标题： 红外天文卫星（IRAS）星系样本中的一氧化碳（CO）、星形成率（HI）和冷尘 显示英文标题

标题： CO, HI and cold dust in a sample of IRAS galaxies

摘要： 使用IRAM 30米、SEST 15米和Nancay射电望远镜，我们获得了两个样本的红外天文卫星（IRAS）星系的1毫米连续辐射、J=1–0的CO线谱以及21厘米HI线谱。利用这些数据，我们估算了HI质量、H$_2$质量和尘埃质量。 我们发现，对于远红外选择的星系：（1）M$_{H2}$/M$_{HI}$的中值为0.5，这意味着这些星系中原子相占主导地位。分子形式气体的比例随着FIR亮度的增加而增加，但与其他星系属性没有明显趋势。（2）H$H2$表面密度（s.d.）与冷尘表面密度的相关性优于HI表面密度，但HI与尘埃的相关性也不可忽略。总体上，在这些星系中，冷尘发射既与分子相相关又与原子相相关。（3）FIR表面亮度随S60um/S100um比值的三次方增加，它与H$_2$和尘埃表面密度有紧密的相关性，与HI表面密度有较弱的相关性：这些星系的大部分远红外发射源自分子介质。（4）气-尘比在100到1000之间变化，平均值为230，接近银河系的值。确实存在一个明显的趋势：这个比例随着FIR表面密度的增加而减小，这一结果可以用星系盘中金属丰度因更高的恒星形成率而增强来解释。 显示英文摘要

摘要： Using IRAM 30m, SEST 15m, and Nancay radiotelescopes, we have gathered the 1mm continuum emission, spectra of the J=1--0 CO line and of the HI line at 21cm for two samples of IRAS galaxies. Using these data, we have estimated the HI masses, the H$_2$ masses and the dust masses. We find that for far-infrared selected galaxies: (1) the median value of M$_{H2}$/M$_{HI}$ is 0.5, meaning that the atomic phase dominates in these galaxies. The fraction of gas in molecular form increases with increasing FIR luminosity but does not show any obvious trend with other galaxy properties. (2) the $H2$ surface density (s.d.) is better correlated with the cold dust s.d. than the HI s.d., but the correlation of HI with dust is not negligible. Globally in these galaxies the cold dust emission is associated with both the molecular and atomic phases. (3) the FIR surface brightness increases as the third power of the S60um/S100um ratio, it shows a tight correlation with both the H$_2$ and dust surface densities and a weaker one with the HI surface density: a large part of the far-infrared emission of these galaxies originates in the molecular medium. (4) the gas-to-dust ratio ranges between 100 and 1000 and its average value is 230, close to the Galactic value. There is indeed a clear trend: this ratio decreases as the FIR surface density increases, a result which can be explained in the framework of an enhancement of metallicity in galaxy discs having a higher star formation rate.