Volume 571, November 2014
|Number of page(s)||5|
|Published online||10 November 2014|
Centro de Astrobiología (CSIC-INTA), Ctra de Torrejón a Ajalvir, km 4,
28850 Torrejón de Ardoz,
e-mail: email@example.com; firstname.lastname@example.org
2 Observatorio Astronómico Nacional (IGN), Alfonso XII 3, 28014 Madrid, Spain
3 Instituto de Radio Astronomía Milimétrica (IRAM), Avenida Divina Pastora, 7, Núcleo Central, 18012 Granada, Spain
Received: 12 June 2014
Accepted: 11 October 2014
The UC-HII region of MWC 349A is the prototype of an ionized wind driven by a massive star surrounded by a disk. Recent high angular resolution observations of the millimeter recombination lines have shown that the disk rotates with a Keplerian law in its outer parts. However, the kinematics of innermost regions in the UC-HII region of MWC 349A is still unknown, in particular, the radius where the wind is launched from the disk. We performed hydrogen recombination line observations with the Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory to study the kinematics of its innermost regions by studying their spectral features. In addition to the two laser peaks, we report the first detection of two new components that are blueshifted with respect to the laser peaks for all the recombination lines with principal quantum number n ≤ 21. These new spectral features originate from the region where the wind is ejected from the disk. We used our 3D non-LTE radiative transfer model for recombination lines (MORELI) to show that these features are consistent with the wind being ejected at a radius of ~24 AU from the star, which supports magnetohydrodynamic wind models.
Key words: stars: massive / masers / HII regions / stars: winds, outflows / accretion, accretion disks
The observed HIFI profiles are available online as FITS files at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/571/L4
Appendix A is available in electronic form at http://www.aanda.org
© ESO, 2014
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