近年來, 由於觀測技術的進步, 使得一些較暗的系統得以被觀測到. 1983年, Infrared Astronomical Satellite (IRAS) 的升空, 一些在可見光部分較弱而紅外線部分較強的系統被觀測到, point source 和 faint source. 其中在 faint source 的目錄中尤以交互作用中的星系最感趣, 在這些系統中, 我們知道由於大量的塵埃環繞在一些新形成且較重的星球旁, 這些星球因為較重, 所以能產生核反應的等級越高, 一些比氫或氦的氣體會被燃燒, 使得這類恆星溫度較高, 所以也就能輻射大量的紅外線.
在這篇論文中我們主要探討交互作用對星系或星球形成的關係. 傳統認為橢圓星系是由兩作用中之漩渦星系結合而成, 但這其中有很多不確定因素存在, 例如：在橢圓星系中氣體的含量很少, 然而漩渦狀星系卻包含了大量的氣體, 這些氣體哪裡去了這是一個目前無法得知的一難題; 再者,在兩作用中之漩渦星系中, 恆星形成速率非常高, 常稱之為星暴, 我們不知星暴是和兩作用之星系的距離有關呢? 或是有其他物理因素. 為了這些目的, 我們選擇了22個這類的系統去瞭解重要的物理參數.

In this article, we select 22 interacting galaxies for studying their physical difference and similarities. I organise this article as following parts. Part. I, I describe their optical, near-infrared, and CO(1-0) properties. Part. II, the main point is their properties of 20 cm radio continuum. Part. III, I discusse the typical interacting galaxies, the Antennae, of its
kinematics of molecular clouds in interacting region. And, the descriptions of interacting galaxies are in Part. IV.

Part. I. We have studied optical, near-infrared, and CO properties of the 22 luminous infrared galaxies in a merging sequence. We find no systematic variations of nuclear color, spectral type, equivalance of stellar absorption lines as a

function of nuclear separation. However, we find a weak correlation of the line width and star formation rate as a function of nuclear separation. These results suggest that star formation activity initiates at any moment of tidal interaction with relatively short period of time and this activity can occur recursively since we find no systematic change of starburst age as a function of nuclear separation.

Part. II. Star formation rate ($SFR$), especially in the nucleus region is enhanced by the merging process of two galaxies. The $SFR$ in interacting galaxies with massive bulge would be enhanced by 20-150 times compared to that in the isolated galaxies (Mihos \& Hernquist; 1994, 1996). In order to study $SFR$ in interacting galaxies, we have selected 22 galaxies based on the infrared luminosity. For these galaxies, we have observed CO(1-0) line emission with the $BIMA$ b, c

array and 20 cm radio continuum with the $VLA$ telescope.

We find that there's no clear trends that $SFR$ correlates with the projected nuclear separation. The $SFR$ correlates with the mass of molecular hydrogen but not with the dust temperature.

Part. III. The non-starburst galaxy, the Antennae, is active in the overlap region of two disks. Previous work concluded that the active star formation activity is due to the collision of these two disks. The near-infrared line spectroscopy conflicts with this claim. We conclude that these two molecular clouds are leaving from each other rather than approaching to each

other, therefore there must be other mechanisms for this active star formation activity.

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