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SUMMARY:VLBI Studies of Star Forming Regions using Molecular Masers
DTSTART;VALUE=DATE-TIME:20151202T083500Z
DTEND;VALUE=DATE-TIME:20151202T085500Z
DTSTAMP;VALUE=DATE-TIME:20260414T143524Z
UID:indico-contribution-16@cern.ch
DESCRIPTION:Speakers: Dr. GODDI\, Ciriaco (Radboud University\, Nijmegen\,
  The Netherlands)\nOwing to their compactness and high brightness\, molecu
 lar masers are ideal targets for high-angular resolution VLBI. At cm wavel
 engths\, intense maser transitions\, in particular the 6.7 GHz CH$_3$OH an
 d the 22.2 GHz H$_2$O lines\, are extensively observed in high-mass star f
 orming regions and provide unique diagnostic probes. Multi-epoch VLBI obse
 rvations can provide the 3D kinematics of the circumstellar gas and sensit
 ive polarimetric observations can yield the strength and structure of the 
 magnetic field around forming stars on scales (10-1000 AU) not accessible 
 with other techniques.  At mm wavelengths\, VLBI imaging of masers is larg
 ely unexplored\, with the only exception of SiO transitions (at 43 GHz and
  86 GHz)\, which enabled us to exceptionally resolve the launch and collim
 ation region of an outflow from a compact disk in the closest known high-m
 ass protostar.  Maser transitions from methanol and water have also been d
 etected at mm and submm wavelengths with single-dish telescopes (in the fr
 equency range 80-700 GHz).  Multi-frequency VLBI observations from cm to m
 m wavelengths would be very useful: \nI) to infer the physical conditions 
 from maser line ratios (if they originate from the same gas)\; \nII) to ma
 p out more of the source structure\, dynamics\, and physical conditions (i
 f they probe different portions of the circumstellar gas)\; \nIII) to meas
 ure proper motions with higher accuracy on shorter time baselines at highe
 r frequencies (owing to smaller synthesised beams).   \nProspects of imagi
 ng mm masers with VLBI will be discussed (time permitting).\n\nhttps://eve
 nts.mpifr-bonn.mpg.de/indico/event/4/session/6/contribution/16
LOCATION:Max-Planck-Institut für Radioastronomie\, Bonn\, Germany 0.02
URL:https://events.mpifr-bonn.mpg.de/indico/event/4/session/6/contribution
 /16
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