IRAS 23385+6053: A Prototype Massive Class 0 Object


S. Molinari(1), L. Testi (2), J. Brand(3), R. Cesaroni(4), P. Palla (4)

(1) IPAC/Caltech, MS 100-22, Pasadena, CA 91125, USA

(2) Division of Physics, Mathematics and Astronomy, Caltech, MS 105-24, Pasadena, CA 91125, USA

(3) Istituto di Radioastronomia - CNR, Via Gobetti 101, I-40129, Bologna, Italy

(4) Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy


IRAS23385+6053 is a Young Stellar Object with luminosity ~1.6x10^4 Lsun at a kinematic distance of 4.9kpc. This candidate precursor of an ultracompact HII egion 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 3.4mm in the continuum, HCO+(1-0), H13CO+(1-0), and SiO(v=0,2-1) line emission, and with CAM aboard ISO at 6.75um and 15um. The IRAS source is coincident with a 3.4mm compact (r(core)~0.048pc) and massive (M~370 Msun) core, which is undetected at 15um to a 3sigma level of 6Jy; this is compatible with the derived H2 column density of ~2x10^24 cm^-2 and the estimated visual extinction AV~2000mag. We find Lsubmm/Lbol~3x10^-3 and Menv/Mstar>>1, typical of Class 0 objects. The source is also associated with a compact outflow characterized by a size less than r(core), a dynamical timescale of 7000years, and a mass loss rate ~10^-3 Msun/year. The axis of the outflow is oriented nearly perpendicular to the plane of the sky, ruling out the possibility that the non-detection at 15um is the result of a geometric effect. ll these properties suggest that IRAS 23385+6053 is the first example of a bona fide massive Class 0 object.

Mantained by: Leonardo Testi