IRAS 23385+6053 is a young stellar object with a luminosity of ~1.6×104 Lsolar at a kinematic distance of 4.9 kpc. This candidate precursor of an ultracompact H II region is associated with a millimeter source detected at the James Clerk Maxwell Telescope but is undetected at centimeter wavelengths 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), H13CO+ (1-->0), and SiO (v=0, 2-->1) line emission and with CAM aboard the Infrared Space Observatory at 6.75 and 15 μm. The IRAS source is coincident with a 3.4 mm compact (rcore~=0.048 pc) and massive (M~=370 Msolar) core, which is undetected at 15 μm to a 3 σ level of 6 mJy; this is compatible with the derived H2 column density of ~2×1024 cm-2 and the estimated visual extinction AV~2000 mag. We find Lsubmm/Lbol~3×10-3 and Menv/M*>>1, which is typical of class 0 objects. The source is also associated with a compact outflow characterized by a size <~rcore, a dynamical timescale of <~7×103 yr, and a mass-loss rate Ṁ>~10-3 Msolar yr-1. The axis of the outflow is oriented nearly perpendicular to the plane of the sky, ruling out the possibility that the nondetection at 15 μm 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 object.
Molinari S, Testi L, Brand J, Cesaroni R, Palla F (1998). IRAS 23385+6053: A Prototype Massive Class 0 Object. THE ASTROPHYSICAL JOURNAL LETTERS, 505, 39-42.
IRAS 23385+6053: A Prototype Massive Class 0 Object
Testi L;
1998
Abstract
IRAS 23385+6053 is a young stellar object with a luminosity of ~1.6×104 Lsolar at a kinematic distance of 4.9 kpc. This candidate precursor of an ultracompact H II region is associated with a millimeter source detected at the James Clerk Maxwell Telescope but is undetected at centimeter wavelengths 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), H13CO+ (1-->0), and SiO (v=0, 2-->1) line emission and with CAM aboard the Infrared Space Observatory at 6.75 and 15 μm. The IRAS source is coincident with a 3.4 mm compact (rcore~=0.048 pc) and massive (M~=370 Msolar) core, which is undetected at 15 μm to a 3 σ level of 6 mJy; this is compatible with the derived H2 column density of ~2×1024 cm-2 and the estimated visual extinction AV~2000 mag. We find Lsubmm/Lbol~3×10-3 and Menv/M*>>1, which is typical of class 0 objects. The source is also associated with a compact outflow characterized by a size <~rcore, a dynamical timescale of <~7×103 yr, and a mass-loss rate Ṁ>~10-3 Msolar yr-1. The axis of the outflow is oriented nearly perpendicular to the plane of the sky, ruling out the possibility that the nondetection at 15 μm 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 object.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
