Molecular Jets and H2O Masers in AFGL 5142


T.R. Hunter (1), L. Testi (2,3), Q. Zhang (1), T.K. Sridharan (1,4)

(1) Harvard-Smithsonian Center for Astrophysics, MS-78, 60 Garden St., Cambridge, MA 02138, USA

(2) Division of Mathematics, Physics and Astronomy, MS105-24, California Institute of Technology, Pasadena, CA 91125, USA

(3) Present address: Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy

(4) On leave from: Raman Research Institute, Bangalore, India


We present centimeter and millimeter interferometric continuum and molecular line images of the massive star-forming region AFGL 5142. A compact (2.5 arcsec) 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 Msun) 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 ~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 ZAMS 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 A.U., and dynamical mass of ~1 Msun. 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.

Mantained by: Leonardo Testi