2006PASJ...58L..15S

begin{HTML} The rotational spectral lines of methylformate (HCOOCH₃) have been detected toward a low-mass protostar, NGC 1333 IRAS 4B, with the Nobeyama 45m radio telescope. The column density is derived to be (7 - 37) x 10¹⁵ cm^-2, assuming a source size of 1'' and the range of the excitation temperature to be from 50K to 200K. The column density is almost comparable to those found in other low-mass star-forming regions, NGC 1333 IRAS 4A and IRAS 16293-2422. The line width of HCOOCH₃ is (1.0 - 1.2) km s^-1, which is narrower than that of the high-excitation line of CH₃OH (8_-4- 9_-3). Since NGC 1333 IRAS 4B is likely to be a very young protostar, HCOOCH₃ appears even in the early stage of protostellar evolution. The spectral lines of HCOOCH₃ could be used as a novel tracer for detecting an onset of star formation.