MUNA Lunch Talk:

James Chibueze

Kagoshima University (Japan)

Exploration of Massive Star Formation Using Japanese Radio Astronomy Facilities

June 25

12:10PM, Room 230, NRAO, Edgemont Road


Both high resolution very long baseline interferometry (VLBI) studies and large scale mapping observations aid our understanding of how high-mass stars form, and how their strong winds affect their surroundings. We have carried out multi-epoch water (H2O) maser observations carried out with the VLBI Exploration of Radio Astrometry (VERA) toward the HW3d object within the Cepheus A star-forming region. We studied the proper motions of 30 water maser features, tracing a compact bipolar outflow. This outflow is highly collimated with an opening angle of ~30 deg, extending through ~ 400 mas (290 AU), and having a typical proper motion velocity of ~ 21 mas/yr (~ 6 km/s). The dynamical time-scale of the outflow was estimated to be ~ 100 years, showing that the outflow is tracing a very early star-formation phase. The comparative result of the VLA 1.3 cm HW3d continuum emission suggests the possibility of the existence of distinct young stellar objects in HW3d and/or strong variability in one of their radio continuum emission components. VLBI astrometric observations are vital in order to accurately measure the annual parallax and corresponding parallax distance to massive star forming regions, which in turn is necessary for the estimation of the physical parameters around massive stars (for example Gemini OB1).