Dust from Comet 209P/LINEAR during its 2014 Return: Parent Body of a New Meteor Shower, the May Camelopardalids

We report a new observation of the Jupiter-family comet 209P/LINEAR during its 2014 return. The comet is recognized as a dust source of a new meteor shower, the May Camelopardalids. 209P/LINEAR was apparently inactive at a heliocentric distance rh = 1.6 au and showed weak activity at rh < 1.4 au. We found an active region of <0.001% of the entire nuclear surface during the comet's dormant phase. An edge-on image suggests that particles up to 1 cm in size (with an uncertainty of factor 3-5) were ejected following a differential power-law size distribution with index q=-3.25+-0.10. We derived a mass loss rate of 2-10 kg/s during the active phase and a total mass of ~5x10^7 kg during the 2014 return. The ejection terminal velocity of millimeter- to centimeter-sized particles was 1-4 m/s, which is comparable to the escape velocity from the nucleus (1.4 m/s). These results imply that such large meteoric particles marginally escaped from the highly dormant comet nucleus via the gas drag force only within a few months of the perihelion passage.Comment: 18 pages, 4 figures, accepted on 2014 December 11 for publication in the Astrophysical Journal Letter

Improved Method for Transient Stability with Dynamic Unbalanced Condition

The symmetric coordinates are very popular method to model unbalanced faults in power system analysis. It is not only easy to handle with a single fault, but also it can be extended to multiple faults. But it is not easy to handle with situations whose unbalanced situations change continuously, like a SVC (Static Var Compensator) with unbalanced fault in power system or an unbalanced nonlinear load. Though, we had proposed a simulation method that can handle with these unbalanced and dynamic situations, it needs to handle with complex unbalanced faults. Under these situations, we will propose more efficient method