The molecular core in the AFGL 5157 region

DOI: 
Publication date: 
01/01/1992
Main author: 
Torrelles J.M.
IAA authors: 
Torrelles J.M.
Authors: 
Torrelles J.M., Eiroa C., Mauersberger R., Estalella R., Miranda L.F., Anglada G.
Journal: 
Astrophysical Journal
Publication type: 
Article
Volume: 
384
Pages: 
528-535
Number: 
Abstract: 
We present 40″ resolution observations of the (1, 1) and (2, 2) ammonia transition lines toward the molecular core in the AFGL 5157 region. The observed high-density condensation has a size of 1′.3 × ≤0′7. This structure has an orientation perpendicular to the axis of the bipolar molecular outflow previously observed in the region. The mass of the ammonia core is much larger than the mass of the bipolar molecular outflow. These results suggest that the observed elongated molecular condensation preceded, rather than followed, the outflow phenomenon phase, and that it can play an important role in the collimation processes at interstellar scales (∼0.1 pc). A rotational temperature TR(2, 2; 1, 1) ≃ 17 K is obtained for the ammonia core, implying the presence of an internal heating source with a luminosity L ≥ 5 × 102(d/1800 pc)2 L⊙ to keep that temperature. We have also carried out near-infrared observations (JHKL) and I, Hα, [S II], and red continuum CCD images. There are two reflection nebulae in the field of our images: one is NGC 1985, which coincides with AFGL 5157 (IRAS 05345 + 3157), and the other one is GM 39, which has a bipolar-like morphology and is probably excited by a pre-main-sequence star. Both nebulosities do not seem to be related to the powering source of the outflow. We failed to detect emission down to I = 23 mag at the peak of the ammonia condensation. There are also five small nebulosities, only detected with the emission-line filters, which probably are Herbig-Haro objects. Four of them are around the reflection nebula NGC 1985. The fifth is located near to a star in the field, at the southern border of the ammonia core. We suggest that some of these candidate HH objects, as well as a previously detected strong H2O maser in the region, could be excited by the same powering source as the molecular outflow. This powering source could be deeply embedded at the center of the ammonia core.
Database: 
SCOPUS
Keywords: 
ISM : individual (AFGL 5157); ISM : jets and outflows; ISM : kinematics and dynamics; ISM : molecules; Stars : pre-main-sequence