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#contents ** No. 323: April 26 (Thu), 2018, 15:30 - 16:30 [#vcd09466] *** 講師: 福島登志夫（国立天文台） [#b0e9a86c] *** 題目: 自然科学における温故知新のすすめ [#sfcf2590] 要旨: 「温故知新」は孔子の初学者に対する助言である。新しき学問や研究を 企てる際に重要なこの姿勢は自然科学においても有効な処方箋である と思われる。にもかかわらず、理系の研究現場において重要視される ことは少なく、、むしろ「今を温（たず）ねて新しきを知る」ことが尊ばれる。 しかし、現実は、そう単純ではない。「故（ふる）きを温（たず）ねなかった」 ばかりに「世紀の大発見」の登場が１６０年遅れた事例が実際にある。 １９６５年に発表された高速フーリエ変換(Fast Fourier Transform通称 FFT)は２０世紀で最も偉大な工学上の発見とまで称えられたが、実は １８０５年にガウスが考案していたことが現在では知られている。他にも、 ニュートンのプリンキピアには人工衛星の着想が描かれていたとか、 ラプラスはブラックホールの半径を計算していたとか、この種のエピソード は枚挙にいとまがない。どうすれば「車輪の再発明」のような愚行を避ける ことができるのであろうか。それには、故（ふる）きを温（たず）ねて、 温（たず）ねて、温（たず）ね抜くしかない。幸い、Googleに代表される 高速検索技法やProject Gutenbergに代表される無料電子図書館の 発展により、事態は改善されつつある。ただ文献量の一方的な増大に どのように対処するかは今後の課題であり、このままでは学問の最前線に たどり着くまでに一生を費やしかねない。我々にはＡＩの進展に望みを つなぐほか道はないのであろうか。 *** Speaker: Toshio FUKUSHIMA (NAOJ) [#s4001340] *** Title: Study Old and Find New [#nf7a2c82] Abstract: "Study Old and Find New" is a Confucian advice to beginners. Although it is a general principle, this motto is not so advocated in natural sciences. Rather, we are told to "Study Now and Find New." However, the reality is not so simple. Indeed, there exists an educative specimen that a great discovery was delayed to be popularized because nobody did study old. The well-known FFT (Fast Fourier Transform) was said to be invented by Cooley and Tukey in 1965. Nevertheless, Gauss did propose the exact same method in 1805. An older example is Newton's cannon ball depicted in Vol. 3 of PRINCIPIA, which is nothing but the artificial satellites. Also, Laplace estimated an upper bound of Sun's density by using the fact that its escape velocity is less than the speed of light. This means that the Sun is never a black hole, which the general theory of relativity was said to have discovered. Then, how can we avoid such a re-invention of the existing but not popular idea? The only solution may be to "Study Old, Study Old, and Study Old". Fortunately, the development of searching engines as the Google and the spread of free electronic library systems like the Project Gutenberg seem to have improved the situation. Having said so, we must admit that remained is a big issue: exponentially increasing literature. It might mean that the whole lifetime of a researcher is spent before reaching the cutting-edge. Is there any other way to resolve this problem than relying on the advancement of the Artificial Intelligence? ** No. 324: 14 May, 2018 (Mon) 15:30 - 16:30 [#f4e17407] *** Speaker: Susanne Aalto (Chalmers University of Technology) [#e6efcf83] *** Title: Hidden outflows and obscured nuclei in Luminous Infrared Galaxies - Starbursts or AGNs? [#r4c6c640] Abstract: Cold gas plays a central role in feeding and regulating star formation and growth of supermassive black holes (SMBH) in galaxy nuclei. Particularly powerful activity occurs when interactions of gas-rich galaxies funnel large amounts of gas and dust into nuclei of luminous and ultra luminous infrared galaxies (LIRGs/ULIRGs). These dusty objects are of key importance to galaxy mass assembly over cosmic time. It is also increasingly clear that feedback from star formation and AGNs is fundamental to regulating the evolution of galaxies in the nearby Universe as well as at earlier epochs. Mechanical feedback occurs in the form of winds (stellar, AGN, galactic), turbulence, supernova bubbles and superbubbles, AGN jets and backflows. With the advent of ALMA and the NOEMA telescopes we can now study the extent, morphology, velocity structure, physical conditions and even chemistry of these cold flows at unprecedented sensitivity and resolution. I will focus on recent ALMA and NOEMA studies of AGN and starburst outflows from dusty galaxies. I will for example present recent ALMA studies with resolutions of 20-30 milli arcseconds (2 – 7 pc) of the dusty cores and molecular outflows and jets in the nearby LIRGs NGC1377 and IC860. The relation between collimated molecular flows and nuclear growth will be discussed. Recent developments on the physical and chemical conditions in outflow will be presented. How can we connect the properties of the outflowing gas to the nature of the driving source and the origin of the outflowing gas? I will also show how one can use the JVLA telescope for high-resolution molecular observations of nuclear outflows. ** No. 325: 16 May, 2018 (Wed) 15:30 - 16:30 [#jcaf5cc2] *** Speaker: Shuta J. Tanaka (Aoyama Gakuin University) [#t926462f] *** Title: Blocking Metal Accretion onto Population III Stars by Stellar Wind [#q6c9a3a4] Abstract: Recent studies of the formation of first stars (PopIII stars) show that low-mass PopIII stars could be formed via the fragmentation of the circumstellar disk around the primary proto-first-stars, although the initial mass function (IMF) of PopIII stars are considered to be top-heavy compared with the IMF of the present stars. Because low-mass PopIII stars of < 0.8 M could survive up until the present, the non-detection of them in our Galaxy has already put a stringent constraint on the IMF of PopIII. On the other hand, some claim that the lack of such stars stems from the metal enrichment of their surfaces by the accretion of heavy elements from the interstellar medium (ISM). In this study, we investigated the effects of the stellar wind on metal accretion onto low-mass PopIII stars because accretion of the local ISM onto the Sun is prevented by the solar wind, even for neutrals. We found that the stellar wind and radiation block the metal accretion if the wind has the similar power to that of the Sun. This demonstrates that low-mass PopIII stars remain pristine and will be found as metal-free stars and that further searches for them are valuable in constraining the IMF of PopIII stars. Language: English
