { \mathrm { H _ { 2 } } } \sim r ^ { -0.4 } , clearly flatter than that of the outer part , \sim r ^ { -1.0 } .
The complex velocity/spatial structure obtained with previous ALMA observations is located inside the inner flatter region , which may reflect the dynamical status of the dense core .