Molecular Jets and H[TINF]2[/TINF]O Masers in the AFGL 5142 Hot Core

Abstract

We present centimeter and millimeter continuum and molecular line images of the massive star-forming region AFGL 5142. A compact (25) millimeter continuum core with integrated flux density of 125 mJy has been detected at 88 GHz. The emission peak coincides with a 1.5 mJy centimeter continuum source. A massive (~35 M☉) highly collimated north-south outflow emanating from the core is seen in both the HCO+ (1–0) and SiO (v = 0, J = 2–1) transitions. The millimeter continuum source coincides with a molecular core traced by the ambient velocity HCO+ (1–0), SiO (v = 0, J = 2–1), and H13CO+ (1–0) emission. CH3CN (14–13) and (12–11) spectra indicate a gas temperature of approximately 65 K in the innermost core. While the millimeter continuum emission is probably mostly due to optically thin thermal emission from dust grains, the centimeter continuum source is consistent with an ionized wind. From the Lyman continuum flux required to sustain the ionized gas, we estimate that the exciting source should be a B2 or earlier zero-age main-sequence star. The 22 GHz H2O masers most closely associated with the central object have undergone substantial variability in flux and position during three epochs spread over eight years. In addition, two new water maser features have been detected significantly offset (3''–4'', 0.03 pc) from the centimeter continuum peak position. One of these maser features exhibits a linear structure of spots with spatial-kinematic evidence for a rotating circumstellar disk of radius 40 AU and dynamical mass of ≈1 M☉. The other is found to be associated with a near-infrared source with large infrared excess. In addition to the 28 embedded stars previously seen in infrared images, we conclude that this cluster is concurrently forming both low- and high-mass stars.