The galactic infrared/submillimeter dust radiation

Summary The unprecedented quality of the IRAS data prompted a series of papers reinvestigating the origin of the galactic infrared/submillimeter radiation and the nature of the heating sources of the interstellar dust. The scope of this paper is to review the main results of these new studies. Sect. 1 contains a general introduction to the subject and an overview of the earlier work. In Sect. 2 and 3, we summarize our current knowledge on dust properties and on the interstellar radiation field. Then, we present the recent interpretations of the infrared emission of our Galaxy, which are based on the IRAS data: in Sect. 4 we present the results from the galactic disk; Sect. 5 covers the question of the contribution from small dust particles, and in Sect. 6 we describe the infrared radiation from the galactic center. The nature of the heating sources and the origin of the galactic infrared radiation is then discussed in Sect. 7. Finally, Sect. 8 presents a comparison of our Galaxy with external galaxies     

攀枝花市大气污染物降水清除机制的研究

本文采用了主成份分析及因子分析的方法,研究了影响降水pH值的主要源及其贡献和这些源被降水清除的机制。分析结果表明:大气中一次污染物是影响降水pH及各种成分浓度的主要因素。人为污染源包括高排放源、低排放源和汽车源,它们的排放物以碱性物质为主;自然污染源包括输送物、腐烂物、自然NOx等,它们的排放物主要是酸性物质;在一般情况下,降水的pH值取决于高、低排放源排放的碱性物质的多寡;降水量越大,清除的污染物越多,在雨季各测点降水平均pH值为6.31～7.10。在高排放源影响小的地方,对持续时间长的大雨,降水后期的pH能反映自然源的影响,其值小于5.60。可见,攀枝花市酸雨几率极低甚至降水呈碱性,     

Rotation and luminosity variations in post-main sequence stars

Previous first-order analytic treatments of rotation acting upon stellar equilibria are extended to include later, post-Helium burning, stages of stellar evolution. Strong differential rotation is capable of substantially increasing the photon luminosities of post-main sequence stars, and thus accelerating their evolution. On the other hand, uniform rotation reduces the photon flux for a wide range of stellar interior types and conditions. Similar conclusions are drawn regarding the effects of rotation on the emission of neutrinos in pre-collapse phases of evolution. A brief discussion of the gravitational radiation emitted during these phases is also given.     

Evidence for Co-Propagation of 4765- and 1720-MHz OH Masers in Star-Forming Regions

Two star-forming regions Cepheus A and W75N, were searched for the 4765-MHz OH maser emission using the multi-element radio linked interferometer network (MERLIN). The excited OH emission has an arc-like structure of 40 mas in Cep A and a linear structure of size 45 mas in W75N. We also found the 1720-MHz line in Cep A and Hutawarakorn [MNRAS 330 (2002) 349] reported the 1720-MHz emission in W75N. The 1720- and 4765-MHz OH spots coincided in space within 60 mas and in velocity within 0.3 km s^–1 in both targets implying that both maser transitions arise from the same region. According to the modelling by Gray [MNRAS 252 (1991) 30] the 1720/4765-MHz co-propagation requires a low density, warm environment. The masers lie at the edges of H II regions where such conditions are expected.     

Comoving frame calculations of spectral lines formed in rapidly expanding media with the partial frequency redistribution function for zero natural line width

Comoving frame calculations have been used to compute the spectral lines formed in rapidly expanding spherical media. We have employed the angle-averaged partial frequency redistribution functionR _I with a two-level atom model in non-LTE atom approximation. A linear velocity law increasing with radius has been employed with maximum velocity at Τ=0 being set equal to 30 mean thermal units. It is found that one obtains almost symmetric emission line profiles at large velocities similar to those found in quasars.     

太阳黑子磁力线随深度扭绞的诊断

本文把我们在文[1]和[2]中建立的诊断方法,应用于美国高山天文台斯托克斯参量仪对1978年12月11日太阳黑子本影和半影取得的Q和U两个参数的轮廓,发现这个黑子的磁力线不呈现较强的扭绞。     

XPer的新发射相：光谱与红外观测

ＸＰｅｒ的新发射相：光谱与红外观测杭恒荣，夏剑萍中国科学院紫金山天文台，南京２１０００８中国科学院光学天文联合实验室关键词Ｂｅ星／Ｘ射线双星，发射线，ＪＨＫ测光１引言ＸＰｅｒ是一颗Ｂｅ／Ｘ射线双星（４Ｕ０３５２＋３０）的光学对应体［１－３］，中子星的...     

Zinc, Lead and Cadmium Content in Meadow Plants and Mosses Along the M3 Motorway (Hungary)

The heavy metal content was investigated in meadow plants located in a cultivated area and situated along the M3 motorway (Hungary). In addition to the meadow plants used as passive bioindicators, active bioindicators were also exposed to examine the accumulation rate of air pollutants. Tortula ruralis (Hedw.) Geartn. ssp. ruralis was applied to monitor the status of the environment. Meadow plant samples were collected at distances of 5, 10, 25, 50 and 100 m from the motorway and moss samples were exposed at the same distances. The zinc, lead and cadmium content of meadow plants and moss samples were analysed by ICP spectrophotometry. It was found that the zinc, lead and cadmium contents of the meadow plants decreased as the distance increased from the motorway. There was a significant difference even between values measured at the distances of 5 m and 10 m. The heavy metal contents in the moss samples exceeded those of the meadow plants. The heavy metal content in moss samples decreased with distance from the motorway. On comparing the data with Hungarian standards, it was found that measured values did not exceed the maximum allowed concentration levels.     

First observations of the Na exosphere of Mercury with the high-resolution spectrograph of the 3.5M Telescopio Nazionale Galileo

Analysis of three spectra of the exosphere of Mercury in the Na-D lines are presented. Spectra were secured with the high-resolution spectrograph (SARG) of the 3.5 M Telescopio Nazionale Galileo (TNG, located on the Roque de los Muchachos, Canaries) on the evenings of August 23 and 24, 2002. Spectra have resolution ; the slit length was 26.7”. The Na column abundances range from 4.3 to with the highest abundances being close to the illuminated limb. Our observations at true anomaly angles (TAA) from 171°to 174°show the traces of the emission lines to be strongly peaked at the illuminated limb, supportive of recent modeling that shows thermal desorption to be a strong factor in determining the distribution of Na about the planet.     

kSZ from patchy reionization: The view from the simulations

We present the first calculation of the kinetic Sunyaev–Zel’dovich (kSZ) effect due to the inhomogeneus reionization of the universe based on detailed large-scale radiative transfer simulations of reionization. The resulting sky power spectra peak at ℓ = 2000–8000 with maximum values of [ℓ(ℓ + 1)C_ℓ/(2π)]_max  4–7 × 10 ⁻¹³. The scale roughly corresponds to the typical ionized bubble sizes observed in our simulations, of 5–20 Mpc. The kSZ anisotropy signal from reionization dominates the primary CMB signal above ℓ = 3000. At large-scales the patchy kSZ signal depends only on the source efficiencies. It is higher when sources are more efficient at producing ionizing photons, since such sources produce larger ionized regions, on average, than less efficient sources. The introduction of sub-grid gas clumping in the radiative transfer simulations produce significantly more power at small-scales, but has little effect at large-scales. The patchy reionization kSZ signal is dominated by the post-reionization signal from fully-ionized gas, but the two contributions are of similar order at scales ℓ  3000 − 10⁴, indicating that the kSZ anisotropies from reionization are an important component of the total kSZ signal at these scales.