We report on the results of ^(12)CO (1-0) emission associated with H2O masers and massive star formation regions to identify high-velocity H2O masers. Several masers have a large blueshift, even up to 120km·s^(-1...We report on the results of ^(12)CO (1-0) emission associated with H2O masers and massive star formation regions to identify high-velocity H2O masers. Several masers have a large blueshift, even up to 120km·s^(-1), with respect to the CO peak, but no large redshifted maser appears. This result suggests that high-velocity H_(2)O masers can most probably occur in high mass star-forming regions and quite a number of masers stem from the amplifications of a background source, which may enable those undetectable weak masers to come to an observable level.展开更多
The water maser emission from the unusual supergiant,VY CMa,has been observed with the Urumqi 25 m radio telescope.A simple red-shifted maser spectrum was detected in the 1.6 Jy noise level during our monitoring obser...The water maser emission from the unusual supergiant,VY CMa,has been observed with the Urumqi 25 m radio telescope.A simple red-shifted maser spectrum was detected in the 1.6 Jy noise level during our monitoring observations.All of the H2O maser features are red-shifted with respect to the VY CMa stellar velocity of 17.6 km.s-1.The spectrum appears to be consisted of two striking like groups and each group has three features.The appearances and the ratio of these three features in the two maser groups are very similar.The H2O maser emission arises from a region close to the supergiant,about 10 stellar radii of the star.The simple red-shifted spectrum could be due to infall masing gas on the near side of the disk.Pulsation of the central star causes oscillations in this portion of the envelope,with shock wave propagating outward and with material falling inward.The masing gas motions are very complex,by which the dramatic changes or the quasi-sinusoidal fluctuation in flux may be explained.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.19973017。
文摘We report on the results of ^(12)CO (1-0) emission associated with H2O masers and massive star formation regions to identify high-velocity H2O masers. Several masers have a large blueshift, even up to 120km·s^(-1), with respect to the CO peak, but no large redshifted maser appears. This result suggests that high-velocity H_(2)O masers can most probably occur in high mass star-forming regions and quite a number of masers stem from the amplifications of a background source, which may enable those undetectable weak masers to come to an observable level.
基金Supported by the National Natural Science Foundation of China under Grant No.10073004.
文摘The water maser emission from the unusual supergiant,VY CMa,has been observed with the Urumqi 25 m radio telescope.A simple red-shifted maser spectrum was detected in the 1.6 Jy noise level during our monitoring observations.All of the H2O maser features are red-shifted with respect to the VY CMa stellar velocity of 17.6 km.s-1.The spectrum appears to be consisted of two striking like groups and each group has three features.The appearances and the ratio of these three features in the two maser groups are very similar.The H2O maser emission arises from a region close to the supergiant,about 10 stellar radii of the star.The simple red-shifted spectrum could be due to infall masing gas on the near side of the disk.Pulsation of the central star causes oscillations in this portion of the envelope,with shock wave propagating outward and with material falling inward.The masing gas motions are very complex,by which the dramatic changes or the quasi-sinusoidal fluctuation in flux may be explained.
