A non-LTE radiative transfer model to study ionized outflows and disks. The case of MWC349A
Abstract
Context. The best example of a massive star with an ionized outflow launched from its photoevaporating disk is MWC349A. The large amount of reported radio-continuum and radio-recombination line (RRL) observations toward this galactic UC-HII region offers a unique possibility to build a model of the ionized envelope of this source.
Aims: To understand the physical conditions and kinematics of the ionized region of the circumstellar disk and also of the outflow of MWC349A.
Methods: We compared the bulk of radio-continuum maps, RRL profiles, and the H30α centroid map published to date with the predictions of our non-LTE 3D radiative transfer model, MOdel for REcombination LInes (MORELI), which we describe here in detail.
Results: Our non-LTE 3D radiative transfer model provides new evidence that the UC-HII region of MWC349A is composed of an ionized circumstellar disk rotating in Keplerian fashion around a star of 38 M⊙, and an ionized outflow expanding with a terminal velocity of 60 km s-1 and rotating in the same sense as the disk. The model shows that while maser amplification is the dominant process involved for Hnα RRL emission with quantum numbers n < 41, stimulated emission is relevant for the emission of RRLs with n > 41 up at least the H76α line.
Conclusions: For the first time, we present a model of MWC349A which satisfactorily explains the vast amount of reported observational data for a very wide range of frequencies and angular resolutions.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 2013
- DOI:
- 10.1051/0004-6361/201219889
- arXiv:
- arXiv:1307.3896
- Bibcode:
- 2013A&A...553A..45B
- Keywords:
-
- stars: massive;
- masers;
- HII regions;
- stars: winds;
- outflows;
- accretion;
- accretion disks;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Galaxy Astrophysics
- E-Print:
- Astronomy &