Iras 23385+6053: a Prototype Massive Class 0 Object 0

IRAS 23385+6053 is a Young Stellar Object with luminosity 1:6 10 4 L at a kinematic distance of 4.9 kpc. This candidate precursor of an ultracompact Hii region is associated with a millimeter source detected at the JCMT but is undetected at centimeter wavelengths with the VLA. We observed this source with the OVRO millimeter array at 3.4 mm in the continuum, HCO + (1 ! 0), H 13 CO + (1 ! 0) and SiO(v=0, 2 ! 1) line emission, and with CAM aboard ISO at 6.75m and 15m. The IRAS source is coincident with a 3.4 mm compact (r core ' 0:048 pc) and massive (M ' 370 M) core, which is undetected at 15m to a 3 level of 6 mJy; this is compatible with the derived H 2 column density of 2 10 24 cm ?2 and the estimated visual extinction A V 2000 mag. We nd L submm /L bol 310 ?3 and M env /M ? 1, typical of Class 0 objects. The source is also associated with a compact outtow characterized by a size < r core , a dynamical timescale of < 710 3 years, and a mass loss rate _ The axis of the outtow is oriented nearly perpendicular to the plane of the sky, ruling out the possibility that the non-detection at 15 m is the result of a geometric eeect. All these properties suggest that IRAS 23385+6053 is the rst example of a bona de massive Class 0 object.