Rapidly increasing collimation and magnetic field changes of a protostellar H2O maser outflow
Artikel i vetenskaplig tidskrift, 2014

Context. W75N(B) is a massive star-forming region that contains three radio continuum sources (VLA 1, VLA 2, and VLA 3), which are thought to be three massive young stellar objects at three different evolutionary stages. VLA 1 is the most evolved and VLA 2 the least evolved source. The 22 GHz H2O masers associated with VLA 1 and VLA 2 have been mapped at several epochs over eight years. While the H2O masers in VLA 1 show a persistent linear distribution along a radio jet, those in VLA 2 are distributed around an expanding shell. Furthermore, H2O maser polarimetric measurements revealed magnetic fields aligned with the two structures. Aims. Using new polarimetric observations of H2O masers, we aim to confirm the elliptical expansion of the shell-like structure around VLA 2 and, at the same time, to determine if the magnetic fields around the two sources have changed. Methods. The NRAO Very Long Baseline Array was used to measure the linear polarization and the Zeeman-splitting of the 22 GHz H2O masers towards the massive star-forming region W75N(B). Results. The H2O maser distribution around VLA 1 is unchanged from that previously observed. We made an elliptical fit of the H2O masers around VLA 2. We find that the shell-like structure is still expanding along the direction parallel to the thermal radio jet of VLA 1. While the magnetic field around VLA 1 has not changed in the past similar to 7 years, the magnetic field around VLA 2 has changed its orientation according to the new direction of the major-axis of the shell-like structure and it is now aligned with the magnetic field in VLA 1.

magnetic fields

ISM: individual objects: W75N

masers

stars: formation

polarization

Författare

G. Surcis

Joint Institute for VLBI in Europe (JIVE)

Wouter Vlemmings

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

H. J. van Langevelde

Universiteit Leiden

Joint Institute for VLBI in Europe (JIVE)

C. Goddi

Joint Institute for VLBI in Europe (JIVE)

J. M. Torrelles

CSIC - Instituto de Ciencias del Espacio (ICE)

J. Canto

Universidad Nacional Autonoma de Mexico

S. Curiel

Universidad Nacional Autonoma de Mexico

S. W. Kim

Korea Astronomy and Space Science Institute

J. S. Kim

National Institutes of Natural Sciences - National Astronomical Observatory of Japan

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 565 L8

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/201423877

Mer information

Senast uppdaterat

2018-09-06