Star dust

Infrared astronomy has shown that certain classes of stars are abundant producers of refractory grains, which condense in their atmospheres and are blown into interstellar space by the radiation pressure of these stars. Metallic silicates of the kind that produce terrestrial planets are injected by the oxygen-rich stars and carbon and its refractories by carbon stars. Much of the interstellar dust may be produced by this mechanism. A number of "infrared stars" are completely surrounded by their own dust, and a few of these exhibit a unique morphology that suggests the formation of a planetary system or a stage in the evolution of a planetary nebula. Certain novae also condense grains, which are blown out in their shells. In our own solar system, comets are found to contain the same silicates that are present elsewhere in the galaxy, suggesting that these constituents were present in the primeval solar nebula.     

星天牛的防治试验研究

星天牛在我国分布较广泛,能危害多种林木,近年来在椒江市木麻黄防护林中发生较严重,主要以幼虫钻蛀木质部,形成弯曲的蛀道,被害木轻则生长衰弱,重则易造成风折、风倒或整株枯死。此虫在椒江1年发生1代,以幼虫在木质部中越冬。对它有效的防治方法主要是:人工捕捉成虫;击杀卵和初龄幼虫;喷洒25％菊乐合酯或40％SN-851乳油1500倍液杀卵和小幼虫,用80％敌敌畏、90％敌百虫或40％SN-851乳油2000倍液,也可用20％杀灭菊酯、2.5％溴氰菊酯乳油2500倍液,将上述药液注入通气孔可收到90％的防治效果,用百部的块根堵塞通气孔,可获得87％左右的防治效果。     

Star formation in irregular galaxies

Irregular galaxies can be viewed as laboratories for studying the processes of star formation. This class of galaxy, unlike the more familiar spiral galaxies, forms stars without spiral arms and does so from a chemically less-evolved interstellar medium. In this article the problems associated with star formation in irregular galaxies are outlined and their relevance to our understanding of star formaton as a general astrophysical process is discussed.     

八角茴香的加工及开发利用

八角茴香在食品调味料中占据着及其重要的地位,该文从原基物料八角、八角茴香加工制作方法、等级规格、化学成分、提取芳香油种类用途、呈香物质、药用作用等几方面对八角茴香进行综述.     

Star formation around supermassive black holes

The presence of young massive stars orbiting on eccentric rings within a few tenths of a parsec of the supermassive black hole in the galactic center is challenging for theories of star formation. The high tidal shear from the black hole should tear apart the molecular clouds that form stars elsewhere in the Galaxy, and transport of stars to the galactic center also appears unlikely during their lifetimes. We conducted numerical simulations of the infall of a giant molecular cloud that interacts with the black hole. The transfer of energy during closest approach allows part of the cloud to become bound to the black hole, forming an eccentric disk that quickly fragments to form stars. Compressional heating due to the black hole raises the temperature of the gas up to several hundred to several thousand kelvin, ensuring that the fragmentation produces relatively high stellar masses. These stars retain the eccentricity of the disk and, for a sufficiently massive initial cloud, produce an extremely top-heavy distribution of stellar masses. This potentially repetitive process may explain the presence of multiple eccentric rings of young stars in the presence of a supermassive black hole.     

中子星性质的模型依赖性

采用相对论平均场理论(RMFT)下的GL85,GL92,TM1和TM2等核物质参数组,研究了这些参数组对中子星的粒子数密度分布、状态方程及质量-半径关系的影响.结果表明,在不同的参数组下,超子出现的密度、顺序和种类均不同;状态方程的软硬情况也较大不同;中子星的引力质量和相应的半径有明显不同.计算结果也表明,采用GL85,TM1和TM2等参数组得到的中子星质量和半径均在脉冲星的观测数据范围内,而采用GL92参数组得到的中子星质量小于中子星质量下限1.4M⊙(M⊙=1.99×1030kg为太阳质量).     

一品红品种彼得之星的叶片培养技术研究

“彼得之星”是近几年从国外引进的矮生一品红品种，其植株紧凑，分枝强，平均每株花头达5－7朵，并且植株矮化，一般高度在30cm左右，因其叶片碧绿干净、苞片大而色彩沈重，故近年来在国内市场上前景看好。但该品种利用常规扦插法繁殖系数低，而利用茎尖组织培养技术繁殖时由于自然矮化而可供组培的茎尖少，为此我们进行了该品种的叶片组织培养技术研究。