Letter to the Editor
Cross-calibrated VLA observations of H2O maser and 1.3 cm continuum emission in IRAS 18162-2048 (= HH 80-81 IRS)
Josep Martí 1,
Luis F. Rodríguez 2 and
José M. Torrelles 3
Received 10 March 1999 / Accepted 29 March 1999
We report simultaneous continuum (1.3 cm) and H2O maser line observations, made with the Very Large Array (A configuration), toward IRAS 18162-2048, the luminous exciting source of the HH 80-81 complex. The continuum observations, cross-calibrated with the H2O maser emission, provide information of the thermal jet of this young massive star with unprecedented angular resolution and fidelity. We find that the jet is already collimated on scales smaller than 100 AU. The analysis of the new 1.3 cm data and of previously obtained 3.6 cm data show that the source has the frequency dependences in major axis and flux density that characterize biconical jets. In particular, we find and . An improved determination of the mass loss rate in ionized gas, yr-1, is provided with these new observations.
As it was known from previous studies, the H2O maser emission does not coincide with the thermal jet but with a faint source of radio continuum emission displaced by 7" to the northeast of the thermal jet. The H2O masers appear in two compact clusters separated by 20 mas. One of the clusters is formed by spots in a linear geometry. The kinematics of these maser spots and their large blueshift with respect to the radial velocity of the parental molecular cloud suggest that they trace material accelerated by outflow phenomena, instead of a possible disk.
Key words: stars: individual: IRAS 18162-2048 stars: individual: HH 80-81 IRS stars: formation ISM: Herbig-Haro objects ISM: jets and outflows
Send offprint requests to: J. Martí, firstname.lastname@example.org
© European Southern Observatory (ESO) 1999
Online publication: April 12, 1999