IRAS 23385+6053: A Prototype Massive Class 0 Object
by
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
Abstract:
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
lt@arcetri.astro.it