15 research outputs found
EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions. IV. Magnetic field strength limits and structure for seven additional sources
Magnetohydrodynamical simulations show that the magnetic field can drive molecular outflows during the formation of massive protostars. The best probe to observationally measure both the morphology and the strength of this magnetic field at scales of 10-100 au is maser polarization.
We measure the direction of magnetic fields at milliarcsecond resolution around a sample of massive star-forming regions to determine whether there is a relation between the orientation of the magnetic field and of the outflows. In addition, by estimating the magnetic field strength via the Zeeman splitting measurements, the role of magnetic field in the dynamics of the massive star-forming region is investigated. We selected a flux-limited sample of 31 massive star-forming regions to perform a statistical analysis of the magnetic field properties with respect to the molecular outflows characteristics. We report the linearly and circularly polarized emission of 6.7 GHz CH3OH masers towards seven massive star-forming regions of the total sample with the European VLBI Network. The sources are: G23.44-0.18, G25.83-0.18, G25.71-0.04, G28.31-0.39, G28.83-0.25, G29.96-0.02, and G43.80-0.13. We identified a total of 219 CH3OH maser features, 47 and 2 of which showed linearly and circularly polarized emission, respectively. We measured well-ordered linear polarization vectors around all the massive young stellar objects and Zeeman splitting towards G25.71-0.04 and G28.83-0.25. Thanks to recent theoretical results, we were able to provide lower limits to the magnetic field strength from our Zeeman splitting measurements. We further confirm (based on ∼80% of the total flux-limited sample) that the magnetic field on scales of 10-100 au is preferentially oriented along the outflow axes. The estimated magnetic field strength of |B||| > 61 mG and >21 mG towards G25.71-0.04 and G28.83-0.25, respectively, indicates that it dominates the dynamics of the gas in both regions
Multi-epoch VLBI of a double maser super burst
In a rare and spectacular display, two well-known massive star forming
regions, W49N and G25.65+1.05, recently underwent maser 'super burst' - their
fluxes suddenly increasing above 30,000 and 18,000 Jy, respectively, reaching
several orders of magnitude above their usual values. In quick-response, ToO
observations with the EVN, VLBA and KaVA were obtained constituting a 4 week
campaign - producing a high-cadence multi-epoch VLBI investigation of the maser
emission. The combination of high-resolution, polarisation and flux monitoring
during the burst provides one of the best accounts, to date, of the maser super
burst phenomenon, aiding their use as astrophysical tools. These proceedings
contain the preliminary results of our campaign
Recent updates on the Maser Monitoring Organisation
The Maser Monitoring Organisation (M2O) is a research community of telescope operators, astronomy researchers and maser theoreticians pursuing a joint goal of reaching a deeper understanding of maser emission and exploring its variety of uses as tracers of astrophysical events. These proceedings detail the origin, motivations and current status of the M2O, as was introduced at the 2021 EVN symposium
Astronomy in Thailand
During the last few years, Thailand has seen a significant change in the way as- tronomical research and education is pursued in the country. The government has approved the establishment of the National Astronomical Research Institute of Thailand (NARIT) which aims to develop not only astronomical research but also astronomy education at all levels, both in formal and informal education. A framework of national key projects exists which includes national facilities, national collaborative research networks, teacher training and public outreach programmes. Examples of these programmes will be presented in this paper