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碩博班專題討論(Colloquium)

Electron and magnetic turbulence fluctuations in the interstellar medium measured by scintillations of pulsar radio waves and in-situ Voyagers 1 & 2 observations

演講者 : 李羅權 院士 (中央研究院地球科學研究所)
演講時間 : 2021 / 09 / 24 14:10
線上+ 實體: 理學教學新大樓1F 36102教室
線上演講網址:https://youtu.be/sTtuTTkbfVo
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The electron density power spectrum with scales of 50m to 15au (2´1012m) in the local interstellar medium is obtained from in situ observations of Voyager 1. By combining the in situ data with the earlier ground remote observations, we now have the turbulent spectrum extending from 50m to 100 light-years, over 16 orders of magnitude.
In 1941, Kolmogorov proposed the first hydrodynamic turbulent model for the fluid and gave the well-known power law index, -11/3, of energy spectrum. In 1976, Lee and Jokipii first suggested that the interstellar turbulence at the length scale λ of 108m to 1018m (100 light-years) also has a Kolmogorov-like spectrum based on observations of radio wave scintillations and interstellar clouds. Armstrong et al. (1995) constructed the composite spectrum extending from 106m to 1018m based on ground telescope observational results. In 1977, two satellites named Voyager 1 & 2 were launched. Voyager 1 (2) entered the local interstellar medium in 2012 (2018). Kun-Han Lee and Lou Lee (2019) uses the data from in situ measurements to determine the spectrum of the turbulent density fluctuations from 50m to 2´1012m (15 au) in the local interstellar medium. By combining the in situ measured spectrum and the earlier remote observed data, they obtain a composite spectrum, the Grand Power Law in the Milky Way, extending from 50m to 1018m (100 light-years), over 16 orders of magnitude in length scale.