摘要
最近十几年来,银河系已被确认为是一个棒旋星系,而不是无棒结构的普通旋涡星系。人们利用各类示踪源,如气体的(l,v)图、红外面测光、红团簇星、恒星计数、微引力透镜效应、恒星运动学等,来探测银河系内区的棒结构和它的结构参数,该文对此做了简要评述.
The presence of a large scale bar in the inner Galaxy has been well established by various tracers since 1990s, such as near infrared radiation （NIR） light, red clump giants, AGB stars and IRAS sources, and by different methods, such as kinematics of Galactic Center gas, bulge surface brightness, NIR star counts and kinematics of stars. Therefore, our Milky Way should be morphologically catalogued as a barred spiral galaxy instead of a normal spiral one. In earlier years the（l, v） diagrams of the 21cm emission of neutral hydrogen and/or the 2.6 mm emission of CO were used to detect the bar-like structure in the inner Galaxy. Based on the noncircular radial motions seen in the HI in the inner suggested the Galaxy is likely to be a barred spiral region of our Galaxy, de Because of the presence the（l, v） diagram in the inner Galaxy differs remarkably from what it would be on circular orbits in an axisymmetric potential. Vaucouleurs first of a triaxial bar, if the gas was all All-sky surveys in the infrared bands are powerful tools for exploring the structure at the Galactic center since the dust absorption is greatly reduced in the IR. In 1991, the first direct evidence for a triaxial stellar bar at the galactic center was detected in the 2.4μm. Since the bar is oriented obliquely to the Sun-Galactic center line, for stars at the closer end of the bar their heliocentric distances should be smaller relatively to stars at the farther end, and hence their surface brightness should be relatively brighter. In this respect, the low angular resolution maps of the Galactic bulge at infrared bands obtained by COBE have provided very useful observational data. The bulge red clump stars can be used as quite good tracers to investigate the barlike structure in the inner Galaxy, From the distribution in the CM diagram of red clump stars and stellar evolution theory it is expected that these stars are relatively bright and have a narrow luminosity distribution, so they can be adopted as a standard candle to estima
出处
《天文学进展》
CSCD
北大核心
2009年第2期116-128,共13页
Progress In Astronomy
基金
国家自然科学基金资助项目(10778003
10773020)
关键词
银河系
旋涡星系
棒旋星系
棒结构
核球
Milky Way Galaxy
spiral
barred spiral
barlike structure
bulge
