Astron. Astrophys. 345, 949-964 (1999)

5. Conclusions

The main goal of this paper was to allow a better analysis of the disk-outflow system studied by CFTWO, using the high angular resolution (0:007) capability of the PdBI at 1.3 mm. This aim has been completely accomplished. In particular the following results have been obtained:

• The observations in the CH₃CN(12-11) lines confirm the existence of a rotating disk at the nominal position of IRAS 20126+4104. Such a disk probably extends over a much larger region than that traced by CH₃CN, as suggested by maps in the H¹³CO⁺(1-0) line.

• Along the axis of the disk a bipolar jet is seen in the SiO(2-1) line. Such a jet is in very good agreement with the H₂ line image at 2.122 µm (CFTWO; 1998) and seems to feed the bipolar outflow mapped by CFTWO in the HCO⁺(1-0) line. The jet axis turns out to lie almost in the plane of the sky.

• The IRAS source is embedded in a hot core of 1500 AU, traced by the CH₃CN lines as well as by the continuum emission from 10 µm to 3 mm. In particular, the 10 and 20 µm emission - unlike that in near-infrared (see CFTWO) - is probably due to thermal emission arising from the core and from a small "tail" tracing the inner part of the jet seen in the SiO and H₂ lines.

• A study of the CH₃CN(12-11) lines indicates that the disk is Keplerian and probably collapsing towards a central object with mass 24 . It is also possible to estimate the mass accretion rate from the collapse velocity and continuum emission at 1.3 mm.

• Since the observed luminosity of IRAS 20126+4104 () is much less than expected for a 24  ZAMS star, we conclude that if a single object is responsible for the Keplerian rotation, then this must be a massive protostar . The estimated accretion luminosity () is indeed consistent with the measured one.

We conclude that IRAS 20126+4104 could represent the first example of a high-mass protostar complete with Keplerian accretion disk and bipolar jet/outflow.

© European Southern Observatory (ESO) 1999

Online publication: April 28, 1999
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