In dense molecular clouds the grains become the main charged particles.When the hydrogen gas density reaches as high as nH=10^(11)cm^(-3) and the grains are assumed to be small polycyclic aromatic hydrocarbons(PAHs),t...In dense molecular clouds the grains become the main charged particles.When the hydrogen gas density reaches as high as nH=10^(11)cm^(-3) and the grains are assumed to be small polycyclic aromatic hydrocarbons(PAHs),the lower hybrid drift instability develops,leading to the creation of anomalous electric conductivity,which makes the magnetic Reynold's number of the system R_(M)~1 indicating the dissipation of magnetic fields.When the gas density continues to go up and over10^(11)cm_(-3),the collision frequency between PAHs and gas particles becomes larger than the plasma frequency,resulting in the collision process being dominant.In that case the magnetic field also dissipates because R_(M)~1 is still kept.展开更多
Massive stars often tend to be in cluster when they form in molecular clouds,and bipolar molecular outflows occur during the forming process of stars.On the basis of newly observed bipolar molecular outflows associate...Massive stars often tend to be in cluster when they form in molecular clouds,and bipolar molecular outflows occur during the forming process of stars.On the basis of newly observed bipolar molecular outflows associated with massive stars,three properties are proposed to statistically identify massive stars whether in cluster or not as the driving engines of the flows.For clustering massive stars with some exceptions,their outflow collimation factors are generally poor and less than two,and the correlations of the flow momentum rate and the mass flow rate with the central source bolometric luminosity deviate the ones for selected well-resolved 16 flows.展开更多
We develop a model to explain the high velocities of the ionized stellar winds around young stellar objects associated with magnetic fields.The plasma which is produced by the hot object nearby is turbulent and plays ...We develop a model to explain the high velocities of the ionized stellar winds around young stellar objects associated with magnetic fields.The plasma which is produced by the hot object nearby is turbulent and plays a significant role to accelerate particles.Then the high velocity winds encounter the ambient gas in a molecular cloud to form shock waves.The shocked gas emmision produces broad wings of CO line profiles.展开更多
文摘In dense molecular clouds the grains become the main charged particles.When the hydrogen gas density reaches as high as nH=10^(11)cm^(-3) and the grains are assumed to be small polycyclic aromatic hydrocarbons(PAHs),the lower hybrid drift instability develops,leading to the creation of anomalous electric conductivity,which makes the magnetic Reynold's number of the system R_(M)~1 indicating the dissipation of magnetic fields.When the gas density continues to go up and over10^(11)cm_(-3),the collision frequency between PAHs and gas particles becomes larger than the plasma frequency,resulting in the collision process being dominant.In that case the magnetic field also dissipates because R_(M)~1 is still kept.
文摘Massive stars often tend to be in cluster when they form in molecular clouds,and bipolar molecular outflows occur during the forming process of stars.On the basis of newly observed bipolar molecular outflows associated with massive stars,three properties are proposed to statistically identify massive stars whether in cluster or not as the driving engines of the flows.For clustering massive stars with some exceptions,their outflow collimation factors are generally poor and less than two,and the correlations of the flow momentum rate and the mass flow rate with the central source bolometric luminosity deviate the ones for selected well-resolved 16 flows.
文摘We develop a model to explain the high velocities of the ionized stellar winds around young stellar objects associated with magnetic fields.The plasma which is produced by the hot object nearby is turbulent and plays a significant role to accelerate particles.Then the high velocity winds encounter the ambient gas in a molecular cloud to form shock waves.The shocked gas emmision produces broad wings of CO line profiles.
