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> ==>發信人: Morbert.bbs@ptt.cc (), 信區: Astronomy
> from:   1999 ApJ, 525C, p.735
> title:  GALACTIC STRUCTURE AND THE STELLAR LUMINOSITY FUNCTION
> author: MAARTEN SCHMIDT
> ....(略)
> McCuskey's study was to be the last largescale survey based on star counts
> in the galactic plane carried out in this century.
> Almost all subsequent work on star counts was directed at intermediate or
> high galactic latitudes to avoid the strong interstellar absorption in the
> galactic plane.
> ....(略)
> 想請教，
>  2. "to avoid the strong interstellar absorption" 這句話是什麼意思呢？
      避免強烈的星際物質吸收

      因為越靠近銀河盤面 (低銀緯), 星際物質越多.  而星際物質越多, 
      造成的消光就越嚴重, 這將會導致在銀河盤面較暗的星體無法被觀測
      到. 

      星際消光對可見光觀測的影響很大, 一些濃密的分子雲可以消光好幾
      個星等, 近紅外的的觀測結果 (例如2MASS) 會有助於解決這個問題 
      或許你可以參考一下 http://www.ipac.caltech.edu/2mass/

      

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