Universität zu Köln

Beltran, M. T., Cesaroni, R., Moscadelli, L., Sanchez-Monge, A., Hirota, T. and Kumar, M. S. N. (2016). Binary system and jet precession and expansion in G35.20-0.74N. Astron. Astrophys., 593. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

Full text not available from this repository.

Abstract

Context. Atacama Large Millimeter/submillimeter Array ( ALMA) observations of the high-mass star-forming region G35.20-0.74N have revealed the presence of a Keplerian disk in core B rotating about a massive object of 18 M-circle dot, as computed from the velocity field. The luminosity of such a massive star would be comparable to (or higher than) the luminosity of the whole star-forming region. To solve this problem it has been proposed that core B could harbor a binary system. This could also explain the possible precession of the radio jet associated with this core, which has been suggested by its S-shaped morphology. Aims. We establish the origin of the free-free emission from core B and investigate the existence of a binary system at the center of this massive core and the possible precession of the radio jet. Methods. We carried out VLA continuum observations of G35.20-0.74N at 2 cm in the B configuration and at 1.3 cm and 7 mm in the A and B configurations. The bandwidth at 7 mm covers the CH3OH maser line at 44.069 GHz. Continuum images at 6 and 3.6 cm in the A configuration were obtained from the VLA archive. We also carried out VERA observations of the H2O maser line at 22.235 GHz. Results. The observations have revealed the presence of a binary system of UC/HC HII regions at the geometrical center of the radio jet in G35.20-0.74N. This binary system, which is associated with a Keplerian rotating disk, consists of two B-type stars of 11 and 6 M-circle dot. The S-shaped morphology of the radio jet has been successfully explained as being due to precession produced by the binary system. The analysis of the precession of the radio jet has allowed us to better interpret the IR emission in the region, which would be not tracing a wide-angle cavity open by a single outflow with a position angle of similar to 55 degrees, but two different flows: a precessing one in the NE-SW direction associated with the radio jet, and a second one in an almost E-W direction. Comparison of the radio jet images obtained at different epochs suggests that the jet is expanding at a maximum speed on the plane of the sky of 300 km s(1). The proper motions of the H2O maser spots measured in the region also indicate expansion in a direction similar to that of the radio jet. Conclusions. We have revealed a binary system of high-mass young stellar objects embedded in the rotating disk in G35.20-0.74N. The presence of a massive binary system is in agreement with the theoretical predictions of high-mass star formation, according to which the gravitational instabilities during the collapse would produce the fragmentation of the disk and the formation of such a system. For the first time, we have detected a high-mass young star associated with an UC/HC HII region and at the same time powering a radio jet.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Beltran, M. T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cesaroni, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Moscadelli, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sanchez-Monge, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hirota, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kumar, M. S. N. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-263552
DOI:	10.1051/0004-6361/201628588
Journal or Publication Title:	Astron. Astrophys.
Volume:	593
Date:	2016
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language YOUNG STELLAR OBJECTS; STAR-FORMING REGIONS; I METHANOL MASERS; MASSIVE PROTOSTAR; PROPER MOTIONS; TRIGONOMETRIC PARALLAXES; COLLIMATED OUTFLOWS; CONTINUUM EMISSION; SPECTRAL INDEXES; IRAS 20126+4104 Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/26355