标题： ISO_CAM中红外光谱学与近红外 photometry 对于LMC中的HII复合体N4的研究 显示英文标题

标题： ISOCAM Mid-infrared spectroscopy and NIR photometry of the HII complex N4 in LMC

摘要： [摘要] 我们展示了对大麦哲伦云中HII区域复合体N4的ISOCAM-CVF和近红外（NIR）测光数据的分析。 目标有两个：1）研究星际物质与该区域恒星成分之间的联系；2）探讨低于银河系金属丰度对尘埃特性的影响。 一种基于数据的尘埃特征-气体线-连续拟合技术，可以生成每个单独发射的图像，并详细分析尘埃和电离气体。 近红外测光首次提供了关于N4恒星成分的信息。 单一尘埃特征带和气体线的图像清楚地表明，HII区域的核心完全缺乏负责芳香特征（AFs）的载体。 另一方面，电离气体几乎完全出现在这个尘埃空腔中，N4的两个主要激发星也位于此处。 我们发现证据表明，低于银河系金属丰度对负责AFs的载体的影响并不是阻止它们形成或改变其化学性质，而是通过强烈的高能星际辐射场增强它们的破坏。 我们显示这种机制在较小的尘埃颗粒/分子上更有效，从而影响尘埃尺寸分布。 我们认为，在分析更遥远且相对较低金属丰度的星系时，应考虑对尘埃尺寸分布的影响，而不是由于较低金属丰度导致的不同尘埃特性。 最后，N4恒星成分的分析揭示了7颗恒星：4颗红化的O型主序星和3颗带有包层的恒星。 特别是其中一颗，似乎是一个包含嵌入式YSO的超紧致HII区。 显示英文摘要

摘要： [Abridged] We present the analysis of ISOCAM-CVF and NIR photometry data of the HII region complex N4 in LMC. The aim is twofold: 1) to study the connection between the ISM and the star content of this region; 2)to investigate the effects of the lower than galactic metallicity on dust properties. A dust features -- gas lines -- continuum fitting technique on the data, allows the production of images in each single emission and the detailed analysis of dust, and ionized gas. The NIR photometry provides, for the first time, information on the stellar content of N4. The images in single dust feature bands and gas lines clearly show that the HII region core is completely devoid of the carriers responsible for the Aromatic Features (AFs). On the other hand, the ionized gas arises almost completely in this dust cavity, where also the two main exciting stars of N4 are located. We find evidences that the effect of lower than Galactic metallicity on the carriers responsible for the AFs, is not to prevent their formation or to modify their chemical properties, but to enhance their destruction by the high and hard ISRF. We show that this mechanism is more efficient on smaller dust particles/molecules thus affecting the dust-size distribution. We argue that effects on dust--size distribution, rather than thedifferent dust properties due to a lower metallicity, should be taken into account when analyzing more distant relatively low metallicity galaxies. Finally, the analysis of the stellar content of N4 reveals 7 stars: 4 reddened O MS stars and 3 stars with envelopes. In particular, one of these, seems to be an Ultra Compact HII region containing an embedded YSO.