Ion Tail Disturbance of Comet C/Hyakutake 1996B2 Observed around the Closest Approach to the Earth

[摘要] AsequentialimagingobservationoftheiontailofCometC/Hyakutake1996B2wascarriedouton1996March25withawide-fieldCCDimagingcameradevelopedattheNationalAstronomicalObservatoryofJapan.Wedetectedapeculiarknotrecedingalongthemainaxisoftheiontailduringourobservation.Thisknotwaslocatedat5.0×106kmfromthenucleusonMarch25.6UT,andmovedabout2.0×106kmduring5hr.Themeasuredvelocityalongtheaxisoftheiontailwasderivedtobe99.2±0.3kms−1,whichisalmostconstantwithintheobservationallimit.Wealsomeasuredtheperpendicularmotionofthisknottotheaxis,andidentifiedrapidacceleration.Thebrightnessoftheknotdecreasedduringtheobservation.Wereportonpreliminaryresultsofananalysisofthisphenomenon,anddiscusssomecharacteristicsinthispaper.

[学科分类] 天文学(综合)

[关键词] "Comets: individual (Comet C/Hyakutake 1996B2)";"Interplanetary medium";"Magnetic field";Plasmas