IRAS 23385+6053: A prototype massive class 0 object

IRAS 23385+6053 is a young stellar object with a luminosity of similar to 1 .6 x 10(4) L. at a kinematic distance of 4.9 kpc, This candidate precursor of an ultracompact H II region is associated with a millimeter source detec ted at the James Clerk Maxwell Telescope but is undetected at centimeter wa velengths with the VLA. We observed this source with the Owens Valley Radio Observatory millimeter array at 3.4 mm in the continuum, HCO+ (1 --> 0), ( HCO+)-C-13 (1 --> 0), and SiO (upsilon = 0, 2 --> 1) line emission and with CAM aboard the Infared Space Observatory at 6.75 and 15 mu m. The IRAS sou rce is coincident with a 3.4 mm compact (r(core) similar or equal to 0.048 pc) and massive (M similar or equal to 370 M.) core, which is undetected at 15 mu m to a 3 sigma level of 6 mJy; this is compatible with the derived H -2 column density of similar to 2 x 10(24) cm(-2) and the estimated visual extinction A(V) similar to 2000 mag. We find L-submm/L-bol similar to 3 x 1 0(-3) and M-env/M-star >> 1, which is typical of class O objects. The sourc e is also associated with a compact outflow characterized by a size less th an or similar to r(core), a dynamical timescale of less than or similar to 7 x 10(3) yr, and a mass-loss rate (M) over dot greater than or similar to 10(-3) M. yr(-1). The axis of the outflow is oriented nearly perpendicular to the plane of the sky, ruling out the possibility that the nondetection a t 15 mu m is the result of a geometric effect. All these properties suggest that IRAS 23385+6053 is the first example of a bona fide massive class 0 o bject.