星周天體物理

星周天體物理屬於天體物理學科名詞。它廣泛存在於許多天體物理環境中，其特性隨環境而變化。

矽酸鹽塵粒是宇宙塵埃的主要成分之一，它廣泛存在於許多天體物理環境中，其特性隨環境而變化。由於近年來觀測數據的不斷增加和紅外光譜質量的逐步提高，宇宙空間中的矽酸鹽塵粒正受到越來越多的關注。該文詳細地介紹了在各種天體環境（星際空間、演化晚期恆星的星周塵埃包層、繞年輕恆星和主序星的星周塵埃盤、彗星的彗發和行星際空間）中的矽酸鹽塵粒的觀測特徵，並分別對其物理和化學性質進行了綜合比較。觀測已經證實在星際塵埃演化的前身（演化晚期恆星的星周塵埃包層）和其遺蹟（彗星）均有可觀數量的結晶矽酸鹽存在，但是至今還沒有在其中間態（彌散星際介質）找到結晶矽酸鹽存在的證據。這一尚未解決的難題突出了結晶態矽酸鹽在天體物理研究中的重要意義。
Silicategrains,oneofthemajorcosmicdustspecies,areubiquitouslyseeninvariousastronomicalenvironmentsthroughtheirvibrationalabsorptionoremissionhands:Si-Ostretchingatabout9.7μmandO-Si-Obendingatabout18μm.Theirphysicalandchemicalpropertiesvarywithlocalenvironments,asrevealedthroughthevariationsinthespectralshapes,relativeintensities,andpeakwavelengthsofthesilicatebands,bothamorphousandcrystalline.Withtheadventofbothground-basedandspace-borneinfraredtelescopesandtherapidaccumulationofhigh-qualityobservationaldata,astronomicalsilicateshavebeenreceivingmuchattentioninrecentyears.Inthisreview,wesummarizetheobservationalcharacteristicsofsilicategrainsintheinterstellarmedium,dusttorusaroundActiveGalacticNuclei,protoplanetarydustdisksaroundpre-mainsequencestars,debrisdisksaroundmainsequencestars,circumstellarenvelopesaroundevolvedstars,cometarycoma,andinterplanetaryspace.Theirphysicalandchemicalpropertiesindifferentastronomicalregionsarestudiedonacomparisonbasis,withspecialattentionpaidtocrystallinesilicates:whereascrystallinityisprevalentatthebeginning(i.e.circumstellarenvelopesaroundevolvedstars)andend(i.e.cometarydust)ofdustgrains'lifecycle,nocrystallinityisfoundintheintermediatephase(i.e.,inthediffuseinterstellarmedium).Theastrophysicalimplicationsofthepresenceandabsenceofcrystallinesilicatesincertainastrophysicalregionsarediscussed.