EVN observations of 6.7 GHz methanol masers from Medicina survey

Abstract

We report VLBI observations of methanol masers in the brightest 5(1)-6(0) A+ transition at 6.7 GHz in NGC 281W, 18151-1208 and 19388+2357. Using the fringe rate method absolute positions were obtained for all observed sources. A linear ordered structure with a velocity gradient was revealed in NGC 281W. Under assumption that such structure is an edge-on Keplerian disk around the central object with a mass of 30Msun located at a distance of 3.5 kpc from the Sun, we estimated that methanol masers are situated at the distance about 400 a.u. from the center of the disk. A second epoch of observations was reported for L1206, GL2789 and 20062+3550. The upper limits on the relative motions of maser spots are estimated to be 4.7 km/s and 28 km/s for L1206 and GL2789 respectively.